Metal-insulator crossover in superconducting cuprates in strong magnetic fields

International Nuclear Information System (INIS)

Marchetti, P.A.; Su Zhaobin; Yu Lu

2001-02-01

The metal-insulator crossover of the in-plane resistivity upon temperature decrease, recently observed in several classes of cuprate superconductors, when a strong magnetic field suppresses the superconductivity, is explained using the U(1)xSU(2) Chern-Simons gauge field theory. The origin of this crossover is the same as that for a similar phenomenon observed in heavily underdoped cuprates without magnetic field. It is due to the interplay between the diffusive motion of the charge carriers and the 'peculiar' localization effect due to short-range antiferromagnetic order. We also calculate the in-plane transverse magnetoresistance which is in a fairly good agreement with available experimental data. (author)

Phenomenological Theory for Pseudogap States in High Tc Cuprate

Directory of Open Access Journals (Sweden)

Zhang Fuchun

2012-03-01

Full Text Available Pseudogap phase in the underdoped region of high-Tc cuprate is one of the challenging issues in condensed matter physics. In this talk, I will describe a phenomenological theory for this phase, based on analogies to the approach to Mott localization at weak coupling in lower dimensional systems. I will make comparisons of the theory to a series of the experiments, including angle resolved photoemission spectroscope, scanning tunneling microscope.

NMR studies of spin dynamics in cuprates

International Nuclear Information System (INIS)

Takigawa, M.; Mitzi, D.B.

1994-01-01

The authors report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi 2.1 Sr 1.94 Ca 0.88 Cu 2.07 O 8+σ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa 2 Cu 3 O 6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector

NMR studies of spin dynamics in cuprates

Science.gov (United States)

Takigawa, M.; Mitzi, D. B.

1994-04-01

We report recent NMR results in cuprates. The oxygen Knight shift and the Cu nuclear spin-lattice relaxation rate in Bi2.1Sr1.94Ca0.88Cu2.07O8+δ single crystals revealed a gapless superconducting state, which can be most naturally explained by a d-wave pairing state and the intrinsic disorder in this material. The Cu nuclear spin-spin relaxation rate in underdoped YBa2Cu3O6.63 shows distinct temperature dependence from the spin-lattice relaxation rate, providing direct evidence for a pseudo spin-gap near the antiferromagnetic wave vector.

Annealing Effects on the Normal-State Resistive Properties of Underdoped Cuprates

Science.gov (United States)

Vovk, R. V.; Khadzhai, G. Ya.; Nazyrov, Z. F.; Kamchatnaya, S. N.; Feher, A.; Dobrovolskiy, O. V.

2018-05-01

The influence of room-temperature annealing on the parameters of the basal-plane electrical resistance of underdoped YBa_2Cu_3O_{7-δ } and HoBa_2Cu_3O_{7-δ } single crystals in the normal and superconducting states is investigated. The form of the derivatives dρ (T)/dT makes it possible to determine the onset temperature of the fluctuation conductivity and indicates a nonuniform distribution of the labile oxygen. Annealing has been revealed to lead to a monotonic decrease in the oxygen deficiency, that primarily manifests itself as a decrease in the residual resistance, an increase of T_c, and a decrease in the Debye temperature.

Scanning Hall Probe Microscopy of Magnetic Vortices inVery Underdoped yttrium-barium-copper-oxide

Energy Technology Data Exchange (ETDEWEB)

Guikema, Janice Wynn; /SLAC, SSRL

2005-12-02

Since their discovery by Bednorz and Mueller (1986), high-temperature cuprate superconductors have been the subject of intense experimental research and theoretical work. Despite this large-scale effort, agreement on the mechanism of high-T{sub c} has not been reached. Many theories make their strongest predictions for underdoped superconductors with very low superfluid density n{sub s}/m*. For this dissertation I implemented a scanning Hall probe microscope and used it to study magnetic vortices in newly available single crystals of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} (Liang et al. 1998, 2002). These studies have disproved a promising theory of spin-charge separation, measured the apparent vortex size (an upper bound on the penetration depth {lambda}{sub ab}), and revealed an intriguing phenomenon of ''split'' vortices. Scanning Hall probe microscopy is a non-invasive and direct method for magnetic field imaging. It is one of the few techniques capable of submicron spatial resolution coupled with sub-{Phi}{sub 0} (flux quantum) sensitivity, and it operates over a wide temperature range. Chapter 2 introduces the variable temperature scanning microscope and discusses the scanning Hall probe set-up and scanner characterizations. Chapter 3 details my fabrication of submicron GaAs/AlGaAs Hall probes and discusses noise studies for a range of probe sizes, which suggest that sub-100 nm probes could be made without compromising flux sensitivity. The subsequent chapters detail scanning Hall probe (and SQUID) microscopy studies of very underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} crystals with T{sub c} {le} 15 K. Chapter 4 describes two experimental tests for visons, essential excitations of a spin-charge separation theory proposed by Senthil and Fisher (2000, 2001b). We searched for predicted hc/e vortices (Wynn et al. 2001) and a vortex memory effect (Bonn et al. 2001) with null results, placing upper bounds on the vison energy inconsistent with

The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors.

Science.gov (United States)

Hinton, J P; Thewalt, E; Alpichshev, Z; Mahmood, F; Koralek, J D; Chan, M K; Veit, M J; Dorow, C J; Barišić, N; Kemper, A F; Bonn, D A; Hardy, W N; Liang, Ruixing; Gedik, N; Greven, M; Lanzara, A; Orenstein, J

2016-04-13

In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic "pseudogap" phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO(4+δ) (Hg-1201) and YBa2Cu3O(6+x) (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

Mechanisms for Superconductivity in Cuprates compared with results from the Generalized MacMillan-Rowell Analysis of High Resolution Laser- ARPES

Science.gov (United States)

Varma, Chandra; Choi, Han-Yong; Zhang, Wentao; Zhou, Xingjiang

2012-02-01

The spectra of fluctuations and their coupling to fermions has been deduced from extensive high resolution laser ARPES in several BISCCO samples and quantitatively analyzed. We ask the question whether some of the theories for superconductivity in Cuprates are consistent or inconsistent with the frequency and the momentum dependence of the deductions. We find that any fluctuation spectra, for example that of Antiferromagnetic Fluctuations, whose frequency dependence depends significantly on momentum dependence are excluded. We consider the quantum-critical spectra of the loop-current order observed in under-doped cuprates and its coupling to fermions and find it consistent with the data.

Pseudogap temperature T* of cuprate superconductors from the Nernst effect

Science.gov (United States)

Cyr-Choinière, O.; Daou, R.; Laliberté, F.; Collignon, C.; Badoux, S.; LeBoeuf, D.; Chang, J.; Ramshaw, B. J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Yan, J.-Q.; Cheng, J.-G.; Zhou, J.-S.; Goodenough, J. B.; Pyon, S.; Takayama, T.; Takagi, H.; Doiron-Leyraud, N.; Taillefer, Louis

2018-02-01

We use the Nernst effect to delineate the boundary of the pseudogap phase in the temperature-doping phase diagram of hole-doped cuprate superconductors. New data for the Nernst coefficient ν (T ) of YBa2Cu3Oy (YBCO), La1.8 -xEu0.2SrxCuO4 (Eu-LSCO), and La1.6 -xNd0.4SrxCuO4 (Nd-LSCO) are presented and compared with previously published data on YBCO, Eu-LSCO, Nd-LSCO, and La2 -xSrxCuO4 (LSCO). The temperature Tν at which ν /T deviates from its high-temperature linear behavior is found to coincide with the temperature at which the resistivity ρ (T ) deviates from its linear-T dependence, which we take as the definition of the pseudogap temperature T★—in agreement with the temperature at which the antinodal spectral gap detected in angle-resolved photoemission spectroscopy (ARPES) opens. We track T★ as a function of doping and find that it decreases linearly vs p in all four materials, having the same value in the three LSCO-based cuprates, irrespective of their different crystal structures. At low p ,T★ is higher than the onset temperature of the various orders observed in underdoped cuprates, suggesting that these orders are secondary instabilities of the pseudogap phase. A linear extrapolation of T★(p ) to p =0 yields T★(p →0 ) ≃TN (0), the Néel temperature for the onset of antiferromagnetic order at p =0 , suggesting that there is a link between pseudogap and antiferromagnetism. With increasing p ,T★(p ) extrapolates linearly to zero at p ≃pc 2 , the critical doping below which superconductivity emerges at high doping, suggesting that the conditions which favor pseudogap formation also favor pairing. We also use the Nernst effect to investigate how far superconducting fluctuations extend above the critical temperature Tc, as a function of doping, and find that a narrow fluctuation regime tracks Tc, and not T★. This confirms that the pseudogap phase is not a form of precursor superconductivity, and fluctuations in the phase of the

Bec Model of HIGH-Tc Superconductivity in Layered Cuprates

Science.gov (United States)

Lomnitz, M.; Villarreal, C.; de Llano, M.

2013-11-01

High-Tc superconductivity in layered cuprates is described in a BCS-BEC formalism with linearly-dispersive s- and d-wave Cooper pairs moving in quasi-2D finite-width layers around the CuO2 planes. This yields a closed formula for Tc involving the layer width, the Debye frequency, the pairing energy and the in-plane penetration depth. The new formula has no free parameters and reasonably reproduces empirical values of superconducting Tcs for 11 different layered superconductors over a wide doping regime including YBCO itself as well as other compounds like LSCO, BSCCO and TBCCO. In agreement with the London formalism, the formula also yields a fair description of the Tc dependence of the lower critical magnetic field in highly underdoped YBCO.

Nernst effect in the electron-doped cuprate superconductor L a2 -xC exCu O4

Science.gov (United States)

Mandal, P. R.; Sarkar, Tarapada; Higgins, J. S.; Greene, Richard L.

2018-01-01

We report a systematic study of the Nernst effect in films of the electron-doped cuprate superconductor L a2 -xC exCu O4 as a function of temperature and magnetic field (up to 14 T) over a range of doping from underdoped (x =0.08 ) to overdoped (x =0.16 ). We have determined the characteristic field scale HC2 * of superconducting fluctuation which is found to track the domelike dependence of superconductivity (TC). The fall of HC2 * and TC with underdoping is most likely due to the onset of long-range antiferromagnetic order. We also report the temperature onset, Tonset, of superconducting fluctuations above TC. For optimally doped x =0.11 Tonset (≅39 K ) is high compared to TC (26 K). For higher doping Tonset decreases and tends to zero along with the critical temperature at the end of the superconducting dome. The superconducting gap closely tracks HC2 * measured from the temperature- and field-dependent Nernst signal.

Quantum oscillation signatures of spin-orbit interactions controlling the residual nodal bilayer-splitting in underdoped high-Tc cuprates

Science.gov (United States)

Harrison, Neil; Shekhter, Arkady

2015-03-01

We investigate the origin of the small residual nodal bilayer-splitting in the underdoped high-Tc superconductor YBa2Cu3O6+x using the results of recently published angle-resolved quantum oscillation data [Sebastian et al., Nature 511, 61 (2014)]. A crucial clue to the origin of the residual bilayer-splitting is found to be provided by the anomalously small Zeeman-splitting of some of the observed cyclotron orbits. We show that such an anomalously Zeeman-splitting (or small effective g-factor) for a subset of orbits can be explained by spin-orbit interactions, which become significant in the nodal regions as a result of the vanishing bilayer coupling. The primary effect of spin-orbit interactions is to cause quasiparticles traversing the nodal region of the Brillouin zone to undergo a spin flip. We suggest that the Rashba-like spin-orbit interactions, naturally present in bilayer systems, have the right symmetry and magnitude to give rise to a network of coupled orbits consistent with experimental observations in underdoped YBa2Cu3O6+x. This work is supported by the DOEm BES proposal LANLF100, while the magnet lab is supported by the NSF and Florida State.

Strong-coupling approach to nematicity in the cuprates

Science.gov (United States)

Orth, Peter Philipp; Jeevanesan, Bhilahari; Schmalian, Joerg; Fernandes, Rafael

The underdoped cuprate superconductor YBa2Cu3O7-δ is known to exhibit an electronic nematic phase in proximity to antiferromagnetism. While nematicity sets in at large temperatures of T ~ 150 K, static spin density wave order only emerges at much lower temperatures. The magnetic response shows a strong in-plane anisotropy, displaying incommensurate Bragg peaks along one of the crystalline directions and a commensurate peak along the other one. Such an anisotropy persists even in the absence of long-range magnetic order at higher temperatures, marking the onset of nematic order. Here we theoretically investigate this situation using a strong-coupling method that takes into account both the localized Cu spins and the holes doped into the oxygen orbitals. We derive an effective spin Hamiltonian and show that charge fluctuations promote an enhancement of the nematic susceptibility near the antiferromagnetic transition temperature.

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

International Nuclear Information System (INIS)

Yung Moo Huh

2001-01-01

Thermodynamics has been studied systematically for the high temperature cuprate superconductor La 2-x Sr x CuO 4-δ , La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H(parallel)c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T c , magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T c0 vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La 2-x Sr x CuO 4 (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T c . The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance ζ c becomes comparable to the spacing between adjacent CuO 2 layers s at sufficiently high magnetic fields near H c2

Thermodynamic Critical Field and Superconducting Fluctuation of Vortices for High Temperature Cuprate Superconductor: La-214

International Nuclear Information System (INIS)

Finnemore, Douglas K.

2001-01-01

Thermodynamics has been studied systematically for the high temperature cuprate superconductor La 2-x Sr x CuO 4-δ , La-214, in the entire superconductive region from strongly underdoped to strongly overdoped regimes. Magnetization studies with H (parallel) c have been made in order to investigate the changes in free energy of the system as the number of carriers is reduced. Above the superconducting transition temperature, the normal-state magnetization exhibits a two-dimensional Heisenberg antiferromagnetic behavior. Below T c , magnetization data are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. As the Sr concentration is varied over the wide range from 0.060 (strongly underdoped) to 0.234 (strongly overdoped), the free energy change goes through a maximum at the optimum doped in a manner similar to the T c0 vs. x curve. The density of states, N(0), remains nearly constant in the overdoped and optimum doped regimes, taking a broad maximum around x = 0.188, and then drops abruptly towards zero in the underdoped regime. The La 2-x Sr x CuO 4 (La-214) system displays the fluctuating vortex behavior with the characteristic of either 2D or 3D fluctuations as indicated by clearly identifiable crossing points T* close to T c . The dimensional character of the fluctuations depends on both applied magnetic fields and the density of charge carriers. The dimensional crossover from 2D to 3D occurs in the strongly underdoped regime when the c-axis coherence distance ξ c becomes comparable to the spacing between adjacent CuO 2 layers s at sufficiently high magnetic field near H c2

Reassessment of the electronic state, magnetism, and superconductivity in high-T{sub c} cuprates with the Nd{sub 2}CuO{sub 4} structure

Energy Technology Data Exchange (ETDEWEB)

Naito, Michio, E-mail: minaito@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan); Krockenberger, Yoshiharu; Ikeda, Ai; Yamamoto, Hideki [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

2016-04-15

Highlights: • The 30-year history of “electron-doped” cuprates is reviewed, including basic physics and material issues. • Undoped cuprates with the Nd{sub 2}CuO{sub 4} (T’) structure are superconducting with T{sub c} over 30 K. • Electron doping by Ce in T’-RE{sub 2}CuO{sub 4} lowers T{sub c} and the highest T{sub c} is obtained at no doping. - Abstract: The electronic phase diagram of the cuprates remains enigmatic and is still a key ingredient to understand the mechanism of high-T{sub c} superconductivity. It has been believed for a long time that parent compounds of cuprates were universally antiferromagnetic Mott insulators (charge-transfer insulators) and that high-T{sub c} superconductivity would develop upon doping holes or electrons in a Mott–Hubbard insulator (“doped Mott-insulator scenario”). However, our recent discovery of superconductivity in the parent compounds of square-planar cuprates with the Nd{sub 2}CuO{sub 4} (T’) structure and the revised electronic phase diagram in T’ cuprates urged a serious reassessment to the above scenario. In this review, we present the main results derived from our synthesis and experiments on T’ cuprates in the undoped or heavily underdoped regime over 20 years, including material issues and basic physics. The key material issue is how to remove excess oxygen ions at the apical site without introducing oxygen vacancies in the CuO{sub 2} planes. In order to put this into practice, the basic knowledge of complex solid-state chemistry in T’ cuprates is required, which is also included in this review.

Microscopic theory of longitudinal sound velocity in CDW and SDW ordered cuprate systems

International Nuclear Information System (INIS)

Rout, G.C.; Panda, S.K.

2011-01-01

Research highlights: → Reported the study of the interplay of the CDW and SDW interactions in the high-Tc cuprates. → The longitudinal velocity of sound is studied in the under-doped region. → The velocity of sound exhibits suppression in both the CDW and SDW phases. → Strong electron-phonon interaction is observed in normal phases. - Abstract: We address here the self-consistent calculation of the spin density wave and the charge density wave gap parameters for high-T c cuprates on the basis of the Hubbard model. In order to describe the experimental observations for the velocity of sound, we consider the phonon coupling to the conduction band in the harmonic approximation and then the expression for the temperature dependent velocity of sound is calculated from the real part of the phonon Green's function. The effects of the electron-phonon coupling, the frequency of the sound wave, the hole doping concentration, the CDW coupling and the SDW coupling parameters on the sound velocity are investigated in the pure CDW phase as well as in the co-existence phase of the CDW and SDW states. The results are discussed to explain the experimental observations.

Microscopic theory of longitudinal sound velocity in CDW and SDW ordered cuprate systems

Energy Technology Data Exchange (ETDEWEB)

Rout, G.C., E-mail: gcr@iopb.res.i [Condensed Matter Physics Group, PG Dept. of Applied Physics and Ballistics, FM University, Balasore 756 019 (India); Panda, S K [KD Science College, Pochilima, Hinjilicut 761 101, Ganjam, Orissa (India)

2011-02-15

Research highlights: {yields} Reported the study of the interplay of the CDW and SDW interactions in the high-Tc cuprates. {yields} The longitudinal velocity of sound is studied in the under-doped region. {yields} The velocity of sound exhibits suppression in both the CDW and SDW phases. {yields} Strong electron-phonon interaction is observed in normal phases. - Abstract: We address here the self-consistent calculation of the spin density wave and the charge density wave gap parameters for high-T{sub c} cuprates on the basis of the Hubbard model. In order to describe the experimental observations for the velocity of sound, we consider the phonon coupling to the conduction band in the harmonic approximation and then the expression for the temperature dependent velocity of sound is calculated from the real part of the phonon Green's function. The effects of the electron-phonon coupling, the frequency of the sound wave, the hole doping concentration, the CDW coupling and the SDW coupling parameters on the sound velocity are investigated in the pure CDW phase as well as in the co-existence phase of the CDW and SDW states. The results are discussed to explain the experimental observations.

Microscopic theory of longitudinal sound velocity in CDW and SDW ordered cuprate systems

Energy Technology Data Exchange (ETDEWEB)

Rout, G.C., E-mail: gcr@iopb.res.i [Condensed Matter Physics Group, PG Dept. of Applied Physics and Ballistics, FM University, Balasore 756 019 (India); Panda, S.K. [KD Science College, Pochilima, Hinjilicut 761 101, Ganjam, Orissa (India)

2011-02-15

Research highlights: {yields} Reported the study of the interplay of the CDW and SDW interactions in the high-Tc cuprates. {yields} The longitudinal velocity of sound is studied in the under-doped region. {yields} The velocity of sound exhibits suppression in both the CDW and SDW phases. {yields} Strong electron-phonon interaction is observed in normal phases. - Abstract: We address here the self-consistent calculation of the spin density wave and the charge density wave gap parameters for high-T{sub c} cuprates on the basis of the Hubbard model. In order to describe the experimental observations for the velocity of sound, we consider the phonon coupling to the conduction band in the harmonic approximation and then the expression for the temperature dependent velocity of sound is calculated from the real part of the phonon Green's function. The effects of the electron-phonon coupling, the frequency of the sound wave, the hole doping concentration, the CDW coupling and the SDW coupling parameters on the sound velocity are investigated in the pure CDW phase as well as in the co-existence phase of the CDW and SDW states. The results are discussed to explain the experimental observations.

Electromagnetic response in kinetic energy driven cuprate superconductors: Linear response approach

International Nuclear Information System (INIS)

Krzyzosiak, Mateusz; Huang, Zheyu; Feng, Shiping; Gonczarek, Ryszard

2010-01-01

Within the framework of the kinetic energy driven superconductivity, the electromagnetic response in cuprate superconductors is studied in the linear response approach. The kernel of the response function is evaluated and employed to calculate the local magnetic field profile, the magnetic field penetration depth, and the superfluid density, based on the specular reflection model for a purely transverse vector potential. It is shown that the low temperature magnetic field profile follows an exponential decay at the surface, while the magnetic field penetration depth depends linearly on temperature, except for the strong deviation from the linear characteristics at extremely low temperatures. The superfluid density is found to decrease linearly with decreasing doping concentration in the underdoped regime. The problem of gauge invariance is addressed and an approximation for the dressed current vertex, which does not violate local charge conservation is proposed and discussed.

d-Wave density waves in high Tc cuprates and CeCoIn5

International Nuclear Information System (INIS)

Maki, Kazumi; Dora, Balazs; Vanyolos, Andras; Virosztek, Attila

2007-01-01

Unconventional density waves (UDW) have a long history starting with the speculation of Halperin and Rice in 1968. However, a more realistic approach started around 1999 in order to clarify the nature of the pseudogap in the underdoped region of hole-doped high T c cuprates. Also d-wave density waves (dDW) evolved from early unrealistic 2D model with Z 2 symmetry to more realistic 3D mean-field condensate with U(1) gauge symmetry. More recently, the giant Nernst effect and the angle dependent magnetoresistance in LSCO, YBCO, Bi2212 and CeCoIn 5 are successfully described in terms of dDW, where the Landau quantization of the quasiparticle spectrum in dDW in a magnetic field (the Nersesyan effect) plays the crucial role

A universal order underlying the pseudogap regime of the underdoped high Tc cuprates

Science.gov (United States)

Harrison, Neil

2014-03-01

A major achievement in condensed matter physics in the last quarter century has been a step towards the understanding of the unconventional d-wave superconducting state in the copper-oxide materials. Surprisingly, the normal state out of which the superconducting state emerges remains a mystery at low charge carrier densities, i.e., in the underdoped regime. This regime is of particular interest because it is characterised by an unusual momentum dependent energy pseudogap in the excitation spectrum that has defied explanation and is key to a full understanding of the unconventional d-wave superconducting state. I will present new quantum oscillation experimental results within the pseudogap regime of the high Tc superconductors YBa2Cu3O6+x and YBa2Cu4O8 which now extend up to the optimally-doped regime. These data reveal the evolution of the Fermi surface approaching the putative quantum critical point under the superconducting dome. A comprehensive angle-resolved study of the Fermi surface enables us to unambiguously identify a specific form of order that accounts for the observed quantum oscillations as well as other spectroscopic, transport and thermodynamic probes within the pseudogap regime. The author would like to thank B. Ramshaw, S. Sebastian, F. Balakirev, C. Mielke, M. Altarawneh, P. Goddard, S. Sabok, B. Babrowski, D. Bonn, W. Hardy, R. Liang and G. Lonzarich. This work was supported by the DOE BES ``Science of 100 tesla'' project and by the NSF and Florida State.

Mirror nesting of the Fermi contour and enhanced diamagnetism of the pseudogap state in cuprates

Energy Technology Data Exchange (ETDEWEB)

Kapaev, V.V.; Belyavsky, V.I. [P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow 119991 (Russian Federation); Kopaev, Yu.V. [P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow 119991 (Russian Federation)], E-mail: kopaev@sci.lebedev.ru; Smirnov, M.Yu. [State Pedagogical University, Voronezh 394043 (Russian Federation)

2007-09-01

Since the insulating gap in parent spin antiferromagnet survives under a hole underdoping, it might result in a rise of a metal state with a pocket-like Fermi contour with both conventional and mirror nesting corresponding to the same momentum K = ({pi}, {pi}). The nesting leads to a possibility of singlet orbital antiferromagnetic order whereas the mirror nesting promotes the superconducting pairing with the momentum K. We assume screened Coulomb repulsion to be the dominating pairing interaction in the cuprates resulting in the two-component superconducting order parameter. The relative phase of the parameter can be related to orbital current circulations as it follows from the Ginzburg-Landau phenomenology. The orbital antiferromagnetic state with the insulating gap on the Fermi contour is related to the pseudogap state with enhanced diamagnetic response.

Mirror nesting of the Fermi contour and enhanced diamagnetism of the pseudogap state in cuprates

International Nuclear Information System (INIS)

Kapaev, V.V.; Belyavsky, V.I.; Kopaev, Yu.V.; Smirnov, M.Yu.

2007-01-01

Since the insulating gap in parent spin antiferromagnet survives under a hole underdoping, it might result in a rise of a metal state with a pocket-like Fermi contour with both conventional and mirror nesting corresponding to the same momentum K = (π, π). The nesting leads to a possibility of singlet orbital antiferromagnetic order whereas the mirror nesting promotes the superconducting pairing with the momentum K. We assume screened Coulomb repulsion to be the dominating pairing interaction in the cuprates resulting in the two-component superconducting order parameter. The relative phase of the parameter can be related to orbital current circulations as it follows from the Ginzburg-Landau phenomenology. The orbital antiferromagnetic state with the insulating gap on the Fermi contour is related to the pseudogap state with enhanced diamagnetic response

A phenomenological theory of the pseudogap state

International Nuclear Information System (INIS)

Rice, T.M.; Yang Kaiyu; Zhang Fuchun

2007-01-01

An ansatz is proposed for the coherent part of the single particle Green's function in a doped resonant valence bond (RVB) state by analogy with the form derived by Konik and coworkers for an array of 2-leg Hubbard ladders near half-filling. The parameters of the RVB state are taken from the renormalized mean field theory of Zhang and coworkers for underdoped cuprates. The ansatz shows good agreement with recent angle resolved photoemission on underdoped cuprates and resolves an apparent disagreement with the Luttinger sum rule

Phonon anomalies in trilayer high-Tc cuprate superconductors

International Nuclear Information System (INIS)

Dubroka, Adam; Munzar, Dominik

2004-01-01

We present an extension of the model proposed recently to account for dramatic chAes below T c (anomalies) of some c-axis polarized infrared-active phonons in bilayer cuprate superconductors, that applies to trilayer high-T c compounds. We discuss several types of phonon anomalies that can occur in these systems and demonstrate that our model is capable of explaining the spectral chAes occurring upon entering the superconducting state in the trilayer compound Tl 2 Ba 2 Ca 2 Cu 3 O 10 . The low-temperature spectra of this compound obtained by Zetterer and coworkers display an additional broad absorption band, similar to the one observed in underdoped YBa 2 Cu 3 O 7-δ and Bi 2 Sr 2 CaCu 2 O 8 . In addition, three phonon modes are strongly anomalous. We attribute the absorption band to the transverse Josephson plasma resonance, similar to that of the bilayer compounds. The phonon anomalies are shown to result from a modification of the local fields induced by the formation of the resonance. The spectral chAes in Tl 2 Ba 2 Ca 2 Cu 3 O 10 are compared with those occurring in Bi 2 Sr 2 Ca 2 Cu 3 O 10 , reported recently by Boris and coworkers

The electronic structure of the high-TC cuprates within the hidden rotating order

Science.gov (United States)

Azzouz, M.; Ramakko, B. W.; Presenza-Pitman, G.

2010-09-01

The doping dependence of the Fermi surface and energy distribution curves of the high-TC cuprate materials La2 - xSrxCuO4 and Bi2Sr2CaCu2O8 + δ are analyzed within the rotating antiferromagnetism theory. Using three different quantities; the k-dependent occupation probability, the spectral function, and the chemical potential (energy spectra), the Fermi surface is calculated and compared to experimental data for La2 - xSrxCuO4. The Fermi surface we calculate evolves from hole-like pockets in the underdoped regime to large electron-like contours in the overdoped regime. This is in agreement with recent findings by Sebastian et al for the α-pocket of Y Ba2Cu3O6 + x (2010 Phys. Rev. B 81 214524). In addition, the full width at half maximum of the energy distribution curves is found to behave linearly with their peak position in agreement with experiment for Bi2Sr2CaCu2O8 + δ. The effect of scattering on both the Fermi surface and energy distribution curves is examined.

Superconducting fluctuations and pseudogap in high-Tc cuprates

Directory of Open Access Journals (Sweden)

Alloul H.

2012-03-01

Full Text Available Large pulsed magnetic fields up to 60 Tesla are used to suppress the contribution of superconducting fluctuations (SCF to the ab-plane conductivity above Tc in a series of YBa2Cu3O6+x. These experiments allow us to determine the field Hc’(T and the temperature Tc’ above which the SCFs are fully suppressed. A careful investigation near optimal doping shows that Tc’ is higher than the pseudogap temperature T*, which is an unambiguous evidence that the pseudogap cannot be assigned to preformed pairs. Accurate determinations of the SCF contribution to the conductivity versus temperature and magnetic field have been achieved. They can be accounted for by thermal fluctuations following the Ginzburg-Landau scheme for nearly optimally doped samples. A phase fluctuation contribution might be invoked for the most underdoped samples in a T range which increases when controlled disorder is introduced by electron irradiation. Quantitative analysis of the fluctuating magnetoconductance allows us to determine the critical field Hc2(0 which is found to be be quite similar to Hc’ (0 and to increase with hole doping. Studies of the incidence of disorder on both Tc’ and T* allow us to to propose a three dimensional phase diagram including a disorder axis, which allows to explain most observations done in other cuprate families.

Pair-density waves, charge-density waves, and vortices in high-Tc cuprates

Science.gov (United States)

Dai, Zhehao; Zhang, Ya-Hui; Senthil, T.; Lee, Patrick A.

2018-05-01

A recent scanning tunneling microscopy (STM) experiment reports the observation of a charge-density wave (CDW) with a period of approximately 8a in the halo region surrounding the vortex core, in striking contrast to the approximately 4a period CDWs that are commonly observed in the cuprates. Inspired by this work, we study a model where a bidirectional pair-density wave (PDW) with period 8 is at play. This further divides into two classes: (1) where the PDW is a competing state of the d -wave superconductor and can exist only near the vortex core where the d -wave order is suppressed and (2) where the PDW is the primary order, the so-called "mother state" that persists with strong phase fluctuations to high temperature and high magnetic field and lies behind the pseudogap phenomenology. We study the charge-density wave structures near the vortex core in these models. We emphasize the importance of the phase winding of the d -wave order parameter. The PDW can be pinned by the vortex core due to this winding and become static. Furthermore, the period-8 CDW inherits the properties of this winding, which gives rise to a special feature of the Fourier transform peak, namely, it is split in certain directions. There is also a line of zeros in the inverse Fourier transform of filtered data. We propose that these are key experimental signatures that can distinguish between the PDW-driven scenario from the more mundane option that the period-8 CDW is primary. We discuss the pro's and con's of the options considered above. Finally, we attempt to place the STM experiment in the broader context of pseudogap physics of underdoped cuprates and relate this observation to the unusual properties of x-ray scattering data on CDW carried out to very high magnetic field.

The oxygen-isotope effect on the in-plane penetration depth in underdoped Y{sub 1-x} Pr{sub x} Ba{sub 2} Cu{sub 3} O{sub 7-{delta}} as revealed by muon-spin rotation

Energy Technology Data Exchange (ETDEWEB)

Khasanov, R [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland); Shengelaya, A [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland); Conder, K [Laboratory for Neutron Scattering, ETH Zuerich and PSI Villigen, CH-5232 Villigen PSI (Switzerland); Morenzoni, E [Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Savic, I M [Faculty of Physics, University of Belgrade, 11001 Belgrade (Yugoslavia); Keller, H [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland)

2003-01-22

The oxygen-isotope ({sup 16}O/{sup 18}O) effect (OIE) on the in-plane penetration depth {lambda}{sub ab} (0) in underdoped Y{sub 1-x} Pr{sub x} Ba{sub 2} Cu{sub 3} O{sub 7-{delta}} was studied by means of muon-spin rotation. A pronounced OIE on {lambda}{sub ab}{sup -2} (0) was observed with a relative isotope shift of {delta}{lambda}{sub ab}{sup -2} /{lambda} {sub ab}{sup -2} = -5(2)% for x=0.3 and -9(2)% for x=0.4. The OIE exponents of T{sub c} and of {lambda}{sub ab}{sup -2} (0) exhibit a relation that appears to be generic for cuprate superconductors. (letter to the editor)

Investigation of the effect of Zn impurities and magnetic field on the spin dynamics in underdoped YBa2(Cu1-yZny)3Ox

International Nuclear Information System (INIS)

Suchaneck, Anton

2009-01-01

This work employs neutron scattering to examine the changes in the spin excitation spectrum of the underdoped high-temperature superconductor YBa 2 Cu 3 O x which is doped with zinc or subject to a strong magnetic field. Doping levels of x=6.6 and x=6.45 are used with an optional zinc substitution of 2% zinc per copper atom. A detwinning procedure is an important factor in order to reorient all twinning domains of the orthorhombic crystal cell in the same direction. Numerous single crystals were oriented and assembled to create a sample of total mass 2 g neccessary for neutron scattering experiments. The experiments were performed on triple axis neutron scattering spectrometers to measure spin excitations around the antiferromagnetic wave vector at energies up to 50 meV. Zinc substitution and magnetic field influence the spin excitations, which in the pure compound feature the resonance mode, a spin gap and an hour-glass dispersion. Upon zinc substitution the spectrum of YBa 2 (Cu 0.98 Zn 0.02 ) 3 O 6.6 is quantitatively unchanged around the resonance energy, however its marked temperature onset disappears. At lower energies new induced quasi-static excitations emerge. Similar finding have been observed in other cuprate compounds. The induced excitation exhibit a strong anisotropy in the copper planes. All these results are compared to other experimental techniques which provide comparable experimental evidence. Another compounds examined in this work is the more strongly oxygen underdoped YBa 2 (Cu 0.98 Zn 0.02 ) 3 O 6.45 . The common bilayer related signal remains unchanged with zinc substitution, however a new inter-plane correlated signal is induced indicating ordering between copper planes. A comparison with other experimental techniques indicated that the superconducting critical temperature is the sole determining factor of the qualitative spin excitation spectrum, no matter what factor are responsible for it. Additional examinations have been devoted to the

In-plane optical response in underdoped YBCO

Science.gov (United States)

Kakeshita, Teruhisa; Masui, Takahiko; Tajima, Setsuko

2005-03-01

The recent STM experiments demonstrated that the electronic state in CuO2 plane is inhomogeneous [1], which becomes conspicuous in the underdoped regime. In such an inhomogeneous state, it is not obvious whether a superfluid density is correctly estimated by a conventional way. We investigated the in-plane optical response for underdoped YBCO crystal to discuss the relation between inhomogeneity and superfluid density in the pseudo-gapped state. The a-axis optical spectrum shows a larger residual conductivity than that for the optimum doping. The superfluid density estimated from our optical spectrum at the lowest temperature is substantially smaller than that determined by μSR. We discuss this strongly suppressed superfluid density and the large residual conductivity in terms of the inhomogeneity in real- and k-space. This work was supported by the New Energy and Industrial Technology Development Organization(NEDO) through ISTEC as the Collaborative Research and Development of Fundamental Technologies for Superconductivity Applications. [1]K.M.Lang et al., Nature 415, 412 (2002). *present address: Dept. of Physics, Osaka University, Machikaneyama 1-1, Toyonaka, Osaka 560-0043, Japan

Rapid enhancement of nodal quasiparticle mass with heavily underdoping in Bi2212

Science.gov (United States)

Anzai, Hiroaki; Arita, Masashi; Namatame, Hirofumi; Taniguchi, Masaki; Ishikado, Motoyuki; Fujita, Kazuhiro; Ishida, Shigeyuki; Uchida, Shin-ichi; Ino, Akihiro

2018-05-01

We report substantial advance of our low-energy angle-resolved photoemission study of nodal quasiparticles in Bi2Sr2CaCu2O8+δ. The new data cover the samples from underdoped down to heavily underdoped levels. We also present the nodal Fermi velocities that determined by using an excitation-photon energy of hν = 7.0 eV over a wide doping range. The consistency between the results with hν = 8.1 and 7.0 eV allows us to rule out the effect of photoemission matrix elements. In comparison with the data previously reported, the nodal effective mass increases by a factor of ∼ 1.5 in going from optimally doped to heavily underdoped levels. We find a rapid enhancement of the nodal quasiparticle mass at low doping levels near the superconductor-to-insulator transition. The effective coupling spectrum, λ (ω) , is extracted directly from the energy derivatives of the quasiparticle dispersion and scattering rate, as a causal function of the mass enhancement factor. A steplike increase in Reλ (ω) around ∼ 65 meV is demonstrated clearly by the Kramers-Kronig transform of Imλ (ω) . To extract the low-energy renormalization effect, we calculated a simple model for the electron-boson interaction. This model reveals that the contribution of the renormalization at | ω | ≤ 15 meV to the quasiparticle mass is larger than that around 65 meV in underdoped samples.

On the 590cm-1 B1g feature in underdoped Bi2Sr2CaCu2O8+delta

OpenAIRE

Hewitt, Kevin C.; Wang, N. L.; Irwin, J. C.; Pooke, D. M.; Pantoja, A. E.; Trodahl, H. J.

1999-01-01

Raman scattering studies have been performed on underdoped Bi2Sr2CaCu2O8+delta. In single crystals underdoped by oxygen removal, a 590 cm-1 peak is observed in the B1g spectrum. The feature is observed to soften in frequency by 3.8% with isotopic exchange for 16-O by 18-O. In contrast, the 590cm-1 peak is not observed in crystals underdoped by Y substitution which suggests that it correspond to a disorder induced vibrational mode. We have also found that underdoping leads to a depletion of lo...

The 590 cm-1 B_1g feature in underdoped Bi_2Sr_2CaCu_2O_8+δ

Science.gov (United States)

Hewitt, Kevin C.; Wang, N. L.; Irwin, J. C.; Pooke, D. M.; Pantoja, A. E.; Trodahl, H. J.

1999-05-01

Raman scattering studies have been performed on underdoped Bi_2Sr_2CaCu_2O_8+δ. In single crystals underdoped by oxygen removal, a 590 cm-1 peak is observed in the B_1g spectrum. The feature is observed to soften in frequency by 3.8% with isotopic exchange of ^16O by ^18O. In contrast, the 590 cm-1 peak is not observed in crystals underdoped by Y substitution which suggests that it corresponds to a disorder induced vibrational mode. We have also found that underdoping leads to a depletion of low energy spectral weight from regions of the Fermi surface located near the Brillouin zone axes.

Optical Study of Electron-Doped Cuprate Pr1.3-xLa0.7CexCuO4+δ in Under-Doped Regime: Revisit the Phase Diagram

Science.gov (United States)

Ohnishi, Ryota; Nakajima, Masamichi; Miyasaka, Shigeki; Tajima, Setsuko; Adachi, Tadashi; Ohgi, Taro; Takahashi, Akira; Koike, Yoji

2018-04-01

A recent progress of reduction process for electron-doped cuprates enabled us to get superconducting samples at very low doping levels. In order to clarify the electronic state of strongly reduced Pr1.3-xLa0.7CexCuO4+δ (x = 0.05, 0.10) which exhibit high Tc (˜27 K) superconductivity, we have measured their optical spectra. The reflectivity of these samples was found much higher than the published data for the moderately reduced and non-superconducting samples with the same Ce concentrations. Moreover, the estimated effective electron numbers Neff for x = 0.05 and 0.10 were close to that of the optimally doped and superconducting sample with x = 0.15. Given that the parent compound is a Mott insulator, these results indicate that in the electron-doped cuprates only a small amount of carrier doping changes the system to a high Tc superconductor with a large Fermi surface. At low temperatures, a broad mid-infrared peak appeared even in the superconducting samples.

The color of polarization in cuprate superconductors

International Nuclear Information System (INIS)

Hoff, H.A.; Osofsky, M.S.; Lechter, W.L.; Pande, C.S.

1991-01-01

A technique for the identification of individual anisotropic grains in a heterogeneous and opaque material involves the observation of grain color in reflected light through crossed polarizers (color of polarization). Such colors are generally characteristic of particular phases. When grains of many members of the class of hole carrier cuprate superconductors are so viewed at room temperature with a 'daylight' source, a characteristic color of polarization is observed. This color was studied in many of these cuprate superconductors and a strong correlation was found between color and the existence of superconductivity. Two members were also examined of the electron cuprate superconductors and it was found that they possess the same color of polarization as the hole carrier cuprate superconductors so far examined. The commonality of the characteristic color regardless of charge carrier indicates that the presence of this color is independent of carrier type. The correlation of this color with the existence of superconductivity in the cuprate superconductors suggests that the origin of the color relates to the origin of superconductivity. Photometric techniques are also discussed

Isotope shift of the 590-cm-1 Raman feature in underdoped Bi2Sr2CaCu2O8+δ

Science.gov (United States)

Hewitt, K. C.; Wang, N. L.; Irwin, J. C.; Pooke, D. M.; Pantoja, A. E.; Trodahl, H. J.

1999-10-01

Raman-scattering studies have been performed on underdoped Bi2Sr2CaCu2O8+δ. In single crystals underdoped by oxygen removal, a 590-cm-1 peak is observed in the B1g spectrum. The feature is observed to soften in frequency by 3.8% with isotopic exchange of 16O by 18O. In contrast, the 590-cm-1 peak is not observed in crystals underdoped by Y substitution which suggests that it is a vibrational mode activated by oxygen deficency. We have also found that underdoping leads to a depletion of low-energy spectral weight from regions of the Fermi surface located near the Brillouin-zone axes.

Impurity-induced moments in underdoped cuprates

International Nuclear Information System (INIS)

Khaliullin, G.; Kilian, R.; Krivenko, S.; Fulde, P.

1997-01-01

We examine the effect of a nonmagnetic impurity in a two-dimensional spin liquid in the spin-gap phase, employing a drone-fermion representation of spin-1/2 operators. The properties of the local moment induced in the vicinity of the impurity are investigated and an expression for the nuclear-magnetic-resonance Knight shift is derived, which we compare with experimental results. Introducing a second impurity into the spin liquid an antiferromagnetic interaction between the moments is found when the two impurities are located on different sublattices. The presence of many impurities leads to a screening of this interaction as is shown by means of a coherent-potential approximation. Further, the Kondo screening of an impurity-induced local spin by charge carriers is discussed. copyright 1997 The American Physical Society

The collapse of the columnar spatial topology of pseudogap excitations in the underdoped-overdoped transition of cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Roehler, Juergen [Universitaet zu Koeln, 50937 Koeln (Germany)

2016-07-01

The intensity I{sub Q{sub 0}} of the Q=0 nematic pseudogap excitations in Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x} was found to increase between p ≥ 0.06 and 0.14 and to collapse at p{sub opt}=0.16, reaching zero at p=0.2. Evidentially it maps the growth and the collapse of the bulge in the doping dependence of the basal-plane area (ab) of p-type cuprates. The nematic topology of the pseudogap excitations results from the non-occupancy constraint for nn ZR-holes excluding 1a dimerization, but favoring 3a pair states with inequivalent O{sub x,y} sites. 3a pair states have hard core properties, yield d-type CDW excitations, and inflate the basal-plane area by a columnar topology against covalency-driven contraction. We show that optimal delocalization of ZR-holes at p{sub opt}=1/6 ≅ 0.17, tantamount to maximal connectedness of 3a pair states, will transform the columnar nematic pattern into isotropic tweedy striations, hence collapses I{sub Q{sub 0}}, and the bulge.

Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

International Nuclear Information System (INIS)

Raj, B.K.; Panda, S.K.; Rout, G.C.

2013-01-01

Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T C systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ c ± Δ s ). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy

Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

Energy Technology Data Exchange (ETDEWEB)

Raj, B. K. [Dept. of Physics, Govt. Autonomous College, Angul, Orissa (India); Panda, S. K. [KD Science College, Pochilima, Hinjilicut, 761 101 Ganjam, Orissa (India); Rout, G.C., E-mail: gcr@iopb.res.in [Condensed Matter Physics Group, PG Dept. of Applied Physics and Ballistics, FM University, Balasore 756 019 (India)

2013-09-15

Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T{sub C} systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ{sub c} ± Δ{sub s}). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy.

Correlation and disorder-enhanced nematic spin response in superconductors with weakly broken rotational symmetry

DEFF Research Database (Denmark)

Andersen, Brian Møller; Graser, S.; Hirschfeld, P. J.

2012-01-01

Recent experimental and theoretical studies have highlighted the possible role of an electronic nematic liquid in underdoped cuprate superconductors. We calculate, within a model of d-wave superconductor with Hubbard correlations, the spin susceptibility in the case of a small explicitly broken...

Pseudogap in normal underdoped phase of Bi2212: LDA + DMFT + Σk

International Nuclear Information System (INIS)

Nekrasov, I.A.; Kuchinskii, E.Z.; Pchelkina, Z.V.; Sadovskii, M.V.

2007-01-01

Pseudogap phenomena are observed for normal underdoped phase of different high-T c cuprates. Among others Bi 2 Sr 2 CaCu 2 O 8-δ (Bi2212) compound is one of the most studied experimentally [A. Damascelli, Z. Hussain, Z.-X. Shen, Rev. Mod. Phys. 75 (2003) 473; J.C. Campuzano, M.R. Norman, M. Randeria, in: K.H. Bennemann, J.B. Ketterson (Eds.), Physics of Superconductors, vol. 2, Springer, Berlin, 2004, p. 167; J. Fink et al., (cond-mat/0512307); X.J. Zhou et al., (cond-mat/0604284)]. To describe pseudogap regime in Bi2212, we employ novel generalized DMFT + Σ k approach [E.Z. Kuchinskii, I.A. Nekrasov, M.V. Sadovskii, JETP Lett. 82 (2005) 198; M.V. Sadovskii et al., Phys. Rev. B 72 (2005) 155105, and these proceedings, (doi:10.1016/j.physc.2007.03.367)]. This approach gives possibility to preserve conventional dynamical mean-field theory (DMFT) equations [A. Georges et al., Rev. Mod. Phys. 68 (1996) 13] and include an additional (momentum dependent) self-energy Σ k . In the present case, Σ k describes non-local dynamical correlations induced by short-ranged collective Heisenberg-like antiferromagnetic spin fluctuations [M.V. Sadovskii, Physics-Uspekhi 44 (2001) 515, (cond-mat/0408489)]. The effective single impurity problem in the DMFT + Σ k is solved by numerical renormalization group (NRG) [R. Bulla, A.C. Hewson, Th. Pruschke, J. Phys. Cond. Mat. 10 (1998) 8365; R. Bulla, Phys. Rev. Lett. 83 (1999) 136]. To take into account material specific properties of two neighboring CuO 2 layers of Bi2212 we employ local density approximation (LDA) to calculate necessary model parameters, e.g. the values of intra- and interlayer hopping integrals between Cu-sites. Onsite Coulomb interaction U for x 2 -y 2 orbital was calculated in constrained LDA method [O. Gunnarsson et al., Phys. Rev. B 39 (1989) 1708]. The value of pseudogap potential Δ was obtained within DMFT(NRG) [E.Z. Kuchinskii, I.A. Nekrasov, M.V. Sadovskii, JETP Lett. 82 (2005) 198; M.V. Sadovskii et al

Amperean Pairing and the Pseudogap Phase of Cuprate Superconductors

Science.gov (United States)

Lee, Patrick A.

2014-07-01

The enigmatic pseudogap phase in underdoped cuprate high-Tc superconductors has long been recognized as a central puzzle of the Tc problem. Recent data show that the pseudogap is likely a distinct phase, characterized by a medium range and quasistatic charge ordering. However, the origin of the ordering wave vector and the mechanism of the charge order is unknown. At the same time, earlier data show that precursive superconducting fluctuations are also associated with this phase. We propose that the pseudogap phase is a novel pairing state where electrons on the same side of the Fermi surface are paired, in strong contrast with conventional Bardeen-Cooper-Schrieffer theory which pairs electrons on opposite sides of the Fermi surface. In this state the Cooper pair carries a net momentum and belongs to a general class called pair density wave. The microscopic pairing mechanism comes from a gauge theory formulation of the resonating valence bond (RVB) picture, where spinons traveling in the same direction feel an attractive force in analogy with Ampere's effects in electromagnetism. We call this Amperean pairing. Charge order automatically appears as a subsidiary order parameter even when long-range pair order is destroyed by phase fluctuations. Our theory gives a prediction of the ordering wave vector which is in good agreement with experiment. Furthermore, the quasiparticle spectrum from our model explains many of the unusual features reported in photoemission experiments. The Fermi arc, the unusual way the tip of the arc terminates, and the relation of the spanning vector of the arc tips to the charge ordering wave vector also come out naturally. Finally, we propose an experiment that can directly test the notion of Amperean pairing.

Spectroscopic Imaging Scanning Tunneling Microscopy Studies of Electronic Structure in the Superconducting and Pseudogap Phases of Cuprate High-Tc Superconductors

Science.gov (United States)

Fujita, Kazuhiro; Schmidt, Andrew R.; Kim, Eun-Ah; Lawler, Michael J.; Lee, Dung Hai; Davis, J. C.; Eisaki, Hiroshi; Uchida, Shin-ichi

2012-01-01

One of the key motivations for the development of atomically resolved spectroscopic imaging scanning tunneling microscopy (SI-STM) has been to probe the electronic structure of cuprate high temperature superconductors. In both the d-wave superconducting (dSC) and the pseudogap (PG) phases of underdoped cuprates, two distinct classes of electronic states are observed using SI-STM. The first class consists of the dispersive Bogoliubov quasiparticles of a homogeneous d-wave superconductor. These are detected below a lower energy scale |E|=Δ0 and only upon a momentum space (k-space) arc which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). Below optimal doping, this ``nodal'' arc shrinks continuously with decreasing hole density. In both the dSC and PG phases, the only broken symmetries detected in the |E|≤Δ0 states are those of a d-wave superconductor. The second class of states occurs at energies near the pseudogap energy scale |E|˜ Δ1 which is associated conventionally with the ``antinodal'' states near k=±(π/a0,0) and k=±(0,π/a0). We find that these states break the expected 90°-rotational (C4) symmetry of electronic structure within CuO2 unit cells, at least down to 180°-rotational (C2) symmetry (nematic) but in a spatially disordered fashion. This intra-unit-cell C4 symmetry breaking coexists at |E|˜Δ1 with incommensurate conductance modulations locally breaking both rotational and translational symmetries (smectic). The characteristic wavevector Q of the latter is determined, empirically, by the k-space points where Bogoliubov quasiparticle interference terminates, and therefore evolves continuously with doping. The properties of these two classes of |E|˜Δ1 states are indistinguishable in the dSC and PG phases. To explain this segregation of k-space into the two regimes distinguished by the symmetries of their electronic states and their energy scales |E|˜Δ1 and |E|≤Δ0, and to understand how this impacts the electronic

Effects of impurities and vortices on the low-energy spin excitations in high-Tc materials

DEFF Research Database (Denmark)

Andersen, Brian Møller; Graser, S.; Schmid, M.

2011-01-01

We review a theoretical scenario for the origin of the spin-glass phase of underdoped cuprate materials. In particular it is shown how disorder in a correlated d-wave superconductor generates a magnetic phase by inducing local droplets of antiferromagnetic order which eventually merge and form...

Pseudogap and cuprate superconductivity: MaxEnt-μSR studies

International Nuclear Information System (INIS)

Boekema, C.; Schwartz, R.; Love, A.; Browne, M.C.

2013-01-01

Highlights: • A magnetic origin of cuprate superconductivity is plausible. • Cuprate loop currents are observed, close to predictions. • Pseudogap effects are seen above and below T c . -- Abstract: The basic physics of cuprate superconductivity is still much deliberated after 27 years of research. In contrast to phononic or polaronic roots, Varma’s theory promotes a magnetic origin. To probe cuprate magnetism, we examine zero field (ZF) muon-spin-rotation (μSR) data of RBa 2 Cu 3 O 7−δ (RBCO; R = Gd, Eu) especially near T c . Possible weak effects are analyzed using Maximum Entropy (MaxEnt, ME) to transform our μSR time series. Concerning predicted pseudogap loop currents, we have observed μSR signals in zero field for GdBCO above and now also below T c . These are near predicted fields of about 100 Oe. Using MaxEnt, we analyze transverse field (TF) μSR data of optimal doped EuBCO. Our focus is also on a temperature interval above T c to comprehend precursor effects. Our results point toward magnetic roots of cuprate superconductivity

Electronic Raman response in electron-doped cuprate superconductors

International Nuclear Information System (INIS)

Geng Zhihao; Feng Shiping

2012-01-01

The electronic Raman response in the electron-doped cuprate superconductors is studied based on the t-t'-J model. It is shown that although the domelike shape of the doping dependent peak energy in the B 2g symmetry is a common feature for both electron-doped and hole-doped cuprate superconductors, there are pronounced deviations from a cubic response in the B 2g channel and a linear response in the B 2g channel for the electron-doped case in the low energy limit. It is also shown that these pronounced deviations are mainly caused by a nonmonotonic d-wave gap in the electron-doped cuprate superconductors.

Transport anomalies and quantum criticality in electron-doped cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xu; Yu, Heshan; He, Ge; Hu, Wei; Yuan, Jie; Zhu, Beiyi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Jin, Kui, E-mail: kuijin@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

2016-06-15

Highlights: • Electrical transport and its complementary thermal transport on electron-doped cuprates are reviewed. • The common features of electron-doped cuprates are sorted out and shown in the last figure. • The complex superconducting fluctuations and quantum fluctuations are distinguished. - Abstract: Superconductivity research is like running a marathon. Three decades after the discovery of high-T{sub c} cuprates, there have been mass data generated from transport measurements, which bring fruitful information. In this review, we give a brief summary of the intriguing phenomena reported in electron-doped cuprates from the aspect of electrical transport as well as the complementary thermal transport. We attempt to sort out common features of the electron-doped family, e.g. the strange metal, negative magnetoresistance, multiple sign reversals of Hall in mixed state, abnormal Nernst signal, complex quantum criticality. Most of them have been challenging the existing theories, nevertheless, a unified diagram certainly helps to approach the nature of electron-doped cuprates.

Incommensurate Phonon Anomaly and the Nature of Charge Density Waves in Cuprates

Science.gov (United States)

Miao, H.; Ishikawa, D.; Heid, R.; Le Tacon, M.; Fabbris, G.; Meyers, D.; Gu, G. D.; Baron, A. Q. R.; Dean, M. P. M.

2018-01-01

While charge density wave (CDW) instabilities are ubiquitous to superconducting cuprates, the different ordering wave vectors in various cuprate families have hampered a unified description of the CDW formation mechanism. Here, we investigate the temperature dependence of the low-energy phonons in the canonical CDW-ordered cuprate La1.875 Ba0.125 CuO4 . We discover that the phonon softening wave vector associated with CDW correlations becomes temperature dependent in the high-temperature precursor phase and changes from a wave vector of 0.238 reciprocal lattice units (r.l.u.) below the ordering transition temperature to 0.3 r.l.u. at 300 K. This high-temperature behavior shows that "214"-type cuprates can host CDW correlations at a similar wave vector to previously reported CDW correlations in non-214-type cuprates such as YBa2 Cu3 O6 +δ . This indicates that cuprate CDWs may arise from the same underlying instability despite their apparently different low-temperature ordering wave vectors.

Investigation of the effect of Zn impurities and magnetic field on the spin dynamics in underdoped YBa{sub 2}(Cu{sub 1-y}Zn{sub y}){sub 3}O{sub x}

Energy Technology Data Exchange (ETDEWEB)

Suchaneck, Anton

2009-04-20

This work employs neutron scattering to examine the changes in the spin excitation spectrum of the underdoped high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub x} which is doped with zinc or subject to a strong magnetic field. Doping levels of x=6.6 and x=6.45 are used with an optional zinc substitution of 2% zinc per copper atom. A detwinning procedure is an important factor in order to reorient all twinning domains of the orthorhombic crystal cell in the same direction. Numerous single crystals were oriented and assembled to create a sample of total mass 2 g neccessary for neutron scattering experiments. The experiments were performed on triple axis neutron scattering spectrometers to measure spin excitations around the antiferromagnetic wave vector at energies up to 50 meV. Zinc substitution and magnetic field influence the spin excitations, which in the pure compound feature the resonance mode, a spin gap and an hour-glass dispersion. Upon zinc substitution the spectrum of YBa{sub 2}(Cu{sub 0.98}Zn{sub 0.02}){sub 3}O{sub 6.6} is quantitatively unchanged around the resonance energy, however its marked temperature onset disappears. At lower energies new induced quasi-static excitations emerge. Similar finding have been observed in other cuprate compounds. The induced excitation exhibit a strong anisotropy in the copper planes. All these results are compared to other experimental techniques which provide comparable experimental evidence. Another compounds examined in this work is the more strongly oxygen underdoped YBa{sub 2}(Cu{sub 0.98}Zn{sub 0.02}){sub 3}O{sub 6.45}. The common bilayer related signal remains unchanged with zinc substitution, however a new inter-plane correlated signal is induced indicating ordering between copper planes. A comparison with other experimental techniques indicated that the superconducting critical temperature is the sole determining factor of the qualitative spin excitation spectrum, no matter what factor are responsible

Tunneling spectroscopy of heavily underdoped crystals of Bi2Sr2CaCu2O8+δ

International Nuclear Information System (INIS)

Ozyuzer, L.; Zasadzinski, J.F.; Miyakawa, N.; Kendziora, C.; Jian, S.; Hinks, D. G.; Gray, K.E.

2000-01-01

Crystals of Bi 2 Sr 2 CaCu 2 O 8+δ with optimal Tc = 95 K have been underdoped using two different methods and the superconducting gaps have been obtained by tunneling. In some cases, three different tunneling geometries have been utilized: point contact, STM and break junctions. The first doping method involves control of the oxygen content by annealing in various partial pressures of oxygen. These crystals exhibit a narrow spread of gap values over a wide doping range from overdoped (Tc = 56 K) to underdoped with Tc = 70 K. However, for underdoped crystals with Tc midpoints in the range 25 K--63 K, there is a dramatic increase in the spread of gap values which may signal the development of static phase separation of either chemical or electronic origin. To avoid possible chemical phase separation, the authors have explored another doping procedure which incorporates Dy substitution on the Ca site. These crystals exhibit a relatively narrow superconducting transition width and some preliminary tunneling spectra will be presented

Excess Oxygen Defects in Layered Cuprates

Science.gov (United States)

Lightfoot, P.; Pei, S. Y.; Jorgensen, J. D.; Manthiram, A.; Tang, X. X.; Goodenough, J. B.

1990-09-01

Neutron powder diffraction has been used to study the oxygen defect chemistry of two non-superconducting layered cuprates, La{sub 1. 25}Dy{sub 0.75}Cu{sub 3.75}F{sub 0.5}, having a T{sup {asterisk}}- related structure, and La{sub 1.85}Sr{sub 1.15}Cu{sub 2}O{sub 6.25}, having a structure related to that of the newly discovered double-layer superconductor La{sub 2-x}Sr{sub x}CaCu{sub 2}O{sub 6}. The role played by oxygen defects in determining the superconducting properties of layered cuprates is discussed.

High-Temperature Cuprate Superconductors Experiment, Theory, and Applications

CERN Document Server

Plakida, Nikolay Maksimilianovich

2010-01-01

High-Temperature Cuprate Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. The essential properties of high-temperature cuprate superconductors are reviewed on the background of their theoretical interpretation. The experimental results for structural, magnetic, thermal, electric, optical and lattice properties of various cuprate superconductors are presented with respect to relevant theoretical models. A critical comparison of various theoretical models involving strong electron correlations, antiferromagnetic spin fluctuations, phonons and excitons provides a background for understanding of the mechanism of high-temperature superconductivity. Recent achievements in their applications are also reviewed. A large number of illustrations and tables gives valuable information for specialists. A text-book level presentation with formulation of a general theory of strong-coupling superconductivity will help students and researches to consolidate their...

High-temperature cuprate superconductors. Experiment, theory, and applications

International Nuclear Information System (INIS)

Plakida, Nikolay

2010-01-01

High-Temperature Cuprate Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. The essential properties of high-temperature cuprate superconductors are reviewed on the background of their theoretical interpretation. The experimental results for structural, magnetic, thermal, electric, optical and lattice properties of various cuprate superconductors are presented with respect to relevant theoretical models. A critical comparison of various theoretical models involving strong electron correlations, antiferromagnetic spin fluctuations, phonons and excitons provides a background for understanding of the mechanism of high-temperature superconductivity. Recent achievements in their applications are also reviewed. A large number of illustrations and tables gives valuable information for specialists. A text-book level presentation with formulation of a general theory of strong-coupling superconductivity will help students and researches to consolidate their knowledge of this remarkable class of materials. (orig.)

Role of disorder in the multi-critical region of d-wave superconductivity and antiferromagnetism

International Nuclear Information System (INIS)

Yanase, Youichi; Ogata, Masao

2007-01-01

We investigate the disorder-induced microscopic inhomogeneity in the multi-critical region of d-wave superconductivity and antiferromagnetism on the basis of the microscopic t-t ' -U-V model. We find that a small amount of point disorder induces the nano-scale inhomogeneity of spin and superconducting fluctuations when the coherence length of superconductivity is remarkably short as in the under-doped cuprates. Then, the two fluctuations spatially segregate to avoid their competition. We show the remarkable electron-hole asymmetry in high-T c cuprates where the quite different spatial structure is expected in the electron-doped materials

Evidence for a pseudogap above T{sub c} in underdoped superconductors

Energy Technology Data Exchange (ETDEWEB)

Mesot, J; Boettger, G; Furrer, A [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Berastegui, P; Mutka, H [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

1997-09-01

Our measurements of the temperature dependence of the relaxation rate of crystal field excitations in underdoped high temperature superconductors show clear evidences for the opening of a pseudogap in the normal state. The critical temperature related to the opening of the pseudogap appears to be extremely dependent upon the energy window at which the static susceptibility is being probed. (author) 2 figs., 4 refs.

Tl Cuprate Superconductors Studied by XPS

Energy Technology Data Exchange (ETDEWEB)

Vasquez, R. P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099 (United States); Siegal, M. P. [Sandia National Laboratories, Albuquerque, NM 87185-1421 (United States); Overmyer, D. L. [Sandia National Laboratories, Albuquerque, NM 87185-1421 (United States); Ren, Z. F. [Department of Chemistry, State University of New York, Buffalo, NY 14260-3000 (United States); Lao, J. Y. [Department of Chemistry, State University of New York, Buffalo, NY 14260-3000 (United States); Wang, J. H. [Department of Chemistry, State University of New York, Buffalo, NY 14260-3000 (United States)

1999-07-01

XPS measurements on epitaxial thin films of the Tl cuprate superconductors Tl2Ba2CaCu2O8, Tl2Ba2Ca2Cu3O10, and Tl0.78Bi0.22Ba0.4Sr1.6Ca2Cu3O9-{delta} are presented. These data, together with previous measurements in this lab on Tl2Ba2CuO6-{delta} and TlBa2CaCu2O7-{delta}, comprise a comprehensive data set for comparison of Tl cuprates in which the number of Tl-O and Cu-O layers, and hence the chemical and electronic properties, vary. (c) 2000 American Vacuum Society.

Tl Cuprate Superconductors Studied by XPS

International Nuclear Information System (INIS)

Vasquez, R. P.; Siegal, M. P.; Overmyer, D. L.; Ren, Z. F.; Lao, J. Y.; Wang, J. H.

1999-01-01

XPS measurements on epitaxial thin films of the Tl cuprate superconductors Tl2Ba2CaCu2O8, Tl2Ba2Ca2Cu3O10, and Tl0.78Bi0.22Ba0.4Sr1.6Ca2Cu3O9-δ are presented. These data, together with previous measurements in this lab on Tl2Ba2CuO6-δ and TlBa2CaCu2O7-δ, comprise a comprehensive data set for comparison of Tl cuprates in which the number of Tl-O and Cu-O layers, and hence the chemical and electronic properties, vary. (c) 2000 American Vacuum Society

Bosonic Spectral Function and the Electron-Phonon Interaction in HTSC Cuprates

International Nuclear Information System (INIS)

Maksimov, E. G.; Tamm, I. E.; Kulic, M.L.; Kulic, M.L.; Dolgov, O. V.

2010-01-01

In this paper we discuss experimental evidence related to the structure and origin of the bosonic spectral function a2F(ο) in high-temperature superconducting (HTSC) cuprates at and near optimal doping. Global properties of a2F(ο), such as number and positions of peaks, are extracted by combining optics, neutron scattering, ARPES and tunnelling measurements. These methods give evidence for strong electron-phonon interaction (EPI) with 1<λep <3.5 in cuprates near optimal doping. We clarify how these results are in favor of the modified Migdal-Eliashberg (ME) theory for HTSC cuprates near optimal doping. In Section 2 we discuss theoretical ingredients such as strong EPI, strong correlations which are necessary to explain the mechanism of d-wave pairing in optimally doped cuprates. These comprise the ME theory for EPI in strongly correlated systems which give rise to the forward scattering peak. The latter is supported by the long-range part of EPI due to the weakly screened Madelung interaction in the ionic-metallic structure of layered HTSC cuprates. In this approach EPI is responsible for the strength of pairing while the residual Coulomb interaction and spin fluctuations trigger the d-wave pairing.

Spin dynamics in high-TC superconducting cuprates

International Nuclear Information System (INIS)

Bourges, Ph.

2003-07-01

This work is dedicated to the detailed investigations of the magnetic resonance peak in the superconducting state of cuprates. The existence of such a peak could be the signature of a mechanism linked to magnetism that could explain high critical temperature superconductivity. Inelastic neutron scattering is an adequate tool for the understanding of cuprate properties because it reveals magnetic fluctuations whose behaviour and variety depend strongly on temperature and on the level of doping. The last part of this work is dedicated to the study of spin dynamics in YBa 2 Cu 3 O 6+x system

Doping dependence of Meissner effect in cuprate superconductors

International Nuclear Information System (INIS)

Feng Shiping; Huang Zheyu; Zhao Huaisong

2010-01-01

Within the t-t'-J model, the doping dependence of the Meissner effect in cuprate superconductors is studied based on the kinetic energy driven superconducting mechanism. Following the linear response theory, it is shown that the electromagnetic response consists of two parts, the diamagnetic current and the paramagnetic current, which exactly cancels the diamagnetic term in the normal state, and then the Meissner effect is obtained for all the temperature T ≤ T c throughout the superconducting dome. By considering the two-dimensional geometry of cuprate superconductors within the specular reflection model, the main features of the doping and temperature dependence of the local magnetic field profile, the magnetic field penetration depth, and the superfluid density observed on cuprate superconductors are well reproduced. In particular, it is shown that in analogy to the domelike shape of the doping dependent superconducting transition temperature, the maximal superfluid density occurs around the critical doping δ ∼ 0.195, and then decreases in both lower doped and higher doped regimes.

Optical and electron microanalysis of cuprate superconductors

International Nuclear Information System (INIS)

Hoff, H.A.; Osofsky, M.S.; Toth, L.E.; Richards, L.E.; Pande, C.S.; Lechter, W.L.

1990-01-01

Individual anisotropic grains in heterogeneous and opaque cuprate materials, when viewed in a reflected-light optical microscope through crossed polarizers, often have characteristic colors, when a daylight source is used. Of the cuprate superconductors, regardless of charge carrier type, examined so far, only one characteristic color has been observed We have studied the presence of color and found a strong correlation with the existence of superconductivity. The change in color from insulator to metal to superconductor and the compositions corresponding to these changes found by quantitative energy dispersive x-ray spectroscopy on superconducting Tl-Sr-Ca-Cu-O and metallic but not superconducting La-Sr-Cu-O materials is discussed

Competing charge, spin, and superconducting orders in underdoped YBa2Cu3Oy

DEFF Research Database (Denmark)

Hücker, M.; Christensen, Niels Bech; Holmes, A. T.

2014-01-01

order decreases with underdoping to TCDW~90 K in YBa2Cu3O6.44. Together with a weakened order parameter this suggests a competition between CDW and SDW orders. In addition, the CDW order in YBa2Cu3O6.44 shows the same type of competition with superconductivity as a function of temperature and magnetic...

Electronic structure of the cuprate superconducting and pseudogap phases from spectroscopic imaging STM

Science.gov (United States)

Schmidt, A. R.; Fujita, K.; Kim, E.-A.; Lawler, M. J.; Eisaki, H.; Uchida, S.; Lee, D.-H.; Davis, J. C.

2011-06-01

We survey the use of spectroscopic imaging scanning tunneling microscopy (SI-STM) to probe the electronic structure of underdoped cuprates. Two distinct classes of electronic states are observed in both the d-wave superconducting (dSC) and the pseudogap (PG) phases. The first class consists of the dispersive Bogoliubov quasiparticle excitations of a homogeneous d-wave superconductor, existing below a lower energy scale E=Δ0. We find that the Bogoliubov quasiparticle interference (QPI) signatures of delocalized Cooper pairing are restricted to a k-space arc, which terminates near the lines connecting k=±(π/a0,0) to k=±(0,π/a0). This arc shrinks continuously with decreasing hole density such that Luttinger's theorem could be satisfied if it represents the front side of a hole-pocket that is bounded behind by the lines between k=±(π/a0,0) and k=±(0,π/a0). In both phases, the only broken symmetries detected for the |E|modulations, locally breaking both rotational and translational symmetries, coexist with this intra-unit-cell electronic symmetry breaking at E=Δ1. Their characteristic wavevector Q is determined by the k-space points where Bogoliubov QPI terminates and therefore changes continuously with doping. The distinct broken electronic symmetry states (intra-unit-cell and finite Q) coexisting at E~Δ1 are found to be indistinguishable in the dSC and PG phases. The next challenge for SI-STM studies is to determine the relationship of the E~Δ1 broken symmetry electronic states with the PG phase, and with the E<Δ0 states associated with Cooper pairing.

The oxygen isotope effect on the in-plane penetration depth in cuprate superconductors

International Nuclear Information System (INIS)

Khasanov, R; Shengelaya, A; Morenzoni, E; Conder, K; Savic, I M; Keller, H

2004-01-01

Muon spin rotation (μSR) studies of the oxygen isotope ( 16 O/ 18 O) effect (OIE) on the in-plane magnetic field penetration depth λ ab in cuprate high-temperature superconductors (HTS) are presented. First, the doping dependence of the OIE on the transition temperature T c in various HTS is briefly discussed. It is observed that different cuprate families show similar doping dependences of the OIE on T c . Then, bulk μSR, low-energy μSR, and magnetization studies of the total and site-selective OIE on λ ab are described in some detail. A substantial OIE on λ ab was observed in various cuprate families at all doping levels, suggesting that cuprate HTS are non-adiabatic superconductors. The experiments clearly demonstrate that the total OIE on T c and λ ab arise from the oxygen sites within the superconducting CuO 2 planes, demonstrating that the phonon modes involving the movement of planar oxygen are dominantly coupled to the supercarriers. Finally, it is shown that the OIE on T c and λ ab exhibit a relation that appears to be generic for different families of cuprate HTS. The observation of these unusual isotope effects implies that lattice effects play an essential role in cuprate HTS and have to be considered in any realistic model of high-temperature superconductivity

Tunneling spectroscopy of heavily underdoped crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}

Energy Technology Data Exchange (ETDEWEB)

Ozyuzer, L.; Zasadzinski, J. F.; Miyakawa, N.; Kendziora, C.; Jian, S.; Hinks, D. G.; Gray, K. E.

2000-02-17

Crystals of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} with optimal {Tc} = 95 K have been underdoped using two different methods and the superconducting gaps have been obtained by tunneling. In some cases, three different tunneling geometries have been utilized: point contact, STM and break junctions. The first doping method involves control of the oxygen content by annealing in various partial pressures of oxygen. These crystals exhibit a narrow spread of gap values over a wide doping range from overdoped ({Tc} = 56 K) to underdoped with {Tc} = 70 K. However, for underdoped crystals with {Tc} midpoints in the range 25 K--63 K, there is a dramatic increase in the spread of gap values which may signal the development of static phase separation of either chemical or electronic origin. To avoid possible chemical phase separation, the authors have explored another doping procedure which incorporates Dy substitution on the Ca site. These crystals exhibit a relatively narrow superconducting transition width and some preliminary tunneling spectra will be presented.

Deeply bound pionic atom

International Nuclear Information System (INIS)

Toki, Hiroshi; Yamazaki, Toshimitsu

1989-01-01

The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

Fragile charge order in the nonsuperconducting ground state of the underdoped high-temperature superconductors.

Science.gov (United States)

Tan, B S; Harrison, N; Zhu, Z; Balakirev, F; Ramshaw, B J; Srivastava, A; Sabok-Sayr, S A; Sabok, S A; Dabrowski, B; Lonzarich, G G; Sebastian, Suchitra E

2015-08-04

The normal state in the hole underdoped copper oxide superconductors has proven to be a source of mystery for decades. The measurement of a small Fermi surface by quantum oscillations on suppression of superconductivity by high applied magnetic fields, together with complementary spectroscopic measurements in the hole underdoped copper oxide superconductors, point to a nodal electron pocket from charge order in YBa2Cu3(6+δ). Here, we report quantum oscillation measurements in the closely related stoichiometric material YBa2Cu4O8, which reveals similar Fermi surface properties to YBa2Cu3(6+δ), despite the nonobservation of charge order signatures in the same spectroscopic techniques, such as X-ray diffraction, that revealed signatures of charge order in YBa2Cu3(6+δ). Fermi surface reconstruction in YBa2Cu4O8 is suggested to occur from magnetic field enhancement of charge order that is rendered fragile in zero magnetic fields because of its potential unconventional nature and/or its occurrence as a subsidiary to more robust underlying electronic correlations.

Visualizing electron pockets in cuprate superconductors

Science.gov (United States)

Das, Tanmoy; Markiewicz, R. S.; Bansil, A.; Balatsky, A. V.

2012-06-01

Fingerprints of the electron pocket in cuprates have been obtained only in numerous magnetotransport measurements, but its absence in spectroscopic observations poses a long-standing mystery. We develop a theoretical tool to provide ways to detect electron pockets via spectroscopies including scanning tunneling microscopy (STM) spectra, inelastic neutron scattering (INS), and angle-resolved photoemission spectroscopy (ARPES). We show that the quasiparticle-interference (QPI) pattern, measured by STM, shows an additional seven q vectors associated with the scattering on the electron pocket than that on the hole pocket. Furthermore, the Bogolyubov quasiparticle scatterings of the electron pocket lead to a second magnetic resonance mode in the INS spectra at a higher resonance energy. Finally, we reanalyze some STM, INS, and ARPES experimental data of several cuprates which dictates the direct fingerprints of electron pockets in these systems.

Insights on the cuprate high energy anomaly observed in ARPES

International Nuclear Information System (INIS)

Moritz, B.; Johnston, S.; Devereaux, T.P.

2010-01-01

Recently, angle-resolved photoemission spectroscopy has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). The anomaly is present for both hole- and electron-doped cuprates as well as the half-filled parent insulators with different energy scales arising on either side of the phase diagram. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. creating a 'waterfall'-like appearance, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram. We find that the anomaly demarcates a transition, or cross-over, from a quasiparticle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character.

Insights on the cuprate high energy anomaly observed in ARPES

Energy Technology Data Exchange (ETDEWEB)

Moritz, B., E-mail: moritzb@slac.stanford.ed [Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Department of Physics and Astrophysics, University of North Dakota, Grand Forks, ND 58202 (United States); Johnston, S. [Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1 (Canada); Devereaux, T.P. [Stanford Institute for Materials and Energy Science, SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States)

2010-07-15

Recently, angle-resolved photoemission spectroscopy has been used to highlight an anomalously large band renormalization at high binding energies in cuprate superconductors: the high energy 'waterfall' or high energy anomaly (HEA). The anomaly is present for both hole- and electron-doped cuprates as well as the half-filled parent insulators with different energy scales arising on either side of the phase diagram. While photoemission matrix elements clearly play a role in changing the aesthetic appearance of the band dispersion, i.e. creating a 'waterfall'-like appearance, they provide an inadequate description for the physics that underlies the strong band renormalization giving rise to the HEA. Model calculations of the single-band Hubbard Hamiltonian showcase the role played by correlations in the formation of the HEA and uncover significant differences in the HEA energy scale for hole- and electron-doped cuprates. In addition, this approach properly captures the transfer of spectral weight accompanying doping in a correlated material and provides a unifying description of the HEA across both sides of the cuprate phase diagram. We find that the anomaly demarcates a transition, or cross-over, from a quasiparticle band at low binding energies near the Fermi level to valence bands at higher binding energy, assumed to be of strong oxygen character.

The oxygen isotope effect on the in-plane penetration depth in cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Khasanov, R [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland); Shengelaya, A [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland); Morenzoni, E [Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Conder, K [Laboratory for Neutron Scattering, ETH Zuerich and PSI Villigen, CH-5232 Villigen PSI (Switzerland); Savic, I M [Faculty of Physics, University of Belgrade, 11001 Belgrade (Serbia and Montenegro); Keller, H [Physik-Institut der Universitaet Zuerich, CH-8057 Zurich (Switzerland)

2004-10-13

Muon spin rotation ({mu}SR) studies of the oxygen isotope ({sup 16}O/{sup 18}O) effect (OIE) on the in-plane magnetic field penetration depth {lambda}{sub ab} in cuprate high-temperature superconductors (HTS) are presented. First, the doping dependence of the OIE on the transition temperature T{sub c} in various HTS is briefly discussed. It is observed that different cuprate families show similar doping dependences of the OIE on T{sub c}. Then, bulk {mu}SR, low-energy {mu}SR, and magnetization studies of the total and site-selective OIE on {lambda}{sub ab} are described in some detail. A substantial OIE on {lambda}{sub ab} was observed in various cuprate families at all doping levels, suggesting that cuprate HTS are non-adiabatic superconductors. The experiments clearly demonstrate that the total OIE on T{sub c} and {lambda}{sub ab} arise from the oxygen sites within the superconducting CuO{sub 2} planes, demonstrating that the phonon modes involving the movement of planar oxygen are dominantly coupled to the supercarriers. Finally, it is shown that the OIE on T{sub c} and {lambda}{sub ab} exhibit a relation that appears to be generic for different families of cuprate HTS. The observation of these unusual isotope effects implies that lattice effects play an essential role in cuprate HTS and have to be considered in any realistic model of high-temperature superconductivity.

Superconducting thallium cuprates obtained by substitution of copper for thallium in the double-thallium layer cuprate (Tl2212)

International Nuclear Information System (INIS)

Gopalakrishnan, J.; Shivakumara, C.; Manivannan, V.

1994-01-01

A new series of superconducting thallium cuprates of nominal composition, (Tl 2-x Cu x )Ba 2 CaCu 2 O 8 (0 c s in the range 110--99K. The phases are metastable, decomposing at higher temperatures (∼1,150K) to a mixture of thallium cuprates, CuO and BaCuO 2 . Significantly, x=1 member decomposes at 1,150K to mixture of Tl2223, CuO and BaCuO 2 . Chemical titrations involving oxidation of bromide ions reveals that the copper substituting for thallium in (Tl 2-x Cu x )Ba 2 CaCu 2 O 8 most likely occurs in the III oxidation state for x≤0.25 and in a mixed state (II,III) state for x>0.25

Fermion local charged boson model and cuprate superconductors

International Nuclear Information System (INIS)

Sinha, K.P.; Kakani, S.L.

2002-01-01

One of the most exciting developments in Science in past few years is the discovery of high temperature superconductivity (HTSC) in cuprates. It has been observed that the superconducting state in these cuprates is rather normal compared to the anomalous normal state. This discovery has led to deluge of experimental and theoretical researches all along the world. These cuprates are close to metal-insulator transition and the stability of the insulating and metallic phase depends on the degree of doping. Measurements of physical properties of these systems have revealed many anomalous results both in the superconducting and normal states, e.g. d-wave superconducting gap, the presence of pseudo gap in the normal state, static or dynamic striped structure of CuO 2 planes etc. These have posed serious theoretical challenges towards formulating the mechanisms of pairing and explanation of anomalous behaviour. Several theoretical proposals have been advanced and only a few are likely to survive in the teeth of some reliable experimental data. A combined mechanism mediated by phonons and lochons (local charged bosons, local pairs or bipolarons) for the pairing of fermions (holes or electrons) belonging to a wide band provides a microscopic explanation of anomalous normal state properties of HTSC cuprates and vindicates features of the phenomenological marginal Fermi liquid formulation. In the present review article detailed features of combined lochon and phonon mediated pairing mechanism are presented and a contact with the normal and superconducting state properties of HTSC in YBa 2 Cu 3 O x does indicate pair hopping between planes via such resonant centres lying in between the CuO 2 planes. (author)

Spin fluctuations and the

Directory of Open Access Journals (Sweden)

V.M. Loktev

2008-09-01

Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

Fermi-surface reconstruction by stripe order in cuprate superconductors

Science.gov (United States)

Laliberté, Francis

2012-02-01

The origin of pairing in a superconductor resides in the underlying normal state. In the cuprate high-temperature superconductor YBCO, application of a magnetic field to suppress superconductivity reveals a ground state that appears to break the translational symmetry of the lattice, pointing to some density-wave order [1,2,3]. In another cuprate, Eu-LSCO, the onset of stripe order - a modulation of spin and charge densities - at low temperature is well established [4]. By a comparative study of thermoelectric transport in the cuprates YBCO and Eu-LSCO, we show that the two materials exhibit a very similar process of Fermi-surface reconstruction as a function of temperature and doping [5,6]. This strongly suggests that Fermi-surface reconstruction is caused by stripe order in both cases, compelling evidence that stripe order is a generic tendency of hole-doped cuprates.[4pt] Work done in collaboration with J. Chang, N. Doiron-Leyraud, E. Hassinger, R. Daou, D. LeBoeuf, M. Rondeau, B. J. Ramshaw, R. Liang, D. A. Bonn, W. N. Hardy, S. Pyon, T. Takayama, H. Takagi, I. Sheikin, L. Malone, C. Proust, K. Behnia and L. Taillefer.[4pt] [1] N. Doiron-Leyraud et al., Nature 447, 565 (2007).[0pt] [2] D. LeBoeuf et al., Nature 450, 533 (2007).[0pt] [3] D. LeBoeuf et al., Phys. Rev. B 83, 054506 (2011).[0pt] [4] J. Fink et al., Phys. Rev. B 83, 092503 (2011).[0pt] [5] J. Chang et al., Phys. Rev. Lett. 104, 057005 (2010).[0pt] [6] F. Lalibert'e et al., Nat. Commun. 2, 432 (2011).

Diffusion of nonequilibrium quasi-particles in a cuprate superconductor

International Nuclear Information System (INIS)

Gedik, N.; Orenstein, J.; Liang, Ruixing; Bonn, D.A.; Hardy, W.N.

2003-01-01

We report a transport study of nonequilibrium quasi-particles in a high-transition-temperature cuprate superconductor using the transient grating technique. Low-intensity laser excitation (at a photon energy of 1.5 electron volts) was used to introduce a spatially periodic density of quasi-particles into a high-quality untwinned single crystal of YBa2Cu3O6.5. Probing the evolution of the initial density through space and time yielded the quasi-particle diffusion coefficient and the inelastic and elastic scattering rates. The technique reported here is potentially applicable to precision measurements of quasi-particle dynamics not only in cuprate superconductors but in other electronic systems as well

Oxygen hole mechanism of superconductivity in cuprates and other metal oxides

International Nuclear Information System (INIS)

Rao, C.N.R.

1989-01-01

Several theoretical models have been proposed to explain high-temperature superconductivity in cuprates. An issue that is central to any model is the nature of copper and oxygen species in the cuprates since superconductivity clearly owes its origin to the Cu-O sheets universally present in all the cuprate families. Thus, the five families of cuprate superconductors, La 2 - x M x CuO 4 (M = Ca, Sr or Ba) of the K 2 NiF 4 structure, LnBa 2 Cu 3 O 7 - δ (Ln = Y or rare earth), Bi 2 (Ca, Sr) n + 1 Cu n O 2n + 4 , Tl 2 (Ca, Ba) n + 1 Cu n O 2n + 4 and Tl (Ca, Ba) n + 1 Cu n O 2n + 3 , all contain two-dimensional Cu-O sheets. The Cu-O chains additionally present in the 123 compounds do not seem to play any crucial role. It has been generally believed that magnetic, superconducting and related properties of cuprates have some thing to do with the mixed valency of copper. For example, the resonating valence bond (RVB) model requires the presence of holes on Cu sites (Cu 3 + species). There are also a few models, however, based on the presence of holes on oxygen sites (O - species); dimerization of oxygen holes has also been suggested to occur by a few workers. It is the purpose of this article to briefly present the available experimental evidence for the presence of oxygen holes and to discuss their role in high-temperature conductivity. It will be shown that these holes play a role in other oxide materials as well as including the Cu-free Ba 1 - x K x BiO 3 superconductor

Interpretation of scanning tunneling quasiparticle interference and impurity states in cuprates.

Science.gov (United States)

Kreisel, A; Choubey, Peayush; Berlijn, T; Ku, W; Andersen, B M; Hirschfeld, P J

2015-05-29

We apply a recently developed method combining first principles based Wannier functions with solutions to the Bogoliubov-de Gennes equations to the problem of interpreting STM data in cuprate superconductors. We show that the observed images of Zn on the surface of Bi_{2}Sr_{2}CaCu_{2}O_{8} can only be understood by accounting for the tails of the Cu Wannier functions, which include significant weight on apical O sites in neighboring unit cells. This calculation thus puts earlier crude "filter" theories on a microscopic foundation and solves a long-standing puzzle. We then study quasiparticle interference phenomena induced by out-of-plane weak potential scatterers, and show how patterns long observed in cuprates can be understood in terms of the interference of Wannier functions above the surface. Our results show excellent agreement with experiment and enable a better understanding of novel phenomena in the cuprates via STM imaging.

Vortex phase diagram for extremely underdoped Bi2.2Sr1.72La0.08CaCu2O8+δ

International Nuclear Information System (INIS)

Yamaguchi, Yuij; Oka, Kunihiko; Mumtaz, Arif; Bando, Hiroshi

2003-01-01

Vortex phase diagram for H parallel c of extremely underdoped Bi 2.2 Sr 1.72 La 0.08 CaCu 2 O 8+δ superconductor was determined from a magnetization measurement. In the magnetization curve, a second peak in the low temperature region and a sharp change in the high temperature region were observed. The second-peak field and the sharp-change field are explained based on the three-to-two dimensional crossover and the decoupling transition of the vortex lattice, respectively. For the most underdoped sample, which has the transition temperature T c =60.2 K, the anisotropy constant γ and the ab plane penetration length λ 0 have been deduced to be γ=320 and λ 0 ∼340 nm, respectively

High-energy kink in the single-particle spectra of cuprates

International Nuclear Information System (INIS)

Cojocaru, S.; Citro, R.; Marinaro, M.

2008-01-01

Within a phenomenological model where electrons are coupled to a bosonic mode in a generic form of damped oscillator, we analyze the high-energy kink recently observed in ARPES experiments on cuprates. It is shown that the model allows to describe the main anomalous features found in experiments, such as the broad incoherent spectral weight, the 'waterfall dispersion', its doping and temperature dependence. In contrast to the low-energy kink, presence of significant damping is required to account for the anomalies. The 'bosonic mode' is related to the incoherent excitation peak observed in optical conductivity spectra of cuprates

High-energy kink in the single-particle spectra of cuprates

Energy Technology Data Exchange (ETDEWEB)

Cojocaru, S. [Dipartimento di Fisica ' E. R. Caianiello' and C.N.I.S.M., Universita degli Studi di Salerno, Via S. Allende, I-84081 Baronissi (Italy); Institute of Applied Physics, Chisinau 2028 (Moldova, Republic of); Citro, R. [Dipartimento di Fisica ' E. R. Caianiello' and C.N.I.S.M., Universita degli Studi di Salerno, Via S. Allende, I-84081 Baronissi (Italy)], E-mail: citro@sa.infn.it; Marinaro, M. [Dipartimento di Fisica ' E. R. Caianiello' and C.N.I.S.M., Universita degli Studi di Salerno, Via S. Allende, I-84081 Baronissi (Italy); I.I.A.S.S., Via G. Pellegrino, n. 19 84019 Vietri sul Mare (Italy)

2008-04-01

Within a phenomenological model where electrons are coupled to a bosonic mode in a generic form of damped oscillator, we analyze the high-energy kink recently observed in ARPES experiments on cuprates. It is shown that the model allows to describe the main anomalous features found in experiments, such as the broad incoherent spectral weight, the 'waterfall dispersion', its doping and temperature dependence. In contrast to the low-energy kink, presence of significant damping is required to account for the anomalies. The 'bosonic mode' is related to the incoherent excitation peak observed in optical conductivity spectra of cuprates.

Damped spin excitations in a doped cuprate superconductor with orbital hybridization

DEFF Research Database (Denmark)

Ivashko, O.; Shaik, N. E.; Lu, X.

2017-01-01

A resonant inelastic x-ray scattering study of overdamped spin excitations in slightly underdoped La2-xSrxCuO4 (LSCO) with x = 0.12 and 0.145 is presented. Three high-symmetry directions have been investigated: (1) the antinodal (0,0) -> (½,0), (2) the nodal (0,0) -> (¼, ¼), and (3) the zone-boun...

Superconducting Mercury-Based Cuprate Films with a Zero-Resistance Transition Temperature of 124 Kelvin

Science.gov (United States)

Tsuei, C. C.; Gupta, A.; Trafas, G.; Mitzi, D.

1994-03-01

The synthesis of high-quality films of the recently discovered mercury-based cuprate films with high transition temperatures has been plagued by problems such as the air sensitivity of the cuprate precursor and the volatility of Hg and HgO. These processing difficulties have been circumvented by a technique of atomic-scale mixing of the HgO and cuprate precursors, use of a protective cap layer, and annealing in an appropriate Hg and O_2 environment. With this procedure, a zero-resistance transition temperature as high as 124 kelvin in c axis-oriented epitaxial HgBa_2CaCu_2O6+δ films has been achieved.

Superconducting mercury-based cuprate films with a zero-resistance transition temperature of 124 Kelvin.

Science.gov (United States)

Tsuei, C C; Gupta, A; Trafas, G; Mitzi, D

1994-03-04

The synthesis of high-quality films of the recently discovered mercury-based cuprate films with high transition temperatures has been plagued by problems such as the air sensitivity of the cuprate precursor and the volatility of Hg and HgO. These processing difficulties have been circumvented by a technique of atomic-scale mixing of the HgO and cuprate precursors, use of a protective cap layer, and annealing in an appropriate Hg and O(2) environment. With this procedure, a zero-resistance transition temperature as high as 124 kelvin in c axis-oriented epitaxial HgBa(2)CaCu(2)O(6+delta) films has been achieved.

Competing pseudogap and impurity effects on the normal-state specific heat properties of cuprate superconductors

Science.gov (United States)

Dzhumanov, S.; Karimboev, E. X.

2014-07-01

In this paper, we show that the pseudogap in the excitation spectra of high-Tc cuprates together with the impurity phase and charge inhomogeneity plays key roles in determining the essential features of their anomalous specific heat properties observed above Tc. We consider the doped cuprate superconductor as a multi-carrier model system (which consists of intrinsic and extrinsic polarons and pre-formed bosonic Cooper pairs) and study the competing pseudogap and impurity effects on the normal-state electronic specific heat of high-Tc cuprates taking into account charge inhomogeneities. We argue that unconventional electron-phonon interactions are responsible for the precursor Cooper pairing in the polaronic band below a mean-field temperature T∗ and the existence of a pseudogap above Tc in the cuprates. The electronic specific heat Ce(T) of doped cuprates below T∗ is calculated taking into account three contributions coming from the excited components of Cooper pairs, the ideal Bose-gas of incoherent Cooper pairs and the unpaired carriers in the impurity band. Above T∗, two contributions to Ce(T) coming from the unpaired intrinsic and extrinsic polarons are calculated within the two-component degenerate Fermi-gas model. By comparing our results with the experimental Ce(T) data obtained for La- and Y-based cuprates, we find that the observed behaviors of Ce(T) (below and above T∗) are similar to the calculated results for Ce(T) and the BCS-type jumps of Ce(T) at T∗ may be depressed by the impurity effects and may become more or less pronounced BCS-type anomalies in Ce(T) .

Temperature and doping dependence of the high-energy kink in cuprates.

Science.gov (United States)

Zemljic, M M; Prelovsek, P; Tohyama, T

2008-01-25

It is shown that spectral functions within the extended t-J model, evaluated using the finite-temperature diagonalization of small clusters, exhibit the high-energy kink in single-particle dispersion consistent with recent angle-resolved photoemission results on hole-doped cuprates. The kink and waterfall-like features persist up to large doping and to temperatures beyond J; hence, the origin can be generally attributed to strong correlations and incoherent hole propagation at large binding energies. In contrast, our analysis predicts that electron-doped cuprates do not exhibit these phenomena in photoemission.

Quantum critical scaling at the edge of Fermi liquid stability in a cuprate superconductor.

Science.gov (United States)

Butch, Nicholas P; Jin, Kui; Kirshenbaum, Kevin; Greene, Richard L; Paglione, Johnpierre

2012-05-29

In the high-temperature cuprate superconductors, the pervasiveness of anomalous electronic transport properties suggests that violation of conventional Fermi liquid behavior is closely tied to superconductivity. In other classes of unconventional superconductors, atypical transport is well correlated with proximity to a quantum critical point, but the relative importance of quantum criticality in the cuprates remains uncertain. Here, we identify quantum critical scaling in the electron-doped cuprate material La(2-x)Ce(x)CuO(4) with a line of quantum critical points that surrounds the superconducting phase as a function of magnetic field and charge doping. This zero-temperature phase boundary, which delineates a metallic Fermi liquid regime from an extended non-Fermi liquid ground state, closely follows the upper critical field of the overdoped superconducting phase and gives rise to an expanse of distinct non-Fermi liquid behavior at finite temperatures. Together with signatures of two distinct flavors of quantum fluctuations, these facts suggest that quantum criticality plays a significant role in shaping the anomalous properties of the cuprate phase diagram.

Angle-resolved photoemission in high Tc cuprates from theoretical viewpoints

International Nuclear Information System (INIS)

Tohyama, T.; Maekawa, S.

2000-01-01

The angle-resolved photoemission (ARPES) technique has been developed rapidly over the last decade, accompanied by the improvement of energy and momentum resolutions. This technique has been established as the most powerful tool to investigate the high T c cuprate superconductors. We review recent ARPES data on the cuprates from a theoretical point of view, with emphasis on the systematic evolution of the spectral weight near the momentum (π, 0) from insulator to overdoped systems. The effects of charge stripes on the ARPES spectra are also reviewed. Some recent experimental and theoretical efforts to understand the superconducting state and the pseudogap phenomenon are discussed. (author)

Magnetic excitations and phase separation in the underdoped La2-xSrxCuO4 superconductor measured by resonant inelastic X-ray scattering.

Science.gov (United States)

Braicovich, L; van den Brink, J; Bisogni, V; Sala, M Moretti; Ament, L J P; Brookes, N B; De Luca, G M; Salluzzo, M; Schmitt, T; Strocov, V N; Ghiringhelli, G

2010-02-19

We probe the collective magnetic modes of La2CuO4 and underdoped La2-xSrxCuO4 (LSCO) by momentum resolved resonant inelastic x-ray scattering (RIXS) at the Cu L3 edge. For the undoped antiferromagnetic sample, we show that the single magnon dispersion measured with RIXS coincides with the one determined by inelastic neutron scattering, thus demonstrating that x rays are an alternative to neutrons in this field. In the spin dynamics of LSCO, we find a branch dispersing up to approximately 400 meV coexisting with one at lower energy. The high-energy branch has never been seen before. It indicates that underdoped LSCO is in a dynamic inhomogeneous spin state.

Renormalized modes in cuprate superconductors

Science.gov (United States)

Gupta, Anushri; Kumari, Anita; Verma, Sanjeev K.; Indu, B. D.

2018-04-01

The renormalized mode frequencies are obtained with the help of quantum dynamical approach of many body phonon Green's function technique via a general Hamiltonian (excluding BCS Hamiltonian) including the effects of phonons and electrons, anharmonicities and electron-phonon interactions. The numerical estimates have been carried out to study the renormalized mode frequency of high temperature cuprate superconductor (HTS) YBa2Cu3O7-δ using modified Born-Mayer-Huggins interaction potential (MBMHP) best applicable to study the dynamical properties of all HTS.

Elucidation of the origins of transport behaviour and quantum oscillations in high temperature superconducting cuprates

International Nuclear Information System (INIS)

Wilson, John A

2009-01-01

A detailed exposition is given of recent transport and 'quantum oscillation' results from high temperature superconducting (HTSC) systems covering the full carrier range from overdoped to underdoped material. This now very extensive and high quality data set is here interpreted within the framework developed by the author of local pairs and boson-fermion resonance, arising in the context of negative- U behaviour within an inhomogeneous electronic environment. The strong inhomogeneity comes with the mixed-valence condition of these materials, which when underdoped lie in close proximity to the Mott-Anderson transition. The observed intense scattering is presented as resulting from pair formation and from electron-boson collisions in the resonant crossover circumstance. The high level of scattering carries the systems to incoherence in the pseudogapped state, p c (= 0.183). In a high magnetic field the striped partition of the inhomogeneous charge distribution becomes much strengthened and regularized. Magnetization and resistance oscillations, of period dictated by the favoured positioning of the fluxon array within the real space environment of the diagonal 2D charge striping array, are demonstrated to be responsible for the recently reported behaviour hitherto widely attributed to the quantum oscillation response of a much more standard Fermi liquid condition. A detailed analysis embracing all the experimental data serves to reveal that in the given conditions of very high field, low temperature, 2D-striped, underdoped, d-wave superconducting, HTSC material the flux quantum becomes doubled to h/e.

First-principles study on the creation of holes in high Tc cuprates

International Nuclear Information System (INIS)

Ambrosch-Draxl, C.; Sherman, E.Ya.; Auer, H.; Thonhauser, T.

2004-01-01

We investigate the charge redistribution in high T c cuprates as a function of pressure, composition, and doping. To this extent we have performed first-principles calculations based on density functional theory for several representatives of the Hg based cuprates. In particular, we focus on the creation of holes in the copper-oxygen planes. Conclusions are drawn about the similarities and differences between the three parameters influencing the superconducting transition temperature. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Manganite/Cuprate Superlattice as Artificial Reentrant Spin Glass

KAUST Repository

Ding, Junfeng; Cossu, Fabrizio; Lebedev, Oleg I.; Zhang, Yuqin; Zhang, Zhidong; Schwingenschlö gl, Udo; Wu, Tao

2016-01-01

magnetic memory effect discovered in oxide heterostructures composed of ultrathin manganite La0.7Sr0.3MnO3 (LSMO) and cuprate La2CuO4 (LCO) layers. These heterostructures are featured with enhanced ferromagnetism before entering the spin glass state: a

Towards a complete Fermi surface in underdoped high Tc superconductors

Science.gov (United States)

Harrison, Neil

The discovery of magnetic quantum oscillations in underdoped high Tc superconductors raised many questions, and initiated a quest to understand the origin of the Fermi surface the like of which had not been seen since the very first discovery of quantum oscillations in elemental bismuth. While studies of the Fermi surface of materials are today mostly assisted by computer codes for calculating the electronic band structure, this was not the case in the underdoped high Tc materials. The Fermi surface was shown to reconstructed into small pockets, yet there was no hint of a viable order parameter. Crucial clues to understanding the origin of the Fermi surface were provided by the small value of the observed Fermi surface cross-section, the negative Hall coefficient and the small electronic heat capacity at high magnetic fields. We also know that the magnetic fields were likely to be too weak to destroy the pseudogap and that vortex pinning effects could be seen to persist to high magnetic fields at low temperatures. I will show that the Fermi surface that appears to fit best with the experimental observations is a small electron pocket formed by connecting the nodal `Fermi arcs' seen in photoemission experiments, corresponding to a density-wave state with two different orthogonal ordering vectors. The existence of such order has subsequently been detected by x-ray scattering experiments, thereby strengthening the case for charge ordering being responsible for reconstructing the Fermi surface. I will discuss new efforts to understand the relationship between the charge ordering and the pseudogap state, discussing the fate of the quasiparticles in the antinodal region and the dimensionality of the Fermi surface. The author acknowledges contributions from Suchitra Sebastian, Brad Ramshaw, Mun Chan, Yu-Te Hsu, Mate Hartstein, Gil Lonzarich, Beng Tan, Arkady Shekhter, Fedor Balakirev, Ross McDonald, Jon Betts, Moaz Altarawneh, Zengwei Zhu, Chuck Mielke, James Day, Doug

Enhancing critical current density of cuprate superconductors

Science.gov (United States)

Chaudhari, Praveen

2015-06-16

The present invention concerns the enhancement of critical current densities in cuprate superconductors. Such enhancement of critical current densities include using wave function symmetry and restricting movement of Abrikosov (A) vortices, Josephson (J) vortices, or Abrikosov-Josephson (A-J) vortices by using the half integer vortices associated with d-wave symmetry present in the grain boundary.

Magnetic-Field-Enhanced Incommensurate Magnetic Order in the Underdoped High-Temperature Superconductor YBa2Cu3O6.45

DEFF Research Database (Denmark)

Haug, D.; Hinkov, V.; Suchaneck, A.

2009-01-01

We present a neutron-scattering study of the static and dynamic spin correlations in the underdoped high-temperature superconductor YBa2Cu3O6.45 in magnetic fields up to 15 T. The field strongly enhances static incommensurate magnetic order at low temperatures and induces a spectral-weight shift...

Zeeman and orbital limiting magnetic fields in cuprates: The ...

Indian Academy of Sciences (India)

1IBM T. J. Watson Research Center, Yorktown Heights, New York 10598, ... In cuprates, in a view where pairing correlations set in at the pseudogap ... the field Hc2 bounding the superconducting response and the pseudogap closing field.

Theory of superconductivity and spin excitations in cuprates

Science.gov (United States)

Plakida, Nikolay M.

2018-06-01

A microscopic theory of high-temperature superconductivity in strongly correlated systems as cuprates is presented. The two-subband extended Hubbard model is considered where the intersite Coulomb repulsion and electron-phonon interaction are taken into account. The low-energy spin excitations are considered within the t-J model.

Condensation energy of the superconducting bilayer cuprates

Indian Academy of Sciences (India)

cuprates also depends on the number of CuO2 layers per unit cell and the extent of doping. In a bilayer or ... unit cell is smaller than the adjacent layers in a single layer system; therefore it is natural to include interlayer .... energy conservation principle, the change in the kinetic energy of the electrons in the out- of-plane ...

Oxygen diffusion in cuprate superconductors

International Nuclear Information System (INIS)

Routbort, J.L.; Rothman, S.J.

1995-01-01

Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La 2-x Sr x CuO 4 , YBa 2 Cu 3 O 7- δ, YBa 2 Cu 4 O 8 , and the Bi 2 Sr 2 Ca n-1 Cu n O 2+4 (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible

Flop transitions in cuprate and color superconductors: From SO(5) to SO(10) unification?

Energy Technology Data Exchange (ETDEWEB)

Chandrasekharan, S.; Chudnovsky, V.; Schlittgen, B.; Wiese, U.-J

2001-03-01

The phase diagrams of cuprate superconductors and of QCD at non-zero baryon chemical potential are qualitatively similar. The Neel phase of the cuprates corresponds to the chirally broken phase of QCD, and the high-temperature superconducting phase corresponds to the color superconducting phase. In the SO(5) theory for the cuprates the SO(3){sub s} spin rotational symmetry and the U(1){sub em} gauge symmetry of electromagnetism are dynamically unified. This suggests that the SU(2){sub L} x SU(2){sub R} x U(1){sub B} chiral symmetry of QCD and the SU(3){sub c} color gauge symmetry may get unified to SO(10). Dynamical enhancement of symmetry from SO(2){sub s} x Z(2) to SO(3){sub s} is known to occur in anisotropic antiferromagnets. In these systems the staggered magnetization flops from an easy 3-axis into the 12-plane at a critical value of the external magnetic field. Similarly, the phase transitions in the SO(5) and SO(10) models are flop transitions of a 'superspin'. Despite this fact, a renormalization group flow analysis in 4 -- {epsilon} dimensions indicates that a point with full SO(5) or SO(10) symmetry exists neither in the cuprates nor in QCD.

Flop transitions in cuprate and color superconductors: From SO(5) to SO(10) unification?

International Nuclear Information System (INIS)

Chandrasekharan, S.; Chudnovsky, V.; Schlittgen, B.; Wiese, U.-J.

2001-01-01

The phase diagrams of cuprate superconductors and of QCD at non-zero baryon chemical potential are qualitatively similar. The Neel phase of the cuprates corresponds to the chirally broken phase of QCD, and the high-temperature superconducting phase corresponds to the color superconducting phase. In the SO(5) theory for the cuprates the SO(3) s spin rotational symmetry and the U(1) em gauge symmetry of electromagnetism are dynamically unified. This suggests that the SU(2) L x SU(2) R x U(1) B chiral symmetry of QCD and the SU(3) c color gauge symmetry may get unified to SO(10). Dynamical enhancement of symmetry from SO(2) s x Z(2) to SO(3) s is known to occur in anisotropic antiferromagnets. In these systems the staggered magnetization flops from an easy 3-axis into the 12-plane at a critical value of the external magnetic field. Similarly, the phase transitions in the SO(5) and SO(10) models are flop transitions of a 'superspin'. Despite this fact, a renormalization group flow analysis in 4 -- ε dimensions indicates that a point with full SO(5) or SO(10) symmetry exists neither in the cuprates nor in QCD

Charge and current orders in the spin-fermion model with overlapping hot spots

Science.gov (United States)

Volkov, Pavel A.; Efetov, Konstantin B.

2018-04-01

Experiments carried over the last years on the underdoped cuprates have revealed a variety of symmetry-breaking phenomena in the pseudogap state. Charge-density waves, breaking of C4 rotational symmetry as well as time-reversal symmetry breaking have all been observed in several cuprate families. In this regard, theoretical models where multiple nonsuperconducting orders emerge are of particular interest. We consider the recently introduced [Volkov and Efetov, Phys. Rev. B 93, 085131 (2016), 10.1103/PhysRevB.93.085131] spin-fermion model with overlapping `hot spots' on the Fermi surface. Focusing on the particle-hole instabilities we obtain a rich phase diagram with the chemical potential relative to the dispersion at (0 ,π );(π ,0 ) and the Fermi surface curvature in the antinodal regions being the control parameters. We find evidence for d-wave Pomeranchuk instability, d-form factor charge density waves, as well as commensurate and incommensurate staggered bond current phases similar to the d-density wave state. The current orders are found to be promoted by the curvature. Considering the appropriate parameter range for the hole-doped cuprates, we discuss the relation of our results to the pseudogap state and incommensurate magnetic phases of the cuprates.

Quasiparticle states driven by a scattering on the preformed electron pairs

Directory of Open Access Journals (Sweden)

T. Domanski

2016-02-01

Full Text Available We analyze evolution of the single particle excitation spectrum of the underdoped cuprate superconductors near the anti-nodal region, considering temperatures below and and above the phase transition. We inspect the phenomenological self-energy that reproduces the angle-resolved-photoemission-spectroscopy (ARPES data and we show that above the critical temperature, such procedure implies a transfer of the spectral weight from the Bogoliubov-type quasiparticles towards the in-gap damped states. We also discuss some possible microscopic arguments explaining this process.

Ginzburg-Landau equation and vortex liquid phase of Fermi liquid superconductors

International Nuclear Information System (INIS)

Ng, T-K; Tse, W-T

2007-01-01

In this paper we study the Ginzburg-Landau (GL) equation for Fermi liquid superconductors with strong Landau interactions F 0s and F 1s . We show that Landau interactions renormalize two parameters entering the GL equation, leading to the renormalization of the compressibility and superfluid density. The renormalization of the superfluid density in turn leads to an unconventional (2D) Berezinskii-Kosterlitz-Thouless (BKT) transition and vortex liquid phase. Application of the GL equation to describe underdoped high-T c cuprates is discussed

Hybrid crystals of cuprates and iron-based superconductors

Science.gov (United States)

Xia, Dai; Cong-Cong, Le; Xian-Xin, Wu; Jiang-Ping, Hu

2016-07-01

We propose two possible new compounds, Ba2CuO2Fe2As2 and K2CuO2Fe2Se2, which hybridize the building blocks of two high temperature superconductors, cuprates and iron-based superconductors. These compounds consist of square CuO2 layers and antifluorite-type Fe2 X 2 (X = As, Se) layers separated by Ba/K. The calculations of binding energies and phonon spectra indicate that they are dynamically stable, which ensures that they may be experimentally synthesized. The Fermi surfaces and electronic structures of the two compounds inherit the characteristics of both cuprates and iron-based superconductors. These compounds can be superconductors with intriguing physical properties to help to determine the pairing mechanisms of high T c superconductivity. Project supported by the National Basic Research Program of China (Grant No. 2015CB921300), the National Natural Science Foundation of China (Grant Nos. 1190020 and 11334012), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07000000).

Normal state Raman spectra of high-Tc cuprates

International Nuclear Information System (INIS)

Bishoyi, K.C.; Rout, G.C.; Behera, S.N.

2003-01-01

We present a microscopic theory to explain Raman spectra of high-T c cuprates R 2-x M x CuO 4 in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green function technique of Zubarev at zero wave vector and finite (room) temperature limit. Parameter dependence of Raman active phonon frequencies are studied by varying model parameters of the system i.e. the position of f-level (ε f ), the effective electron-phonon coupling strength (g), the staggered magnetic field (h 1 ), and the hybridization parameter (v). The four Raman active peaks (P 1 to P 4 ) represent the electronic states of the atomic sub-systems of the cuprate systems. They show up as phonon excitations due to the coupling of the phonon to the electrons and the anti-ferromagnetic gap. (author)

Aspects of electron correlations in the cuprate superconductors

International Nuclear Information System (INIS)

Brenig, W.

1995-01-01

We review concepts and effects of electron correlations in the copper-oxide superconductors. The purpose of this article is twofold. First, we provide an overview of results of various electron spectroscopies, Raman scattering and optical conductivity studies with a particular emphasis on experiments which identify the charge and spin correlations relevant to the cuprates. Second, we focus on microscopic theories of the single-particle excitations, and the charge and spin dynamics in the normal state of cuprates considering those models which incorporate strong electron correlations. The single-particle spectrum of the three-band Hubbard model is reviewed and related to results of electron spectroscopy. The carrier dynamics in the t-J model and the one-band Hubbard model at low doping is discussed in detail. We examine approaches which describe the single-particle excitations of correlated electron systems at finite doping. Theories of the static and dynamic magnetic correlations are considered and we speculate on the consequences of the spin dynamics for Raman scattering and the optical conductivity. Finally, selected phenomenological ideas are reviewed. ((orig.))

Compensated electron and hole pockets in an underdoped high- Tc superconductor

Science.gov (United States)

Sebastian, Suchitra E.; Harrison, N.; Goddard, P. A.; Altarawneh, M. M.; Mielke, C. H.; Liang, Ruixing; Bonn, D. A.; Hardy, W. N.; Andersen, O. K.; Lonzarich, G. G.

2010-06-01

We report quantum oscillations in the underdoped high-temperature superconductor YBa2Cu3O6+x over a wide range in magnetic field 28≤μ0H≤85T corresponding to ≈12 oscillations, enabling the Fermi surface topology to be mapped to high resolution. As earlier reported by Sebastian [Nature (London) 454, 200 (2008)10.1038/nature07095], we find a Fermi surface comprising multiple pockets, as revealed by the additional distinct quantum oscillation frequencies and harmonics reported in this work. We find the originally reported broad low-frequency Fourier peak at ≈535T to be clearly resolved into three separate peaks at ≈460 , ≈532 , and ≈602T , in reasonable agreement with the reported frequencies of Audouard [Phys. Rev. Lett. 103, 157003 (2009)10.1103/PhysRevLett.103.157003]. However, our increased resolution and angle-resolved measurements identify these frequencies to originate from two similarly sized pockets with greatly contrasting degrees of interlayer corrugation. The spectrally dominant frequency originates from a pocket (denoted α ) that is almost ideally two-dimensional in form (exhibiting negligible interlayer corrugation). In contrast, the newly resolved weaker adjacent spectral features originate from a deeply corrugated pocket (denoted γ ). On comparison with band structure, the d -wave symmetry of the interlayer dispersion locates the minimally corrugated α pocket at the “nodal” point knodal=(π/2,π/2) , and the significantly corrugated γ pocket at the “antinodal” point kantinodal=(π,0) within the Brillouin zone. The differently corrugated pockets at different locations indicate creation by translational symmetry breaking—a spin-density wave has been suggested from the suppression of Zeeman splitting for the spectrally dominant pocket. In a broken-translational symmetry scenario, symmetry points to the nodal (α) pocket corresponding to holes, with the weaker antinodal (γ) pocket corresponding to electrons—likely responsible

Non-separable pairing interaction kernels applied to superconducting cuprates

International Nuclear Information System (INIS)

Haley, Stephen B.; Fink, Herman J.

2014-01-01

Highlights: • Non-separable interaction kernels with weak interactions produces HTS. • A probabilistic approach is used in filling the electronic states in the unit cell. • A set of coupled equations is derived which describes the energy gap. • SC properties of separable with non-separable interactions are compared. • There is agreement with measured properties of the SC and normal states. - Abstract: A pairing Hamiltonian H(Γ) with a non-separable interaction kernel Γ produces HTS for relatively weak interactions. The doping and temperature dependence of Γ(x,T) and the chemical potential μ(x) is determined by a probabilistic filling of the electronic states in the cuprate unit cell. A diverse set of HTS and normal state properties is examined, including the SC phase transition boundary T C (x), SC gap Δ(x,T), entropy S(x,T), specific heat C(x,T), and spin susceptibility χ s (x,T). Detailed x,T agreement with cuprate experiment is obtained for all properties

Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212

Energy Technology Data Exchange (ETDEWEB)

Hussain, Zahid; Lee, W.S.; Vishik, I.M.; Tanaka, K.; Lu, D.H.; Sasagawa, T.; Nagaosa, N.; Devereaux, T.P.; Hussain, Z.; Shen, Z.-X.

2007-05-26

he superconducting gap--an energy scale tied to the superconducting phenomena--opens on the Fermi surface at the superconducting transition temperature (Tc) in conventional BCS superconductors. In underdoped high-Tc superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above Tc (refs 1, 2). Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above Tc is one of the central questions in high-Tc research3, 4, 5, 6, 7, 8. Although some experimental evidence suggests that the two gaps are distinct9, 10, 11, 12, 13, 14, 15, 16, 17, 18, this issue is still under intense debate. A crucial piece of evidence to firmly establish this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+delta in the momentum space region overlooked in previous measurements. Near the diagonal of Cu?O bond direction (nodal direction), we found a gap that opens at Tc and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of superconductivity. This is in sharp contrast to the pseudogap near the Cu?O bond direction (antinodal region) measured in earlier experiments19, 20, 21.

A spatial interpretation of emerging superconductivity in lightly doped cuprates

Science.gov (United States)

Deutscher, Guy; de Gennes, Pierre-Gilles

The formation of domains comprising alternating 'hole rich' and 'hole poor' ladders recently observed by Scanning Tunneling Microscopy by Kohsaka et al., on lightly hole doped cuprates, is interpreted in terms of an attractive mechanism which favors the presence of doped holes on Cu sites located each on one side of an oxygen atom. This mechanism leads to a geometrical pattern of alternating hole-rich and hole-poor ladders with a periodicity equal to 4 times the lattice spacing in the CuO plane, as observed experimentally. Cuprates supraconducteurs peu dopés : une interprétation des structures spatiales. Des arrangements électroniques réguliers ont été détectés récemment par Kohsaka et al. dans des cuprates sous dopés (via une sonde tunnel locale). Certaines paires Cu-O-Cu sont « actives », et forment une échelle. Les autres sites sont peu actifs. Pour expliquer ces structures, nous postulons que, lorsqu'une liaison Cu-O-Cu est occupée par deux trous, la distance (Cu-Cu) rétrécit et l'intégrale de transfert (t) est fortement augmentée. Ceci peut engendrer des paires localisées (réelles ou virtuelles). Aux taux de dopage étudiés, la période de répétition vaudrait 4 mailles élémentaires.

Earthquakes - a danger to deep-lying repositories?

International Nuclear Information System (INIS)

2012-03-01

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at geological factors concerning earthquakes and the safety of deep-lying repositories for nuclear waste. The geological processes involved in the occurrence of earthquakes are briefly looked at and the definitions for magnitude and intensity of earthquakes are discussed. Examples of damage caused by earthquakes are given. The earthquake situation in Switzerland is looked at and the effects of earthquakes on sub-surface structures and deep-lying repositories are discussed. Finally, the ideas proposed for deep-lying geological repositories for nuclear wastes are discussed

Chasing the cuprates with dilatonic dyons

Energy Technology Data Exchange (ETDEWEB)

Amoretti, Andrea [Department of Applied Mathematics and Theoretical Physics, University of Cambridge,Cambridge, CB3 OWA (United Kingdom); Baggioli, Matteo [Institut de Física d’Altes Energies (IFAE), Universitat Autònoma de Barcelona,The Barcelona Institute of Science and Technology,Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Magnoli, Nicodemo [Dipartimento di Fisica, Università di Genova, and I.N.F.N. - Sezione di Genova,via Dodecaneso 33, I-16146, Genova (Italy); Musso, Daniele [Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, I-34151 Trieste (Italy)

2016-06-20

Magnetic field and momentum dissipation are key ingredients in describing condensed matter systems. We include them in gauge/gravity and systematically explore the bottom-up panorama of holographic IR effective field theories based on bulk Einstein-Maxwell Lagrangians plus scalars. The class of solutions here examined appears insufficient to capture the phenomenology of charge transport in the cuprates. We analyze in particular the temperature scaling of the resistivity and of the Hall angle. Keeping an open attitude, we illustrate weak and strong points of the approach.

A simple model for normal state in- and out-of-plane resistivities of hole doped cuprates

Energy Technology Data Exchange (ETDEWEB)

Naqib, S.H., E-mail: shnaqib.physicsru@gmail.com [Department of Physics, University of Rajshahi, Rajshahi 6205 (Bangladesh); Azam, M. Afsana [Department of Physics, University of Rajshahi, Rajshahi 6205 (Bangladesh); Department of Physics, DUET, Gazipur, Dhaka (Bangladesh); Uddin, M. Borhan [Department of Physics, University of Rajshahi, Rajshahi 6205 (Bangladesh); Department of CSE, International Islamic University Chittagong, Sitakunda, IIUC Rd, Kumira 4314 Bangladesh (Bangladesh); Cole, J.R. [Cambridge Flow Solutions Ltd., Histon, Cambridge CB24 9AD (United Kingdom)

2016-05-15

Highlights: • In- and out-of-plane charge transport have been investigated for hole doped cuprates. • Effect of quantum critical point (QCP) on non-Fermi liquid behavior has been explored. • The impact of pseudogap (PG) on carrier scattering rate has been studied. • In- and out-of plane resistivities have been modeled by considering the QCP and the PG. • The model explains the non-Fermi liquid charge transport in hole doped cuprates. - Abstract: The highly anisotropic and qualitatively different nature of the normal state in- and out-of-plane charge dynamics in high-T{sub c} cuprates cannot be accommodated within the conventional Boltzmann transport theory. The variation of in-plane and out-of-plane resistivities with temperature and hole content are anomalous and cannot be explained by Fermi-liquid theory. In this study, we have proposed a simple phenomenological model for the dc resistivity of cuprates by incorporating two firmly established generic features of all hole doped cuprate superconductors—(i) the pseudogap in the quasiparticle energy spectrum and (ii) the T-linear resistivity at high temperatures. This T-linear behavior over an extended temperature range can be attributed to a quantum criticality, affecting the electronic phase diagram of cuprates. Experimental in-plane and out-of-plane resistivities (ρ{sub p}(T) and ρ{sub c}(T), respectively) of double-layer Y(Ca)123 have been analyzed using the proposed model. This phenomenological model describes the temperature and the hole content dependent resistivity over a wide range of temperature and hole content, p. The characteristic PG energy scale, ε{sub g}(p), extracted from the analysis of the resistivity data, agrees quite well with those found in variety of other experiments. Various other extracted parameters from the analysis of ρ{sub p}(T) and ρ{sub c}(T) data showed systematic trends with changing hole concentration. We have discussed important features found from the analysis in

Determination of Retardation Effects in the High Tc Cuprates from Sharvin Contact Measurements

International Nuclear Information System (INIS)

Deutscher, G.

1995-01-01

It is well known that retardation effects are essential to allow the attractive part of the electron-electron interaction (for instance, phonon mediated) to overcome the Coulomb repulsion. In new superconductors such as the cuprates for which the interaction is a priori unknown, it is therefore essential to determine the retarded and non retarded parts of the interaction. We show how this can be achieved by an analysis of Sharvin contact measurements between a noble metal tip and a cuprate. It turns out that both the retarded and non retarded parts are large, the former being however larger than the later

Novel interplay between high-Tc superconductivity and antiferromagnetism in Tl-Based Six-CuO2-layered cuprates. 205Tl- and 63Cu-NMR probes

International Nuclear Information System (INIS)

Mukuda, Hidekazu; Shiki, Nozomu; Kimoto, Naoki; Yashima, Mitsuharu; Kitaoka, Yoshio; Tokiwa, Kazuyasu; Iyo, Akira

2016-01-01

We report 63 Cu- and 205 Tl-NMR studies on six-layered (n = 6) high-T c superconducting (SC) cuprate TlBa 2 Ca 5 Cu 6 O 14+δ (Tl1256) with T c ∼ 100 K, which reveal that antiferromagnetic (AFM) order takes place below T N ∼ 170 K. In this compound, four underdoped inner CuO 2 planes [n(IP) = 4] sandwiched by two outer planes (OPs) are responsible for the onset of AFM order, whereas the nearly optimally-doped OPs responsible for the onset of bulk SC. It is pointed out that an increase in the out-of-plane magnetic interaction within an intra-unit-cell causes T N ∼ 45 K for Tl1245 with n(IP) = 3 to increase to ∼170 K for Tl1256 with n(IP) = 4. It is remarkable that the marked increase in T N and the AFM moments for the IPs does not bring about any reduction in T c , since T c ∼ 100 K is maintained for both compounds with nearly optimally doped OP. We highlight the fact that the SC order for n ≥ 5 is mostly dominated by the long-range in-plane SC correlation even in the multilayered structure, which is insensitive to the magnitude of T N and the AFM moments at the IPs or the AFM interaction among the IPs. These results demonstrate a novel interplay between the SC and AFM orders when the charge imbalance between the IPs and OP is significantly large. (author)

Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Palczewski, Ari Deibert [Iowa State Univ., Ames, IA (United States)

2010-01-01

This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl₂Ba₂CuO_6+δ (Tl2201) T_{c, max} ≈ 95 K and (Bi _1.35Pb_0.85)(Sr_1.47La_0.38)CuO_6+δ (Bi2201) T_{c, max} ≈ 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major differences in the band structure. First, the Fermi surface segments close to (π,0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher T_c Tl2201. The second study looks at the different ways of doping Bi₂Sr₂CaCu₂O_8+δ (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the absorption of oxygen from CO₂/CO molecules, prime contaminants present in UHV systems. Second, in a very clean UHV system at elevated temperatures (above about 200 K), the carrier concentration decreases due to the loss of oxygen atoms from the Bi-O layer. The final study probed the particle-hole symmetry of the pseudogap phase in high temperature superconducting cuprates by looking at the thermally excited bands above the Fermi level. The data showed a particle-hole symmetric pseudogap which symmetrically closes away from the nested FS before the node. The data is

Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Palczewski, Ari Deibert [Iowa State Univ., Ames, IA (United States)

2010-01-01

This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl₂Ba₂CuO_6+δ (Tl2201) T_c,max ~95 K and (Bi_1.35Pb_0.85)(Sr_1.47La_0.38)CuO_6+δ (Bi2201) T_c,max 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major di erences in the band structure. First, the Fermi surface segments close to ( π,0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher T_c Tl2201. The second study looks at the different ways of doping Bi₂Sr₂CaCu₂O_8+δ (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the absorption of oxygen from CO₂/CO molecules, prime contaminants present in UHV systems. Second, in a very clean UHV system at elevated temperatures (above about 200 K), the carrier concentration decreases due to the loss of oxygen atoms from the Bi-O layer. The final study probed the particle-hole symmetry of the pseudogap phase in high temperature superconducting cuprates by looking at the thermally excited bands above the Fermi level. The data showed a particle-hole symmetric pseudogap which symmetrically closes away from the nested FS before the node. The data is consistent with

Superconducting gap anisotropy and d-wave pairing in YBa2Cu3O7-δ

Science.gov (United States)

Verma, Sanjeev K.; Gupta, Anushri; Kumari, Anita; Indu, B. D.

2018-02-01

Considering Born-Mayer-Huggins potential as a most suitable potential to study the dynamical properties of high-temperature superconductors (HTS), the many-body quantum dynamics to obtain phonon Green’s functions has been developed via a Hamiltonian that incorporates the contributions of harmonic electron and phonon fields, phonon field anharmonicities, defects and electron-phonon interactions without considering BCS structure. This enables one to develop the quasiparticle renormalized frequency dispersion in the representative high-temperature cuprate superconductor YBa2Cu3O7-δ. The superconducting gap shows substantial changes with increased doping. The in-plane gap study revealed a v-shape gap with a nodal point along kx = ±ky direction for optimum doping (δ = 0.16) and the nodal point vanished in underdoped and overdoped regimes. The dx2-y2 pairing symmetry is observed at optimum doping with the presence of s or dxy components ( < 3%) in underdoped and overdoped regimes.

Scaling properties of YBa{sub 2}Cu{sub 3}O{sub x} films

Energy Technology Data Exchange (ETDEWEB)

Arushanov, E [Institute of Applied Physics, Academy of Sciences of the Moldova Republic, Academie street 5, Chisinau, MD 2028 (Moldova, Republic of); Levcenko, S [Institute of Applied Physics, Academy of Sciences of the Moldova Republic, Academie street 5, Chisinau, MD 2028 (Moldova, Republic of); Alami, H El [GPMD-Universite Paris 12, 61 avenue De Gaulle, 94010 CRETEIL Cedex (France); Cavellin, C Deville [GPMD-Universite Paris 12, 61 avenue De Gaulle, 94010 CRETEIL Cedex (France)

2005-11-01

An alternative simple method is proposed for analysing the scaling properties of the high-T{sub c} superconductor cuprates. The temperature is rescaled with a parameter T{sub R} determined from the precise analysis of R{sub H}(1/T), where R{sub H} is the Hall coefficient, in the high-temperature range. To illustrate this new method, the resistivity and Hall effect data obtained on underdoped YBa{sub 2}Cu{sub 3}O{sub x} epitaxial thin films are analysed. It is shown that the temperature-dependent resistivity {rho}(T), Hall coefficient R{sub H}(T) and the cotangent of the Hall angle cot {theta}{sub H}(T) of underdoped YBa{sub 2}Cu{sub 3}O{sub x} can be scaled into universal curves using this parameter T{sub R} to make a linear transformation of temperature and {rho}(T), R{sub H}(T) or cot{theta}{sub H}(T)

Compensated electron and hole pickets in an underdoped high Tc superconductor

Energy Technology Data Exchange (ETDEWEB)

Harrison, Neil [Los Alamos National Laboratory; Altarawneh, Moaz M [Los Alamos National Laboratory; Mielke, Charles H [Los Alamos National Laboratory; Sebastian, Suchitra E [CAMBRIDGE U; Goddard, P A [U OF OXFORD; Liang, Ruixing [U BRITISH COLUMBIA; Bonn, D A [U BRITISH COLUMBIA; Hardy, W N [U BRITISH COLUMBIA; Andersen, O K [MAX PLANCK INST.; Lonzarich, G G [CAMBRIDGE U

2010-01-01

Important to the question of high temperature superconductivity is whether bound fermionic pairs with zero or finite momentum - exhibiting bosonic physics - are involved. Here we use angle-dependent magnetic quantum oscillation measurements in underdoped YBa{sub 2}Cu{sub 3}O{sub 6+x} to reveal two significantly differently corrugated small sections of Fermi surface, identifying them as comprising opposite carriers located at different locations of the Brillouin zone. The surprising finding that these disproportionately heavy small pockets are equal in size indicates they are prone to a finite momentum excitonic insulator instability. We discuss the possibility that reducing the doping drives YBa{sub 2}Cu{sub 3}O{sub 6+x} closer to an instability of this nature, its ultimate realization occuring at the metal-insulator quantum critical point, accompanied by a potential enhancement of superconducting transition temperatures.

Dynamic spin susceptibility of superconducting cuprates: a microscopic theory of the magnetic resonance mode

International Nuclear Information System (INIS)

Vladimirov, A.A.; Plakida, N.M.; Ihle, D.

2010-01-01

A microscopic theory of the dynamic spin susceptibility (DSS) in the superconducting state within the t-J model is presented. It is based on an exact representation for the DSS obtained by applying the Mori-type projection technique for the relaxation function in terms of Hubbard operators. The static spin susceptibility is evaluated by a sum-rule-conserving generalized mean-field approximation, while the self-energy is calculated in the mode-coupling approximation. The spectrum of spin excitations is studied in the underdoped and optimally doped regions. The DSS reveals a resonance mode (RM) at the antiferromagnetic wave vector Q=π(1,1) at low temperatures due to a strong suppression of the damping of spin excitations. This is explained by an involvement of spin excitations in the decay process besides the particle-hole continuum usually considered in random-phase-type approximations. The spin gap in the spin-excitation spectrum at Q plays a dominant role in limiting the decay in comparison with the superconducting gap which results in the observation of the RM even above T c in the underdoped region. A good agreement with inelastic neutron-scattering experiments on the RM in YBCO compounds is found

Pressure tuning of structure, superconductivity, and novel magnetic order in the Ce-underdoped electron-doped cuprate ${{T}}^{{}^{\text{'}}}\text{-}{\mathrm{Pr}}_{1.3-x}{\mathrm{La}}_{0.7}{\mathrm{Ce}}_x{\mathrm{CuO}}_4$ ( $x=0.1$ )

Energy Technology Data Exchange (ETDEWEB)

Guguchia, Z. [Columbia Univ., New York, NY (United States); Paul Scherrer Inst. (PSI), Villigen (Switzerland); Brookhaven National Lab. (BNL), Upton, NY (United States); Adachi, T. [Sophia Univ., Tokyo (Japan); Shermadini, Z. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ohgi, T. [Tohoku Univ., Sendai (Japan); Chang, J. [Univ. of Zurich (Switzerland); Bozin, E. S. [Brookhaven National Lab. (BNL), Upton, NY (United States); von Rohr, F. [Univ. of Zurich (Switzerland); dos Santos, A. M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Molaison, J. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Boehler, R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Carnegie Inst. of Washington, Washington, DC (United States); Koike, Y. [Tohoku Univ., Sendai (Japan); Wieteska, A. R. [Columbia Univ., New York, NY (United States); Frandsen, B. A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Morenzoni, E. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Amato, A. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Billinge, S. J. L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Columbia Univ., New York, NY (United States); Uemura, Y. J. [Columbia Univ., New York, NY (United States); Khasanov, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

2017-09-14

High-pressure neutron powder diffraction, muon-spin rotation, and magnetization studies of the structural, magnetic, and the superconducting properties of the Ce-underdoped superconducting (SC) electron-doped cuprate system with the Nd 2 CuO 4 (the so-called T ' ) structure T ' - Pr 1.3 - x La 0.7 Ce x CuO 4 with x = 0.1 are reported. A strong reduction of the in-plane and out-of-plane lattice constants is observed under pressure. However, no indication of any pressure-induced phase transition from T ' to the K 2 NiF 4 (the so-called T) structure is observed up to the maximum applied pressure of p = 11 GPa. Large and nonlinear increase of the short-range magnetic order temperature T so in T ' - Pr 1.3 - x La 0.7 Ce x CuO 4 ( x = 0.1 ) was observed under pressure. Simultaneous pressure causes a nonlinear decrease of the SC transition temperature T c . All these experiments establish the short-range magnetic order as an intrinsic and competing phase in SC T ' - Pr 1.3 - x La 0.7 Ce x CuO 4 ( x = 0.1 ). The observed pressure effects may be interpreted in terms of the improved nesting conditions through the reduction of the in-plane and out-of-plane lattice constants upon hydrostatic pressure.

2011 Aspen Winter Conference on Contrasting Superconductivity of Pnictides and Cuprates

Energy Technology Data Exchange (ETDEWEB)

Johnson, P. [Aspen Center for Physics, CO (United States); Schmalian, J. [Aspen Center for Physics, CO (United States); Canfield, P. [Aspen Center for Physics, CO (United States); Chakravarty, S. [Aspen Center for Physics, CO (United States)

2011-05-02

Our quest for materials with better properties is closely integral to the fabric of our society. Currently the development of materials that will allow for improved generation, transport, and storage of energy is at the forefront of our research in condensed matter physics and materials science. Among these materials, compounds that exhibit correlated electron states and emergent phenomena such as superconductivity have great promise, but also difficulties that need to be overcome: problems associated with our need to reliably find, understand, improve and control these promising materials. At the same time, the field of correlated electrons represents the frontier of our understanding of the electronic properties of solids. It contains deep open scientific issues within the broad area of quantum phenomena in matter. The aim of this workshop is to explore and understand the physics of recently discovered Fe-based high-temperature superconductors and contrast and compare them with the cuprates. The superconductivity in iron pnictides, with transition temperatures in excess of 55 K, was discovered in early 2008. The impact of this discovery is comparable to cuprates discovered in 1986. At the same time a number of recent experimental developments in cuprates may lead to a shift in our thinking with regards to these materials. There is therefore much to be learned by devoting a conference in which both classes of superconductors are discussed, especially at this nascent stage of the pnictides.

Temperature and carrier density dependence of anisotropy in supercurrent density in layered cuprate superconductors

International Nuclear Information System (INIS)

Singh, M.P.; Tewari, B.S.; Ajay

2006-01-01

In the present work, we have studied the effect of temperature and carrier density on anisotropy in supercurrent density in bilayer cuprate superconductors. Here, we have considered a tight binding bilayered Hubbard Hamiltonian containing intra and interlayer attractive interactions. The situation considered here is similar to a SIS junction. We have got the expressions for the superconducting order parameters, carrier density and anisotropy in superconducting density (I ab /I c ) for such SIS junction. The numerical analysis show that the anisotropy in the supercurrent density depends on temperature and carrier density in layered high T c cuprates. (author)

High-Tc cuprate superconductivity in a nutshell

International Nuclear Information System (INIS)

Won, Hyekyung; Haas, Stephan; Parker, David; Maki, Kazumi

2005-01-01

Since the discovery of high-T c cuprate superconductivity in 1986 many new experimental techniques and theoretical concepts have been developed. In particular it was shown that the BCS theory of d-wave superconductivity describes semi-quantitatively the high-T c superconductivity. Furthermore, it was demonstrated that Volovik's approach is extremely useful for finding the quasiparticle properties in the vortex state. Here we survey these developments and forecast future directions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Gossamer superconductivity, new paradigm?

Energy Technology Data Exchange (ETDEWEB)

Won, Hyekyung [Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Haas, Stephan; Parker, David [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Maki, Kazumi [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Max-Planck Institute for the Physics of Complex Systems, Noethnitzer Str. 38, 01187 Dresden (Germany); Dora, Balazs [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Virosztek, Attila [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary); Research Institute for Solid State Physics and Optics, P.O. Box 49, 1525 Budapest (Hungary)

2006-01-01

We review our recent works on d-wave density wave (dDW) and gossamer superconductivity (i.e. d-wave superconductivity in the presence of dDW) in high-T{sub c} cuprates and CeCoIn{sub 5}. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn{sub 5} are manifestations of dDW. b) The phase diagram of high-T{sub c} cuprates is understood in terms of mean field theory, which includes two order parameters {delta}{sub 1} and {delta}{sub 2}, where one order paremeter is from dDW and the other from d-wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where {delta}{sub 2}/{delta}{sub 1}<<1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high-T{sub c} cuprate superconductors, the heavy-fermion superconductor CeCoIn{sub 5} and the organic superconductors {kappa}-(ET){sub 2}Cu(NCS){sub 2} and (TMTSF){sub 2}PF{sub 6}. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Oxygen diffusion in cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Routbort, J.L.; Rothman, S.J.

1995-01-01

Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La{sub 2}{sub {minus}}{sub {times}}Sr{sub {times}}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7}{sub {minus}}{delta}, YBa{sub 2}Cu{sub 4}O{sub 8}, and the Bi{sub 2}Sr{sub 2}Ca{sub n}{sub {minus}}{sub 1}Cu{sub n}O{sub 2}{sub +}{sub 4} (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible.

Half-integer flux quantum effect in cuprate superconductors - a probe of pairing symmetry

International Nuclear Information System (INIS)

Tsuei, C.C.; Kirtley, J.R.; Gupta, A.; Sun, J.Z.; Moler, K.A.; Wang, J.H.

1996-01-01

Based on macroscopic quantum coherence effects arising from pair tunneling and flux quantization, a series of tricrystal experiments have been designed and carried out to test the order parameter symmetry in high-T c cuprate superconductors. By using a scanning SQUID microscope, we have directly and non-invasively observed the spontaneously generated half-integer flux quantum effect in controlled-orientation tricrystal cuprate superconducting systems. The presence or absence of the half-integer flux quantum effect as a function of the tricrystal geometry allows us to prove that the order parameter symmetry in the YBCO and Tl2201 systems is consistent with that of the d x 2 -y 2 pair state. (orig.)

Dielectric properties of glasses prepared by quenching melts of superconducting Bi-Ca-Sr-Cu-O cuprates

Energy Technology Data Exchange (ETDEWEB)

Varma, K. B. R.; Subbanna, G. N.; Ramakrishnan, T. V.; Rao, C. N. R.

1989-07-03

Glasses obtained from quenching melts of superconducting bismuth cuprates of the formula Bi/sub 2/(Ca,Sr)/sub /ital n/+1/Cu/sub /ital n//O/sub 2/ital n/+4/ with /ital n/=1 and 3 exhibit novel dielectric properties. They possess relatively high dielectric constants as well as high electrical conductivity. The novel dielectric properties of these cuprate glasses are likely to be of electronic origin. They exhibit a weak microwave absorption due to the presence of microcrystallites.

NMR evidence for spin fluctuations in underdoped LaO{sub 1-x}F{sub x}FeAs

Energy Technology Data Exchange (ETDEWEB)

Hammerath, Franziska; Grafe, Hans-Joachim; Lang, Guillaume; Behr, Guenter; Werner, Jochen; Buechner, Bernd [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung, Dresden (Germany); Paar, Dalibor [Department of Physics, Faculty of Science, University of Zagreb (Croatia)

2012-07-01

We present {sup 75}As Nuclear Magnetic Resonance (NMR) measurements on the iron-based superconductor LaO{sub 1-x}F{sub x}FeAs with 0 {<=} x {<=} 0.1, covering a broad range of the phase diagram from magnetically-ordered to optimally-doped superconducting samples. For underdoped samples (x=0.05,x=0.075) the {sup 75}As NMR spin-lattice relaxation rate (T{sub 1}T){sup -1} shows a Curie-Weiss-like increase at intermediate temperatures, indicating the slowing down of spin fluctuations. However, a simple Curie-Weiss fit fails to describe (T{sub 1}T){sup -1}(T) above 250 K and the occurrence of a peak in (T{sub 1}T){sup -1} slightly above T{sub c}. Instead, the data can be well described by considering a BPP-model for fluctuating magnetic fields in combination with a doping-independent linear temperature dependence at high temperature. At optimal doping (x=0.1) spin fluctuations are suppressed and only the linear contribution to (T{sub 1}T){sup -1} is left. This stands in contrast to other pnictides, such as Ba(Fe{sub 1-x}Co{sub x}As){sub 2} and Ba(FeAs{sub 1-x}P{sub x}){sub 2}. Our analysis is consistent with charge carrier localization in underdoped LaO{sub 1-x}F{sub x}FeAs as seen by means of resistivity measurements.

Unparticles and anomalous dimensions in the cuprates

Energy Technology Data Exchange (ETDEWEB)

Karch, Andreas [Department of Physics, University of Washington,3910 15th Ave. NE, Seattle, WA 98195-1560 (United States); Limtragool, Kridsanaphong; Phillips, Philip W. [Department of Physics and Institute for Condensed Matter Theory, University of Illinois,1110 W. Green Street, Urbana, IL 61801 (United States)

2016-03-25

Motivated by the overwhelming evidence some type of quantum criticality underlies the power-law for the optical conductivity and T−linear resistivity in the cuprates, we demonstrate here how a scale-invariant or unparticle sector can lead to a unifying description of the observed scaling forms. We adopt the continuous mass formalism or multi band (flavor) formalism of the unparticle sector by letting various microscopic parameters be mass-dependent. In particular, we show that an effective mass that varies with the flavor index as well as a running band edge and lifetime capture the AC and DC transport phenomenology of the cuprates. A key consequence of the running mass is that the effective dynamical exponent can differ from the underlying bare critical exponent, thereby providing a mechanism for realizing the fractional values of the dynamical exponent required in a previous analysis http://dx.doi.org/10.1103/PhysRevB.91.155126. We also predict that regardless of the bare dynamical exponent, z, a non-zero anomalous dimension for the current is required. Physically, the anomalous dimension arises because the charge depends on the flavor, mass or energy. The equivalent phenomenon in a d+1 gravitational construction is the running of the charge along the radial direction. The nature of the superconducting instability in the presence of scale invariant stuff shows that the transition temperature is not necessarily a monotonic function of the pairing interaction.

Electronic Phase Separation in the Slightly Underdoped Iron Pnictide Superconductor Ba1-xKxFe2As2

DEFF Research Database (Denmark)

Park, J.T.; Inosov, D.S.; Niedermayer, C.

2009-01-01

Here we present a combined study of the slightly underdoped novel pnictide superconductor Ba1-xKxFe2As2 by means of x-ray powder diffraction, neutron scattering, muon-spin rotation (µSR), and magnetic force microscopy (MFM). Static antiferromagnetic order sets in below Tm70 K as inferred from......-state regions on a lateral scale of several tens of nanometers. Our findings indicate that such mesoscopic phase separation can be considered an intrinsic property of some iron pnictide superconductors....

Collective Dynamics and Strong Pinning near the Onset of Charge Order in La1.48Nd0.4Sr0.12CuO4

Science.gov (United States)

Baity, P. G.; Sasagawa, T.; Popović, Dragana

2018-04-01

The dynamics of charge-ordered states is one of the key issues in underdoped cuprate high-temperature superconductors, but static short-range charge-order (CO) domains have been detected in almost all cuprates. We probe the dynamics across the CO (and structural) transition in La1.48Nd0.4Sr0.12CuO4 by measuring nonequilibrium charge transport, or resistance R as the system responds to a change in temperature and to an applied magnetic field. We find evidence for metastable states, collective behavior, and criticality. The collective dynamics in the critical regime indicates strong pinning by disorder. Surprisingly, nonequilibrium effects, such as avalanches in R , are revealed only when the critical region is approached from the charge-ordered phase. Our results on La1.48Nd0.4Sr0.12CuO4 provide the long-sought evidence for the fluctuating order across the CO transition, and also set important constraints on theories of dynamic stripes.

Considerations for improved polycrystalline cuprate superconductors

International Nuclear Information System (INIS)

Shinde, S.L.; Shaw, T.M.

1990-01-01

Polycrystalline cuprate superconductors exhibit two-stage superconducting transitions, that are characteristic of granular systems. This behaviour suggests approaches involving improvements in intra and inter-grain properties in order to improve the technologically important superconducting properties such as the magnetic remanent moment and transport critical current density. This paper reports results of our studies on oxygenation, twin density control through grain size and changes in flux pinning within the YBa 2 Cu 3 O 7-δ matrix with Ag substitution under the heading of intra-grain properties and the detrimental effect of grain boundary phases and the effect of Ag substitution on grain boundary pinning under the heading of inter-grain properties

Manganite/Cuprate Superlattice as Artificial Reentrant Spin Glass

KAUST Repository

Ding, Junfeng

2016-05-04

Emerging physical phenomena at the unit-cell-controlled interfaces of transition-metal oxides have attracted lots of interest because of the rich physics and application opportunities. This work reports a reentrant spin glass behavior with strong magnetic memory effect discovered in oxide heterostructures composed of ultrathin manganite La0.7Sr0.3MnO3 (LSMO) and cuprate La2CuO4 (LCO) layers. These heterostructures are featured with enhanced ferromagnetism before entering the spin glass state: a Curie temperature of 246 K is observed in the superlattice with six-unit-cell LSMO layers, while the reference LSMO film with the same thickness shows much weaker magnetism. Furthermore, an insulator-metal transition emerges at the Curie temperature, and below the freezing temperature the superlattices can be considered as a glassy ferromagnetic insulator. These experimental results are closely related to the interfacial spin reconstruction revealed by the first-principles calculations, and the dependence of the reentrant spin glass behavior on the LSMO layer thickness is in line with the general phase diagram of a spin system derived from the infinite-range SK model. The results of this work underscore the manganite/cuprate superlattices as a versatile platform of creating artificial materials with tailored interfacial spin coupling and physical properties. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Muon and other studies of magnetic ordering in cuprate layer-compounds

International Nuclear Information System (INIS)

Portis, A.M.; Celio, M.

1989-01-01

Muon spin rotation studies of magnetic ordering in the planar cuprates are reviewed. Particular attention is given to doped La 2 CuO 4 and oxygen-depleted YBa 2 Cu 3 O 7-δ and to related experimental investigations. Studies of transition element substituted compounds are also reviewed. (orig.)

Magnetic excitations of layered cuprates studied by RIXS at Cu L{sub 3} edge

Energy Technology Data Exchange (ETDEWEB)

Ghiringhelli, G., E-mail: giacomo.ghiringhelli@fisi.polimi.it [CNR/SPIN, CNISM and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano (Italy); Braicovich, L. [CNR/SPIN, CNISM and Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano (Italy)

2013-06-15

Highlights: ► We have developed very high resolution RIXS instrumentation. ► Cu L{sub 3} RIXS is ideal for studying magnetic excitations in layered cuprates. ► RIXS has been used to map magnon and paramagnon dispersion in HTcS. ► We have developed the first partial polarization analyzer for RIXS in the soft X-rays. -- Abstract: The inelastic scattering of X-rays is becoming a powerful alternative to better established techniques, based on neutrons or low energy photons, for the study of low- and medium-energy excitations in solids. When performed in the soft range the resonant inelastic X-ray scattering (RIXS) is ideal for strongly correlated electron systems based on 3d transition metals. The remarkable evolution of Cu L{sub 3} RIXS has been boosted by the steady improvement of experimental energy resolution, and by the fortunate fact that cuprates give intense and richly featured spectra. Over the last 8 years several key results were obtained using the AXES (ESRF) and the SAXES (SLS) spectrometers. This initial success is now supporting several new projects for soft X-ray RIXS worldwide. We briefly present here the case of spin excitation dispersion in insulating and superconducting cuprates and the first RIXS spectra with partial polarization analysis of the scattered photons.

The rich variety of cuprates

International Nuclear Information System (INIS)

Rice, T.M.

1997-01-01

The discovery of high-T c superconductivity focussed attention on the cuprates. Square planar coordinated Cu 2+ -ions are ideal S=1/2 ions. The exchange interaction between neighboring ions is very different for edge sharing (weak and ferromagnetic) and corner sharing (strong and antiferromagnetic) configurations. Many different magnetic structures are possible, e.g. chains, zig-zag chains, ladders, etc., weakly coupled to each other. The spin-liquid state of the two-leg ladder is especially interesting, not least because of the possible quantum critical point separating the spin liquid and long-range ordered states as the interladder coupling is increased. Hole doping to introduce mobile Cu 3+ -ionic configuration opens new possibilities. The recent discovery of superconductivity under pressure in a doped ladder system is encouraging. (orig.)

D-wave condensate and essential phenomenological description of some properties of high-Tc cuprate superconductors

International Nuclear Information System (INIS)

Dunne, L.J.; Univ. of Sussex, Falmer; Braendas, E.J.; Murrell, J.N.

1999-01-01

The discovery of high T c superconducting cuprates occurred over a decade ago but the cause of the superconducting condensation and electronic structure of such compounds is still a matter of considerable debate. While there is no agreement as to the pairing mechanism, there is, on the other hand, a wide consensus about the main properties which a theoretical description should provide. In this article, a theory is presented which accounts in a straightforward way for many of the essential properties of the high T c cuprate superconductors. Some further developments of the model are suggested, particularly relating to the normal state spin-gap which the model does not currently describe

Marginal Fermi liquid and kink structure of quasiparticles in cuprates

International Nuclear Information System (INIS)

Kakehashi, Y.; Fulde, P.

2007-01-01

On the basis of the self-consistent projection operator method for nonlocal excitations, we show that a kink structure appears in the quasiparticle excitation spectrum of the two-dimensional Hubbard model at low doping concentrations. It is caused by a mixing between the quasiparticle state and the excitations with short-range antiferromagnetic order. The results explain the kink in high-T c cuprates

Nonlinear optical control of Josephson coupling in cuprates

Energy Technology Data Exchange (ETDEWEB)

Casandruc, Eliza

2017-03-15

In High-T{sub C} cuprates superconducting Cu-O planes alternate with insulating layers along the crystallographic c-axis, making the materials equivalent to Josephson junctions connected in series. The most intriguing consequence is that the out-of-plane superconducting transport occurs via Cooper pairs tunneling across the insulating layers and can be predicted by the Josephson tunneling equations. Nonlinear interaction between light fields and the superconducting carriers serves as a powerful dynamical probe of cuprates, while offering opportunities for controlling them in an analogous fashion to other stimuli such as pressure and magnetic fields. The main goal of this thesis work is to use intense transient light fields to control the interlayer superconducting transport on ultrafast time scales. This was achieved by tuning the wavelength of such light pulses to completely different ranges, in order to either directly excite Josephson Plasma Waves in the nonlinear regime, or efficiently melt the competing charge and spin order phase, which in certain cuprates quenches the Josephson tunneling at equilibrium. In a first study, I have utilized strong field terahertz transients with frequencies tuned to the Josephson plasma resonance (JPR) to coherently control the c-axis superconducting transport. The Josephson relations have a cubic nonlinearity which is exploited to achieve two related, albeit slightly different, phenomena. Depending on the driving pulse, solitonic breathers were excited with narrow-band multi-cycle pulses in La{sub 1.84}Sr{sub 0.16}CuO{sub 4} while broad-band half-cycle pulses were employed to achieve a parametric amplification of Josephson Plasma Waves in La{sub 1.905}Ba{sub 0.095}CuO{sub 4}. These experiments are supported by extensive modeling, showing exceptional agreement. A comprehensive study illustrates the strong enhancement of the nonlinear effects near the JPR frequency. Then, I turned to investigate the competition between

Chemical bonding in Tl cuprates studied by x-ray photoemission

International Nuclear Information System (INIS)

Vasquez, R.P.; Siegal, M.P.; Overmyer, D.L.; Ren, Z.F.; Lao, J.Y.; Wang, J.H.

1999-01-01

Epitaxial thin films of the Tl cuprate superconductors Tl 2 Ba 2 CaCu 2 O 8 , Tl 2 Ba 2 Ca 2 Cu 3 O 10 , and Tl 0.78 Bi 0.22 Ba 0.4 Sr 1.6 Ca 2 Cu 3 O 9-δ are studied with x-ray photoemission spectroscopy. These data, together with previous measurements in this lab of Tl 2 Ba 2 CuO 6+δ and TlBa 2 CaCu 2 O 7-δ , comprise a comprehensive data set for a comparative study of Tl cuprates with a range of chemical and electronic properties. In the Cu 2p spectra, a larger energy separation between the satellite and main peaks (E s -E m ) and a lower intensity ratio (I s /I m ) are found to correlate with higher values of T c . Analysis of these spectra within a simple configuration interaction model suggests that higher values of T c are related to low values of the O 2p→Cu 3d charge transfer energy. In the O 1s region, a smaller bond length between Ba and Cu-O planar oxygen is found to correlate with a lower binding energy for the signal associated with Cu-O bonding, most likely resulting from the increased polarization screening by Ba 2+ ions. For samples near optimum doping, maximum T c is observed to occur when the Tl 4f 7/2 binding energy is near 117.9 eV, which is near the middle of the range of values observed for Tl cuprates. Higher Tl 4f 7/2 binding energies, corresponding to formal oxidation states nearer Tl 1+ , are also found to correlate with longer bond lengths between Ba and Tl-O planar oxygen, and with higher binding energies of the O 1s signal associated with Tl-O bonding. copyright 1999 The American Physical Society

Images of interlayer Josephson vortices in single-layer cuprates

International Nuclear Information System (INIS)

Moler, K. A.; Kirtley, J. R.; Liang, R.; Bonn, D. A.; Hardy, W. N.; Williams, J. M.; Schlueter, J. A.; Hinks, D.; Villard, G.; Maignan, A.; Nohara, M.; Takagi, H.

2000-01-01

The interlayer penetration depth in layered superconductors may be determined from scanning Superconducting QUantum Interference Device (SQUID) microscope images of interlayer Josephson vortices. The authors compare their findings at 4 K for single crystals of the organic superconductor κ-(BEDT-TTF) 2 Cu(NCS) 2 and three near-optimally doped cuprate superconductors: La 2-x Sr x CuO 4 , (Hg, Cu)Ba 2 CuO 4+δ , and Tl 2 Ba 2 CuO 6+δ

Two band model for the cuprates

Science.gov (United States)

Liu, Shiu; White, Steven

2009-03-01

We use a numerical canonical transformation approach to derive an effective two-band model for the hole-doped cuprates, which keeps both oxygen and copper orbitals but removes double occupancy from each. A similar model was considered previously by Frenkel, Gooding, Shraiman, and Siggia (PRB 41, number 1, page 350). We compare the numerically derived model with previously obtained analytical results. In addition to the usual hopping terms between oxygens tpp and Cu-Cu exchange terms Jdd, the model also includes a strong copper-oxygen exchange interaction Jpd and a Kondo-like spin-flip oxygen-oxygen hopping term Kpdp. We use the density matrix renormalization group to study the charge, spin, and pairing properties of the derived model on ladder systems.

Investigation of renormalization effects in high temperature cuprate superconductors

International Nuclear Information System (INIS)

Zabolotnyy, Volodymyr B.

2008-01-01

It has been found that the self-energy of high-T C cuprates indeed exhibits a well pronounced structure, which is currently attributed to coupling of the electrons either to lattice vibrations or to collective magnetic excitations in the system. To clarify this issue, the renormalization effects and the electronic structure of two cuprate families Bi 2 Sr 2 CaCu 2 O 8+δ and YBa 2 Cu 3 O 7-δ were chosen as the main subject for this thesis. With a simple example of an electronic system coupled to a collective mode unusual renormalization features observed in the photoemission spectra are introduced. It is shown that impurity substitution in general leads to suppression of the unusual renormalization. Finally an alternative possibility to obtain a purely superconducting surface of Y-123 via partial substitution of Y atoms with Ca is introduced. It is shown that renormalization in the superconducting Y-123 has similar strong momentum dependence as in the Bi-2212 family. It is also shown that in analogy to Bi-2212 the renormalization appears to have strong dependence on the doping level (no kinks for the overdoped component) and practically vanishes above T C suggesting that coupling to magnetic excitations fits much better than competing scenarios, according to which the unusual renormalization in ARPES spectra is caused by the coupling to single or multiple phononic modes. (orig.)

Universal spectral signatures in pnictides and cuprates: the role of quasiparticle-pair coupling.

Science.gov (United States)

Sacks, William; Mauger, Alain; Noat, Yves

2017-11-08

Understanding the physical properties of a large variety of high-T c superconductors (SC), the cuprate family as well as the more recent iron-based superconductors, is still a major challenge. In particular, these materials exhibit the 'peak-dip-hump' structure in the quasiparticle density of states (DOS). The origin of this structure is explained within our pair-pair interaction (PPI) model: The non-superconducting state consists of incoherent pairs, a 'Cooper-pair glass' which, due to the PPI, undergoes a Bose-like condensation below T c to the coherent SC state. We derive the equations of motion for the quasiparticle operators showing that the DOS 'peak-dip-hump' is caused by the coupling between quasiparticles and excited pair states, or 'super-quasiparticles'. The renormalized SC gap function becomes energy-dependent and non retarded, reproducing accurately the experimental spectra of both pnictides and cuprates, despite the large difference in gap value.

A tale of two metals: contrasting criticalities in the pnictides and hole-doped cuprates

Science.gov (United States)

Hussey, N. E.; Buhot, J.; Licciardello, S.

2018-05-01

The iron-based high temperature superconductors share a number of similarities with their copper-based counterparts, such as reduced dimensionality, proximity to states of competing order, and a critical role for 3d electron orbitals. Their respective temperature-doping phase diagrams also contain certain commonalities that have led to claims that the metallic and superconducting (SC) properties of both families are governed by their proximity to a quantum critical point (QCP) located inside the SC dome. In this review, we critically examine these claims and highlight significant differences in the bulk physical properties of both systems. While there is now a large body of evidence supporting the presence of a (magnetic) QCP in the iron pnictides, the situation in the cuprates is much less apparent, at least for the end point of the pseudogap phase. We argue that the opening of the normal state pseudogap in cuprates, so often tied to a putative QCP, arises from a momentum-dependent breakdown of quasiparticle coherence that sets in at much higher doping levels but which is driven by the proximity to the Mott insulating state at half filling. Finally, we present a new scenario for the cuprates in which this loss of quasiparticle integrity and its evolution with momentum, temperature and doping plays a key role in shaping the resultant phase diagram. This key issues review is dedicated to the memory of Dr John Loram whose pioneering measurements, analysis and ideas inspired much of its content.

Angle-resolved photoelectron spectroscopy studies of the many-body effects in the electronic structure of high-Tc cuprates

International Nuclear Information System (INIS)

Inosov, Dmytro S.

2008-01-01

In the present work some steps are done towards understanding the anomalous effects observed in the single-particle excitation spectra of cuprates. First, the electronic properties of BSCCO are considered. The main result of this part of the work is a model of the Green's function that is later used for calculating the two-particle excitation spectrum. Then, the matrix element effects in the photoemission spectra of cuprates are discussed. After a general introduction to the problem, the thesis focuses on the recently discovered anomalous behavior of the ARPES spectra that partially originates from the momentum-dependent photoemission matrix element. The momentum- and excitation energy dependence of the anomalous high-energy dispersion, termed ''waterfalls'', is covered in full detail. Understanding the role of the matrix element effects in this phenomenon proves crucial, as they obstruct the view of the underlying excitation spectrum that is of indisputable interest. For the optimally doped bilayer Bi-based cuprate, the renormalized two-particle correlation function in the superconducting state is calculated from ARPES data within an itinerant model based on the random phase approximation (RPA). (orig.)

Probing the phase diagram of cuprates with YBa2Cu3O7 -δ thin films and nanowires

Science.gov (United States)

Arpaia, Riccardo; Andersson, Eric; Trabaldo, Edoardo; Bauch, Thilo; Lombardi, Floriana

2018-02-01

We have grown and characterized 30-nm-thick YBa2Cu3O7 -δ (YBCO) films, deposited by pulsed laser deposition on both MgO (110) and SrTiO3 (001) substrates, which induce opposite strain to the superconducting layer. By carefully tuning the in situ post-annealing oxygen pressure, we achieved, in a reproducible way, films at different oxygen doping, spanning from the slightly overdoped down to the strongly underdoped region of the phase diagram. The transport properties of the films, investigated through resistance versus temperature measurements, are in perfect qualitative agreement with single crystals. Starting from these films, we have also successfully fabricated nanowires with widths down to 65 nm, at different oxygen doping. The nanostructures exhibit characteristic temperatures (as the critical temperature Tc and the pseudogap temperature T*) similar to those of the as-grown films and carry critical current densities Jc close to the critical depairing value, limited by vortex entry. This implies that the superconducting and the normal state properties of underdoped YBCO are preserved in our films, and they can be studied as a function of the dimensionality of the system, down to the nanoscale.

Role of Coulomb repulsion in multilayer cuprate superconductor

International Nuclear Information System (INIS)

Singh Chauhan, Ekta; Singh, Vipul; Masih, Piyush

2012-01-01

Although BCS theory completely neglects coulomb repulsion; Anderson and Morel showed very early that it plays a central role in superconductivity. Since all high T c superconductors are based on the structure of closely spaced square planner CuO 2 layers and role of interlayer interaction plays important role in enhancement of T c . Therefore the work has been dealt with 'Role of Coulomb repulsion in Multilayer Cuprate Superconductors'. An expression for transition temperature T c is obtained by using simple integration technique and is numerically solved. It has found that T c decreases with electronic repulsion. (author)

High-T{sub c} cuprate superconductivity in a nutshell

Energy Technology Data Exchange (ETDEWEB)

Won, Hyekyung [Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Haas, Stephan; Parker, David; Maki, Kazumi [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States)

2005-02-01

Since the discovery of high-T{sub c} cuprate superconductivity in 1986 many new experimental techniques and theoretical concepts have been developed. In particular it was shown that the BCS theory of d-wave superconductivity describes semi-quantitatively the high-T{sub c} superconductivity. Furthermore, it was demonstrated that Volovik's approach is extremely useful for finding the quasiparticle properties in the vortex state. Here we survey these developments and forecast future directions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Heavy fermions and superconductivity in doped cuprates

International Nuclear Information System (INIS)

Tornow, S.; Zevin, V.; Zwicknagl, G.

1996-01-01

We present a Fermi liquid description for the low-energy excitations in rare Earth cuprates Nd 2-x Ce x CuO 4 . The strongly renormalized heavy quasiparticles which appear in the doped samples originate from the coherent decoupling of rare earth spins and correlated conduction electrons. The correlations among the conduction electrons are simulated by assuming a spin density wave ground state. We discuss results for the thermodynamic properties in the insulating, normal metallic and superconducting phases which are in fair agreement with experimental data. In addition, the model predicts interesting behaviour for the superconducting state of samples with low transition temperature T c which may help to assess the validity of the underlying assumptions. (orig.)

Fluctuating Charge-Order in Optimally Doped Bi- 2212 Revealed by Momentum-resolved Electron Energy Loss Spectroscopy

Science.gov (United States)

Husain, Ali; Vig, Sean; Kogar, Anshul; Mishra, Vivek; Rak, Melinda; Mitrano, Matteo; Johnson, Peter; Gu, Genda; Fradkin, Eduardo; Norman, Michael; Abbamonte, Peter

Static charge order is a ubiquitous feature of the underdoped cuprates. However, at optimal doping, charge-order has been thought to be completely suppressed, suggesting an interplay between the charge-ordering and superconducting order parameters. Using Momentum-resolved Electron Energy Loss Spectroscopy (M-EELS) we show the existence of diffuse fluctuating charge-order in the optimally doped cuprate Bi2Sr2CaCu2O8+δ (Bi-2212) at low-temperature. We present full momentum-space maps of both elastic and inelastic scattering at room temperature and below the superconducting transition with 4meV resolution. We show that the ``rods'' of diffuse scattering indicate nematic-like fluctuations, and the energy width defines a fluctuation timescale of 160 fs. We discuss the implications of fluctuating charge-order on the dynamics at optimal doping. This work was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF-4542. An early prototype of the M-EELS instrument was supported by the DOE Center for Emergent Superconductivity under Award No. DE-AC02-98CH10886.

Identification of Raman peaks of high-Tc cuprates in normal state through density of states

International Nuclear Information System (INIS)

Bishoyi, K.C.; Rout, G.C.; Behera, S.N.

2007-01-01

We present a microscopic theory to explain and identify the Raman spectral peaks of high-T c cuprates R 2-x M x CuO 4 in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green's function technique of Zubarev at zero wave vector and finite (room) temperature limit. The four Raman active peaks (P 1 -P 4 ) representing the electronic states of the atomic sub-systems of the cuprate system are identified by the calculated quasi-particle energy bands and electron density of states (DOS). The effect of interactions on these peaks are also explained

Deeply Virtual Neutrino Scattering

International Nuclear Information System (INIS)

Ales Psaker

2007-01-01

We investigate the extension of the deeply virtual Compton scattering process into the weak interaction sector. Standard electromagnetic Compton scattering provides a unique tool for studying hadrons, which is one of the most fascinating frontiers of modern science. In this process the relevant Compton scattering amplitude probes the hadron structure by means of two quark electromagnetic currents. We argue that replacing one of the currents with the weak interaction current can promise a new insight. The paper is organized as follows. In Sec. II we briefly discuss the features of the handbag factorization scheme. We introduce a new set of phenomenological functions, known as generalized parton distributions (GPDs) [1-6], and discuss some of their basic properties in Sec. III. An application of the GPD formalism to the neutrino-induced deeply virtual Compton scattering in the kinematics relevant to future high-intensity neutrino experiments is given in Sec. IV. The cross section results are presented in Sec. V. Finally, in Sec. VI we draw some conclusions and discuss future prospects. Some of the formal results in this paper have appeared in preliminary reports in Refs. [7] and [8], whereas a comprehensive analysis of the weak neutral and weak charged current DVCS reactions in collaboration with W. Melnitchouk and A. Radyushkin has been presented in Ref. [9

Dynamics of correlation-frozen antinodal quasiparticles in superconducting cuprates

Science.gov (United States)

Cilento, Federico; Manzoni, Giulia; Sterzi, Andrea; Peli, Simone; Ronchi, Andrea; Crepaldi, Alberto; Boschini, Fabio; Cacho, Cephise; Chapman, Richard; Springate, Emma; Eisaki, Hiroshi; Greven, Martin; Berciu, Mona; Kemper, Alexander F.; Damascelli, Andrea; Capone, Massimo; Giannetti, Claudio; Parmigiani, Fulvio

2018-01-01

Many puzzling properties of high–critical temperature (Tc) superconducting (HTSC) copper oxides have deep roots in the nature of the antinodal quasiparticles, the elementary excitations with wave vector parallel to the Cu–O bonds. These electronic states are most affected by the onset of antiferromagnetic correlations and charge instabilities, and they host the maximum of the anisotropic superconducting gap and pseudogap. We use time-resolved extreme-ultraviolet photoemission with proper photon energy (18 eV) and time resolution (50 fs) to disclose the ultrafast dynamics of the antinodal states in a prototypical HTSC cuprate. After photoinducing a nonthermal charge redistribution within the Cu and O orbitals, we reveal a dramatic momentum-space differentiation of the transient electron dynamics. Whereas the nodal quasiparticle distribution is heated up as in a conventional metal, new quasiparticle states transiently emerge at the antinodes, similarly to what is expected for a photoexcited Mott insulator, where the frozen charges can be released by an impulsive excitation. This transient antinodal metallicity is mapped into the dynamics of the O-2p bands, thus directly demonstrating the intertwining between the low- and high-energy scales that is typical of correlated materials. Our results suggest that the correlation-driven freezing of the electrons moving along the Cu–O bonds, analogous to the Mott localization mechanism, constitutes the starting point for any model of high-Tc superconductivity and other exotic phases of HTSC cuprates. PMID:29507885

Investigation of renormalization effects in high temperature cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Zabolotnyy, Volodymyr B.

2008-04-16

It has been found that the self-energy of high-T{sub C} cuprates indeed exhibits a well pronounced structure, which is currently attributed to coupling of the electrons either to lattice vibrations or to collective magnetic excitations in the system. To clarify this issue, the renormalization effects and the electronic structure of two cuprate families Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} and YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} were chosen as the main subject for this thesis. With a simple example of an electronic system coupled to a collective mode unusual renormalization features observed in the photoemission spectra are introduced. It is shown that impurity substitution in general leads to suppression of the unusual renormalization. Finally an alternative possibility to obtain a purely superconducting surface of Y-123 via partial substitution of Y atoms with Ca is introduced. It is shown that renormalization in the superconducting Y-123 has similar strong momentum dependence as in the Bi-2212 family. It is also shown that in analogy to Bi-2212 the renormalization appears to have strong dependence on the doping level (no kinks for the overdoped component) and practically vanishes above T{sub C} suggesting that coupling to magnetic excitations fits much better than competing scenarios, according to which the unusual renormalization in ARPES spectra is caused by the coupling to single or multiple phononic modes. (orig.)

Simulation of ion-beam induced defects in cuprate superconductors

International Nuclear Information System (INIS)

Dineva, M.; Marksteiner, M.; Lang, W.

2005-01-01

Full text: Heavy-ion irradiation of cuprate superconductors is well known to produce columnar defect tracks along which magnetic vortices can be pinned. Hence, this effect has a large potential for practical applications and can enhance the critical current of the high-temperature superconducting materials. On the other hand, little work has been devoted to light-ion irradiation of the new superconductors. Our previous experimental results have indicated a systematic change of electric transport properties when irradiating YBa 2 Cu 3 O 7 (YBCO) with 75 KEXV He + ions. The purpose of the present study is the investigation of the ion-target interactions with computer simulation programs based on the binary collision approximation. The program package SRIM (Stopping and Range of Ions in Matter) is widely used to simulate the impact of energetic ions (10 eV to 2 GeV) on a solid target using a quantum mechanical treatment of ion-atom collisions under the assumption of an unstructured target material. A similar program, MARLOWE, includes the exact crystalline structure of the target and, thus, is able to calculate ion channeling effects and angle dependences. Detailed results of the penetration range of ions into YBCO, scattering cascades, creation of vacancies and interstitials, are reported for various kinds of ions. One of the central results is that light ions with energy of about 80 KEXV can penetrate through thin films of the cuprate superconductors and create point defects, mainly by oxygen displacement. (author)

Chemical Bonding in Tl Cuprates Studied by X-Ray Photoemission

Energy Technology Data Exchange (ETDEWEB)

Lao, J.Y.; Overmyer, D.L.; Ren, Z.F.; Siegal, M.P.; Vasquez, R.P.; Wang, J.H.

1999-04-05

Epitaxial thin films of the Tl cuprate superconductors Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}, Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}, and TL{sub 0.78}Bi{sub 0.22}Ba{sub 0.4}Sr{sub 1.6}Ca{sub 2}Cu{sub 3}O{sub 9{minus}{delta}} are studied with x-ray photoemission spectroscopy. These data, together with previous measurements in this lab of Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7{minus}{delta}}, comprise a comprehensive data set for a comparative study of Tl cuprates with a range of chemical and electronic properties. In the Cu 2p spectra, a larger energy separation between the satellite and main peaks (E{sub s}-E{sub m}) and a lower intensity ratio (I{sub s}/I{sub m}) are found to correlate with higher values of T{sub c}. Analysis of these spectra within a simple configuration interaction model suggests that higher values of T{sub c} are related to low values of the O 2p {r_arrow} Cu 3d charge transfer energy. In the O 1s region, a smaller bond length between Ba and Cu-O planar oxygen is found to correlate with a lower binding energy for the signal associated with Cu-O bonding, most likely resulting from the increased polarization screening by Ba{sup 2+} ions. For samples near optimum doping, maximum T{sub c} is observed to occur when the Tl 4f{sub 7/2} binding energy is near 117.9 eV, which is near the middle of the range of values observed for Tl cuprates. Higher Tl 4f{sub 7/2} binding energies, corresponding to formal oxidation states nearer Tl{sup 1+}, are also found to correlate with longer bond lengths between Ba and Tl-O planar oxygen, and with higher binding energies of the O 1s signal associated with Tl-O bonding.

Chemical bonding in Tl cuprates studied by x-ray photoemission

Energy Technology Data Exchange (ETDEWEB)

Vasquez, R.P. [Center for Space Microelectronics Technology, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099 (United States); Siegal, M.P.; Overmyer, D.L. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States); Ren, Z.F.; Lao, J.Y.; Wang, J.H. [Materials Synthesis Laboratory, Department of Chemistry, State University of New York, Buffalo, New York 14260-3000 (United States)

1999-08-01

Epitaxial thin films of the Tl cuprate superconductors Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}, Tl{sub 2}Ba{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}, and Tl{sub 0.78}Bi{sub 0.22}Ba{sub 0.4}Sr{sub 1.6}Ca{sub 2}Cu{sub 3}O{sub 9{minus}{delta}} are studied with x-ray photoemission spectroscopy. These data, together with previous measurements in this lab of Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7{minus}{delta}}, comprise a comprehensive data set for a comparative study of Tl cuprates with a range of chemical and electronic properties. In the Cu 2p spectra, a larger energy separation between the satellite and main peaks (E{sub s}{minus}E{sub m}) and a lower intensity ratio (I{sub s}/I{sub m}) are found to correlate with higher values of T{sub c}. Analysis of these spectra within a simple configuration interaction model suggests that higher values of T{sub c} are related to low values of the O&hthinsp;2p{r_arrow}Cu&hthinsp;3d charge transfer energy. In the O&hthinsp;1s region, a smaller bond length between Ba and Cu-O planar oxygen is found to correlate with a lower binding energy for the signal associated with Cu-O bonding, most likely resulting from the increased polarization screening by Ba{sup 2+} ions. For samples near optimum doping, maximum T{sub c} is observed to occur when the Tl 4f{sub 7/2} binding energy is near 117.9 eV, which is near the middle of the range of values observed for Tl cuprates. Higher Tl&hthinsp;4f{sub 7/2} binding energies, corresponding to formal oxidation states nearer Tl{sup 1+}, are also found to correlate with longer bond lengths between Ba and Tl-O planar oxygen, and with higher binding energies of the O&hthinsp;1s signal associated with Tl-O bonding. {copyright} {ital 1999} {ital The American Physical Society}

Deeply virtual Compton scattering. Results and future

International Nuclear Information System (INIS)

Nowak, W.D.

2005-03-01

Access to generalised parton distributions (GPDs) through deeply virtual Compton scattering (DVCS) is briefly described. Presently available experimental results on DVCS are summarized in conjunction with plans for future measurements. (orig.)

Doping dependence of charge order in electron-doped cuprate superconductors

Science.gov (United States)

Mou, Yingping; Feng, Shiping

2017-12-01

In the recent studies of the unconventional physics in cuprate superconductors, one of the central issues is the interplay between charge order and superconductivity. Here the mechanism of the charge-order formation in the electron-doped cuprate superconductors is investigated based on the t-J model. The experimentally observed momentum dependence of the electron quasiparticle scattering rate is qualitatively reproduced, where the scattering rate is highly anisotropic in momentum space, and is intriguingly related to the charge-order gap. Although the scattering strength appears to be weakest at the hot spots, the scattering in the antinodal region is stronger than that in the nodal region, which leads to the original electron Fermi surface is broken up into the Fermi pockets and their coexistence with the Fermi arcs located around the nodal region. In particular, this electron Fermi surface instability drives the charge-order correlation, with the charge-order wave vector that matches well with the wave vector connecting the hot spots, as the charge-order correlation in the hole-doped counterparts. However, in a striking contrast to the hole-doped case, the charge-order wave vector in the electron-doped side increases in magnitude with the electron doping. The theory also shows the existence of a quantitative link between the single-electron fermiology and the collective response of the electron density.

Inverse correlation between quasiparticle mass and T c in a cuprate high-T c superconductor.

Science.gov (United States)

Putzke, Carsten; Malone, Liam; Badoux, Sven; Vignolle, Baptiste; Vignolles, David; Tabis, Wojciech; Walmsley, Philip; Bird, Matthew; Hussey, Nigel E; Proust, Cyril; Carrington, Antony

2016-03-01

Close to a zero-temperature transition between ordered and disordered electronic phases, quantum fluctuations can lead to a strong enhancement of electron mass and to the emergence of competing phases such as superconductivity. A correlation between the existence of such a quantum phase transition and superconductivity is quite well established in some heavy fermion and iron-based superconductors, and there have been suggestions that high-temperature superconductivity in copper-oxide materials (cuprates) may also be driven by the same mechanism. Close to optimal doping, where the superconducting transition temperature T c is maximal in cuprates, two different phases are known to compete with superconductivity: a poorly understood pseudogap phase and a charge-ordered phase. Recent experiments have shown a strong increase in quasiparticle mass m* in the cuprate YBa2Cu3O7-δ as optimal doping is approached, suggesting that quantum fluctuations of the charge-ordered phase may be responsible for the high-T c superconductivity. We have tested the robustness of this correlation between m* and T c by performing quantum oscillation studies on the stoichiometric compound YBa2Cu4O8 under hydrostatic pressure. In contrast to the results for YBa2Cu3O7-δ, we find that in YBa2Cu4O8, the mass decreases as T c increases under pressure. This inverse correlation between m* and T c suggests that quantum fluctuations of the charge order enhance m* but do not enhance T c.

Two types of charge transfer excitations in low dimensional cuprates: an electron energy-loss study

Czech Academy of Sciences Publication Activity Database

Knupfer, M.; Fink, J.; Drechsler, S.-L.; Hayn, R.; Málek, Jiří; Moskvin, A.S.

137-140, - (2004), s. 469-473 ISSN 0368-2048 Institutional research plan: CEZ:AV0Z1010914 Keywords : cuprates * electronic excitations * electron energy-loss spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.069, year: 2004

Probing the singlet character of the two-hole states in cuprate superconductors

NARCIS (Netherlands)

Ghiringhelli, G; Brookes, NB; Tjeng, LH; Mizokawa, T; Tjernberg, O; Menovsky, AA; Steeneken, P.G.

Using spin-resolved resonant photoemission we have probed the singlet vs. triplet character of the two-hole state in the layered cuprates Bi2Sr2CaCu2O8+delta La2-xSrxCuO4 and Sr2CuO2Cl2. The combination of the photon circular polarization with the photoelectron spin detection gives access to the

Heavy fermions and superconductivity in doped cuprates

Energy Technology Data Exchange (ETDEWEB)

Tornow, S. [Max-Planck-Inst. fur Phys. Komplexer Syst., Stuttgart (Germany). Aussenstelle Stuttgart; Zevin, V. [Hebrew Univ., Jerusalem (Israel). Racah Inst. of Physics; Zwicknagl, G. [Max-Planck-Inst. fur Phys. Komplexer Syst., Stuttgart (Germany). Aussenstelle Stuttgart

1996-10-01

We present a Fermi liquid description for the low-energy excitations in rare Earth cuprates Nd{sub 2-x}Ce{sub x}CuO{sub 4}. The strongly renormalized heavy quasiparticles which appear in the doped samples originate from the coherent decoupling of rare earth spins and correlated conduction electrons. The correlations among the conduction electrons are simulated by assuming a spin density wave ground state. We discuss results for the thermodynamic properties in the insulating, normal metallic and superconducting phases which are in fair agreement with experimental data. In addition, the model predicts interesting behaviour for the superconducting state of samples with low transition temperature T{sub c} which may help to assess the validity of the underlying assumptions. (orig.)

Microscopic Superconductivity and Room Temperature Electronics of High-Tc Cuprates

International Nuclear Information System (INIS)

Liu Fusui; Chen Wanfang

2008-01-01

This paper points out that the Landau criterion for macroscopic superfluidity of He II is only a criterion for microscopic superfluidity of 4 He, extends the Landau criterion to microscopic superconductivity in fermions (electron and hole) system and system with Cooper pairs without long-range phase coherence. This paper gives another three non-superconductive systems that are of microscopic superconductivity. This paper demonstrates that one application of microscopic superconductivity is to establish room temperature electronics of the high-T c cuprates

Strong Three-magnon Scattering in Cuprates by Resonant X-rays

OpenAIRE

Ament, Luuk J. P.; Brink, Jeroen van den

2010-01-01

We show that Resonant Inelastic X-ray scattering (RIXS) is sensitive to three-magnon excitations in cuprates. Even if it requires three electrons to simultaneously flip their spin, the RIXS tri-magnon scattering amplitude is not small. At the Cu $L$-edge its intensity is generally larger than the bi-magnon one and at low transferred momentum even larger than the single-magnon intensity. At the copper $M$-edge the situation is yet more extreme: in this case three-magnon scattering is dominatin...

Low-energy charge excitations in an undoped cuprate:Description beyond the standard pdĺ-model?

Czech Academy of Sciences Publication Activity Database

Drechsler, S.L.; Málek, Jiří; Hayn, R.; Knupfer, M.; Moskvin, A. S.; Fink, J.

2003-01-01

Roč. 17, 18, 19 & 20 (2003), s. 3324-3328 ISSN 0217-9792 Institutional research plan: CEZ:AV0Z1010914 Keywords : cuprates * EELS * loss function exact diagonalization Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.473, year: 2003

Study of apical oxygen atoms in a spin-ladder cuprate compound by X-ray absorption spectroscopy near the Cu K edge

Energy Technology Data Exchange (ETDEWEB)

Hatterer, C.J.; Eustache, B.; Collin, L.; Beuran, C.F.; Partiot, C.; Germain, P.; Xu, X.Z.; Lagues, M. [CNRS, Paris (France). Surfaces et Supraconducteurs; Michalowicz, A. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France)]|[LURE, Universite Paris Sud, 91405, Orsay Cedex (France); Moscovici, J. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France); Deville Cavellin, C. [CNRS, Paris (France). Surfaces et Supraconducteurs]|[Laboratoire d`Electronique, Universite Paris XII Val-de-Marne, 61 av. du general de Gaulle, 94010, Creteil Cedex (France); Traverse, A. [LURE, Universite Paris Sud, 91405, Orsay Cedex (France)

1997-04-01

The structure of high-T{sub c} superconducting cuprate compounds is based on CuO{sub 2} planes alternating with blocks that behave as charge reservoirs. The apical oxygen atoms which belong to these reservoirs are suspected to play a role in the mechanism of superconductivity. It thus seems necessary to measure the amount of apical oxygen atoms in various compounds, as a function of the superconducting properties. Polarisation dependent X-ray absorption spectroscopy (XAS) measurements were performed near the Cu K-edge on three types of phases. We collected information about the neighbourhood of the copper atom in the cuprate planes and in the direction perpendicular to these planes. Two of these phases have well known structures: Bi2212 in which copper atoms are on a pyramidal site and infinite layer phase, a square planar cuprate without apical oxygen. We used the obtained results as reference data to study a new copper-rich phase related to the spin-ladder series. (orig.)

Angle-resolved photoemission spectroscopy of band tails in lightly doped cuprates

OpenAIRE

Alexandrov, A. S.; Reynolds, K.

2007-01-01

We amend ab initio strongly-correlated band structures by taking into account the band-tailing phenomenon in doped charge-transfer Mott-Hubbard insulators. We show that the photoemission from band tails accounts for sharp "quasi-particle" peaks, rapid loss of their intensities in some directions of the Brillouin zone ("Fermi-arcs") and high-energy "waterfall" anomalies as a consequence of matrix-element effects of disorder-localised states in the charge-transfer gap of doped cuprates.

dc Resistivity of Quantum Critical, Charge Density Wave States from Gauge-Gravity Duality.

Science.gov (United States)

Amoretti, Andrea; Areán, Daniel; Goutéraux, Blaise; Musso, Daniele

2018-04-27

In contrast to metals with weak disorder, the resistivity of weakly pinned charge density waves (CDWs) is not controlled by irrelevant processes relaxing momentum. Instead, the leading contribution is governed by incoherent, diffusive processes which do not drag momentum and can be evaluated in the clean limit. We compute analytically the dc resistivity for a family of holographic charge density wave quantum critical phases and discuss its temperature scaling. Depending on the critical exponents, the ground state can be conducting or insulating. We connect our results to dc electrical transport in underdoped cuprate high T_{c} superconductors. We conclude by speculating on the possible relevance of unstable, semilocally critical CDW states to the strange metallic region.

Single-particle properties of the Hubbard model in a novel three-pole approximation

Science.gov (United States)

Di Ciolo, Andrea; Avella, Adolfo

2018-05-01

We study the 2D Hubbard model using the Composite Operator Method within a novel three-pole approximation. Motivated by the long-standing experimental puzzle of the single-particle properties of the underdoped cuprates, we include in the operatorial basis, together with the usual Hubbard operators, a field describing the electronic transitions dressed by the nearest-neighbor spin fluctuations, which play a crucial role in the unconventional behavior of the Fermi surface and of the electronic dispersion. Then, we adopt this approximation to study the single-particle properties in the strong coupling regime and find an unexpected behavior of the van Hove singularity that can be seen as a precursor of a pseudogap regime.

dc Resistivity of Quantum Critical, Charge Density Wave States from Gauge-Gravity Duality

Science.gov (United States)

Amoretti, Andrea; Areán, Daniel; Goutéraux, Blaise; Musso, Daniele

2018-04-01

In contrast to metals with weak disorder, the resistivity of weakly pinned charge density waves (CDWs) is not controlled by irrelevant processes relaxing momentum. Instead, the leading contribution is governed by incoherent, diffusive processes which do not drag momentum and can be evaluated in the clean limit. We compute analytically the dc resistivity for a family of holographic charge density wave quantum critical phases and discuss its temperature scaling. Depending on the critical exponents, the ground state can be conducting or insulating. We connect our results to dc electrical transport in underdoped cuprate high Tc superconductors. We conclude by speculating on the possible relevance of unstable, semilocally critical CDW states to the strange metallic region.

Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors.

Science.gov (United States)

Hong, Seung Hwan; Choi, Han-Yong

2013-09-11

We investigated the characteristics of spin fluctuation mediated superconductivity employing the Eliashberg formalism. The effective interaction between electrons was modeled in terms of the spin susceptibility measured by inelastic neutron scattering experiments on single crystal La(2-x)Sr(x)CuO4 superconductors. The diagonal self-energy and off-diagonal self-energy were calculated by solving the coupled Eliashberg equation self-consistently for the chosen spin susceptibility and tight-binding dispersion of electrons. The full momentum and frequency dependence of the self-energy is presented for optimally doped, overdoped, and underdoped LSCO cuprates in a superconductive state. These results may be compared with the experimentally deduced self-energy from ARPES experiments.

Phonon-induced anomalous Raman spectra in undoped high-Tc cuprates

International Nuclear Information System (INIS)

Lee, J.D.; Min, B.I.

1997-01-01

In order to describe a shoulder peak structure near 4J in the magnon Raman spectra of undoped high-T c cuprates, we have explored the phonon contribution to the Raman spectra. Incorporating the magnon-phonon Hamiltonian in the spin-wave theory, we have evaluated the two-magnon Raman spectral function originating from the lowest-order magnon-phonon-magnon scattering. It is found that phonons induce a shoulder peak near 4J besides the dominant two-magnon peak near 3J, in agreement with experiments. (orig.)

NMR initiatives on understanding high-temperature superconductivity

International Nuclear Information System (INIS)

Kitaoka, Y.; Mukuda, H.; Shimizu, S.; Abe, M.; Iyo, A.; Tanaka, Y.; Kito, H.; Tokiwa, K.; Watanabe, T.

2007-01-01

We review a recent progress of NMR studies [H. Mukuda, et al., Phys. Rev. Lett 96 (2006) 087001; S. Shimizu, et al., submitted for publication.] on multi-layered cuprates. This work has shed new light to a generic phase diagram of high-temperature superconductivity (HTSC) which suggests a competition between antiferromagnetism (AFM) and superconductivity (SC). The multi-layered cuprates include two types of CuO 2 planes, an outer CuO 2 plane (OP) in a pyramidal coordination and an inner CuO 2 plane (IP) in a square one with no apical oxygen. Remarkable feature of the multi-layered systems is the presence of ideally flat CuO 2 planes that are homogeneously doped. Systematic Cu-NMR studies on the optimally-doped five-layered HgBa 2 Ca 4 Cu 5 O 12+δ (Hg-1245(OPT)) and slightly overdoped Tl-1245(OVD) have revealed the coexistent phase of SC and AFM in a unit cell [H. Kotegawa, et al., Phys. Rev. B 64 (2001) 064515; H. Kotegawa, et al., Phys. Rev. B 69 (2004) 014501.]. The optimally doped two OPs are predominantly superconducting with T c =108 and 100K, whereas the under-doped three IPs show the AFM order below T N =60 and 45K for Hg-1245(OPT) and Tl-1245(OVD), respectively. Recently exciting is the finding of the uniform mixing of AFM and HTSC in a single CuO 2 layer in the under-doped Hg-1245(UD) and the heavily underdoped four-layered Ba 2 Ca 3 Cu 4 O 8 F 2 (0234F(2.0)) that has fluorine ions (F 1- ) as apical ions [H. Mukuda, et al., Phys. Rev. Lett 96 (2006) 087001; S. Shimizu, et al., submitted for publication.]. In Hg-1245(UD) with T c =72K and T N =290K, the OPs exhibit the uniform mixing of AFM and HTSC with AFM moment of M AFM (OP)=0.1μ B , whereas the IPs are possibly AFM insulators with a small doping [H. Mukuda, et al., Phys. Rev. Lett 96 (2006) 087001.]. In 0234F(2.0) with T c =55K and T N =100K, the uniform mixing of AFM and HTSC is demonstrated to take place in electron (n)-doped IPs [S. Shimizu, et al., submitted for publication.], thanks to insight

The Inward Dispersion of the Neutron Scattering Experiments in HTSC Cuprates

OpenAIRE

Dayan, Moshe

2016-01-01

The theory of the high temperature superconducting cuprates, which is based on the condensation of holes into strings in checker-board geometry, was successful to explain the elastically scattered Neutrons by spin waves. Here it is extended to analyze the inward dispersion curve of its inelastic counterpart, up to the resonance energy- . This extension is done by applying the perturbation theory of the linear response to the condensed strings. The approximated susceptibility is derived by mea...

Characteristics of the Mott transition and electronic states of high-temperature cuprate superconductors from the perspective of the Hubbard model

Science.gov (United States)

Kohno, Masanori

2018-04-01

A fundamental issue of the Mott transition is how electrons behaving as single particles carrying spin and charge in a metal change into those exhibiting separated spin and charge excitations (low-energy spin excitation and high-energy charge excitation) in a Mott insulator. This issue has attracted considerable attention particularly in relation to high-temperature cuprate superconductors, which exhibit electronic states near the Mott transition that are difficult to explain in conventional pictures. Here, from a new viewpoint of the Mott transition based on analyses of the Hubbard model, we review anomalous features observed in high-temperature cuprate superconductors near the Mott transition.

Doping evolution of the electronic structure in the single-layer cuprates Bi2Sr2−xLaxCuO6 delta: Comparison with other single-layer cuprates

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, M.

2010-04-30

We have performed angle-resolved photoemission and core-level x-ray photoemission studies of the single-layer cuprate Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}} (Bi2201) and revealed the doping evolution of the electronic structure from the lightly-doped to optimally-doped regions. We have observed the formation of the dispersive quasi-particle band, evolution of the Fermi 'arc' into the Fermi surface and the shift of the chemical potential with hole doping as in other cuprates. The doping evolution in Bi2201 is similar to that in Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} (Na-CCOC), where a rapid chemical potential shift toward the lower Hubbard band of the parent insulator has been observed, but is quite different from that in La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO), where the chemical potential does not shift, yet the dispersive band and the Fermi arc/surface are formed around the Fermi level already in the lightly-doped region. The (underlying) Fermi surface shape and band dispersions are quantitatively analyzed using tightbinding fit, and the deduced next-nearest-neighbor hopping integral t also confirm the similarity to Na-CCOC and the difference from LSCO.

Theory of high-Tc superconducting cuprates based on experimental evidence

International Nuclear Information System (INIS)

Abrikosov, A. A.

1999-01-01

A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of Tc, features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc

Weak Deeply Virtual Compton Scattering

International Nuclear Information System (INIS)

Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

2006-01-01

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities

Earthquakes - a danger to deep-lying repositories?; erdbeben: eine gefahr fuer tiefenlager?

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-03-15

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at geological factors concerning earthquakes and the safety of deep-lying repositories for nuclear waste. The geological processes involved in the occurrence of earthquakes are briefly looked at and the definitions for magnitude and intensity of earthquakes are discussed. Examples of damage caused by earthquakes are given. The earthquake situation in Switzerland is looked at and the effects of earthquakes on sub-surface structures and deep-lying repositories are discussed. Finally, the ideas proposed for deep-lying geological repositories for nuclear wastes are discussed.

Distinct Nature of Static and Dynamic Magnetic Stripes in Cuprate Superconductors

Science.gov (United States)

Jacobsen, H.; Holm, S. L.; Lǎcǎtuşu, M.-E.; Rømer, A. T.; Bertelsen, M.; Boehm, M.; Toft-Petersen, R.; Grivel, J.-C.; Emery, S. B.; Udby, L.; Wells, B. O.; Lefmann, K.

2018-01-01

We present detailed neutron scattering studies of the static and dynamic stripes in an optimally doped high-temperature superconductor, La2 CuO4 +y . We observe that the dynamic stripes do not disperse towards the static stripes in the limit of vanishing energy transfer. Therefore, the dynamic stripes observed in neutron scattering experiments are not the Goldstone modes associated with the broken symmetry of the simultaneously observed static stripes, and the signals originate from different domains in the sample. These observations support real-space electronic phase separation in the crystal, where the static stripes in one phase are pinned versions of the dynamic stripes in the other, having slightly different periods. Our results explain earlier observations of unusual dispersions in underdoped La2 -xSrx CuO4 (x =0.07 ) and La2 -xBax CuO4 (x =0.095 ).

Angle-resolved photoelectron spectroscopy studies of the many-body effects in the electronic structure of high-T{sub c} cuprates

Energy Technology Data Exchange (ETDEWEB)

Inosov, Dmytro S.

2008-06-18

In the present work some steps are done towards understanding the anomalous effects observed in the single-particle excitation spectra of cuprates. First, the electronic properties of BSCCO are considered. The main result of this part of the work is a model of the Green's function that is later used for calculating the two-particle excitation spectrum. Then, the matrix element effects in the photoemission spectra of cuprates are discussed. After a general introduction to the problem, the thesis focuses on the recently discovered anomalous behavior of the ARPES spectra that partially originates from the momentum-dependent photoemission matrix element. The momentum- and excitation energy dependence of the anomalous high-energy dispersion, termed ''waterfalls'', is covered in full detail. Understanding the role of the matrix element effects in this phenomenon proves crucial, as they obstruct the view of the underlying excitation spectrum that is of indisputable interest. For the optimally doped bilayer Bi-based cuprate, the renormalized two-particle correlation function in the superconducting state is calculated from ARPES data within an itinerant model based on the random phase approximation (RPA). (orig.)

Theory of antiferromagnetic pairing in cuprate superconductors

International Nuclear Information System (INIS)

Plakida, N.M.

2006-01-01

A review of the antiferromagnetic exchange and spin-fluctuation pairing theory in the cuprate superconductors is given. We briefly discuss a phenomenological approach and a theory in the limit of weak Coulomb correlations. A microscopic theory in the strong correlation limit is presented in more detail. In particular, results of our recently developed theory for the effective p-d Hubbard model and the reduced t-J model are given. We have proved that retardation effects for the antiferromagnetic exchange interaction are unimportant that results in pairing of all charge carriers in the conduction band and high Tc proportional to the Fermi energy. The spin-fluctuation interaction caused by kinematic interaction gives an additional contribution to the d-wave pairing. Dependence of Tc on the hole concentration and the lattice constant (or pressure) and an oxygen isotope shift are discussed

Toward (-)-Enterocin: An Improved Cuprate Barbier Protocol To Overcome Strain and Sterical Hindrance.

Science.gov (United States)

Rizzo, Antonio; Trauner, Dirk

2018-04-06

An approach toward (-)-enterocin, an antibiotic isolated from Streptomyces hygroscopicus, is described. Its compact, heavily oxidized protoadamantane core represents a daunting challenge for an efficient synthesis. Convergent assembly of its 2-oxabicyclo[3.3.1]nonane core with a cuprate-mediated Barbier reaction is disclosed. Its functionalization to a suitable substrate for a biomimetic aldol to close the final ring of the natural product is evaluated.

Deeply bound pionic states and modifications of hadrons

International Nuclear Information System (INIS)

Hirenzaki, S.

2000-01-01

We have studied the structure and formation of mesic atoms and mesic nuclei theoretically. The latest results on the deeply bound pionic atoms, the kaonic atoms and the sigma states are reported. (author)

In situ XANES cell used for the study of lanthanum strontium cuprate deNOx catalysts

DEFF Research Database (Denmark)

Hagen, Anke

2011-01-01

, maintaining charge neutrality, with the concentration of oxygen vacancies likely increasing at substitution ratios larger than Sr/La>0.08. During heating in air, the valence of copper ions in the structure increased. Upon exposure to NO at 500 °C the valence of copper ions in a lanthanum strontium cuprate...

Complex force network in marginally and deeply jammed solids

International Nuclear Information System (INIS)

Hu Mao-Bin; Jiang Rui; Wu Qing-Song

2013-01-01

This paper studies the force network properties of marginally and deeply jammed packings of frictionless soft particles from the perspective of complex network theory. We generate zero-temperature granular packings at different pressures by minimizing the inter-particle potential energy. The force networks are constructed as nodes representing particles and links representing normal forces between the particles. Deeply jammed solids show remarkably different behavior from marginally jammed solids in their degree distribution, strength distribution, degree correlation, and clustering coefficient. Bimodal and multi-modal distributions emerge when the system enters the deep jamming region. The results also show that small and large particles can show different correlation behavior in this simple system

Identification of Raman peaks of high-T{sub c} cuprates in normal state through density of states

Energy Technology Data Exchange (ETDEWEB)

Bishoyi, K.C. [P.G. Department of Physics, F.M. College (Auto.), Balasore 756 001 (India)]. E-mail: bishoyi@iopb.res.in; Rout, G.C. [Condensed Matter Physics Group, Govt. Science College, Chatrapur 761 020, Orissa (India); Behera, S.N. [Physics Enclave, H.I.G.-23/1, Housing Board Phase-I, Chandrasekharpur, Bhubaneswar 7510016 (India)

2007-05-31

We present a microscopic theory to explain and identify the Raman spectral peaks of high-T{sub c} cuprates R{sub 2-x}M{sub x}CuO{sub 4} in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green's function technique of Zubarev at zero wave vector and finite (room) temperature limit. The four Raman active peaks (P{sub 1}-P{sub 4}) representing the electronic states of the atomic sub-systems of the cuprate system are identified by the calculated quasi-particle energy bands and electron density of states (DOS). The effect of interactions on these peaks are also explained.

Determination of the rate of energy partition in deeply inelastic collisions

International Nuclear Information System (INIS)

Lazzarini, A.; Vandenbosch, R.

1984-01-01

We discuss how excitation energy is partitioned in a deeply inelastic collision. Using the nucleon exchange mechanism for the deep inelastic scattering process, it is possible to draw on existing information about the evolution of the charge and mass distributions with energy loss and combine this with recent information on the partition of excitation energy in deeply inelastic collisions to obtain rates of heating for the two reaction partners

Thermodynamic and nonstoichiometric behavior of promising Hi-Tc cuprate systems via EMF measurements: a short review

International Nuclear Information System (INIS)

Tetenbaum, M.

1999-01-01

Electromotive force (EMF) measurements of oxygen fugacities as a function of stoichiometry have been made on the YBa 2 Cu 3 O x , GdBa 2 Cu 3 O x , NdBa 2 Cu 3 O x and bismuth cuprate systems in the temperature range ∼400-750 C by means of an oxygen titration technique with an yttria-stabilized zirconia electrolyte. The shapes of the 400 C isotherms as a function of oxygen stoichiometry for the Gd and Nd cuprate systems suggest the presence of miscibility gaps at values of x that are higher than those in the YBa 2 Cu 3 O x system. For a given oxygen stoichiometry, oxygen partial pressures above GdBa 2 Cu 3 O x and NdBa 2 Cu 3 O x are higher (above x=6.5) than that for the promising YBa 2 Cu 3 O x system. A thermodynamic assessment and intercomparison of our partial pressure measurements with the results of related measurements will be presented

The Origin of Tc Enhancement in Heterostructure Cuprate Superconductors

Directory of Open Access Journals (Sweden)

Doron L. Bergman

2011-10-01

Full Text Available Recent experiments on heterostructures composed of two or more films of cuprate superconductors of different oxygen doping levels have shown a remarkable Tc enhancement (up to 50% relative to single compound films. We provide a simple explanation of the enhancement which arises naturally from a collection of experimental works. We show that the enhancement could be caused by a structural change in the lattice, namely an increase in the distance of the apical oxygen from the copper-oxygen plane. This increase modifies the effective off-site interaction in the plane which in turn enhances the d-wave superconductivity order parameter. To illustrate this point we study the extended Hubbard model using the fluctuation exchange approximation.

In-plane electronic anisotropy of underdoped '122' Fe-arsenide superconductors revealed by measurements of detwinned single crystals

International Nuclear Information System (INIS)

Fisher, I R; Shen, Z X; Degiorgi, L

2011-01-01

The parent phases of the Fe-arsenide superconductors harbor an antiferromagnetic ground state. Significantly, the Neel transition is either preceded or accompanied by a structural transition that breaks the four-fold symmetry of the high-temperature lattice. Borrowing language from the field of soft condensed matter physics, this broken discrete rotational symmetry is widely referred to as an Ising nematic phase transition. Understanding the origin of this effect is a key component of a complete theoretical description of the occurrence of superconductivity in this family of compounds, motivating both theoretical and experimental investigation of the nematic transition and the associated in-plane anisotropy. Here we review recent experimental progress in determining the intrinsic in-plane electronic anisotropy as revealed by resistivity, reflectivity and angle-resolved photoemission spectroscopy measurements of detwinned single crystals of underdoped Fe-arsenide superconductors in the '122' family of compounds.

In-Plane Electronic Anisotropy of Underdoped ___122___ Fe-Arsenide Superconductors Revealed by Measurements of Detwinned Single Crystals

Energy Technology Data Exchange (ETDEWEB)

Fisher, Ian Randal

2012-05-08

The parent phases of the Fe-arsenide superconductors harbor an antiferromagnetic ground state. Significantly, the Neel transition is either preceded or accompanied by a structural transition that breaks the four fold symmetry of the high-temperature lattice. Borrowing language from the field of soft condensed matter physics, this broken discrete rotational symmetry is widely referred to as an Ising nematic phase transition. Understanding the origin of this effect is a key component of a complete theoretical description of the occurrence of superconductivity in this family of compounds, motivating both theoretical and experimental investigation of the nematic transition and the associated in-plane anisotropy. Here we review recent experimental progress in determining the intrinsic in-plane electronic anisotropy as revealed by resistivity, reflectivity and ARPES measurements of detwinned single crystals of underdoped Fe arsenide superconductors in the '122' family of compounds.

Spin dynamics in high-T{sub C} superconducting cuprates; Dynamique de spins dans les oxydes de cuivre supraconducteurs a haute temperature critique

Energy Technology Data Exchange (ETDEWEB)

Bourges, Ph

2003-07-01

This work is dedicated to the detailed investigations of the magnetic resonance peak in the superconducting state of cuprates. The existence of such a peak could be the signature of a mechanism linked to magnetism that could explain high critical temperature superconductivity. Inelastic neutron scattering is an adequate tool for the understanding of cuprate properties because it reveals magnetic fluctuations whose behaviour and variety depend strongly on temperature and on the level of doping. The last part of this work is dedicated to the study of spin dynamics in YBa{sub 2}Cu{sub 3}O{sub 6+x} system.

Electron energy-loss spectroscopy of quasi-one-dimensional cuprates and vanadates

International Nuclear Information System (INIS)

Atzkern, S.

2001-01-01

In a combination of experimental and theoretical methods in this thesis the electronic structures of quasi-one-dimensional cuprates and vanadates were studied. For this the momentum-dependent loss function was measured by means of the electron energy-loss spectroscopy in transmission on monocrystals of Li 2 CuO 2 , CuGeO 3 , V 2 O 5 and α'-NaVO 5 . The comparison of the experimental data with results from band-structure and cluster calculations allowed conclusions on the mobility and correlations of the electrons in these systems

Magnetic field induced incommensurate resonance in cuprate superconductors

International Nuclear Information System (INIS)

Zhang Jingge; Cheng Li; Guo Huaiming; Feng Shiping

2009-01-01

The influence of a uniform external magnetic field on the dynamical spin response of cuprate superconductors in the superconducting state is studied based on the kinetic energy driven superconducting mechanism. It is shown that the magnetic scattering around low and intermediate energies is dramatically changed with a modest external magnetic field. With increasing the external magnetic field, although the incommensurate magnetic scattering from both low and high energies is rather robust, the commensurate magnetic resonance scattering peak is broadened. The part of the spin excitation dispersion seems to be an hourglass-like dispersion, which breaks down at the heavily low energy regime. The theory also predicts that the commensurate resonance scattering at zero external magnetic field is induced into the incommensurate resonance scattering by applying an external magnetic field large enough

Tunneling in cuprate and bismuthate superconductors

International Nuclear Information System (INIS)

Zasadzinski, J.F.; Huang, Qiang; Tralshawala, N.

1991-10-01

Tunneling measurements using a point-contact technique are reported for the following high temperature superconducting oxides: Ba 1-x K x BiO 3 (BKBO), Nd 2-x Ce x CuO 4 (NCCO), Bi 2 Sr 2 CaCu 2 O 7 (BSCCO) and Tl 2 Ba 2 CaCu 2 O x (TBCCO). For the bismuthate, BKBO, ideal, S-I-N tunneling characteristics are observed using a Au tip. The normalized conductance is fitted to a BCS density of states and thermal smearing only proving there is no fundamental limitation in BKBO for device applications. For the cuprates, the normalized conductance displays BCS-like characteristics, but with a broadening larger than from thermal smearing. Energy gap values are presented for each material. For BKBO and NCCO the Eliashberg functions, α 2 F(ω), obtained from the tunneling are shown to be in good agreement with neutron scattering results. Proximity effect tunneling studies are reported for Au/BSCCO bilayers and show that the energy gap of BSCCO can be observed through Au layers up to 600 Angstrom thick

Quasi-particles ultrafastly releasing kink bosons to form Fermi arcs in a cuprate superconductor.

Science.gov (United States)

Ishida, Y; Saitoh, T; Mochiku, T; Nakane, T; Hirata, K; Shin, S

2016-01-05

In a conventional framework, superconductivity is lost at a critical temperature (Tc) because, at higher temperatures, gluing bosons can no longer bind two electrons into a Cooper pair. In high-Tc cuprates, it is still unknown how superconductivity vanishes at Tc. We provide evidence that the so-called ≲ 70-meV kink bosons that dress the quasi-particle excitations are playing a key role in the loss of superconductivity in a cuprate. We irradiated a 170-fs laser pulse on Bi2Sr2CaCu2O(8+δ) and monitored the responses of the superconducting gap and dressed quasi-particles by time- and angle-resolved photoemission spectroscopy. We observe an ultrafast loss of superconducting gap near the d-wave node, or light-induced Fermi arcs, which is accompanied by spectral broadenings and weight redistributions occurring within the kink binding energy. We discuss that the underlying mechanism of the spectral broadening that induce the Fermi arc is the undressing of quasi-particles from the kink bosons. The loss mechanism is beyond the conventional framework, and can accept the unconventional phenomena such as the signatures of Cooper pairs remaining at temperatures above Tc.

Superconductivity and antiferromagnetism in cuprates and pnictides: Evidence of the role of Coulomb correlation

International Nuclear Information System (INIS)

Fan, J.D.; Malozovsky, Y.M.

2013-01-01

Highlights: • In a layered 2D cuprates the long-range order antiferromagnetism is driven mainly by the Van Hove singularity. • The long-range antiferromagnetism quickly disappear with doping away from the Van Hove singularity. • For pnictides the antiferromagnetism exists as a result of the nesting condition. • Since the doping steadily changes the nesting conditions, the antiferromagnetism and superconductivity may coexist. -- Abstract: We consider the Hubbard model in terms of the perturbative diagrammatic approach (UN F ⩽1) where the interaction between two electrons with antiparallel spins in the lowest order of perturbation is described by the short-range repulsive contact (on-site) interaction (U>0). We argue that in layered 2D cuprates the long-range order antiferromagnetism is driven mainly by the Van Hove singularity, whereas in the case of pnictides the antiferromagnetism exists as a result of the nesting condition. We show that when the interaction is quite strong (UN F ≈1) in the case of the Van Hove singularity the electron system undergoes the antiferromagnetic phase transition with the log-range order parameter and large insulating gap. The long-range antiferromagnetism quickly disappear, as shown, with the doping away from the Van Hove singularity, but the antiferromagnetic short-range correlation persists (UN F < 1) due to Coulomb repulsive interaction which is the mechanism for superconductivity in cuprates. We argue that in the case of pnictides the antiferromagnetism appears when the nesting conditions for the Fermi surface are met. Since the doping steadily changes the nesting conditions, the antiferromagnetism and superconductivity may coexist as has been observed in pnictides. We show that the proximity of the antiferromagnetism and superconductivity implies the repulsive interaction between electrons, which turns into attractive between quasiparticles as shown by the authors in the article published on the same issue as this one

Magnetic excitations in underdoped Ba (Fe1-x Cox)2 As2 with x = 0.047

International Nuclear Information System (INIS)

Tucker, G.S.; Fernandes, R.M.; Li, Haifeng; Thampy, Vivek; Ni, N.; Abernathy, Douglas L.; Budko, S.L.; Broholm, C.; Canfield, Paul; Vaknin, D.; Schmalian, J.; Mcqueeney, R.J.

2012-01-01

The magnetic excitations in the paramagnetic-tetragonal phase of underdoped Ba(Fe0.953Co0.047)2As2, as measured by inelastic neutron scattering, can be well described by a phenomenological model with purely diusive spin dynamics. At low energies, the spec- trum around the magnetic ordering vector Q AFM consists of a single peak with elliptical shape in momentum space. At high energies, this inelastic peak is split into two peaks across the direction perpendicular to Q AFM . We use our fittings to argue that such a splitting is not due to incommensurability or propagating spin-wave excitations, but is rather a consequence of the anisotropies in the Landau damping and in the magnetic correlation length, both of which are allowed by the tetragonal symmetry of the system. We also measure the magnetic spectrum deep inside the magnetically-ordered phase, and find that it is remarkably similar to the spectrum of the paramagnetic phase, revealing the strongly overdamped character of the magnetic excitations.

Effects of magnetic field on the cuprate high-Tc superconductor La2-xSrxCuO4

DEFF Research Database (Denmark)

Lake, B.; Aeppli, G.; Christensen, N.B.

2004-01-01

This article discusses neutron scattering measurements on the cuprate, high transition temperature superconductor La2-xSrxCuO4 (LSCO) in an applied magnetic field. LSCO is a type-II superconductor and magnetic flux can penetrate the material via the formation of vorticies. Phase coherent...

Problems of synthesis and thermal treatment of bismuth-strontium-calcium superconducting cuprates

International Nuclear Information System (INIS)

Tret'yakov, Yu.D.; Os'kina, T.E.; Putlyaev, V.I.

1990-01-01

The results, which have recently appeared in literature on synthesis and high-temperature treatment of Bi-Sr-Ca superconducting cuprates, are generalized. The review will contribute to the overcoming of experimental difficulties in the process of synthesis of monophase superconducting materials with a high transition temperature T c , including optimization of cation composition and heat treatment regime. Radional selection of synthesis conditions (component ratio, temperature, time, reactive area geometry, medium, cooling) was realized, taking into account the newest achievements in crystallochemistry of the phases

Persistence of deeply sourced iron in the Pacific Ocean.

Science.gov (United States)

Horner, Tristan J; Williams, Helen M; Hein, James R; Saito, Mak A; Burton, Kevin W; Halliday, Alex N; Nielsen, Sune G

2015-02-03

Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe-Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface.

25 CFR 215.25 - Other minerals and deep-lying lead and zinc minerals.

Science.gov (United States)

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Other minerals and deep-lying lead and zinc minerals. 215.25 Section 215.25 Indians BUREAU OF INDIAN AFFAIRS, DEPARTMENT OF THE INTERIOR ENERGY AND MINERALS LEAD AND ZINC MINING OPERATIONS AND LEASES, QUAPAW AGENCY § 215.25 Other minerals and deep-lying lead...

Systematics of c-axis phonons in the thallium- and bismuth-based cuprate superconductors

NARCIS (Netherlands)

Tsvetkov, A.A.; Dulic, Diana; Marel, D. van der; Damascelli, A.; Kaljushnaia, G.A.; Gorina, J.I.; Senturina, N.N.; Kolesnikov, N.N.; Ren, Z.F.; Wang, J.H.; Menovsky, A.A.; Palstra, T.T.M.

1999-01-01

We present grazing incidence reflectivity measurements in the far-infrared region at temperatures above and below Tc for a series of thallium- (Tl2Ba2CuO6, Tl2Ba2CaCu2O8) and bismuth- (Bi2Sr2CuO6, Bi2Sr2CaCu2O8, and Bi2-xPbxSr2CaCu2O8) based cuprate superconductors. From the spectra, which are

Atomic substitution in selected high-temperature superconductors: Elucidating the nature of Raman spectra excitations

Science.gov (United States)

Hewitt, Kevin Cecil

2000-10-01

In this thesis, the effects of atomic substitution on the vibrational and electronic excitations found in the Raman spectra of selected high-temperature superconductors (HTS) are studied. In particular, atomic and isotopic substitution methods have been used to determine the character of features observed in the Raman spectra of Bi2Sr2Ca n-1CunO2 n+4+delta (n = 1 - Bi2201, n = 2 - Bi2212) and YBa2Cu3O7-delta (Y123). In Bi2201, Pb substitution for Bi (and Sr) has led to the reduction and eventual removal of the structural modulation, characteristic of all members of the Bi-family of HTS. The high quality single crystals and our sensitive triple spectrometer enabled identification of a pair of low frequency modes. The modes are determined to arise from shear and compressional rigid-layer vibrations. The normal state of underdoped cuprates is characterized by a pseudogap of unknown origin. In crystals of underdoped Bi2212 a spectral peak found at 590 cm-1, previously attributed to the pairing of quasiparticles (above Tc) and hence to the formation of a normal state pseudogap, has been found to soften by 3.8% with oxygen isotope exchange. In addition, the feature is absent in fully oxygenated and yttrium underdoped crystals. In this study, the first of its kind on underdoped and isotope substituted Bi2212, the feature has been assigned to stretching vibrations of oxygen in the a-b plane. Bi2212 crystals with varying hole concentrations (0.07 Raman scattering experiments that sample the diagonal (B 2g) and principal axes (B1 g) of the BZ have led us to conclude that the superconducting gap possesses dx2-y2 symmetry, in the underdoped and overdoped regimes. It is found that the magnitude of the superconducting gap (Delta(k)) is sensitive to changes in p. Studies of the pair-breaking peak found in the B1g spectra allow us to conclude that the magnitude of the maximum gap (Deltamax) decreases monotonically with increasing hole doping, for p > 0.13. The pair

Bosonic excitations and electron pairing in an electron-doped cuprate superconductor

Science.gov (United States)

Wang, M. C.; Yu, H. S.; Xiong, J.; Yang, Y.-F.; Luo, S. N.; Jin, K.; Qi, J.

2018-04-01

By applying ultrafast optical spectroscopy to electron-doped La1.9Ce0.1CuO4 ±δ , we discern a bosonic mode of electronic origin and provide the evolution of its coupling with the charge carriers as a function of temperature. Our results show that it has the strongest coupling strength near Tc and can fully account for the superconducting pairing. This mode can be associated with the two-dimensional antiferromagnetic spin correlations emerging below a critical temperature T† larger than Tc. Our work may help to establish a quantitative relation between bosonic excitations and superconducting pairing in electron-doped cuprates.

Quasiparticle density of states, localization, and distributed disorder in the cuprate superconductors

Science.gov (United States)

Sulangi, Miguel Antonio; Zaanen, Jan

2018-04-01

We explore the effects of various kinds of random disorder on the quasiparticle density of states of two-dimensional d -wave superconductors using an exact real-space method, incorporating realistic details known about the cuprates. Random on-site energy and pointlike unitary impurity models are found to give rise to a vanishing DOS at the Fermi energy for narrow distributions and low concentrations, respectively, and lead to a finite, but suppressed, DOS at unrealistically large levels of disorder. Smooth disorder arising from impurities located away from the copper-oxide planes meanwhile gives rise to a finite DOS at realistic impurity concentrations. For the case of smooth disorder whose average potential is zero, a resonance is found at zero energy for the quasiparticle DOS at large impurity concentrations. We discuss the implications of these results on the computed low-temperature specific heat, the behavior of which we find is strongly affected by the amount of disorder present in the system. We also compute the localization length as a function of disorder strength for various types of disorder and find that intermediate- and high-energy states are quasiextended for low disorder, and that states near the Fermi energy are strongly localized and have a localization length that exhibits an unusual dependence on the amount of disorder. We comment on the origin of disorder in the cuprates and provide constraints on these based on known results from scanning tunneling spectroscopy and specific heat experiments.

Pseudogap-generated a coexistence of Fermi arcs and Fermi pockets in cuprate superconductors

Science.gov (United States)

Zhao, Huaisong; Gao, Deheng; Feng, Shiping

2017-03-01

One of the most intriguing puzzle is why there is a coexistence of Fermi arcs and Fermi pockets in the pseudogap phase of cuprate superconductors? This puzzle is calling for an explanation. Based on the t - J model in the fermion-spin representation, the coexistence of the Fermi arcs and Fermi pockets in cuprate superconductors is studied by taking into account the pseudogap effect. It is shown that the pseudogap induces an energy band splitting, and then the poles of the electron Green's function at zero energy form two contours in momentum space, however, the electron spectral weight on these two contours around the antinodal region is gapped out by the pseudogap, leaving behind the low-energy electron spectral weight only located at the disconnected segments around the nodal region. In particular, the tips of these disconnected segments converge on the hot spots to form the closed Fermi pockets, generating a coexistence of the Fermi arcs and Fermi pockets. Moreover, the single-particle coherent weight is directly related to the pseudogap, and grows linearly with doping. The calculated result of the overall dispersion of the electron excitations is in qualitative agreement with the experimental data. The theory also predicts that the pseudogap-induced peak-dip-hump structure in the electron spectrum is absent from the hot-spot directions.

Two-particle self-consistent analysis for the electron-hole asymmetry of superconductivity in cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Ogura, Daisuke; Kuroki, Kazuhiko [Department of Physics, Graduate School of Science, Osaka University, Toyonaka (Japan)

2017-06-15

In the hole-doped type cuprate superconductors, it is well-known that the superconducting transition temperature T{sub c} exhibits a dome-like structure against doping. On the other hand, recent experiments unveil that T{sub c} in the electron-doped compounds shows a monotonic increase with decreasing the doping, at least down to a very small doping rate. Our recent study for the three-band d-p model has unveiled that this asymmetric behavior can be explained as a combined effect of the intrinsic electron-hole asymmetry in systems comprising Cu3 d and O2 p orbitals and the band-filling-dependent vertex correction. In the present study, we study another compound Tl{sub 2} Ba{sub 2} CuO{sub 6} to show that this explanation can be applied to other cuprate superconductors with the small d{sub z{sup 2}} orbital mixture. By varying the d-p offset, we also study how the strength of the d-p hybridization controls the spin fluctuation and hence the pairing interaction. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Future measurements of deeply virtual Compton scattering

International Nuclear Information System (INIS)

Korotkov, V.A.; Nowak, W.D.

2001-09-01

Prospects for future measurements of Deeply Virtual Compton Scattering are studied using different simple models for parameterizations of generalized parton distributions (GPDs). Measurements of the lepton charge and lepton beam helicity asymmetry will yield important input for theoretical models towards the future extraction of GPDs. The kinematics of the HERMES experiment, complemented with a recoil detector, was adopted to arrive at realistic projected statistical uncertainties. (orig.)

Longitudinal Target-Spin Asymmetries for Deeply Virtual Compton Scattering

Science.gov (United States)

Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Battaglieri, M.; Bedlinskiy, I.; Bono, J.; Boiarinov, S.; Bosted, P.; Briscoe, W.; Brock, J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Carlin, C.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crabb, D.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hirlinger Saylor, N.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joosten, S.; Keith, C. D.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L. L.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, W.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Senderovich, I.; Simonyan, A.; Skorodumina, I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tian, Y.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

2015-01-01

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for e p →e'p'γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2 , xB, t , and ϕ , for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Exact mapping of the dx2-y2 Cooper-pair wavefunction onto the spin fluctuations in cuprates: the Fermi surface as a driver for 'high Tc' superconductivity

International Nuclear Information System (INIS)

McDonald, Ross D; Harrison, Neil; Singleton, John

2009-01-01

We propose that the extraordinarily high superconducting transition temperatures in the cuprates are driven by an exact mapping of the d x 2 -y 2 Cooper-pair wavefunction onto the incommensurate spin fluctuations observed in neutron-scattering experiments. This is manifested in the direct correspondence between the inverse of the incommensurability factor δ seen in inelastic neutron-scattering experiments and the measured superconducting coherence length ξ 0 . Strikingly, the relationship between ξ 0 and δ is valid for both La 2-x Sr x CuO 4 and YBa 2 Cu 3 O 7-x , suggesting a common mechanism for superconductivity across the entire hole-doped cuprate family. Using data from recent quantum-oscillation experiments in the cuprates, we propose that the fluctuations responsible for superconductivity are driven by a Fermi-surface instability. On the basis of these findings, one can specify the optimal characteristics of a solid that will exhibit 'high T c ' superconductivity. (fast track communication)

Similarity in the superconducting properties of chalcogenides, cuprate oxides and fullerides

International Nuclear Information System (INIS)

Tsendin, K.D.; Popov, B.P.; Denisov, D.V.

2004-01-01

The idea of Anderson pairs has been put forward for explanation of many extraordinary properties of chalcogenides glassy semiconductors. Recent decades made obvious that these pairs localized on the centers with negative effective correlation energy (negative-U centers) really exist in chalcogenides. If the concentration of negative-U centers is enough to create the pair band states, this can lead to superconductivity because Anderson pairs are Bose particles. In the present paper we show that several puzzling superconductivity properties of chalcogenides, high-temperature cuprate superconductors and fullerides are similar for these three groups of materials and can be naturally explained in the frame of negative-U centers model of superconductivity

Non-Markovian features of deeply inelastic collisions

International Nuclear Information System (INIS)

Pal, D.; Chattopadhyay, S.; Kar, K.

1988-01-01

To study the effect of memory in the diffusion processes (of charge, mass etc) observed in deeply inelastic heavy-ion reactions, we derive non-Markovian transport equations for the exponential and Gaussian memory kernels. The centroid and the variance of the distribution are expressed in terms of the memory time, drift and diffusion coefficients. The predictions based on this theory show better agreement with the experimental data than the Markovian results. (author)

On Engaging with Others: A Wittgensteinian Approach to (Some) Problems with Deeply Held Beliefs

Science.gov (United States)

Bowell, Tracy

2018-01-01

My starting point for this paper is a problem in critical thinking pedagogy--the difficult of bringing students to a point where they are able, and motivated, critically to evaluate their own deeply held beliefs. I first interrogate the very idea of a deeply held belief, drawing upon Wittgenstein's idea of a framework belief--a belief that forms…

Theory of High-T{sub c} Superconducting Cuprates Based on Experimental Evidence

Science.gov (United States)

Abrikosov, A. A.

1999-12-10

A model of superconductivity in layered high-temperature superconducting cuprates is proposed, based on the extended saddle point singularities in the electron spectrum, weak screening of the Coulomb interaction and phonon-mediated interaction between electrons plus a small short-range repulsion of Hund's, or spin-fluctuation, origin. This permits to explain the large values of T{sub c}, features of the isotope effect on oxygen and copper, the existence of two types of the order parameter, the peak in the inelastic neutron scattering, the positive curvature of the upper critical field, as function of temperature etc.

Interplay of structural transition and superconductivity in cuprates

International Nuclear Information System (INIS)

Ghosh, Haranath; Mitra, Manidipa; Behera, S.N.; Ghatak, S.K.

1997-01-01

The presence of lattice distortion is known to suppress the superconducting (SC) transition in the cuprates. It is now accepted that electron correlation plays a dominant role in shaping the properties of these undoped and doped systems. Furthermore, since the Fermi level in these systems lies in a degenerate band of Cu : d and O : p orbitals the structural transition can be modeled as a band Jahn-Teller effect. We study the coexistence of superconductivity and band Jahn-Teller (J-T) distortion, taking into account the electron correlation within the slave boson formalism. It is shown that with increasing dopant concentration (δ), the structural transition temperature (T s ) remains constant up to a certain value and then vanishes, while the SC transition temperature (T c ) increases to a maximum value. The highest value of T c corresponds to that value of δ where T s vanishes. Besides with increasing lattice distortion superconductivity is suppressed. These findings are in qualitative agreement with the experimental results. (author)

Theoretical Modeling of Various Spectroscopies for Cuprates and Topological Insulators

Science.gov (United States)

Basak, Susmita

Spectroscopies resolved highly in momentum, energy and/or spatial dimensions are playing an important role in unraveling key properties of wide classes of novel materials. However, spectroscopies do not usually provide a direct map of the underlying electronic spectrum, but act as a complex 'filter' to produce a 'mapping' of the underlying energy levels, Fermi surfaces (FSs) and excitation spectra. The connection between the electronic spectrum and the measured spectra is described as a generalized 'matrix element effect'. The nature of the matrix element involved differs greatly between different spectroscopies. For example, in angle-resolved photoemission (ARPES) an incoming photon knocks out an electron from the sample and the energy and momentum of the photoemitted electron is measured. This is quite different from what happens in K-edge resonant inelastic X-ray scattering (RIXS), where an X-ray photon is scattered after inducing electronic transitions near the Fermi energy through an indirect second order process, or in Compton scattering where the incident X-ray photon is scattered inelastically from an electron transferring energy and momentum to the scattering electron. For any given spectroscopy, the matrix element is, in general, a complex function of the phase space of the experiment, e.g. energy/polarization of the incoming photon and the energy/momentum/spin of the photoemitted electron in the case of ARPES. The matrix element can enhance or suppress signals from specific states, or merge signals of groups of states, making a good understanding of the matrix element effects important for not only a robust interpretation of the spectra, but also for ascertaining optimal regions of the experimental phase space for zooming in on states of the greatest interest. In this thesis I discuss a comprehensive scheme for modeling various highly resolved spectroscopies of the cuprates and topological insulators (TIs) where effects of matrix element, crystal

Comprehensive Study of the Model Mercury-Based Cuprate Superconductors

Energy Technology Data Exchange (ETDEWEB)

Greven, Martin [Univ. of Minnesota, Minneapolis, MN (United States)

2017-11-13

This is the Final Report on DE-SC0006858, which opened 15 August 2011 and closed 14 August 2017. The Principal Investigator is Martin Greven, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 555455 (email: greven@umn.edu). The Administrative Point of Contact is Patricia Jondahl, phone: 612-624-5599, email: awards@umn.edu. The DOE Program is the Office of Basic Energy Sciences, Program manager is Dr. P. Thiyagarajan, Neutron Scattering SC-22.2/ Germantown Bldg. (email: Thiyagarajan@science.doe.gov). The chief activity was the crystal growth, characterization, neutron and X-ray scattering study of the mercury-based cuprates, arguably the most desirable high-Tc superconductors for experimental study due to their record values of Tc and their relatively simple crystal structures. It is thought that the unusual magnetic and charge degrees of freedom of the copper-oxygen sheets that form the fundamental building block of all cuprate superconductors give rise to the high Tc and to many other unusual properties exhibited by the class of quantum materials. Neutron scattering experiments were performed to reveal the nature of the magnetic degrees of freedom of the copper-oxygen sheets, whereas X-ray scattering experiments and complementary charge-transport experiments were performed to reveal the nature of the charge degrees of freedom. In addition, collaborations were initiated with experts in the use of complementary experimental techniques. The primary products are (i) scientific articles published in peer-reviewed scientific journals, (ii) scientific presentations at national and international conferences, and (iii) education of postdoctoral researchers, PhD graduate students and undergraduate researchers by providing a research experience in crystal growth, characterization and scattering. Twenty scientific papers were published in peer-reviewed journals, thirty-one invited talks were presented at national or international conferences, or as

Theory of the c-axis penetration depth in the cuprates

International Nuclear Information System (INIS)

Radtke, R.J.; Kostur, V.N.; Levin, K.

1996-01-01

Recent measurements of the London penetration-depth tensor in the cuprates find a weak temperature dependence along the c direction that is seemingly inconsistent with evidence for d-wave pairing deduced from in-plane measurements. We demonstrate in this paper that these disparate results are not in contradiction, but can be explained within a theory based on incoherent quasiparticle hopping between the CuO 2 layers. By relating the calculated temperature dependence of the penetration depth λ c (T) to the c-axis resistivity, we show how the measured ratio λ 2 c (0)/λ 2 c (T) can provide insight into the behavior of c-axis transport below T c and the related issue of open-quote open-quote confinement.close-quote close-quote copyright 1996 The American Physical Society

Exploring the phase diagram of the Bi-cuprates by photoemission

International Nuclear Information System (INIS)

Janowitz, C.

2004-01-01

High temperature superconductivity is achieved by hole doping of parent compounds, which undergo a phase transition from the antiferromagnetic, insulating state to the metallic and superconducting state. This development can only be studied continuously on few members of the cuprate family: Bi 2 Sr 2 Ca 1-x Y x Cu 2 O 8+δ single crystals, where the hole concentration in the two CuO 2 -planes per unit cell (n=2) is controlled by the substitution of Ca by Y, and Bi 2 Sr 2 Ca 1- x La x CuO 6+δ single crystals, where this concentration in the one CuO 2 -plane per unit cell (n=1) is controlled by the substitution of Sr by La enable this study of the doping dependence over a wide range of hole concentrations with ARPES. Investigations of antiferromagnetic parent compounds have so far mostly been reported for oxychlorides, like e.g. Sr 2 CuO 2 Cl 2 and discussed within the t-t'-t'''-J model. Since the character of the CuO derived states near the Fermi level is decisive for the electronic structure, it will be discussed, whether this or other models like the generalized tight binding method (GTBM) give an appropriate description. A detailed treatment by this method with a five band Hubbard Hamiltonian, i.e. involving planar and off planar states of the CuO-planes shows, that the first removal state is composed not only from the Zhang-Rice singlet state but also from states with spin triplet character. In the second part of the talk the electronic structure for hole concentrations in the vicinity of the optimum transition temperature is addressed. It is general consensus that in this region the electronic structure can no longer be described by Fermi liquid (FL) theory. Instead various other non-FL theories are discussed. A class of these models deals with reduced dimensionality in the CuO 2 - planes, leading to Luttinger liquid like behaviour with spin and charge separation. Another route to one-dimensionality comes from the so called striped phase with spin and charge

Helimagnetism and weak ferromagnetism in edge-shared chain cuprates

International Nuclear Information System (INIS)

Drechsler, S.-L.; Richter, J.; Kuzian, R.; Malek, J.; Tristan, N.; Buechner, B.; Moskvin, A.S.; Gippius, A.A.; Vasiliev, A.; Volkova, O.; Prokofiev, A.; Rakoto, H.; Broto, J.-M.; Schnelle, W.; Schmitt, M.; Ormeci, A.; Loison, C.; Rosner, H.

2007-01-01

The present understanding of a novel growing class of chain cuprates with intriguing magnetic properties is reviewed. Among them, several undoped edge-shared CuO 2 chain compounds show at low temperature a clear tendency to helicoidal magnetical ordering with acute pitch angles and sometimes also to weak ferromagnetism. Our analysis is based on the isotropic 1D frustrated J 1 -J 2 Heisenberg model with ferromagnetic (FM) 1st neighbor and antiferromagnetic 2nd neighbor exchange. The achieved assignment is supported by microscopic calculations of the electronic and magnetic structure. We consider Na(Li)Cu 2 O 2 , LiVCuO 4 as the best studied helimagnets, Li 2 ZrCuO 4 and other systems close to a FM quantum critical point, as well as Li 2 CuO 2 with FM inchain ordering. The interplay of frustrated inchain couplings, anisotropy and interchain exchange is discussed

Behaviour of superconductivity energetic characteristics in electron-doped cuprates. A simple model

International Nuclear Information System (INIS)

Kristoffel, N.; Rubin, P.

2008-01-01

A simple model to describe the energetic phase diagram of electron-doped cuprate superconductor is developed. Interband pairing operates between the UHB and the defect states created by doping and supplied by both extincting HB-s. Two defect subbands correspond to the (π,0) and (π/2,π/2) momentum regions. Extended doping quenches the bare normal state gaps (pseudogaps). Maximal transition temperature corresponds to overlapping bands ensemble intersected by the chemical potential. Illustrative results for T c , pseudo- and superconducting gaps are calculated on the whole doping scale. Major characteristic features on the phase diagram are reproduced. Anticipated manifestation of gaps doping dynamics is discussed

Interplay of charge density wave and spin density wave in high-T{sub c} superconductors

Energy Technology Data Exchange (ETDEWEB)

Pradhan, B. [Government Science College, Malkangiri 764 048 (India)], E-mail: brunda@iopb.res.in; Raj, B.K. [B.J.B. College, Bhubaneswar 751 014 (India); Rout, G.C. [Condensed Matter Physics Group, P.G. Department of Applied Physics and Ballistics, F.M. University, Balasore 756 019 (India)], E-mail: gcr@iopb.res.in

2008-12-01

We present a mean-field theory theoretical model study for the coexistence of the two strongly interacting charge density wave (CDW) and spin density wave (SDW) for high-T{sub c} cuprates in the underdoped region before the onset of the superconductivity in the system. The analytic expressions for the temperature dependence of the CDW and SDW order parameters are derived and solved self-consistently. Their interplay is studied by varying their respective coupling constants. It is observed that in the interplay region both the gap parameters exhibit very strong dependence of their gap values for the coupling constants. Further, the electronic density of states (DOS) for the conduction electrons, which represents the scanning tunneling data, show two gap parameters in the interplay region from these experimental data. Our model can help to determine separately the CDW and SDW parameters.

Interplay of charge density wave and spin density wave in high-Tc superconductors

International Nuclear Information System (INIS)

Pradhan, B.; Raj, B.K.; Rout, G.C.

2008-01-01

We present a mean-field theory theoretical model study for the coexistence of the two strongly interacting charge density wave (CDW) and spin density wave (SDW) for high-T c cuprates in the underdoped region before the onset of the superconductivity in the system. The analytic expressions for the temperature dependence of the CDW and SDW order parameters are derived and solved self-consistently. Their interplay is studied by varying their respective coupling constants. It is observed that in the interplay region both the gap parameters exhibit very strong dependence of their gap values for the coupling constants. Further, the electronic density of states (DOS) for the conduction electrons, which represents the scanning tunneling data, show two gap parameters in the interplay region from these experimental data. Our model can help to determine separately the CDW and SDW parameters

Structure of the charge density wave in cuprate superconductors: Lessons from NMR

Science.gov (United States)

Atkinson, W. A.; Ufkes, S.; Kampf, A. P.

2018-03-01

Using a mix of numerical and analytic methods, we show that recent NMR 17O measurements provide detailed information about the structure of the charge-density wave (CDW) phase in underdoped YBa2Cu3O6 +x . We perform Bogoliubov-de Gennes (BdG) calculations of both the local density of states and the orbitally resolved charge density, which are closely related to the magnetic and electric quadrupole contributions to the NMR spectrum, using a microscopic model that was shown previously to agree closely with x-ray experiments. The BdG results reproduce qualitative features of the experimental spectrum extremely well. These results are interpreted in terms of a generic "hot-spot" model that allows one to trace the origins of the NMR line shapes. We find that four quantities—the orbital character of the Fermi surface at the hot spots, the Fermi surface curvature at the hot spots, the CDW correlation length, and the magnitude of the subdominant CDW component—are key in determining the line shapes.

Inequivalence of single-particle and population lifetimes in a cuprate superconductor

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuolong [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Sobota, J. A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Leuenberger, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); He, Y. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Hashimoto, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Lu, D. H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Eisaki, H. [National Institute of Advanced Industrial Science and Technology, Ibaraki (Japan); Kirchmann, P. S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Shen, Z. -X. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)

2015-06-15

We study optimally doped Bi-2212 (T_c=96 K) using femtosecond time- and angle-resolved photoelectron spectroscopy. Energy-resolved population lifetimes are extracted and compared with single-particle lifetimes measured by equilibrium photoemission. The population lifetimes deviate from the single-particle lifetimes in the low excitation limit by 1–2 orders of magnitude. Fundamental considerations of electron scattering unveil that these two lifetimes are in general distinct, yet for systems with only electron-phonon scattering they should converge in the low-temperature, low-fluence limit. As a result, the qualitative disparity in our data, even in this limit, suggests that scattering channels beyond electron-phonon interactions play a significant role in the electron dynamics of cuprate superconductors.

Impurity scattering effect on charge transport in high-Tc cuprate junctions

International Nuclear Information System (INIS)

Tanaka, Y.; Asano, Y.; Kashiwaya, S.

2004-01-01

It is known that the zero-bias conductance peak (ZBCP) is expected in tunneling spectra of normal-metal/high-Tc cuprate junctions because of the formation of the midgap Andreev resonant states (MARS) at junction interfaces. In the present review, we report the recent theoretical study of impurity scattering effects on the tunneling spectroscopy. In the former part of the present paper, we discuss impurity effects in normal metal. We calculate tunneling conductance for diffusive normal metal (DN)/high Tc cuprate junctions based on the Keldysh Green's function technique. Besides the ZBCP due to the MARS, we can expect ZBCP caused by the different origin, i.e., the coherent Andreev reflection (CAR) assisted by the proximity effect in DN. Their relative importance depends on the angle a between the interface normal and the crystal axis of high-Tc superconductors. At α = 0, we find the ZBCP by the CAR for low transparent junctions with small Thouless energies in DN; this is similar to the case of diffusive normal metal/insulator/s-wave superconductor junctions. Under increase of α from zero to π/4, the contribution of MARS to ZBCP becomes more prominent and the effect of the CAR is gradually suppressed. Such complex spectral features would be observable in conductance spectra of high-Tc junctions at very low temperatures. In the latter part of our paper, we study impurity effects in superconductors. We consider impurities near the junction interface on the superconductor side. The conductance is calculated from the Andreev and the normal reflection coefficients which are estimated by using the single-site approximation in an analytic calculation and by the recursive Green function method in a numerical simulation. We find splitting of the ZBCP in the presence of the time reversal symmetry. Thus the zero-field splitting of ZBCP in the experiment does not perfectly prove an existence of broken time reversal symmetry state

Observation of a common symmetry for the pseudogap and the superconducting order parameter near the surface of underdoped YBa2Cu3O6+x

International Nuclear Information System (INIS)

Koren, G.; Shkedy, L.; Polturak, E.

2004-01-01

Measurements of the angular dependence of conductance spectra in the a-b plane of underdoped YBa 2 Cu 3 O 6+x junctions are reported. At zero magnetic field the superconducting gap shows a vertical bar d+is vertical bar-like symmetry. Application of a magnetic field strongly suppresses this gap leaving only the pseudogap feature which also shows a vertical bar d+is vertical bar-like angular dependence. We thus observe the same symmetry for the superconducting gap and the pseudogap characterizing the YBCO electrodes near the interface with the barrier. An H c2 value of ∼5 T of the secondary (is) order parameter can also be deduced from our results

Quantum oscillations in vortex-liquids

Science.gov (United States)

Banerjee, Sumilan; Zhang, Shizhong; Randeria, Mohit

2012-02-01

Motivated by observations of quantum oscillations in underdoped cuprates [1], we examine the electronic density of states (DOS) in a vortex-liquid state, where long-range phase coherence is destroyed by an external magnetic field H but the local pairing amplitude survives. We note that this regime is distinct from that studied in most of the recent theories, which have focused on either a Fermi liquid with a competing order parameter or on a d-wave vortex lattice. The cuprate experiments are very likely in a resistive vortex-liquid state. We generalize the s-wave analysis of Maki and Stephen [2] to d-wave pairing and examine various regimes of the chemical potential, gap and field. We find that the (1/H) oscillations of the DOS at the chemical potential in a d-wave vortex-liquid are much more robust, i.e., have a reduced damping, compared to the s-wave case. We critically investigate the conventional wisdom relating the observed frequency to the area of an underlying Fermi surface. We also show that the oscillations in the DOS cross over to a √H behavior in the low field limit, in agreement with the recent specific heat measurements. [1] L. Taillefer, J. Phys. Cond. Mat. 21, 164212 (2009). [2] M. J. Stephen, Phys. Rev. B 45, 5481 (1992).

Dual structure in the charge excitation spectrum of electron-doped cuprates

Science.gov (United States)

Bejas, Matías; Yamase, Hiroyuki; Greco, Andrés

2017-12-01

Motivated by the recent resonant x-ray scattering (RXS) and resonant inelastic x-ray scattering (RIXS) experiments for electron-doped cuprates, we study the charge excitation spectrum in a layered t -J model with the long-range Coulomb interaction. We show that the spectrum is not dominated by a specific type of charge excitations, but by different kinds of charge fluctuations, and is characterized by a dual structure in the energy space. Low-energy charge excitations correspond to various types of bond-charge fluctuations driven by the exchange term (J term), whereas high-energy charge excitations are due to usual on-site charge fluctuations and correspond to plasmon excitations above the particle-hole continuum. The interlayer coupling, which is frequently neglected in many theoretical studies, is particularly important to the high-energy charge excitations.

Thermal transport in cuprates, cobaltates, and manganites

International Nuclear Information System (INIS)

Berggold, K.

2006-09-01

The subject of this thesis is the investigation of the thermal transport properties of three classes of transition-metal oxides: Cuprates, cobaltates, and manganites. The layered cuprates R 2 CuO 4 with R=La, Pr, Nd, Sm, Eu, and Gd show an anomalous thermal conductivity κ. Two maxima of κ are observed as a function of temperature for a heat current within the CuO 2 planes, whereas for a heat current perpendicular to the CuO 2 planes only a conventional phononic low-temperature maximum of κ is present. Evidence is provided that the high-temperature maximum is caused by heat-carrying excitations on the CuO 2 square lattice. Moreover, it is shown that the complex low-temperature and magnetic-field behavior of κ in Nd 2 CuO 4 is most likely caused by additional phonon scattering rather than by heat-carrying Nd magnons, as it was proposed in the literature. In the cobaltates RCoO 3 with R=La, Pr, Nd, and Eu, a temperature-induced spin-state transition of the Co 3+ ions occurs. It is shown that the additional lattice disorder caused by the random distribution of populated higher spin states causes a large suppression of the thermal conductivity of LaCoO 3 for T>25 K. The effect is much weaker in PrCoO 3 and NdCoO 3 due to the increased spin gap. A quantitative analysis of the responsible mechanisms based on EuCoO 3 as a reference compound is provided. A main result is that the static disorder is sufficient to explain the suppression of κ. No dynamical Jahn-Teller distortion, as proposed in the literature, is necessary to enhance the scattering strength. Below 25 K, k is mainly determined by resonant phonon scattering on paramagnetic impurity levels, e.g. caused by oxygen non-stoichiometry. Such a suppression of the thermal conductivity by resonant scattering processes is e.g. known from Holmium ethylsulfate. This effect is most pronounced in LaCoO 3 , presumably due to magnetic polaron formation. In the doped compounds La 1-x Sr x CoO 3 with 0≤x≤0.25, a large

Coherence and pairing in a doped Mott insulator: application to the cuprates.

Science.gov (United States)

Senthil, T; Lee, Patrick A

2009-08-14

The issues of single particle coherence and its interplay with singlet pairing are studied within the slave boson gauge theory of a doped Mott insulator. Prior work by one of us [T. Senthil, Phys. Rev. B 78, 045109 (2008)10.1103/PhysRevB.78.045109] showed that the coherence scale below which Landau quasiparticles emerge is parametrically lower than that identified in the slave boson mean field theory. Here we study the resulting new non-Fermi liquid intermediate temperature regime characterized by a single particle scattering rate that is linear in temperature (T). In the presence of a d-wave pair amplitude, this leads to a pseudogap state with T-dependent Fermi arcs near the nodal direction. Implications for understanding the cuprates are discussed.

Deeply-etched DBR mirrors for photonic integrated circuits and tunable lasers

NARCIS (Netherlands)

Docter, B.

2009-01-01

Deeply-etched Distributed Bragg Reflector (DBR) mirrors are a new versatile building block for Photonic Integrated Circuits that allows us to create more complex circuits for optical telecommunication applications. The DBR mirrors increase the device design flexibility because the mirrors can be

Temperature behavior of the hole density of (Bi,Pb)-2212 single crystals

Energy Technology Data Exchange (ETDEWEB)

Ghafari, Aliakbar; Janowitz, Christoph; Dwelk, Helmut; Krapf, Alica; Manzke, Recardo [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Ariffin, Ahmad Kamal [Dept. of Physics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim (Malaysia)

2012-07-01

One of the most puzzling anomalies of high-T{sub c} cuprates is the strong temperature dependence of the Hall coefficient (R{sub H}) and the hole density (n{sub H}). Gor'kov and Teitel'baum (GT) showed by using experimental data of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) that the number of holes per Cu atom, n{sub H}, changes with temperature according to n{sub H}(T,x)=n{sub 0}(x)+n{sub 1}(x)exp(-{Delta}(x)/T). To clarify the temperature dependence of n{sub H} we have determined n{sub H} by X-ray absorption spectra (XAS) at the CuL{sub 3} edge for nearly optimum and slightly underdoped (Bi,Pb)-2212 single crystals. Our results point out that the GT formula cannot fit our data and therefore must be extended to the three terms.

Tunnel and thermal c-axis transport in BSCCO in the normal and pseudogap states

International Nuclear Information System (INIS)

Giura, M; Fastampa, R; Sarti, S; Pompeo, N; Silva, E

2007-01-01

We consider the problem of c-axis transport in double-layered cuprates, in particular with reference to Bi 2 Sr 2 CaCu 2 O 8+δ compounds. We exploit the effect of the two barriers on the thermal and tunnel transport. The resulting model is able to describe accurately the normal state c-axis resistivity in Bi 2 Sr 2 CaCu 2 O 8+δ , from the underdoped side up to the strongly overdoped. We extend the model, without introducing additional parameters, in order to allow for the decrease of the barrier when an external voltage bias is applied. The extended model is found to describe properly the c-axis resistivity for small voltage bias above the pseudogap temperature T * , the c-axis resistivity for large voltage bias even below T c , and the differential dI/dV curves taken in mesa structures

Infrared absorption spectra of various doping states in cuprate superconductors

International Nuclear Information System (INIS)

Yonemitsu, K.; Bishop, A.R.; Lorenzana, J.

1992-01-01

Doping states in a two-dimensional three-band extended Peierls-Hubbard model was investigated within inhomogeneous Hartree-Fock and random phase approximation. They are very sensitive to small changes of interaction parameters and their distinct vibrational and optical absorption spectra can be used to identify different doping states. For electronic parameters relevant to cuprate superconductors, as intersite electron-phonon interaction strength increases, the doping state changes from a Zhang-Rice state to a covalent molecular singlet state accompanied by local quenching of the Cu magnetic moment and large local lattice distortion in an otherwise undistorted antiferromagnetic background. In a region where both intersite electron-phonon interaction and on-site electron-electron repulsion are large, we obtain new stable global phases including a bond-order-wave state and a mixed state of spin-Peierls bonds and antiferromagnetic Cu spins, as well as many metastable states. Doping in the bond-order-wave region induces separation of spin and charge. 9 refs

Redistribution of phase fluctuations in a periodically driven cuprate superconductor

Energy Technology Data Exchange (ETDEWEB)

Hoeppner, Robert; Zhu, Beilei; Rexin, Tobias [Zentrum fuer Optische Quantentechnologien und Institut fuer Laserphysik, Hamburg (Germany); Mathey, Ludwig [Zentrum fuer Optische Quantentechnologien und Institut fuer Laserphysik, Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Hamburg (Germany); Cavalleri, Andrea [Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford (United Kingdom)

2015-07-01

We study the thermally fluctuating state of a bi-layer cuprate superconductor under the periodic action of a staggered field oscillating at optical frequencies. This analysis distills essential elements of the recently discovered phenomenon of light enhanced coherence in YBCO, which was achieved by periodically driving infrared active apical oxygen distortions. The effect of a staggered periodic perturbation is studied using a Langevin description of driven, coupled Josephson junctions, which represent two neighboring pairs of layers and their two plasmons. We demonstrate that the external driving leads to a suppression of phase fluctuations of the low-energy plasmon, an effect which is amplified via the resonance of the high energy plasmon, with a striking suppression of the low-energy fluctuations, as visible in the power spectrum. We also find that this effect acts onto the in-plane fluctuations, which are reduced on long length scales and we discuss the behavior of vortices in the ab-planes and across the weakly coupled junctions.

Measurement of Deeply Virtual Compton Scattering at HERA

CERN Document Server

Adloff, C.; Andrieu, B.; Anthonis, T.; Arkadov, V.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Berndt, T.; Bizot, J.C.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cao, Jun; Caron, S.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Solovev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Straumann, U.; Swart, M.; Tasevsky, M.; Chernyshov, V.; Chetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassilev, S.; Vazdik, Y.; Vichnevski, A.; Wacker, K.; Wallny, R.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Werner, C.; Werner, M.; Werner, N.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

2001-01-01

A measurement is presented of elastic Deeply Virtual Compton Scattering e^+ + p -> e^+ + photon + p at HERA using data taken with the H1 detector. The cross section is measured as a function of the photon virtuality, Q^2, and the invariant mass, W, of the gamma p system, in the kinematic range 2 < Q^2 < 20 GeV^2, 30 < W < 120 GeV and |t| < 1 GeV^2, where t is the squared momentum transfer to the proton. The measurement is compared to QCD based calculations.

Deeply inelastic scattering at small x in 20 min

International Nuclear Information System (INIS)

Levin, E.M.

1992-01-01

A status report is presented on new phenomena that are anticipated in deeply inelastic scattering in the low x→0 region. A summary of the theoretical situation in the region of small x is given, including the importance for the understanding of high energy interaction in QCD, and the low x behaviour of deep inelastic structure function. This new area of physics will be studied experimentally at HERA. (R.P.) 16 refs.; 6 figs

Deeply virtual Compton scattering: How to test handbag dominance?

International Nuclear Information System (INIS)

Gousset, T.; Gousset, T.; Diehl, M.; Pire, B.; Diehl, M.; Ralston, J.P.

1998-01-01

We propose detailed tests of the handbag approximation in exclusive deeply virtual Compton scattering. Those tests make no use of any prejudice about parton correlations in the proton which are basically unknown objects and beyond the scope of perturbative QCD. Since important information on the proton substructure can be gained in the regime of light cone dominance we consider that such a class of tests is of special relevance. copyright 1998 American Institute of Physics

Kinematics of current region fragmentation in semi-inclusive deeply inelastic scattering

Energy Technology Data Exchange (ETDEWEB)

Boglione, M., E-mail: elena.boglione@to.infn.it [Dipartimento di Fisica, Università di Torino, INFN - Sezione Torino, Via P. Giuria 1, 10125 Torino (Italy); Collins, J., E-mail: jcc8@psu.edu [Department of Physics, Penn State University, University Park, PA 16802 (United States); Gamberg, L., E-mail: lpg10@psu.edu [Science Division, Penn State University Berks, Reading, PA 19610 (United States); Gonzalez-Hernandez, J.O., E-mail: jogh@jlab.org [Department of Physics, Old Dominion University, Norfolk, VA 23529 (United States); Theory Center, Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Rogers, T.C., E-mail: trogers@odu.edu [Department of Physics, Old Dominion University, Norfolk, VA 23529 (United States); Theory Center, Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); Sato, N., E-mail: nsato@jlab.org [Theory Center, Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States)

2017-03-10

Different kinematical regions of semi-inclusive deeply inelastic scattering (SIDIS) processes correspond to different underlying partonic pictures, and it is important to understand the transition between them. We find criteria in semi-inclusive deeply inelastic scattering (SIDIS) for identifying the current fragmentation region — the kinematical region where a factorization picture with fragmentation functions is appropriate, especially for studies of transverse-momentum-dependent (TMD) functions. This region is distinguished from the central (soft) and target fragmentation regions. The basis of our argument is in the errors in approximations used in deriving factorization. As compared with previous work, we show that it is essential to take account of the transverse momentum of the detected hadron, and we find a much more restricted range for genuine current fragmentation. We show that it is important to develop an extended factorization formulation to treat hadronization in the central region, as well as the current and target fragmentation regions, and to obtain a unified formalism spanning all rapidities for the detected hadron.

Material and Doping Dependence of the Nodal and Anti-Nodal Dispersion Renormalizations in Single- and Multi-Layer Cuprates

Energy Technology Data Exchange (ETDEWEB)

Johnston, S.; /Waterloo U. /SLAC; Lee, W.S.; /Stanford U., Geballe Lab. /SLAC; Nowadnick, E.A.; /SLAC /Stanford U., Phys. Dept.; Moritz, B.; /SLAC /North Dakota U.; Shen, Z.-X.; /Stanford U., Geballe Lab. /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Devereaux, T.P.; /Stanford U., Geballe Lab. /SLAC

2010-02-15

In this paper we present a review of bosonic renormalization effects on electronic carriers observed from angle-resolved photoemission spectra in the cuprates. Specifically, we discuss the viewpoint that these renormalizations represent coupling of the electrons to the lattice and review how materials dependence, such as the number of CuO{sub 2} layers, and doping dependence can be understood straightforwardly in terms of several aspects of electron-phonon coupling in layered correlated materials.

Model Evidence of a Superconducting State with a Full Energy Gap in Small Cuprate Islands

Science.gov (United States)

Black-Schaffer, Annica M.; Golubev, Dmitri S.; Bauch, Thilo; Lombardi, Floriana; Fogelström, Mikael

2013-05-01

We investigate subdominant order parameters stabilizing at low temperatures in nanoscale high-Tc cuprate islands, motivated by the recent observation of a fully gapped state in nanosized YBa2Cu3O7-δ [D. Gustafsson et al., Nature Nanotech. 8, 25 (2013)]. Using complementary quasiclassical and tight-binding Bogoliubov-de Gennes methods, we show on distinctly different properties dependent on the symmetry being dx2-y2+is or dx2-y2+idxy. We find that a surface-induced dx2-y2+is phase creates a global spectroscopic gap which increases with an applied magnetic field, consistent with experimental observation.

Electronic properites of electron-doped cuprate superconductors probed by high-field magnetotransport

International Nuclear Information System (INIS)

Helm, Toni

2013-01-01

In the present work the normal-state properties of the electron-doped cuprate superconductor Nd 2-x Ce x CuO 4 (NCCO) are investigated for a broad doping range, covering almost the whole phase diagram of this material. Magnetotransport measurements in the world's highest non-destructive magnetic fields were used as a spectroscopic tool for probing the electronic structure of single-crystalline NCCO as a function of the carrier concentration x. Quantum and semiclassical oscillations in the magnetoresistance provided new insights into various properties of the Fermi surface and the nature of the ground state in the system. The detailed investigations of the field- and temperature-dependent transport and its dependence on the field orientation have revealed a close correlation between symmetry-breaking ordering instabilities and the superconducting state.

Electronic properites of electron-doped cuprate superconductors probed by high-field magnetotransport

Energy Technology Data Exchange (ETDEWEB)

Helm, Toni

2013-09-18

In the present work the normal-state properties of the electron-doped cuprate superconductor Nd{sub 2-x}Ce{sub x}CuO{sub 4} (NCCO) are investigated for a broad doping range, covering almost the whole phase diagram of this material. Magnetotransport measurements in the world's highest non-destructive magnetic fields were used as a spectroscopic tool for probing the electronic structure of single-crystalline NCCO as a function of the carrier concentration x. Quantum and semiclassical oscillations in the magnetoresistance provided new insights into various properties of the Fermi surface and the nature of the ground state in the system. The detailed investigations of the field- and temperature-dependent transport and its dependence on the field orientation have revealed a close correlation between symmetry-breaking ordering instabilities and the superconducting state.

Electronic properites of electron-doped cuprate superconductors probed by high-field magnetotransport

Energy Technology Data Exchange (ETDEWEB)

Helm, Toni

2013-09-18

In the present work the normal-state properties of the electron-doped cuprate superconductor Nd{sub 2-x}Ce{sub x}CuO{sub 4} (NCCO) are investigated for a broad doping range, covering almost the whole phase diagram of this material. Magnetotransport measurements in the world's highest non-destructive magnetic fields were used as a spectroscopic tool for probing the electronic structure of single-crystalline NCCO as a function of the carrier concentration x. Quantum and semiclassical oscillations in the magnetoresistance provided new insights into various properties of the Fermi surface and the nature of the ground state in the system. The detailed investigations of the field- and temperature-dependent transport and its dependence on the field orientation have revealed a close correlation between symmetry-breaking ordering instabilities and the superconducting state.

Magnetic study of the low temperature anomalies in the underdoped PrBCO compound

Science.gov (United States)

Lahoubi, Mahieddine

2018-05-01

The low temperature anomalous magnetic properties of a non-superconducting PrBCO6+x compound in an underdoped oxygen state of concentration (x = 0.44) are characterized by paraprocess magnetic susceptibility χH(T) measurements carried out as a function of temperature T under different values of a DC magnetic field H up to 110 kOe. The derivatives dχH(T)/dT curves reveal a significant reduction with increasing H in the Néel temperature TN = 9 K of the Pr antiferromagnetic (AFM) ordering for which the transition subsists at 100 kOe. The small anomaly at T2 = 6-7 K is confirmed at 20 kOe and the previous spin reorientation attributed to this transition temperature seems to be suppressed above 60 kOe. The well defined anomaly in the vicinity of the low-critical point Tcr = 4-5 K which occurs simultaneously, is still present when the strength of H is increased up to 100 kOe. Weak field induced phase transitions are observed between T2 and TN at a low transition-field (Ht<11 kOe) in the differential magnetic susceptibility dMT(H)/dH as a function of H deduced from the isothermal magnetizations MT(H) with H up to 21 kOe, whereas a weak ferromagnetic behavior of the Pr sublattice appears below Tcr. The magnetic field effects give rise to more evidence for the Pr-Cu(2) coupling with 'exchange-frustrated AFM' interactions and ascertain the main role of the Pr sublattice whereas the Cu(2) sublattice seems to be less efficient.

Thermal transport in cuprates, cobaltates, and manganites

Energy Technology Data Exchange (ETDEWEB)

Berggold, K.

2006-09-15

The subject of this thesis is the investigation of the thermal transport properties of three classes of transition-metal oxides: Cuprates, cobaltates, and manganites. The layered cuprates R{sub 2}CuO{sub 4} with R=La, Pr, Nd, Sm, Eu, and Gd show an anomalous thermal conductivity {kappa}. Two maxima of {kappa} are observed as a function of temperature for a heat current within the CuO{sub 2} planes, whereas for a heat current perpendicular to the CuO{sub 2} planes only a conventional phononic low-temperature maximum of {kappa} is present. Evidence is provided that the high-temperature maximum is caused by heat-carrying excitations on the CuO{sub 2} square lattice. Moreover, it is shown that the complex low-temperature and magnetic-field behavior of {kappa} in Nd{sub 2}CuO{sub 4} is most likely caused by additional phonon scattering rather than by heat-carrying Nd magnons, as it was proposed in the literature. In the cobaltates RCoO{sub 3} with R=La, Pr, Nd, and Eu, a temperature-induced spin-state transition of the Co{sup 3+} ions occurs. It is shown that the additional lattice disorder caused by the random distribution of populated higher spin states causes a large suppression of the thermal conductivity of LaCoO{sub 3} for T>25 K. The effect is much weaker in PrCoO{sub 3} and NdCoO{sub 3} due to the increased spin gap. A quantitative analysis of the responsible mechanisms based on EuCoO{sub 3} as a reference compound is provided. A main result is that the static disorder is sufficient to explain the suppression of {kappa}. No dynamical Jahn-Teller distortion, as proposed in the literature, is necessary to enhance the scattering strength. Below 25 K, k is mainly determined by resonant phonon scattering on paramagnetic impurity levels, e.g. caused by oxygen non-stoichiometry. Such a suppression of the thermal conductivity by resonant scattering processes is e.g. known from Holmium ethylsulfate. This effect is most pronounced in LaCoO{sub 3}, presumably due to

Use of a Piezosurgery Technique to Remove a Deeply Impacted Supernumerary Tooth in the Anterior Maxilla

Science.gov (United States)

Sukegawa, Shintaro; Kanno, Takahiro; Kawakami, Kiyokazu; Shibata, Akane; Takahashi, Yuka; Furuki, Yoshihiko

2015-01-01

Deeply impacted supernumerary teeth in the anterior maxillary cannot be generally removed by the conventional labial or palatal surgical approach because of the risk of damaging the surrounding soft tissues and the possibility of injuring the roots of adjacent permanent teeth. In piezosurgery, bony tissues are selectively cut, thereby avoiding the soft tissue damage caused by rotary cutting instruments. We report the case of a 15-year-old Japanese boy from whom a deeply impacted supernumerary tooth in the anterior maxillary was safely removed through the floor of the nasal cavity. The surgical extraction was performed without damaging the nasal mucosa or adjacent structures such as the roots of the adjacent permanent teeth. Considering that piezosurgery limits the extent of surgical invasion, this technique can be practiced as a minimally invasive and safe surgical procedure for treating suitably selected cases with a deeply impacted supernumerary tooth. PMID:26779355

Use of a Piezosurgery Technique to Remove a Deeply Impacted Supernumerary Tooth in the Anterior Maxilla

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Shintaro Sukegawa

2015-01-01

Full Text Available Deeply impacted supernumerary teeth in the anterior maxillary cannot be generally removed by the conventional labial or palatal surgical approach because of the risk of damaging the surrounding soft tissues and the possibility of injuring the roots of adjacent permanent teeth. In piezosurgery, bony tissues are selectively cut, thereby avoiding the soft tissue damage caused by rotary cutting instruments. We report the case of a 15-year-old Japanese boy from whom a deeply impacted supernumerary tooth in the anterior maxillary was safely removed through the floor of the nasal cavity. The surgical extraction was performed without damaging the nasal mucosa or adjacent structures such as the roots of the adjacent permanent teeth. Considering that piezosurgery limits the extent of surgical invasion, this technique can be practiced as a minimally invasive and safe surgical procedure for treating suitably selected cases with a deeply impacted supernumerary tooth.

Low-temperature resistivity anomaly in underdoped Pr0.8Sr0.2MnO3 manganite nanoparticles

International Nuclear Information System (INIS)

Das, Proloy T.; Giri, S.K.; Panda, J.; Taraphder, A.; Nath, T.K.; Nigam, A.K.

2013-01-01

High resolution electrical resistivity measurements were carried out of under-doped Pr 0.8 Sr 0.2 MnO 3 manganite nanoparticles with grain size modulation down to 40 nm in magnetic fields H, from 0 to 9 T in the low temperature regime down to a temperature of 4.2 K. In the temperature range below 80 K, a distinct resistivity minima is observed for all the samples with different particle sizes for all H. While trying to fit low temperature resistivity data with different models for the observed resistivity minima with negative temperature coefficient of resistance (TCR) for all H, it appears that all the data for different particle sizes, can be best described by electron-electron (e-e) interaction effect in comparison with other models, e.g., Kondo model, coulomb blockades etc. The low temperature data for all H have been fitted with an expression containing three terms, namely, residual resistivity, inelastic scattering, e-e interaction and Kondo effects. We conclude that the e-e interaction is the dominant transport mechanism at low temperatures for the observed negative TCR in this strongly disordered nanometric Pr 0.8 Sr 0.2 MnO 3 phase separated manganite system. (author)

Magnetic excitations and amplitude fluctuations in insulating cuprates

Science.gov (United States)

Chelwani, N.; Baum, A.; Böhm, T.; Opel, M.; Venturini, F.; Tassini, L.; Erb, A.; Berger, H.; Forró, L.; Hackl, R.

2018-01-01

We present results from light scattering experiments on three insulating antiferromagnetic cuprates, YBa2Cu3O6.05 , Bi2Sr2YCu2O8 +δ , and La2CuO4 as a function of polarization and excitation energy using samples of the latest generation. From the raw data we derive symmetry-resolved spectra. The spectral shape in B1 g symmetry is found to be nearly universal and independent of excitation energy. The spectra agree quantitatively with predictions by field theory [Eur. Phys. J. B 88, 237 (2015), 10.1140/epjb/e2015-60438-1] facilitating the precise extraction of the Heisenberg coupling J . In addition, the asymmetric lineshape on the high-energy side is found to be related to amplitude fluctuations of the magnetization. In La2CuO4 alone, minor contributions from resonance effects may be identified. The spectra in the other symmetries are not universal. The variations may be traced back to weak resonance effects and extrinsic contributions. For all three compounds we find support for the existence of chiral excitations appearing as a continuum in A2 g symmetry having an onset slightly below 3 J . In La2CuO4 an additional isolated excitation appears on top of the A2 g continuum.

Evolution des quasiparticules nodales du cuprate supraconducteur YBa2Cu3Oy en conductivite thermique

Science.gov (United States)

Rene de Cotret, Samuel

Ce memoire presente des mesures de conductivite thermique sur les supraconducteurs YBCO et Tl-2201 afin de statuer sur la presence possible d'un point critique quantique (QCP) dans le diagramme de phase de cuprates. Ce point critique quantique serait a l'origine de la reconstruction de la surface de Fermi, d'un large cylindre de trous en de petites poches de trous et d'electrons. La conductivite thermique dans le regime T → 0 permet d'extraire une quantite purement electronique liee aux vitesses de Fermi et du gap, au noeud. Une discontinuite dans cette quantite pourrait signaler la traversee du dopage critique qui reconstruit la surface de Fermi. Plusieurs sondes experimentales distinguent une transition de phase ou un crossover a T* a temperature finie. D'autres sondes mettent en evidence une transition de phase sous l'effet d'un champ magnetique. La presence ou non de cet ordre, a temperature et champ magnetique nul questionne la communaute depuis plusieurs annees. Dans cette etude, nous detectons une variation brusque de kappa0/T a p = 0.18 dans YBCO et a p = 0.20 dans Tl-2201. Ces sauts sont interpretes comme un signe de la transition a temperature nulle et sont en faveur d'un QCP. Le manque de donnees d'un meme materiau a ces dopages ne permet pas de valider hors de tout doute l'existence d'un point critique quantique. Le modele theorique YRZ decrit aussi bien les donnees de conductivite thermique. Des pistes de travaux experimentaux a poursuivre sont proposees pour determiner la presence ou non du QCP de facon franche. Mots-cles : Supraconducteurs, cuprates, conductivite thermique, point critique quantique.

Effective SU(2) theory for the pseudogap state

Science.gov (United States)

Montiel, X.; Kloss, T.; Pépin, C.

2017-03-01

This paper exposes in a detailed manner the recent findings about the SU(2) scenario for the underdoped phase of the cuprate superconductors. The SU(2) symmetry is formulated as a rotation between the d -wave superconducting (SC) phase and a d -wave charge order. We define the operators responsible for the SU(2) rotations and we derive the nonlinear σ model associated with it. In this framework, we demonstrate that SU(2) fluctuations are massless in finite portions of the Brillouin zone corresponding to the antinodal regions (0 ,π ) and (π ,0 ). We argue that the presence of SU(2) fluctuations in the antinodal region leads to the opening of Fermi arcs around the Fermi surface and to the formation of the pseudogap. Moreover, we show that SU(2) fluctuations lead, in turn, to the emergence of a finite momentum SC order—or pair density wave (PDW)—and more importantly to a new kind of excitonic particle-hole pairs liquid, the resonant excitonic state (RES), which is made of patches of preformed particle-hole pairs with multiple momenta. When the RES liquid becomes critical, we demonstrate that electronic scattering through the critical modes leads to anomalous transport properties. This new finding can account for the strange metal (SM) phase at finite temperature, on the right-hand side of the SC dome, shedding light on another notoriously mysterious part of the phase diagram of the cuprates.

Determining the in-plane Fermi surface topology in high Tc superconductors using angle-dependent magnetic quantum oscillations

International Nuclear Information System (INIS)

Harrison, N; McDonald, R D

2009-01-01

We propose a quantum oscillation experiment by which the rotation of an underdoped YBa 2 Cu 3 O 6+x sample about two different axes with respect to the orientation of the magnetic field can be used to infer the shape of the in-plane cross-section of corrugated Fermi surface cylinder(s). Deep corrugations in the Fermi surface are expected to give rise to nodes in the quantum oscillation amplitude that depend on the magnitude and orientation of the magnetic induction B. Because the symmetries of electron and hole cylinders within the Brillouin zone are expected to be very different, the topology can provide essential clues as to the broken symmetry responsible for the observed oscillations. The criterion for the applicability of this method to the cuprate superconductors (as well as other layered metals) is that the difference in quantum oscillation frequency 2ΔF between the maximum (belly) and minimum (neck) extremal cross-sections of the corrugated Fermi surface exceeds |B|. (fast track communication)

Versatile variable temperature and magnetic field scanning probe microscope for advanced material research

Science.gov (United States)

Jung, Jin-Oh; Choi, Seokhwan; Lee, Yeonghoon; Kim, Jinwoo; Son, Donghyeon; Lee, Jhinhwan

2017-10-01

We have built a variable temperature scanning probe microscope (SPM) that covers 4.6 K-180 K and up to 7 T whose SPM head fits in a 52 mm bore magnet. It features a temperature-controlled sample stage thermally well isolated from the SPM body in good thermal contact with the liquid helium bath. It has a 7-sample-holder storage carousel at liquid helium temperature for systematic studies using multiple samples and field emission targets intended for spin-polarized spectroscopic-imaging scanning tunneling microscopy (STM) study on samples with various compositions and doping conditions. The system is equipped with a UHV sample preparation chamber and mounted on a two-stage vibration isolation system made of a heavy concrete block and a granite table on pneumatic vibration isolators. A quartz resonator (qPlus)-based non-contact atomic force microscope (AFM) sensor is used for simultaneous STM/AFM operation for research on samples with highly insulating properties such as strongly underdoped cuprates and strongly correlated electron systems.

High-energy electroweak neutrino-nucleon deeply virtual Compton scattering

International Nuclear Information System (INIS)

Machado, Magno V. T.

2007-01-01

In this work we estimate the differential and total cross sections for the high-energy deeply virtual Compton scattering in the weak sector. In the weak neutral sector one considers neutrino scattering off an unpolarized proton target through the exchange of Z 0 . We numerically compute the process Z*p→γp within the QCD color dipole formalism, which successfully describes the current high-energy electromagnetic DVCS experimental data. We also discuss possible applications for the weak charged sector and perform predictions for scattering on nuclear targets

New investigations of the guanine trichloro cuprate(II) complex crystal

Science.gov (United States)

Fabijanić, Ivana; Matković-Čalogović, Dubravka; Pilepić, Viktor; Ivanišević, Irena; Mohaček-Grošev, Vlasta; Sanković, Krešimir

2017-01-01

Crystals of the guanine trichloro cuprate(II) complex, (HGua)2[Cu2Cl6]·2H2O (HGua = protonated guanine), were prepared and analysed by spectroscopic (IR, Raman) and computational methods. A new single-crystal X-ray diffraction analysis was conducted to obtain data with lower standard uncertainties than those in the previously published structure. Raman and IR spectroscopy and quantum-mechanical analysis gave us new insight into the vibrational states of the (HGua)2[Cu2Cl6]·2H2O crystal. The vibrational spectra of the crystal were assigned by performing a normal coordinate analysis for a free dimer with a centre of inversion as the only symmetry element. The stretching vibration observed at 279 cm-1 in the infrared spectrum corresponds to the N-Cu bond. The noncovalent interaction (NCI) plots and quantum theory of atoms in molecules (QTAIM) analysis of the electron density obtained from periodic DFT calculations elucidated the interactions that exist within the crystal structure. Closed-shell ionic attractions, as well as weak and medium strength hydrogen bonds, prevailed in the crystal packing.

Photoemission perspective on pseudogap, superconducting fluctuations, and charge order in cuprates: a review of recent progress

Science.gov (United States)

Vishik, I. M.

2018-06-01

In the course of seeking the microscopic mechanism of superconductivity in cuprate high temperature superconductors, the pseudogap phase— the very abnormal ‘normal’ state on the hole-doped side— has proven to be as big of a quandary as superconductivity itself. Angle-resolved photoemission spectroscopy (ARPES) is a powerful tool for assessing the momentum-dependent phenomenology of the pseudogap, and recent technological developments have permitted a more detailed understanding. This report reviews recent progress in understanding the relationship between superconductivity and the pseudogap, the Fermi arc phenomena, and the relationship between charge order and pseudogap from the perspective of ARPES measurements.

The modulation and reconstruction of a BiO layer of cuprate Bi2212

International Nuclear Information System (INIS)

Fan Wei; Zeng, Z

2011-01-01

Studies based on ab initio density functional theory show that the modulated structures of BiO surfaces of cuprate Bi2212 superconductors are spontaneously formed and closely related to the reconstructions of BiO surfaces. The reconstructions of BiO layers occur both on the surface and in the bulk, accompanied with the formations of BiO-zigzag chains and Bi 2 O 2 quadrilaterals. The structural modulations of the BiO surface are along the b axis, perpendicular to the BiO-zigzag chains along the a axis. Our calculations provide a unified understanding of the formation of modulating structures in Bi2212. Another interesting result is that electronic structures of BiO surfaces are significantly influenced by the CuO 2 layer beneath because of the structural modulations and reconstructions.

Large and high-quality single-crystal growth of cuprate superconductor Bi-2223 using the traveling-solvent floating-zone (TSFZ) method

Science.gov (United States)

Adachi, Shintaro; Usui, Tomohiro; Kosugi, Kenta; Sasaki, Nae; Sato, Kentaro; Fujita, Masaki; Yamada, Kazuyoshi; Fujii, Takenori; Watanabe, Takao

In high superconducting transition temperature (high-Tc) cuprates, it is empirically known that Tc increases on increasing the number of CuO2 planes in a unit cell n from 1 to 3. Bi-family cuprates are ideal for investigating the microscopic mechanism involved. However, it is difficult to grow tri-layered Bi-2223, probably owing to its narrow crystallization field. Here, we report improved crystal growth of this compound using the TSFZ method under conditions slightly different from those in an earlier report [J. Cryst. Growth 223, 175 (2001)]. A Bi-rich feed-rod composition of Bi2.2Sr1.9Ca2Cu3Oy and a slightly oxygen-reduced atmosphere (mixed gas flow of O2 (10%) and Ar (90%)) were adopted for the crystal growth. In addition, to increase the supersaturation of the melts, we applied a large temperature gradient along the solid-liquid interface by shielding a high-angle light beam using Al foil around the quartz tube. In this way, we succeeded in preparing large (2 × 2 × 0 . 05 mm3) and high-quality (almost 100% pure) Bi-2223 single crystals. Hirosaki University Grant for Exploratory Research by Young Scientists and Newly-appointed Scientists.

Description of deeply inelastic collisions in terms of a transport equation

International Nuclear Information System (INIS)

Weidenmueller, H.A.

1977-01-01

A transport equation for deeply inelastic collisions is derived from a random-matrix model for the form factors for inelastic scattering and transfer reactions. The parametrization of these form factors is discussed. Results in one dimension indicate the importance of quantum fluctuations, and limitations of other approaches to the same problem. Results of three dimensions are compared with the data

Praseodymium Cuprate Thin Film Cathodes for Intermediate Temperature Solid Oxide Fuel Cells: Roles of Doping, Orientation, and Crystal Structure.

Science.gov (United States)

Mukherjee, Kunal; Hayamizu, Yoshiaki; Kim, Chang Sub; Kolchina, Liudmila M; Mazo, Galina N; Istomin, Sergey Ya; Bishop, Sean R; Tuller, Harry L

2016-12-21

Highly textured thin films of undoped, Ce-doped, and Sr-doped Pr 2 CuO 4 were synthesized on single crystal YSZ substrates using pulsed laser deposition to investigate their area-specific resistance (ASR) as cathodes in solid-oxide fuel cells (SOFCs). The effects of T' and T* crystal structures, donor and acceptor doping, and a-axis and c-axis orientation on ASR were systematically studied using electrochemical impedance spectroscopy on half cells. The addition of both Ce and Sr dopants resulted in improvements in ASR in c-axis oriented films, as did the T* crystal structure with the a-axis orientation. Pr 1.6 Sr 0.4 CuO 4 is identified as a potential cathode material with nearly an order of magnitude faster oxygen reduction reaction kinetics at 600 °C compared to thin films of the commonly studied cathode material La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3-δ . Orientation control of the cuprate films on YSZ was achieved using seed layers, and the anisotropy in the ASR was found to be less than an order of magnitude. The rare-earth doped cuprate was found to be a versatile system for study of relationships between bulk properties and the oxygen reduction reaction, critical for improving SOFC performance.

Pairing symmetries of several iron-based superconductor families and some similarities with cuprates and heavy-fermions

Directory of Open Access Journals (Sweden)

Das Tanmoy

2012-03-01

Full Text Available We show that, by using the unit-cell transformation between 1 Fe per unit cell to 2 Fe per unit cell, one can qualitatively understand the pairing symmetry of several families of iron-based superconductors. In iron-pnictides and iron-chalcogenides, the nodeless s±-pairing and the resulting magnetic resonance mode transform nicely between the two unit cells, while retaining all physical properties unchanged. However, when the electron-pocket disappears from the Fermi surface with complete doping in KFe2As2, we find that the unit-cell invariant requirement prohibits the occurrence of s±-pairing symmetry (caused by inter-hole-pocket nesting. However, the intra-pocket nesting is compatible here, which leads to a nodal d-wave pairing. The corresponding Fermi surface topology and the pairing symmetry are similar to Ce-based heavy-fermion superconductors. Furthermore, when the Fermi surface hosts only electron-pockets in KyFe2-xSe2, the inter-electron-pocket nesting induces a nodeless and isotropic d-wave pairing. This situation is analogous to the electron-doped cuprates, where the strong antiferromagnetic order creates similar disconnected electron-pocket Fermi surface, and hence nodeless d-wave pairing appears. The unit-cell transformation in KyFe2-xSe2 exhibits that the d-wave pairing breaks the translational symmetry of the 2 Fe unit cell, and thus cannot be realized unless a vacancy ordering forms to compensate for it. These results are consistent with the coexistence picture of a competing order and nodeless d-wave superconductivity in both cuprates and KyFe1.6Se2.

IrSr2TbCu2O8, a high-pressure metamagnetic cuprate: Structure, microstructure and properties

International Nuclear Information System (INIS)

Dos Santos-Garcia, A.J.; Duijn, J. van; Saez-Puche, R.; Heymann, G.; Huppertz, H.; Alario-Franco, M.A.

2008-01-01

The synthesis, structure and microstructure of the IrSr 2 TbCu 2 O 8 cuprate showing metamagnetic properties are described. The sample was prepared at high temperatures and pressures up to 9.2 GPa. The structure is tetragonal, showing a 1212 type structure, that derives from the classical YBaCuO superconductor structure, replacing the tetracoordinated square planar copper [Cu-O 4 ] in the 'chains' by octahedral [Ir-O 6 ] groups that form a perovskite-like layer in the basal plane of the unit cell. A 'simple' cell, ∼a p xa p x3a p , where a p is the basic perovskite unit cell parameter (a p ∼3.8 A), is supported by X-ray powder diffraction (XRD) and a so-called 'diagonal' one, ∼√2a p x√2a p x3a p , by SAED; a microdomain texture of latter cell and a series of very interesting extended defects have been observed by HREM. Magnetic susceptibility measurements show a magnetic transition, T N ∼6 K, with negative Weiss temperature, that indicates antiferromagnetic interactions among the Tb moments. The magnetic structure has been determined by neutron diffraction. A detailed magnetic study has revealed a metamagnetic behavior, something not previously observed in this type of cuprates. Specific heat and resistivity measurements have also been performed to characterize the transition. - Graphical abstract: Reconstructed image from the SAED of the long c tetragonal axis (3a p ) of a IrSr 2 TbCu 2 O 8 crystal. A unit cell picture is included for comparison. Display Omitted

Deeply virtual Compton scattering from gauge/gravity duality

Energy Technology Data Exchange (ETDEWEB)

Costa, Miguel S.; Djuric, Marko [University of Porto (Portugal)

2013-04-15

We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.

Deeply virtual Compton scattering from gauge/gravity duality

International Nuclear Information System (INIS)

Costa, Miguel S.; Djurić, Marko

2013-01-01

We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.

Comparison of electromechanical properties and lattice distortions of different cuprate high temperature superconductors

CERN Document Server

Scheuerlein, C.; Grether, A; Rikel, M O; Hudspeth, J; Sugano, M; Ballarino, A; Bottura, L

2016-01-01

The electromechanical properties of different cuprate high-temperature superconductors, notably two ReBCO tapes, a reinforced and a nonreinforced Bi-2223 tape, and a Bi-2212 wire, have been studied. The axial tensile stress and strain, as well as the transverse compressive stress limits at which an irreversible critical current degradation occurs, are compared. The experimental setup has been integrated in a high-energy synchrotron beamline, and the self-field critical current and lattice parameter changes as a function of tensile stress and strain of a reinforced Bi-2223 tape have been measured simultaneously. Initially, the Bi-2223 filaments exhibit nearly linear elastic behavior up to the strain at which an irreversible degradation is observed. At 77 K, an axial Bi-2223 filament precompression of 0.09% in the composite tape and a Bi-2223 Poisson ratio ν = 0.21 have been determined.

Plasmon-phonon pairing mechanism and superconducting state parameters in layered mercury cuprates

International Nuclear Information System (INIS)

Varshney, D.; Tosi, M.P.

1999-06-01

An effective two-dimensional dynamic interaction is developed which incorporated screening of holes by plasmons and by optical phonons to discuss the nature of the pairing mechanism leading to superconductivity in layered mercury cuprates. The system is treated as an ionic solid containing layers of charge carriers and a model dielectric function is set up which fulfils the appropriate sum rules on the electronic and ionic polarizabilities. The values of the coupling strength and of the Coulomb interaction parameter indicate that the superconductor is in the strong coupling regime with effective screening of the charge carriers. The superconducting transition temperature of optically doped HgBa 2 CuO 4+δ is estimated as 94 K from Kresin's strong coupling theory and the energy gap ratio is substantially larger than the BCS value. The value of the isotope exponent is severely reduced below the BCS value. The implications of the model and its analysis are discussed. (author)

Raman scattering in cuprate superconductors : an analysis in the spin bag model

International Nuclear Information System (INIS)

Behera, S.N.; Gaitonde, D.M.

1992-01-01

The spin bag model for the high temperature superconductivity (SC) in the cuprates is reformulated, so that the spin density wave (SDW) collective mode mediated pairing interaction between the doped charge carriers, has a formal similarity to the usual phonon mediated BCS mechanism. The collective modes of the spin bag superconductor are calculated and the spectral density function for the amplitude mode is plotted. The self energy and the spectral density function of an optic phonon are calculated in the spin bag superconducting state. The spectral density function does not couple to the SDW-amplitude mode. A low frequency is shown to harden while the high frequency (greater than the SC-gap) one softens; which are features in qualitative agreement with the behaviour seen in the Raman data. When the phonon frequency is larger than the SC-gap, its spectral function shows a low frequency weak peak, attributed to the SC-gap excitation which is not observed experimentally. (author). 21 refs., 3 figs

Antiferromagnetic and superconducting gaps and their interrelation in high-Tc cuprates

International Nuclear Information System (INIS)

Arrigoni, E.; Zacher, M.G.; Eckl, T.; Hanke, W.

2003-01-01

We propose a phenomenological model, comprising a microscopic SO(5) model plus the on-site Hubbard interaction U (projected SO(5) model) to understand the interrelation between the d-wave-gap modulation observed by recent angle-resolved photoemission experiments in the insulating antiferromagnet Ca 2 CuO 2 Cl 2 and the d-wave gap of high-T c superconducting materials. The on-site interaction U is important in order to produce a Mott gap of the correct order of magnitude, which would be absent in an exact SO(5) theory. The projected SO(5)-model explains the gap characteristics, namely both the symmetry and the different order of magnitude of the gap modulations between the AF and the SCc phases. Furthermore, it is shown that the projected SO(5) theory can provide an explanation for a recent observation [E. Pavarini et al., Phys. Rev. Lett. 87, 47003 (2001)], i. e. that the maximum T c observed in a large variety of high-T c cuprates scales with the next-nearest-neighbor hopping matrix element t'. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Measurement of Deeply Virtual Compton Scattering at HERA

CERN Document Server

Aktas, A.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bahr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J.G.; Coughlan, J.A.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; de Boer, Y.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flucke, G.; Fomenko, A.; Foresti, I.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerlich, C.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B.R.; Grindhammer, Guenter; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R.C.W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, H.; Kapichine, M.; Katzy, J.; Keller, N.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Koutouev, R.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kuckens, J.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leiner, B.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Luke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxeld, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Papadopoulou, T.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauvan, E.; Schatzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schroder, V.; Schultz-Coulon, H.-C.; Sedlak, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, Marcel; Usik, A.; Utkin, D.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

2005-01-01

A measurement is presented of elastic deeply virtual Compton scattering \\gamma* p \\to \\gamma p made using e^+ p collision data corresponding to a luminosity of 46.5 pb^{-1}, taken with the H1 detector at HERA. The cross section is measured as a function of the photon virtuality, Q^2, the invariant mass of the \\gamma* p system, W, and for the first time, differentially in the squared momentum transfer at the proton vertex, t, in the kinematic range 2 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2. QCD based calculations at next-to-leading order using generalized parton distributions can describe the data, as can colour dipole model predictions.

A versatile curve-fit model for linear to deeply concave rank abundance curves

NARCIS (Netherlands)

Neuteboom, J.H.; Struik, P.C.

2005-01-01

A new, flexible curve-fit model for linear to concave rank abundance curves was conceptualized and validated using observational data. The model links the geometric-series model and log-series model and can also fit deeply concave rank abundance curves. The model is based ¿ in an unconventional way

Monte Carlo studies of diamagnetism and charge density wave order in the cuprate pseudogap regime

Science.gov (United States)

Hayward Sierens, Lauren; Achkar, Andrew; Hawthorn, David; Melko, Roger; Sachdev, Subir

2015-03-01

The pseudogap regime of the hole-doped cuprate superconductors is often characterized experimentally in terms of a substantial diamagnetic response and, from another point of view, in terms of strong charge density wave (CDW) order. We introduce a dimensionless ratio, R, that incorporates both diamagnetic susceptibility and the correlation length of CDW order, and therefore reconciles these two fundamental characteristics of the pseudogap. We perform Monte Carlo simulations on a classical model that considers angular fluctuations of a six-dimensional order parameter, and compare our Monte Carlo results for R with existing data from torque magnetometry and x-ray scattering experiments on YBa2Cu3O6+x. We achieve qualitative agreement, and also propose future experiments to further investigate the behaviour of this dimensionless ratio.

Effective medium approximation for deeply subwavelength all-dielectric multilayers: when does it break down?

DEFF Research Database (Denmark)

Lavrinenko, Andrei; Zhukovsky, Sergei; Andryieuski, Andrei

2016-01-01

with different layers ordering and different but still deeply subwavelength thicknesses. Such big reflectance difference values resulted from the special geometrical configuration with an additional resonator layer underneath the multilayers employed for the enhancement of the effect. Our results are important...

Anisotropy of the penetration depth in La2-xSrxCuO4 in underdoped and overdoped regions

Science.gov (United States)

Zaleski, A. J.; Klamut, J.

1999-12-01

We present the results of measurements of the penetration depth anisotropy in pulverized, ceramic La2-xSrxCuO4. The measurements were carried out for x = 0.08, 0.1, 0.125, 0.15 and 0.2. The powdered samples, immersed in wax, were magnetically oriented in a static magnetic field of 10 T. The penetration depth in the a-b plane, icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>ab, and perpendicular to it, icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>icons/Journals/Common/perp" ALT="perp" ALIGN="MIDDLE"/>, were derived from alternating-current susceptibility measurements. For underdoped samples they both vary linearly with temperature (for the low-temperature region), while for the samples from the overdoped region the measured points can be fitted by an exponential function. These results support Uemura's picture (Uemura Y J 1997 Physica C 282-287 194) of crossover from Bose-Einstein condensation to a Bardeen-Cooper-Schrieffer mechanism of superconductivity. The penetration depth values extrapolated to T = 0 may be described by a quadratic function of the strontium concentration (for both icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>ab and icons/Journals/Common/lambda" ALT="lambda" ALIGN="TOP"/>icons/Journals/Common/perp" ALT="perp" ALIGN="MIDDLE"/>). The anisotropy of the penetration depth as a function of the substitution shows a similar dependence to the critical temperature Tc(x).

Charged domain-wall dynamics in doped antiferromagnets and spin fluctuations in cuprate superconductors

International Nuclear Information System (INIS)

Zaanen, J.; Horbach, M.L.; van Saarloos, W.

1996-01-01

Evidence is accumulating that the electron liquid in the cuprate superconductors is characterized by many-hole correlations of the charged magnetic domain-wall type. Here we focus on the strong-coupling limit where all holes are bound to domain walls. We assert that at high temperatures a classical domain-wall fluid is realized and show that the dynamics of such a fluid is characterized by spatial and temporal crossover scales set by temperature itself. The fundamental parameters of this fluid are such that the domain-wall motions dominate the low-frequency spin fluctuations and we derive predictions for the behavior of the dynamical magnetic susceptibility. We argue that a crossover occurs from a high-temperature classical to a low-temperature quantum regime, in direct analogy with helium. We discuss some general characteristics of the domain-wall quantum liquid, realized at low temperatures. copyright 1996 The American Physical Society

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

Science.gov (United States)

Gabovich, Alexander M.; Voitenko, Alexander I.

2016-10-01

The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples' intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous superconducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa2Cu3O7-δ and Bi2Sr2CaCu2O8+δ. The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-Tc superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress.

Modulation-free bismuth-lead cuprate superconductors: BiPbSr1+xL1-xCuO6 and BiPbSr2Y1-xCaxCu2O8

International Nuclear Information System (INIS)

Manivannan, V.; Gopalakrishnan, J.; Rao, C.N.R.

1991-01-01

Modulation-free BiPbSrLCuO 6 (L=La, Pr, Nd) and BiPbSr 2 YCu 2 O 8 , which are isotypic with the n=1 and 2 members of the Bi 2 Sr 2 Ca n-1 Cu n O 2n+4 family, have been prepared and characterized. These parent compounds are nonsuperconducting, but when doped with holes by substitution chemistry give modulation-free superconducting cuprates of the general formulas BiPbSr 1+xL1-x CuO 6 and BiPbSr 2 Y 1-x Ca x Cu 2 O 8 , exhibiting maximum T c 's of 24 and 85 K, respectively. Significantly, the hole concentration at the maximum T c is 0.12 in the cuprate family with a single Cu-O layer and 0.22 in that with two Cu-O layers

Two strongly correlated electron systems: the Kondo mode in the strong coupling limit and a 2-D model of electrons close to an electronic topological transition; Deux systemes d'electrons fortement correles: le modele de reseau Kondo dans la limite du couplage fort et un modele bidimensionnel d'electrons au voisinage d'une transition topologique electronique

Energy Technology Data Exchange (ETDEWEB)

Bouis, F

1999-10-14

Two strongly correlated electron systems are considered in this work, Kondo insulators and high Tc cuprates. Experiments and theory suggest on one hand that the Kondo screening occurs on a rather short length scale and on the other hand that the Kondo coupling is renormalized to infinity in the low energy limit. The strong coupling limit is then the logical approach although the real coupling is moderate. A systematic development is performed around this limit in the first part. The band structure of these materials is reproduced within this scheme. Magnetic fluctuations are also studied. The antiferromagnetic transition is examined in the case where fermionic excitations are shifted to high energy. In the second part, the Popov and Fedotov representation of spins is used to formulate the Kondo and the antiferromagnetic Heisenberg model in terms of a non-polynomial action of boson fields. In the third part the properties of high Tc cuprates are explained by a change of topology of the Fermi surface. This phenomenon would happen near the point of optimal doping and zero temperature. It results in the appearance of a density wave phase in the under-doped regime. The possibility that this phase has a non-conventional symmetry is considered. The phase diagram that described the interaction and coexistence of density wave and superconductivity is established in the mean-field approximation. The similarities with the experimental observations are numerous in particular those concerning the pseudo-gap and the behavior of the resistivity near optimal doping. (author)

Two strongly correlated electron systems: the Kondo mode in the strong coupling limit and a 2-D model of electrons close to an electronic topological transition

International Nuclear Information System (INIS)

Bouis, F.

1999-01-01

Two strongly correlated electron systems are considered in this work, Kondo insulators and high Tc cuprates. Experiments and theory suggest on one hand that the Kondo screening occurs on a rather short length scale and on the other hand that the Kondo coupling is renormalized to infinity in the low energy limit. The strong coupling limit is then the logical approach although the real coupling is moderate. A systematic development is performed around this limit in the first part. The band structure of these materials is reproduced within this scheme. Magnetic fluctuations are also studied. The antiferromagnetic transition is examined in the case where fermionic excitations are shifted to high energy. In the second part, the Popov and Fedotov representation of spins is used to formulate the Kondo and the antiferromagnetic Heisenberg model in terms of a non-polynomial action of boson fields. In the third part the properties of high Tc cuprates are explained by a change of topology of the Fermi surface. This phenomenon would happen near the point of optimal doping and zero temperature. It results in the appearance of a density wave phase in the under-doped regime. The possibility that this phase has a non-conventional symmetry is considered. The phase diagram that described the interaction and coexistence of density wave and superconductivity is established in the mean-field approximation. The similarities with the experimental observations are numerous in particular those concerning the pseudo-gap and the behavior of the resistivity near optimal doping. (author)

Electron Number-Based Phase Diagram of Pr1 -xLaCex CuO4 -δ and Possible Absence of Disparity between Electron- and Hole-Doped Cuprate Phase Diagrams

Science.gov (United States)

Song, Dongjoon; Han, Garam; Kyung, Wonshik; Seo, Jeongjin; Cho, Soohyun; Kim, Beom Seo; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Yoshida, Y.; Eisaki, H.; Park, Seung Ryong; Kim, C.

2017-03-01

We performed annealing and angle resolved photoemission spectroscopy studies on electron-doped cuprate Pr1 -xLaCex CuO4 -δ (PLCCO). It is found that the optimal annealing condition is dependent on the Ce content x . The electron number (n ) is estimated from the experimentally obtained Fermi surface volume for x =0.10 , 0.15 and 0.18 samples. It clearly shows a significant and annealing dependent deviation from the nominal x . In addition, we observe that the pseudo-gap at hot spots is also closely correlated with n ; the pseudogap gradually closes as n increases. We established a new phase diagram of PLCCO as a function of n . Different from the x -based one, the new phase diagram shows similar antiferromagnetic and superconducting phases to those of hole doped ones. Our results raise a possibility for absence of disparity between the phase diagrams of electron- and hole-doped cuprates

Scaling limit of deeply virtual Compton scattering

Energy Technology Data Exchange (ETDEWEB)

A. Radyushkin

2000-07-01

The author outlines a perturbative QCD approach to the analysis of the deeply virtual Compton scattering process {gamma}{sup *}p {r_arrow} {gamma}p{prime} in the limit of vanishing momentum transfer t=(p{prime}{minus}p){sup 2}. The DVCS amplitude in this limit exhibits a scaling behavior described by a two-argument distributions F(x,y) which specify the fractions of the initial momentum p and the momentum transfer r {equivalent_to} p{prime}{minus}p carried by the constituents of the nucleon. The kernel R(x,y;{xi},{eta}) governing the evolution of the non-forward distributions F(x,y) has a remarkable property: it produces the GLAPD evolution kernel P(x/{xi}) when integrated over y and reduces to the Brodsky-Lepage evolution kernel V(y,{eta}) after the x-integration. This property is used to construct the solution of the one-loop evolution equation for the flavor non-singlet part of the non-forward quark distribution.

Deeply virtual compton scattering in color dipole formalism

International Nuclear Information System (INIS)

Machado, Magno V.T.

2007-01-01

In this contribution we summarize recent investigations on the Deeply Virtual Compton Scattering (DVCS) within the color dipole approach. The color dipole cross section is implemented through the phenomenological saturation model. The role played by its QCD evolution and skewedness effects in the DVCS cross section are discussed. The results are compared with the recent H1 and ZEUS Collaborations data. The skewing factor, defined as the ratio of the imaginary parts of the amplitudes Im A(γ* p → γ* p)/ Im A(γ* p → γ p) can be extracted from the data using recent DVCS and the inclusive inelastic cross section measurements at DESY-HERA. We report on this experimental extraction and compare the results to the theoretical predictions for NLO QCD and the color dipole approach. (author)

DBAC: A simple prediction method for protein binding hot spots based on burial levels and deeply buried atomic contacts

Science.gov (United States)

2011-01-01

Background A protein binding hot spot is a cluster of residues in the interface that are energetically important for the binding of the protein with its interaction partner. Identifying protein binding hot spots can give useful information to protein engineering and drug design, and can also deepen our understanding of protein-protein interaction. These residues are usually buried inside the interface with very low solvent accessible surface area (SASA). Thus SASA is widely used as an outstanding feature in hot spot prediction by many computational methods. However, SASA is not capable of distinguishing slightly buried residues, of which most are non hot spots, and deeply buried ones that are usually inside a hot spot. Results We propose a new descriptor called “burial level” for characterizing residues, atoms and atomic contacts. Specifically, burial level captures the depth the residues are buried. We identify different kinds of deeply buried atomic contacts (DBAC) at different burial levels that are directly broken in alanine substitution. We use their numbers as input for SVM to classify between hot spot or non hot spot residues. We achieve F measure of 0.6237 under the leave-one-out cross-validation on a data set containing 258 mutations. This performance is better than other computational methods. Conclusions Our results show that hot spot residues tend to be deeply buried in the interface, not just having a low SASA value. This indicates that a high burial level is not only a necessary but also a more sufficient condition than a low SASA for a residue to be a hot spot residue. We find that those deeply buried atoms become increasingly more important when their burial levels rise up. This work also confirms the contribution of deeply buried interfacial atomic contacts to the energy of protein binding hot spot. PMID:21689480

Electron-phonon coupling, gap anisotropy and multigap structure in the high transition temperature cuprates

International Nuclear Information System (INIS)

Kresin, V.Z.; Wolf, S.A.

1989-01-01

In this paper the authors report on several important properties of the high t c cuprates. Firstly, the authors have developed a method for evaluating the electron-phonon coupling strength λ using an analysis of the heat capacity data. The authors estimate λ to be about 2.0 for La-Sr-Cu-O, which indicates that phonons are important but are not sufficient to explain the measured T c . Secondly, the authors have demonstrated that these materials exhibit gap anisotropy and multigap structure (the latter in the Re-Ba-Cu-O materials) which is responsible for the experimental difficulties in analyzing tunnelling and infrared data. Finally the authors have explained the anomalous results on the Pr substituted Y-Ba-Cu-O by its effects on the two dimensional Cu-O band in the framework of a two band multigap structure

Interplay of superconductivity and magnetism in presence of inter sub-lattice effect in cuprates

International Nuclear Information System (INIS)

Bishoyi, K.C.; Mohapatra, S.P.; Rout, G.C.

2010-01-01

In the present communication, we report a model Hamiltonian to study the interplay between the two long range orders of anti-ferromagnetism (AFM) and superconductivity (SC) in cuprate superconductors in presence of the intersite pairing effect. The BCS type but non-phonon pairing mechanism is considered among the electrons of two equivalent Cu sites. The pairing among the electrons of two nearest neighbour non-equivalent Cu sites is included in the Hamiltonian and its effect on the interplay of SC and AFM is investigated. The Hamiltonian is solved by the Green's function method and the corresponding gap equations are calculated and solved self-consistently. The influence of model parameters like AFM coupling (λ), SC coupling (λ 1 ) and the coupling (λ 2 ) for intersite superconducting interactions on the gaps (SC and AFM) are studied numerically and the results are reported. (author)

Deeply infiltrating endometriosis: Evaluation of retro-cervical space on MRI after vaginal opacification

International Nuclear Information System (INIS)

Fiaschetti, Valeria; Crusco, Sonia; Meschini, Alessandro; Cama, Valentina; Di Vito, Livio; Marziali, Massimiliano; Piccione, Emilio; Calabria, Ferdinando; Simonetti, Giovanni

2012-01-01

Objectives: To prospectively investigate diagnostic value and tolerability of MRI after intra-vaginal gel opacification for diagnosis and preoperative assessment of deeply infiltrating endometriosis. Methods: Sixty-three women with clinical suspicion of deeply infiltrating endometriosis were previously examined with trans-vaginal ultrasonography and then with MRI pre and post administration of vaginal gel. We evaluated the tolerability of this procedure with a scoring scale from 0 to 3. We also assessed with a score from 1 to 4 the visibility of four regions: Douglas-pouch, utero-sacral-ligaments, posterior-vaginal-fornix and recto-vaginal-septum. All patients underwent laparoscopic surgery after MRI. Results: Five patients considered procedure intolerable. Visibility of utero-sacral-ligaments and posterior-vaginal-fornix showed to be increased with gel (p < 0.001). In 57 out of 80 patients the MRI has allowed us to diagnose deeply infiltrating endometriosis. Overall, the percentages of MRI-sensitivity, specificity, positive predictive value and negative predictive value were respectively 67.8%, 95.3%, 89.4 and 83.5% without gel, and 90.8%, 94.6%, 90.8% and 94.6% with gel; trans-vaginal ultrasonography sensitivity, specificity, positive predictive value and negative predictive value were 57.5%, 96.6%, 90.9% and 79.5%. In evaluation of utero-sacral-ligaments trans-vaginal ultrasonography, MRI without gel and with gel sensitivity was respectively 61.9%, 47.6% and 81%; for recto-vaginal-septum these values were 12.5%, 68.7% and 93.7%; for pouch of Douglas 82%, 87% and 97.4%; finally for posterior-vaginal-fornix 27.3%, 36.4% and 81.8%. Conclusions: MRI with gel opacification of vagina should be recommended for suspicion of deep infiltrating endometriosis, in particular for the added value in evaluation of recto-vaginal septum, utero-sacral ligaments and posterior vaginal fornix.

Deeply infiltrating endometriosis: Evaluation of retro-cervical space on MRI after vaginal opacification

Energy Technology Data Exchange (ETDEWEB)

Fiaschetti, Valeria; Crusco, Sonia [Department of Diagnostic and Molecular Imaging, Interventional Radiology and Radiotherapy, Fondazione Policlinico ' Tor Vergata' , Viale Oxford 81, Rome (Italy); Meschini, Alessandro, E-mail: a.mesko@libero.it [Department of Diagnostic and Molecular Imaging, Interventional Radiology and Radiotherapy, Fondazione Policlinico ' Tor Vergata' , Viale Oxford 81, Rome (Italy); Cama, Valentina; Di Vito, Livio [Department of Diagnostic and Molecular Imaging, Interventional Radiology and Radiotherapy, Fondazione Policlinico ' Tor Vergata' , Viale Oxford 81, Rome (Italy); Marziali, Massimiliano; Piccione, Emilio [Department of Gynecology and Obstetrics, Fondazione Policlinico ' Tor Vergata' , Viale Oxford 81, Rome (Italy); Calabria, Ferdinando [Department of Nuclear Medicine and Diagnostic Imaging, IRCCS Neuromed, Pozzilli (Italy); Simonetti, Giovanni [Department of Diagnostic and Molecular Imaging, Interventional Radiology and Radiotherapy, Fondazione Policlinico ' Tor Vergata' , Viale Oxford 81, Rome (Italy)

2012-11-15

Objectives: To prospectively investigate diagnostic value and tolerability of MRI after intra-vaginal gel opacification for diagnosis and preoperative assessment of deeply infiltrating endometriosis. Methods: Sixty-three women with clinical suspicion of deeply infiltrating endometriosis were previously examined with trans-vaginal ultrasonography and then with MRI pre and post administration of vaginal gel. We evaluated the tolerability of this procedure with a scoring scale from 0 to 3. We also assessed with a score from 1 to 4 the visibility of four regions: Douglas-pouch, utero-sacral-ligaments, posterior-vaginal-fornix and recto-vaginal-septum. All patients underwent laparoscopic surgery after MRI. Results: Five patients considered procedure intolerable. Visibility of utero-sacral-ligaments and posterior-vaginal-fornix showed to be increased with gel (p < 0.001). In 57 out of 80 patients the MRI has allowed us to diagnose deeply infiltrating endometriosis. Overall, the percentages of MRI-sensitivity, specificity, positive predictive value and negative predictive value were respectively 67.8%, 95.3%, 89.4 and 83.5% without gel, and 90.8%, 94.6%, 90.8% and 94.6% with gel; trans-vaginal ultrasonography sensitivity, specificity, positive predictive value and negative predictive value were 57.5%, 96.6%, 90.9% and 79.5%. In evaluation of utero-sacral-ligaments trans-vaginal ultrasonography, MRI without gel and with gel sensitivity was respectively 61.9%, 47.6% and 81%; for recto-vaginal-septum these values were 12.5%, 68.7% and 93.7%; for pouch of Douglas 82%, 87% and 97.4%; finally for posterior-vaginal-fornix 27.3%, 36.4% and 81.8%. Conclusions: MRI with gel opacification of vagina should be recommended for suspicion of deep infiltrating endometriosis, in particular for the added value in evaluation of recto-vaginal septum, utero-sacral ligaments and posterior vaginal fornix.

Maximum Correntropy Unscented Kalman Filter for Ballistic Missile Navigation System based on SINS/CNS Deeply Integrated Mode.

Science.gov (United States)

Hou, Bowen; He, Zhangming; Li, Dong; Zhou, Haiyin; Wang, Jiongqi

2018-05-27

Strap-down inertial navigation system/celestial navigation system ( SINS/CNS) integrated navigation is a high precision navigation technique for ballistic missiles. The traditional navigation method has a divergence in the position error. A deeply integrated mode for SINS/CNS navigation system is proposed to improve the navigation accuracy of ballistic missile. The deeply integrated navigation principle is described and the observability of the navigation system is analyzed. The nonlinearity, as well as the large outliers and the Gaussian mixture noises, often exists during the actual navigation process, leading to the divergence phenomenon of the navigation filter. The new nonlinear Kalman filter on the basis of the maximum correntropy theory and unscented transformation, named the maximum correntropy unscented Kalman filter, is deduced, and the computational complexity is analyzed. The unscented transformation is used for restricting the nonlinearity of the system equation, and the maximum correntropy theory is used to deal with the non-Gaussian noises. Finally, numerical simulation illustrates the superiority of the proposed filter compared with the traditional unscented Kalman filter. The comparison results show that the large outliers and the influence of non-Gaussian noises for SINS/CNS deeply integrated navigation is significantly reduced through the proposed filter.

ASSESSMENT OF SEISMIC ANALYSIS METHODOLOGIES FOR DEEPLY EMBEDDED NPP STRUCTURES

International Nuclear Information System (INIS)

XU, J.; MILLER, C.; COSTANTINO, C.; HOFMAYER, C.; GRAVES, H. NRC.

2005-01-01

Several of the new generation nuclear power plant designs have structural configurations which are proposed to be deeply embedded. Since current seismic analysis methodologies have been applied to shallow embedded structures (e.g., ASCE 4 suggest that simple formulations may be used to model embedment effect when the depth of embedment is less than 30% of its foundation radius), the US Nuclear Regulatory Commission is sponsoring a program at the Brookhaven National Laboratory with the objective of investigating the extent to which procedures acceptable for shallow embedment depths are adequate for larger embedment depths. This paper presents the results of a study comparing the response spectra obtained from two of the more popular analysis methods for structural configurations varying from shallow embedment to complete embedment. A typical safety related structure embedded in a soil profile representative of a typical nuclear power plant site was utilized in the study and the depths of burial (DOB) considered range from 25-100% the height of the structure. Included in the paper are: (1) the description of a simplified analysis and a detailed approach for the SSI analyses of a structure with various DOB, (2) the comparison of the analysis results for the different DOBs between the two methods, and (3) the performance assessment of the analysis methodologies for SSI analyses of deeply embedded structures. The resulting assessment from this study has indicated that simplified methods may be capable of capturing the seismic response for much deeper embedded structures than would be normally allowed by the standard practice

A novel ferrimagnetic irido-cuprate: IrSr2GdCu2O8

International Nuclear Information System (INIS)

Dos Santos-Garcia, A.J.; Aguirre, Myriam H.; Moran, E.; Saez Puche, R.; Alario-Franco, M.A.

2006-01-01

We have performed an investigation of the structural, microstructural and magnetic properties of the new compound IrSr 2 GdCu 2 O 8 . The sample was prepared under high temperature (∼1393K) and high-pressure conditions (∼60Kbars) in a Belt type apparatus. X-ray diffraction (XRD) analysis shows that this irido-cuprate is isostructural with the corresponding Ru-1212 phase. Structurally, this material shows an interesting hierarchy of ordering phenomena, whose observation actually depends on the technique used to analyze the material: from a 'simple' cell a p xa p x3a p which is supported by XRD, through a 'diagonal' one, ∼2a p x2a p x3a p as seen by SAED, to a microdomain texture of this last one cell supported by HREM. A ferrimagnetic Ir IV -Gd III spin ordering is observed below 15K. The iridium oxidation state seems to be +4

Stabilization of high Tc phase in bismuth cuprate superconductor by lead doping

Science.gov (United States)

Gupta, Ram. P.; Pachauri, J. P.; Khokle, W. S.; Nagpal, K. C.; Date, S. K.

1991-01-01

It has been widely ascertained that doping of lead in Bi-Sr-Ca-Cu-O systems promotes the growth of high T sub c (110 K) phase, improves critical current density, and lowers processing temperature. A systematic study was undertaken to determine optimum lead content and processing conditions to achieve these properties. A large number of samples with cationic compositions of Bi(2-x)Pb(x)Sr2Ca2Cu3 (x = 0.2 to 2.0) were prepared by conventional solid state reaction technique. Samples of all compositions were annealed together at a temperature and characterized through resistance temperature (R-T) measurements and x ray diffraction to determine the zero resistance temperature, T sub c(0) and to identify presence of phases, respectively. The annealing temperature was varied between 790 and 880 C to optimize processing parameters. Results are given. In brief, an optimum process is reported along with composition of leaded bismuth cuprate superconductor which yields nearly a high T sub c single phase with highly stable superconducting properties.

Ultra-fast pump-probe determination of electron-phonon coupling in cuprate superconductors

Science.gov (United States)

Mihailovic, Dragan

2010-03-01

Fresh femtosecond spectroscopy experiments show the electron-phonon interaction strength λ to be 0.7 and 1.4 for YBCO and LSCO respectively and not around 0.2 as previously reported [1]. The revised estimates arise primarily from improved time-resolution, and also partly from improved modeling. Comparison with classical superconductors and pnictides shows non-monotonic correlation of λ with Tc. Systematic new measurements of the condensate vaporization energy (Uv) in cuprates [2] and pnictides reveals a power-law dependence on Tc with exponent 2. However, Uc is 16-18 times greater than the BCS condensation energy Uc, implying that a significant heat capacity of the ``bosonic glue.'' In contrast, charge-density wave systems with electronically driven ordering transitions have Uv˜Uc. The data suggest BCS and Eliashberg-based models to be inappropriate for describing the physics of high-temperature superconductors, and point towards polaron models which consider strong or intermediate λ.[4pt] [1] C.Gadermeier et al., arXiv:0902.1636[0pt] [2] P.Kusar et al., Phys. Rev. Lett. 101, 227001 (2008)

Fermi-surface reconstruction and the origin of high-temperature superconductivity

International Nuclear Information System (INIS)

Norman, M.R.

2010-01-01

lattice into a d 9 configuration, with one localized hole in the 3d shell per copper site. Given the localized nature of this state, it was questioned whether a momentum-space picture was an appropriate description of the physics of the cuprates. In fact, this question relates to a long-standing debate in the physics community: Since the parent state is also an antiferromagnet, one can, in principle, map the Mott insulator to a band insulator with magnetic order. In this 'Slater' picture, Mott physics is less relevant than the magnetism itself. It is therefore unclear which of the two, magnetism or Mott physics, is more fundamentally tied to superconductivity in the cuprates. After twenty years of effort, definitive quantum oscillations that could be used to map the Fermi surface were finally observed in a high-temperature cuprate superconductor in 2007. This and subsequent studies reveal a profound rearrangement of the Fermi surface in underdoped cuprates. The cause of the reconstruction, and its implication for the origin of high-temperature superconductivity, is a subject of active debate.

Designing a Deeply Digital Science Curriculum: Supporting Teacher Learning and Implementation with Organizing Technologies

Science.gov (United States)

Leary, Heather; Severance, Samuel; Penuel, William R.; Quigley, David; Sumner, Tamara; Devaul, Holly

2016-01-01

This paper examines the impacts of technology (e.g., Chromebooks, Google Drive) on teacher learning and student activity in the development and implementation of a deeply digital high school biology unit. Using design-based implementation research, teachers co-designed with researchers and curriculum specialists a student-centered unit aligned to…

Spatial distribution of superconducting and charge-density-wave order parameters in cuprates and its influence on the quasiparticle tunnel current (Review Article)

International Nuclear Information System (INIS)

Cabovich, Alexander M.; Voitenko, Alexander I.

2016-01-01

The state of the art concerning tunnel measurements of energy gaps in cuprate oxides has been analyzed. A detailed review of the relevant literature is made, and original results calculated for the quasiparticle tunnel current J(V) between a metallic tip and a disordered d-wave superconductor partially gapped by charge density waves (CDWs) are reported, because it is this model of high-temperature superconductors that becomes popular owing to recent experiments in which CDWs were observed directly. The current was calculated suggesting the scatter of both the superconducting and CDW order parameters due to the samples intrinsic inhomogeneity. It was shown that peculiarities in the current-voltage characteristics inherent to the case of homogeneous super-conducting material are severely smeared, and the CDW-related features transform into experimentally observed peak-dip-hump structures. Theoretical results were used to fit data measured for YBa_2Cu_3O_7_-_d_e_l_t_a and Bi_2Sr_2CaCu_2O_8_+_d_e_l_t_a. The fitting demonstrated a good qualitative agreement between the experiment and model calculations. The analysis of the energy gaps in high-Tc superconductors is important both per se and as a tool to uncover the nature of superconductivity in cuprates not elucidated so far despite of much theoretical effort and experimental progress.

Coherence factors in a high-tc cuprate probed by quasi-particle scattering off vortices.

Science.gov (United States)

Hanaguri, T; Kohsaka, Y; Ono, M; Maltseva, M; Coleman, P; Yamada, I; Azuma, M; Takano, M; Ohishi, K; Takagi, H

2009-02-13

When electrons pair in a superconductor, quasi-particles develop an acute sensitivity to different types of scattering potential that is described by the appearance of coherence factors in the scattering amplitudes. Although the effects of coherence factors are well established in isotropic superconductors, they are much harder to detect in their anisotropic counterparts, such as high-superconducting-transition-temperature cuprates. We demonstrate an approach that highlights the momentum-dependent coherence factors in Ca2-xNaxCuO2Cl2. We used Fourier-transform scanning tunneling spectroscopy to reveal a magnetic-field dependence in quasi-particle scattering interference patterns that is sensitive to the sign of the anisotropic gap. This result is associated with the d-wave coherence factors and quasi-particle scattering off vortices. Our technique thus provides insights into the nature of electron pairing as well as quasi-particle scattering processes in unconventional superconductors.

Maximum Correntropy Unscented Kalman Filter for Ballistic Missile Navigation System based on SINS/CNS Deeply Integrated Mode

Directory of Open Access Journals (Sweden)

Bowen Hou

2018-05-01

Full Text Available Strap-down inertial navigation system/celestial navigation system ( SINS/CNS integrated navigation is a high precision navigation technique for ballistic missiles. The traditional navigation method has a divergence in the position error. A deeply integrated mode for SINS/CNS navigation system is proposed to improve the navigation accuracy of ballistic missile. The deeply integrated navigation principle is described and the observability of the navigation system is analyzed. The nonlinearity, as well as the large outliers and the Gaussian mixture noises, often exists during the actual navigation process, leading to the divergence phenomenon of the navigation filter. The new nonlinear Kalman filter on the basis of the maximum correntropy theory and unscented transformation, named the maximum correntropy unscented Kalman filter, is deduced, and the computational complexity is analyzed. The unscented transformation is used for restricting the nonlinearity of the system equation, and the maximum correntropy theory is used to deal with the non-Gaussian noises. Finally, numerical simulation illustrates the superiority of the proposed filter compared with the traditional unscented Kalman filter. The comparison results show that the large outliers and the influence of non-Gaussian noises for SINS/CNS deeply integrated navigation is significantly reduced through the proposed filter.

Deeply virtual compton scattering on a virtual pion target

International Nuclear Information System (INIS)

Amrath, D.; Diehl, M.; Lansberg, J.P.; Heidelberg Univ.

2008-07-01

We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge asymmetries in the leading-twist approximation. Studying Compton scattering on the pion in suitable kinematics puts high demands on both beam energy and luminosity, and we find that the corresponding requirements will first be met after the energy upgrade at Jefferson Laboratory. As a by-product of our study, we construct a parameterization of pion generalized parton distributions that has a non-trivial interplay between the x and t dependence and is in good agreement with form factor data and lattice calculations. (orig.)

Recombination and propagation of quasiparticles in cuprate superconductors

International Nuclear Information System (INIS)

Gedik, Nuh

2004-01-01

Rapid developments in time-resolved optical spectroscopy have led to renewed interest in the nonequilibrium state of superconductors and other highly correlated electron materials. In these experiments, the nonequilibrium state is prepared by the absorption of short (less than 100 fs) laser pulses, typically in the near-infrared, that perturb the density and energy distribution of quasiparticles. The evolution of the nonequilibrium state is probed by time resolving the changes in the optical response functions of the medium that take place after photoexcitation. Ultimately, the goal of such experiments is to understand not only the nonequilibrium state, but to shed light on the still poorly understood equilibrium properties of these materials. We report nonequilibrium experiments that have revealed aspects of the cup rates that have been inaccessible by other techniques. Namely, the diffusion and recombination coefficients of quasiparticles have been measured in both YBa 2 Cu 3 O 6.5 and Bi 2 Sr 2 CaCu 2 O 8+x using time-resolved optical spectroscopy. Dependence of these measurements on doping, temperature and laser intensity is also obtained. To study the recombination of quasiparticles, we measure the change in reflectivity ΔR which is directly proportional to the nonequilibrium quasiparticle density created by the laser. From the intensity dependence, we estimate β, the inelastic scattering coefficient and γ th thermal equilibrium quasiparticle decay rate. We also present the dependence of recombination measurements on doping in Bi 2 Sr 2 CaCu 2 O 8+x . Going from underdoped to overdoped regime, the sign of ΔR changes from positive to negative right at the optimal doping. This is accompanied by a change in dynamics. The decay of ΔR stops being intensity dependent exactly at the optimal doping. We provide possible interpretations of these two observations. To study the propagation of quasiparticles, we interfered two laser pulses to introduce a spatially

Seismic response analysis for a deeply embedded nuclear power plant

International Nuclear Information System (INIS)

Chen, W.W.H.; Chatterjee, M.; Day, S.M.

1979-01-01

One of the important aspect of the aseimic design of nuclear power plants is the evaluation of the seismic soil-structure interaction effect due to design earthquakes. The soil-structure interaction effect can initiate rocking and result in different soil motions compared to the free field motions, thus significantly affecting the structural response. Two methods are generally used to solve the seismic soil-structure interaction problems: the direct finite element method (FLUSH) and the substructure or impedance approach. This paper presents the results of the horizontal seismic soil-structure interaction analysis using the impedance aproach and the direct finite element method for a deeply embedded nuclear power plant. (orig.)

Deep-lying hole states in the optical model

International Nuclear Information System (INIS)

Klevansky, S.P.; Lemmer, R.H.

1982-01-01

The strength function for deep-lying hole states in an optical potential is studied by the method of Green's functions. The role of isospin is emphasized. It is shown that, while the main trends of the experimental data on hole states in isotopes of Sn and Pd can be described by an energy independent optical potential, intermediate structures in these data indicate the specific nuclear polarization effects have to be included. This is done by introducing doorway states of good isospin into the optical model potential. Such states consist of neutron hole plus proton core vibrations as well as more complicated excitations that are analog states of proton hole plus neutron core vibrations of the parent nuclear system. Specific calculations for 115 Sn and 103 Pd give satisfactory fits to the strength function data using optical model and doorway state parameters that are reasonable on physical grounds

Critical Doping for the Onset of Fermi-Surface Reconstruction by Charge-Density-Wave Order in the Cuprate Superconductor La_{2-x}Sr_{x}CuO_{4}

Directory of Open Access Journals (Sweden)

S. Badoux

2016-04-01

Full Text Available The Seebeck coefficient S of the cuprate superconductor La_{2-x}Sr_{x}CuO_{4} (LSCO was measured in magnetic fields large enough to access the normal state at low temperatures, for a range of Sr concentrations from x=0.07 to x=0.15. For x=0.11, 0.12, 0.125, and 0.13, S/T decreases upon cooling to become negative at low temperatures. The same behavior is observed in the Hall coefficient R_{H}(T. In analogy with other hole-doped cuprates at similar hole concentrations p, the negative S and R_{H} show that the Fermi surface of LSCO undergoes a reconstruction caused by the onset of charge-density-wave modulations. Such modulations have indeed been detected in LSCO by x-ray diffraction in precisely the same doping range. Our data show that in LSCO this Fermi-surface reconstruction is confined to 0.085

Unified one-band Hubbard model for magnetic and electronic spectra of the parent compounds of cuprate superconductors

Science.gov (United States)

Dalla Piazza, B.; Mourigal, M.; Guarise, M.; Berger, H.; Schmitt, T.; Zhou, K. J.; Grioni, M.; Rønnow, H. M.

2012-03-01

Using low-energy projection of the one-band t-t'-t'' Hubbard model we derive an effective spin Hamiltonian and its spin-wave expansion to order 1/S. We fit the spin-wave dispersion of several parent compounds to the high-temperature superconducting cuprates La2CuO4, Sr2CuO2Cl2, and Bi2Sr2YCu2O8. Our accurate quantitative determination of the one-band Hubbard model parameters allows prediction and comparison to experimental results. Among those we discuss the two-magnon Raman peak line shape, the K-edge resonant inelastic x-ray scattering 500-meV peak, and the high-energy kink in the angle-resolved photoemission spectroscopy quasiparticle dispersion, also known as the waterfall feature.

Electronic bound states in parity-preserving QED3 applied to high-Tc cuprate superconductors

International Nuclear Information System (INIS)

Christiansen, H.R.; Cima, O.M. Del; Ferreira Junior, M.M.; Maranhao Univ., Sao Luis, MA; Helayel-Neto, J.A.; Centro Brasileiro de Pesquisas Fisicas

2001-08-01

We consider a parity-preserving QED 3 model with spontaneous breaking of the gauge symmetry as a framework for the evaluation of the electron-electron interaction potential underlying high-T e superconductivity. The fact that resulting potential, - C s K o (Mr), is non-confining and weak (in the sense of Kato) strongly suggests the mechanism of pair-condensation. This potential, compatible with an s-wave order parameters, is then applied to the Schrodinger equation for the sake of numerical calculations, thereby enforcing the existence of bound states. The results worked out by means of our theoretical framework are checked by considering a number of phenomenological data extracted from different copper oxide superconductors. The agreement may motivate a deeper analysis of our model viewing an application to quasi-planar cuprate superconductors. The data analyzed here suggest an energy scale of 1-10 meV for the breaking of the U(1)-symmetry. (author)

The search for deeply bound kaonic states with FOPI

International Nuclear Information System (INIS)

Schmid, P.; Buehler, P.; Cargnelli, M.; Marton, J.; Widmann, E.; Zmeskal, J.

2006-01-01

Full text: New formation mechanisms for the creation of dense, exotic nuclear systems involving strangeness were recently proposed by Y. Akaishi and T. Yamazaki. Their calculations show that a K - might form deeply bound states in light nuclei - so called kaonic clusters - with central densities of several times the normal nuclear density. In the presentation a short overview of these exotic nuclear systems will be given and a new experiment with FOPI at GSI will be discussed. The aim of this experiment was to search for the simplest cluster - a ppK - state. This state is produced at GSI in the following high energy reaction: p + ''d'' → ppK - + K + + n'' with incident energies of 3.5 GeV. The experimental set-up will be presented in detail. (author)

Further development of thermal neutron capture therapy for metastatic and deeply-invasive human malignant melanoma

International Nuclear Information System (INIS)

Mishima, Yutaka

1995-03-01

This issue is the collection of the papers presented thermal neutron capture therapy for metastatic and deeply-invasive human malignant melanoma. Separate abstracts were prepared for 2 of the papers in this report. The remaining 32 papers were considered outside the subject scope of INIS. (J.P.N.)

Containerless Heating Process of a Deeply Undercooled Metal Droplet by Electrostatic Levitation

International Nuclear Information System (INIS)

Wang Fei-Long; Dai Bin; Liu Xue-Feng; Sun Yi-Ning; Sun Zhi-Bin; Yu Qiang; Zhai Guang-Jie

2015-01-01

We present the containerless heating process of a deeply undercooled metal droplet by electrostatic levitation. The problem of surface charge loss in the heating process is discussed and specific formulas are given to describe the basic process of charge supplement by the photoelectric and thermoelectric effects. The pure metal zirconium is used to be melted and solidified to analyze the heating process. The temperature-time curve clearly shows the features including melting, undercooling, recalescence and solid-state phase transformation. (paper)

A Glimpse of Gluons through Deeply Virtual Compton Scattering on the Proton

OpenAIRE

Defurne, M.; Jiménez-Argüello, A. Martì; Ahmed, Z.; Albataineh, H.; Allada, K.; Aniol, K. A.; Bellini, V.; Benali, M.; Boeglin, W.; Bertin, P.; Brossard, M.; Camsonne, A.; Canan, M.; Chandavar, S.; Chen, C.

2017-01-01

The proton is composed of quarks and gluons, bound by the most elusive mechanism of strong interaction called confinement. In this work, the dynamics of quarks and gluons are investigated using deeply virtual Compton scattering (DVCS): produced by a multi-GeV electron, a highly virtual photon scatters off the proton which subsequently radiates a high energy photon. Similarly to holography, measuring not only the magnitude but also the phase of the DVCS amplitude allows to perform 3D images of...

Deeply Virtual Compton Scattering Studies at Jefferson Lab

International Nuclear Information System (INIS)

Sabatie, F.

2010-11-01

This document describes the early experimental effort at Jefferson Lab to unravel the Generalized Parton Distributions (GPD), using the Deeply Virtual Compton Scattering (DVCS) process. The GPDs contain the usual form factors and parton distribution functions, but in addition, they include correlations between states of different longitudinal and transverse momenta. They therefore give access to a three-dimensional picture of the nucleon. DVCS is the cleanest process allowing to extract GPDs, and as early as 2000, a number of experiments were proposed for this purpose. The results of the first exploratory experiments are presented as well as the first measurements of linear combinations of GPDs. In addition, a thorough discussion on the insights gained from these early experiments is proposed, linked with the theoretical tools used to extract GPDs from DVCS data. Finally, improvements on what was done for this first experimental phase are proposed and discussed, and new proposals and measurements are described. (author)

Antiferromagnetic and superconducting gaps and their interrelation in high-T sub c cuprates

CERN Document Server

Arrigoni, E; Eckl, T; Hanke, W

2003-01-01

We propose a phenomenological model, comprising a microscopic SO(5) model plus the on-site Hubbard interaction U (projected SO(5) model) to understand the interrelation between the d-wave-gap modulation observed by recent angle-resolved photoemission experiments in the insulating antiferromagnet Ca sub 2 CuO sub 2 Cl sub 2 and the d-wave gap of high-T sub c superconducting materials. The on-site interaction U is important in order to produce a Mott gap of the correct order of magnitude, which would be absent in an exact SO(5) theory. The projected SO(5)-model explains the gap characteristics, namely both the symmetry and the different order of magnitude of the gap modulations between the AF and the SCc phases. Furthermore, it is shown that the projected SO(5) theory can provide an explanation for a recent observation [E. Pavarini et al., Phys. Rev. Lett. 87, 47003 (2001)], i. e. that the maximum T sub c observed in a large variety of high-T sub c cuprates scales with the next-nearest-neighbor hopping matrix e...

Giant superconductivity-induced modulation of the ferromagnetic magnetization in a cuprate-manganite superlattice.

Science.gov (United States)

Hoppler, J; Stahn, J; Niedermayer, Ch; Malik, V K; Bouyanfif, H; Drew, A J; Rössle, M; Buzdin, A; Cristiani, G; Habermeier, H-U; Keimer, B; Bernhard, C

2009-04-01

Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.

Deeply virtual Compton scattering at Jefferson Laboratory

Energy Technology Data Exchange (ETDEWEB)

Biselli, Angela S. [Fairfield University - Department of Physics 1073 North Benson Road, Fairfield, CT 06430, USA; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-08-01

The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $e N \\rightarrow e' N' \\gamma$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs (${H}$, ${E}$, ${\\tilde{H}}$, ${\\tilde{E}}$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.

High abundance of JS-1- and Chloroflexi-related Bacteria in deeply buried marine sediments revealed by quantitative, real-time PCR.

Science.gov (United States)

Blazejak, Anna; Schippers, Axel

2010-05-01

Sequences of members of the bacterial candidate division JS-1 and the classes Anaerolineae and Caldilineae of the phylum Chloroflexi are frequently found in 16S rRNA gene clone libraries obtained from marine sediments. Using a newly designed quantitative, real-time PCR assay, these bacterial groups were jointly quantified in samples from near-surface and deeply buried marine sediments from the Peru margin, the Black Sea, and a forearc basin off the island of Sumatra. In near-surface sediments, sequences of the JS-1 as well as Anaerolineae- and Caldilineae-related Bacteria were quantified with significantly lower 16S rRNA gene copy numbers than the sequences of total Bacteria. In contrast, in deeply buried sediments below approximately 1 m depth, similar quantities of the 16S rRNA gene copies of these specific groups and Bacteria were found. This finding indicates that JS-1 and Anaerolineae- and Caldilineae-related Bacteria might dominate the bacterial community in deeply buried marine sediments and thus seem to play an important ecological role in the deep biosphere.

Deeply Virtual Compton Scattering off a deuterium target at the HERMES experiment

International Nuclear Information System (INIS)

Movsisyan, Aram

2011-05-01

Deeply virtual Compton scattering is studied in this report, using all data collected at the HERMES experiment from 1996 to 2005. Azimuthal asymmetries with respect to beam-helicity, beam-charge and target polarization alone and also to their different combinations for hard exclusive electroproduction of real photons in deep-inelastic scattering from a both unpolarized and longitudinally polarized deuterium targets are measured. The asymmetries are attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes. The asymmetries are observed in the exclusive region -(1.5) 2 GeV 2 2 X 2 GeV 2 of the squared missing mass. The dependences of these asymmetries on -t, x N , or Q 2 are investigated. The results include the coherent process ed→edγ and the incoherent process ed→epnγ where in addition a nucleon may be excited to a resonance. For an unpolarized deuterium target, the leading Fourier amplitude of the beam-helicity asymmetry that is sensitive to the interference term is found to be substantial, but no significant t dependence is observed. The leading amplitude of the beam-charge asymmetry is substantial at large -t, but becomes small at small values of -t. The amplitudes of the beam-helicity asymmetry that are sensitive to the squared DVCS term are found to be consistent with zero. The deuteron Compton form factor H 1 appears to have a similar behavior as H of the proton. (orig.)

Transformation of the superconducting gap to an insulating pseudogap at a critical hole density in the cuprates

Science.gov (United States)

Liu, Ye-Hua; Wang, Wan-Sheng; Wang, Qiang-Hua; Zhang, Fu-Chun; Rice, T. M.

2017-07-01

We apply the recent wave-packet formalism developed by Ossadnik to describe the origin of the short-range ordered pseudogap state as the hole doping is lowered through a critical density in cuprates. We argue that the energy gain that drives this precursor state to Mott localization, follows from maximizing umklapp scattering near the Fermi energy. To this end, we show how energy gaps driven by umklapp scattering can open on an appropriately chosen surface, as proposed earlier by Yang, Rice, and Zhang. The key feature is that the pairing instability includes umklapp scattering, leading to an energy gap not only in the single-particle spectrum but also in the pair spectrum. As a result the superconducting gap at overdoping is turned into an insulating pseudogap in the antinodal parts of the Fermi surface.

Gamma-ray multiplicity moments from deeply inelastic collisions of 86Kr and 144Sm

International Nuclear Information System (INIS)

Christensen, P.R.; Folkmann, F.; Hansen, O.; Nathan, O.; Trautner, N.; Videlbaek, F.; Werf, S.Y.v.d.; Britt, H.C.; Chestnut, R.P.; Freiesleben, H.; Puehlhofer, F.

1978-01-01

First, second, and third moments of gamma-ray multiplicity distributions from deeply inelastic collisions have been measured for the system 8 6Kr on 1 44Sm at 490-MeV Kr energy. The average gamma-ray multiplicities are approx. = 21, independent of reaction angle and fragment charge. The multiplicity distributions are broad, with standard deviations of ν approx. = 10, and they have a negative skewness

Measurement of deeply virtual Compton scattering using the ZEUS detector at HERA

International Nuclear Information System (INIS)

Grabowska-Bold, I.

2004-08-01

The cross sections for deeply virtual compton scattering in the reaction ep → e'γp' has been measured with the ZEUS detector at HERA using integrated luminosities of 95 pb -1 of e + p and 17 pb -1 of e - p collisions. Cross sections are presented as a function of the exchanged photon virtuality, Q 2 , and the centre-of-mass energy, W, of the γ * p system in the region 5 2 2 and 40 < W < 140 GeV. The obtained results are compared to QCD-based calculations. (orig.)

Spin dynamics of the high-Tc cuprates in the metallic state as a result of dual itinerant. Localised nature of magnetism in strongly correlated CuO2 plane

International Nuclear Information System (INIS)

Onufrieva, F.

1994-01-01

Spin dynamics in cuprates is analysed in the framework of a new theory (based on the t-t'-J model and the diagrammatic technique for Hubbard operators) developed to treat correctly strong electron correlations within CuO 2 plane. The dynamic magnetic susceptibility is determined by two contributions different in nature, the ''localized'' and ''itinerant'' ones. The ''itinerant'' contribution reflects a response in the spin susceptibility on Cu related to the propagating carrier quasiparticles. The ''localized'' contribution reflects the existence of short-range correlations between localized spins. As a result of their competition, the spin dynamics evolves continuously within the metallic state from a normal-metal behaviour at high doping (overdoped regime) to a quantum spin-liquid-type dynamics with magnon-like excitations at low doping through a non-Fermi-liquid behaviour in all intermediate regimes. The picture of the spin dynamics in the metallic state of cuprates as a whole and in details in concern to INS and NMR experimental data is presented. Many exotic features of χ(Κ,ω) revealed by these experiments find a natural explanation within the proposed scenario. (author). 64 refs., 17 figs

The intrinsic crossing point of the magnetization vs. temperature curves in superconducting cuprates in the high-magnetic-field limit

International Nuclear Information System (INIS)

Mosqueira, J.; Torron, C.; Veira, J.A.; Vidal, F.

1998-01-01

The crossing point of the magnetization vs. temperature curves that appears below T c in highly anisotropic superconducting cuprates was measured in different compounds, with a different number, N, of superconducting CuO 2 layers per periodicity length, s, and also with different values of s. By correcting the measurements from different extrinsic inhomogeneity effects through the Meissner fraction, it is demonstrated experimentally for the first time that in the high-magnetic-field limit the intrinsic crossing point may be explained at a quantitative level in terms of the Tesanovic and coworkers approach based on thermal fluctuations of quasi-2D vortices (pancakes), with an effective periodicity length equal to s, independently of N. (orig.)

Concurrent 5-fluorouracil and radiotherapy in radical treatment of frail patients with deeply invasive bladder cancer

Energy Technology Data Exchange (ETDEWEB)

Fellin, G.; Mussari, S.; Graffer, U.; Caffo, O.; Valduga, F.; Tomio, L.; Luciani, L. [S. Chiara Hospital, Trento (Italy)

2004-11-01

The radical treatment of deeply invasive bladder cancer with full dose radiotherapy and concomitant 5- fluorouracil continuous infusion is feasible even in frail patients, with an acceptable toxicity and a response rate comparable to that obtained using radiotherapy and simultaneous cisplatin. Many patients can retain a functioning bladder. (author)

Crystal growth velocity in deeply undercooled Ni-Si alloys

Science.gov (United States)

Lü, Y. J.

2012-02-01

The crystal growth velocity of Ni95Si5 and Ni90Si10 alloys as a function of undercooling is investigated using molecular dynamics simulations. The modified imbedded atom method potential yields the equilibrium liquidus temperatures T L ≈ 1505 and 1387 K for Ni95Si5 and Ni90Si10 alloys, respectively. From the liquidus temperatures down to the deeply undercooled region, the crystal growth velocities of both the alloys rise to the maximum with increasing undercooling and then drop slowly, whereas the athermal growth process presented in elemental Ni is not observed in Ni-Si alloys. Instead, the undercooling dependence of the growth velocity can be well-described by the diffusion-limited model, furthermore, the activation energy associated with the diffusion from melt to interface increases as the concentration increases from 5 to 10 at.% Si, resulting in the remarkable decrease of growth velocity.

Temperature dependence of the hole density in high-T{sub C} superconductors Bi{sub 2−y}Pb{sub y}Sr{sub 2}CaCu{sub 2}O{sub 8+δ}

Energy Technology Data Exchange (ETDEWEB)

Ghafari, A. [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Janowitz, C., E-mail: janowitz@physik.hu-berlin.de [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Ariffin, A.K. [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany); Dep. of Physics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim (Malaysia); Dwelk, H.; Krapf, A.; Manzke, R. [Institute of Physics, Humboldt University of Berlin, Newtonstr. 15, D-12489 Berlin (Germany)

2013-02-14

Highlights: ► We have done x-ray absorption spectra on the CuL{sub 3} edge of Bi(Pb)-2212 cuprates. ► We have measured the hole density n{sub H} in the CuO{sub 2} plane of Bi(Pb)-2212 cuprates. ► The measurements were performed from 10 K to 300 K. ► Gor’kov and Teitel’baums formula of n{sub H} consists of a linear and an exponential term. ► We have extended the Gor’kov and Teitel baum formula by a T{sup 3/2} term. -- Abstract: One of the most puzzling anomalies of high-T{sub C} cuprates is the strong temperature dependence of the Hall coefficient (R{sub H}) and the hole density (n{sub H}). Gor’kov and Teitel’baum (GT) proposed by using experimental data of La{sub 2−x}Sr{sub x}CuO{sub 4} (LSCO) a two fluid model. The number of holes per Cu atom n{sub H}, changes with temperature according to n{sub H}(T,x) = n{sub 0}(x) + n{sub 1}(x)exp(−Δ(x)/T) [1]. To clarify the temperature dependence of n{sub H} we have determined n{sub H} from X-ray absorption spectra (XAS) at the CuL{sub 3} edge for nearly optimum and slightly underdoped Bi{sub 2−y}Pb{sub y}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} single crystals yielding directly the absolute value of n{sub H} in the CuO{sub 2} planes and also its change with temperature n{sub H}(T). It shows pronounced structures between 10 K and 300 K. The temperature dependence puts constraints to the applicability of previously developed models: (i) the two-band model without any explicit temperature dependence and (ii) the formula of GT, because the latter is not able to fit our data over the whole temperature range from 10 K to 300 K. Instead the thermal behavior of n{sub H} proposes a function with at least three terms, i.e. a third term added to the formula of GT is of exponential form ∼T{sup 3/2}.

Stabilization of high T(sub c) phase in bismuth cuprate superconductor by lead doping

Science.gov (United States)

Gupta, Ram. P.; Pachauri, J. P.; Khokle, W. S.; Nagpal, K. C.; Date, S. K.

1990-01-01

It has widely been ascertained that doping of lead in Bi:Sr:Ca:Cu:O systems promotes the growth of high T(sub c) (110 K) phase, improves critical current density, and lowers processing temperature. A systematic investigation is undertaken to determine optimum lead content and processing conditions to achieve these. A large number of samples with cationic compositions of Bi(2-x)Pb(x)Sr2Ca2Cu3 (x = 0.2 to 2.0) were prepared by conventional solid state reaction technique. Samples of all compositions were annealed together at a temperature and characterized through resistance-temperature (R-T) measurements and x ray diffraction (XRD) to determine the zero resistance temperature, T(sub c)(0) and to identify presence of phases, respectively. The annealing temperature was varied between 790 C to optimize processing parameters. Results are given. In brief, an optimum process is reported along with composition of leaded bismuth cuprate superconductor which yields nearly a high T(sub c) single phase with highly stable superconducting properties.

Deeply Virtual Compton Scattering off a deuterium target at the HERMES experiment

Energy Technology Data Exchange (ETDEWEB)

Movsisyan, Aram

2011-05-15

Deeply virtual Compton scattering is studied in this report, using all data collected at the HERMES experiment from 1996 to 2005. Azimuthal asymmetries with respect to beam-helicity, beam-charge and target polarization alone and also to their different combinations for hard exclusive electroproduction of real photons in deep-inelastic scattering from a both unpolarized and longitudinally polarized deuterium targets are measured. The asymmetries are attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes. The asymmetries are observed in the exclusive region -(1.5){sup 2} GeV{sup 2}

Earthquake response of nuclear reactor buildings deeply embedded in soil

International Nuclear Information System (INIS)

Masao, T.; Takasaki, Y.; Hirasawa, M.; Okajima, M.; Yamamoto, S.; Kawata, E.; Koori, Y.; Ochiai, S.; Shimizu, N.

1980-01-01

This paper is concerned with experimental and analytical studies to investigate dynamic behavior of deeply embedded structures such as nuclear reactor buildings. The principal points studied are as follows: (1) Examination of stiffness and radiation damping effects according to embedded depth, (2) verification for distributions of earth pressure according to embedded depth, (3) differences of response characteristics during oscillation according to embedded depth, and (4) proposal of an analytical method for seismic design. Experimental studies were performed by two ways: forced vibration test, and earthquake observation against a rigid body model embedded in soil. Three analytical procedures were performed to compare experimental results and to examine the relation between each procedure. Finally, the dynamic behavior for nuclear reactor buildings with different embedded depths were evaluated by an analytical method. (orig.)

Jet shapes in charm photoproduction and deeply inelastic scattering at HERA

International Nuclear Information System (INIS)

Grell, Brian Rosenvold

2010-09-01

This analysis investigates charm production processes in photoproduction and deeply inelastic scattering. The analysed data was collected with the H1 detector at the HERA accelerator in the years 1999-2000 for photoproduction and 2004-2007 for deeply inelastic scattering, corresponding to integrated luminosities of 83 pb -1 , respectively 348 pb -1 . Dijet events are selected with jet transverse momenta of at least 5 GeV, respectively 4 GeV, in the central rapidity region. One jet is tagged by a D * meson to be initiated by a charm quark. The other is studied with respect to its mean integrated jet shape in order to deduce to which fraction it is initiated by a quark or a gluon. The jet shape is described by the fraction ψ(r) of the jet energy inside a cone of radius r around the jet axis; it is found that for r=0:6, ψ(r) is most sensitive to differences between charm and light quark or gluon jets. The shape is measured as a function of various kinematic variables such as the jet energy and pseudorapidity, photon virtuality and x γ obs , the fraction of the photon momentum entering the hard interaction. The photoproduction data is compared to Pythia, the DIS data to RapGap Monte Carlo simulations. In the Monte Carlo calculation, direct and resolved photon processes are simulated separately to compare samples with an enriched fraction of quark, respectively gluon initiated jets. Deviations at low x γ obs are observed for higher values of Q 2 , where direct and resolved expectations are nearly identical, hinting at an overestimation of gluon initiated jets. In most regions of phase space though, the resolution of the measurement excels the difference between direct and resolved predictions, allowing a distinction of such event samples. (orig.)

Jet shapes in charm photoproduction and deeply inelastic scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Grell, Brian Rosenvold

2010-09-15

This analysis investigates charm production processes in photoproduction and deeply inelastic scattering. The analysed data was collected with the H1 detector at the HERA accelerator in the years 1999-2000 for photoproduction and 2004-2007 for deeply inelastic scattering, corresponding to integrated luminosities of 83 pb{sup -1}, respectively 348 pb{sup -1}. Dijet events are selected with jet transverse momenta of at least 5 GeV, respectively 4 GeV, in the central rapidity region. One jet is tagged by a D{sup *} meson to be initiated by a charm quark. The other is studied with respect to its mean integrated jet shape in order to deduce to which fraction it is initiated by a quark or a gluon. The jet shape is described by the fraction {psi}(r) of the jet energy inside a cone of radius r around the jet axis; it is found that for r=0:6, {psi}(r) is most sensitive to differences between charm and light quark or gluon jets. The shape is measured as a function of various kinematic variables such as the jet energy and pseudorapidity, photon virtuality and x{sub {gamma}}{sup obs}, the fraction of the photon momentum entering the hard interaction. The photoproduction data is compared to Pythia, the DIS data to RapGap Monte Carlo simulations. In the Monte Carlo calculation, direct and resolved photon processes are simulated separately to compare samples with an enriched fraction of quark, respectively gluon initiated jets. Deviations at low x{sub {gamma}}{sup obs} are observed for higher values of Q{sup 2}, where direct and resolved expectations are nearly identical, hinting at an overestimation of gluon initiated jets. In most regions of phase space though, the resolution of the measurement excels the difference between direct and resolved predictions, allowing a distinction of such event samples. (orig.)

Relationship between Magnetic Anisotropy below Pseudogap Temperature and Short-Range Antiferromagnetic Order in High-Temperature Cuprate Superconductor

Science.gov (United States)

Morinari, Takao

2018-06-01

The central issue in high-temperature cuprate superconductors is the pseudogap state appearing below the pseudogap temperature T*, which is well above the superconducting transition temperature. In this study, we theoretically investigate the rapid increase of the magnetic anisotropy below the pseudogap temperature detected by the recent torque-magnetometry measurements on YBa2Cu3Oy [Y. Sato et al., 10.1038/nphys4205" xlink:type="simple">Nat. Phys. 13, 1074 (2017)]. Applying the spin Green's function formalism including the Dzyaloshinskii-Moriya interaction arising from the buckling of the CuO2 plane, we obtain results that are in good agreement with the experiment and find a scaling relationship. Our analysis suggests that the characteristic temperature associated with the magnetic anisotropy, which coincides with T*, is not a phase transition temperature but a crossover temperature associated with the short-range antiferromagnetic order.

Transport theory for deeply inelastic heavy-ion collisions within the statistical model

International Nuclear Information System (INIS)

Shlomo, S.

1978-01-01

The theory I am going to describe has been developed recently by Agassi, Ko and Weidenmueller. It is based on a random-matrix model for the form factor (FF) which couples a collective degree of freedom, taken to be the distance anti r between the two ions, with the intrinsic degrees of freedom. This study of dissipative phenomena in a microsystem was triggered by the success of the simple friction and diffusion models in describing experimental data on deeply inelastic collisions. I plan to describe the underlying physical assumptions, to outline the theoretical developments and to show some very recent results. (orig.) [de

A Cross-Layer Framework for Designing and Optimizing Deeply-Scaled FinFET-Based Cache Memories

Directory of Open Access Journals (Sweden)

Alireza Shafaei

2015-08-01

Full Text Available This paper presents a cross-layer framework in order to design and optimize energy-efficient cache memories made of deeply-scaled FinFET devices. The proposed design framework spans device, circuit and architecture levels and considers both super- and near-threshold modes of operation. Initially, at the device-level, seven FinFET devices on a 7-nm process technology are designed in which only one geometry-related parameter (e.g., fin width, gate length, gate underlap is changed per device. Next, at the circuit-level, standard 6T and 8T SRAM cells made of these 7-nm FinFET devices are characterized and compared in terms of static noise margin, access latency, leakage power consumption, etc. Finally, cache memories with all different combinations of devices and SRAM cells are evaluated at the architecture-level using a modified version of the CACTI tool with FinFET support and other considerations for deeply-scaled technologies. Using this design framework, it is observed that L1 cache memory made of longer channel FinFET devices operating at the near-threshold regime achieves the minimum energy operation point.

Deeply Virtual Compton Scattering and its Beam Charge Asymmetry in $e^{\\pm} p$ Collisions at HERA

CERN Document Server

Aaron, F.D.; Alexa, C.; Alimujiang, K.; Andreev, V.; Antunovic, B.; Backovic, S.; Baghdasaryan, A.; Barrelet, E.; Bartel, W.; Begzsuren, K.; Belousov, A.; Bizot, J.C.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eliseev, A.; Elsen, E.; Falkiewicz, A.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.-J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, Samvel; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jonsson, L.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Kogler, R.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Mudrinic, M.; Muller, K.; Murin, P.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Pejchal, O.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R.N.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, Ivan; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, Arnd E.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; von den Driesch, M.; Wegener, D.; Wissing, Ch.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.; Zus, R.

2009-01-01

A measurement of elastic deeply virtual Compton scattering gamma* p -> gamma p using e^+ p and e^- p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 306 pb^-1, almost equally shared between both beam charges. The cross section is measured as a function of the virtuality Q^2 of the exchanged photon and the centre-of-mass energy W of the gamma* p system in the kinematic domain 6.5 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2, where t denotes the squared momentum transfer at the proton vertex. The cross section is determined differentially in t for different Q^2 and W values and exponential t-slope parameters are derived. Using e^+ p and e^- p data samples, a beam charge asymmetry is extracted for the first time in the low Bjorken x kinematic domain. The observed asymmetry is attributed to the interference between Bethe-Heitler and deeply virtual Compton scattering processes. Experimental results are dis...

Earthquake response characteristics of large structure 'JOYO' deeply embedded in quaternary ground, (3)

International Nuclear Information System (INIS)

Yajima, Hiroshi; Sawada, Yoshihiro; Hanada, Kazutake; Sawada, Makoto.

1987-01-01

In order to examine aseismicity of embedded structure and to clarify embedment effect, earthquake observations of the large structure 'JOYO' are carried out which is deeply embedded in quaternary ground, and the results are summarized as follows. (1) Amplification factors of horizontal component in ground surface is about 3 to 4 times against the bedrock. Contrastively on the structure, any amplification is not observed at the underground portion, however, little amplification exists at the ground portion of structure. (2) Transfer function of structure has several predominant peaks at frequencies of 4.3 Hz and 8.0 Hz which are well coincided with values obtained from force excitation tests. It is shown that transfer function between basement and ground surface is similar to that between ground of same level to basement and ground surface, suggesting the behavior of basement to be able to estimate by these under ground earthquake motion. (3) According to earthquake motion analysis using S-R models, without regard to consider or not the side ground stiffness, the calculated response values do not so much differ in each model and mostly correspond with observation data, provided that the underground earthquake motion at same level to basement is used as a input wave. Consequently, the behavior of these deeply embedded structure is subject to setting method of input wave rather than modeling method, and it is very useful in design that the most simple model without side ground stiffness can roughly represent the embedment effect. (author)

Experimental Demonstration of Effective Medium Approximation Breakdown in Deeply Subwavelength All-Dielectric Multilayers

DEFF Research Database (Denmark)

Zhukovsky, Sergei; Andryieuski, Andrei; Takayama, Osamu

2015-01-01

We report the first experimental demonstration of anomalous breakdown of the effective medium approximation in all-dielectric deeply subwavelength thickness (d∼λ/160-λ/30) multilayers, as recently predicted theoretically [H. H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)]. Multilayer...... stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra for structures with 10- vs 20-nm thick layers, as well...

Unconventional superconductivity in magic-angle graphene superlattices

Science.gov (United States)

Cao, Yuan; Fatemi, Valla; Fang, Shiang; Watanabe, Kenji; Taniguchi, Takashi; Kaxiras, Efthimios; Jarillo-Herrero, Pablo

2018-04-01

The behaviour of strongly correlated materials, and in particular unconventional superconductors, has been studied extensively for decades, but is still not well understood. This lack of theoretical understanding has motivated the development of experimental techniques for studying such behaviour, such as using ultracold atom lattices to simulate quantum materials. Here we report the realization of intrinsic unconventional superconductivity—which cannot be explained by weak electron–phonon interactions—in a two-dimensional superlattice created by stacking two sheets of graphene that are twisted relative to each other by a small angle. For twist angles of about 1.1°—the first ‘magic’ angle—the electronic band structure of this ‘twisted bilayer graphene’ exhibits flat bands near zero Fermi energy, resulting in correlated insulating states at half-filling. Upon electrostatic doping of the material away from these correlated insulating states, we observe tunable zero-resistance states with a critical temperature of up to 1.7 kelvin. The temperature–carrier-density phase diagram of twisted bilayer graphene is similar to that of copper oxides (or cuprates), and includes dome-shaped regions that correspond to superconductivity. Moreover, quantum oscillations in the longitudinal resistance of the material indicate the presence of small Fermi surfaces near the correlated insulating states, in analogy with underdoped cuprates. The relatively high superconducting critical temperature of twisted bilayer graphene, given such a small Fermi surface (which corresponds to a carrier density of about 1011 per square centimetre), puts it among the superconductors with the strongest pairing strength between electrons. Twisted bilayer graphene is a precisely tunable, purely carbon-based, two-dimensional superconductor. It is therefore an ideal material for investigations of strongly correlated phenomena, which could lead to insights into the physics of high

Sapphire implant based neuro-complex for deep-lying brain tumors phototheranostics

Science.gov (United States)

Sharova, A. S.; Maklygina, YU S.; Yusubalieva, G. M.; Shikunova, I. A.; Kurlov, V. N.; Loschenov, V. B.

2018-01-01

The neuro-complex as a combination of sapphire implant optical port and osteoplastic biomaterial "Collapan" as an Aluminum phthalocyanine nanoform photosensitizer (PS) depot was developed within the framework of this study. The main goals of such neuro-complex are to provide direct access of laser radiation to the brain tissue depth and to transfer PS directly to the pathological tissue location that will allow multiple optical phototheranostics of the deep-lying tumor region without repeated surgical intervention. The developed complex spectral-optical properties research was carried out by photodiagnostics method using the model sample: a brain tissue phantom. The optical transparency of sapphire implant allows obtaining a fluorescent signal with high accuracy, comparable to direct measurement "in contact" with the tissue.

Study on vertical seismic response characteristics of deeply embedded reactor building

International Nuclear Information System (INIS)

Morishita, H.; Nakamura, N.; Uchiyama, S.; Fukuoka, A.; Ishizaki, M.

1993-01-01

This paper describes vertical response characteristics, especially effects of embedment, and analytical methods for seismic design of a deeply embedded reactor building. The influence of embedment on vertical response was found to be minimal by evaluating results of forced vibration tests of a reactor building model and performing simplified analyses. Subsequently, simulation analyses of the forced vibration test and actual earthquake induced response were performed using both the axisymmetric FEM model and the simplified mass and spring model. It was concluded that the analytical models taking the embedment into the consideration closely simulated the observation records, and the omission of embedment in the analyses tended to increase the predicted response which was conservative in respect an actual design consideration. (author)

Role of Feshbach resonances in enhancing the production of deeply bound ultracold LiRb molecules with laser pulses

Science.gov (United States)

Gacesa, Marko; Ghosal, Subhas; Côté, Robin

2010-03-01

We investigate the possibility of forming deeply bound LiRb molecules in a two-color photoassociation experiment. Ultracold ^6Li and ^87Rb atoms colliding in the vicinity of a magnetic Feshbach resonance are photoassociated into an excited electronic state. A wavepacket is then formed by exciting a few vibrational levels of the excited state and allowed to propagate. We calculate the time-dependent overlaps between the wave packet and the lowest vibrational levels of the ground state. After the optimal overlap is obtained we use the second laser pulse to dump the wave packet and efficiently populate the deeply bound ro-vibrational levels of ^6Li^87Rb in the ground state. The resulting combination of Feshbach-optimized photoassociation (FOPA) with the time-dependent pump-dump approach will produce a large number of stable ultracold molecules in the ground state. This technique is general and applicable to other systems.

Strain effects on point defects and chain-oxygen order-disorder transition in 123 cuprate compounds

International Nuclear Information System (INIS)

Su Haibin; Welch, David O.; Wong-Ng, Winnie

2004-01-01

The energetics of Schottky defects in 123 cuprate superconductor series RBa 2 Cu 3 O 7 (where R=lanthandies) and YA 2 Cu 3 O 7 (A=alkali earths), were found to have unusual relations if one considers only the volumetric strain. Our calculations reveal the effect of nonuniform changes of interatomic distances within the R-123 structures, introduced by doping homovalent elements, on the Schottky defect formation energy. The energy of formation of Frenkel pair defects, which is an elementary disordering event, in 123 compounds can be substantially altered under both stress and chemical doping. Scaling the oxygen-oxygen short-range repulsive parameter using the calculated formation energy of Frenkel pair defects, the transition temperature between orthorhombic and tetragonal phases is computed by quasichemical approximations (QCA's). The theoretical results illustrate the same trend as the experimental measurements in that the larger the ionic radius of R, the lower the orthorhombic/tetragonal phase transition temperature. This study provides strong evidence of the strain effects on order-disorder transition due to oxygens in the CuO chain sites

Deeply inelastic collisions as a source of intermediate mass fragments at E/A = 27 MeV

International Nuclear Information System (INIS)

Borderie, B.; Montoya, M.; Rivet, M.F.; Jouan, D.; Cabot, C.; Fuchs, H.; Gardes, D.; Gauvin, H.; Jacquet, D.; Monnet, F.

1988-01-01

Intermediate-mass fragments detected in coincidence with heavy residues were measured in 40 Ar induced reactions on Ag at E/A = 27 MeV. From the observed characteristics, it is inferred that intermediate-mass fragments associated with the so-called intermediate-velocity source come mainly from deeply inelastic collisions occurring after or at the same time as preequilibrium particle emission. (orig.)

Quantum SDW liquid state originating from 2D electronic topological transition as a source for anomalies in the high-Tc cuprates

International Nuclear Information System (INIS)

Onufrieva, F.; Pfeuty, P.

1999-01-01

A new microscopic scenario for high T c cuprates based on the existence of an electronic topological transition (ETT) in a strongly correlated 2D electron system has been developed recently. We first briefly sketch the principal results concerning the behaviour of a 2D fermion system on a square lattice close to an ETT and the main consequences for a strongly correlated system: d-wave superconductivity and SDW (CDW) quantum liquid state above T SC . We then illustrate how this theory can explain several crucial experimental facts (observed by NMR, angle resolved photoemission spectroscopy (ARPES), tunneling spectroscopy, inelastic neutron scattering) which reveal anomalous behavior in the SC state and in the metallic state above T s c. (orig.)

d+s wave superconductivity: analysis of the electronic Raman data of YBa2Cu3O7-δ and other cuprates

International Nuclear Information System (INIS)

Nemetschek, R.; Hackl, R.; Opel, M.; Philipp, R.; Beal-Monod, M.T.; Bieri, J.B.; Maki, K.; Erb, A.; Walker, E.

1998-01-01

After briefly recalling the d+s model valid for some anisotropic high T c superconductors, we present a theory of electronic Raman spectra in that model and then compare it with new experimental data obtained for an overdoped Y123 single crystal. The d+s model appears to describe satisfactorily the experimental results, indicating a possible doping dependence of the mixing ratio. We note that the Raman spectrum of the overdoped Bi2212 could also be accounted for by the d+s superconductivity model. The case of Hg1212 (or Hg1223) is reexamined. It appears that the spontaneous breakdown of d-wave symmetry may be rather universal in high T c cuprates. (orig.)

Generic superconducting phase behavior in high-Tc cuprates: Tc variation with hole concentration in YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Tallon, J.L.; Bernhard, C.; Shaked, H.; Hitterman, R.L.; Jorgensen, J.D.

1995-01-01

A direct determination of the relationship between T c and hole concentration p for Y 1-x Ca x Ba 2 Cu 3 O 7-δ is obtained by investigating the properties of the fully oxygen-deficient (δ∼1.0) compound for which p=x/2. Measurements of T c , the thermoelectric power S, and bond-valence sums calculated from neutron-diffraction refinements for various values of x and δ allow the full determination of the relations p=p(δ), T c =T c (p), and S=S(T,p) confirming that YBa 2 Cu 3 O 7-δ satisfies the same universal relations in these quantities as the other high-T c superconducting cuprates

Spin-fluctuation mediated superconductivity and magnetic order in the cuprate La_1.88Sr_0.12CuO₄

DEFF Research Database (Denmark)

Rømer, Astrid Tranum

, show a very rich electronic phase diagram. A common feature that characterizes both cuprates, heavy fermions, and iron pnictides is the proximity to magnetic order. Therefore, the idea of spin-uctuation mediated pairing is a popular paradigm proposed for unconventional superconductivity. A _ngerprint...... of the pairing mechanism is found in the superconducting gap symmetry. Therefore the study of gap symmetries constitutes one of the most important parts of resolving the superconducting puzzle. This thesis consists of a theoretical and an experimental part. In the theoretical part, we address spin...

Critical current densities in thick yttrium-barium cuprate (1-2-3) films

International Nuclear Information System (INIS)

Ryvkina, G.G.; Gorlanov, S.F.; Vedernikov, G.E.; Telegin, A.B.; Ryabin, V.A.; Khodos, M.Ya.

1993-01-01

The study of critical current densities j c of oxide superconductors and their thick films is a very important practical task because the value of j c is one of the main criteria for their utilization in modern cryoelectronics. For most devices based on the Josephson effect, the value of j c ∼ 10 2 - 10 3 A/cm 2 is acceptable, which is easily attainable for polycrystalline thick films obtained by stenciling. The study of the current-transport phenomenon involves a number of difficulties, especially for direct current, because both the sample itself and the lead-in contacts are resistance-heated during the measurements, which, in turn, results in lower values of the j c . Measurements with pulsed currents allow one to lower the power that is applied to the sample; the heat that is released in the sample is reduced, in comparison to measurements with direct current, by a factor of the pulsed-current duty cycle. In addition, measurements with direct current detects only the appearance of resistance; it provides no information on the rest of the transition from the normal to the superconductive state, i.e., on the so-called 'tail' of the transition. In this work, the authors studied critical current densities of thick HTSC yttrium-barium cuprate films of the 1-2-3 composition using pulsed current

Interplay of antiferromagnetism and superconductivity in cuprates with impurity effect and d-wave pairing

Energy Technology Data Exchange (ETDEWEB)

Mohapatra, Rasmita, E-mail: rmrmmohapatra@gmail.com [P.G. Department of Applied Physics and Ballistics, F.M. University, Balasore, Odisha 756019 (India); Rout, G.C., E-mail: gcr@iopb.res.in [Physics Enclave, Plot no-664/4825, Lane-4A, Shree Vihar, Patia, Bhubaneswar, Odisha 751024 (India)

2015-05-15

Highlights: • We considered here the interplay of antiferromagnetism (AFM) and Superconductivity (SC) with d-wave pairing symmetry in presence of impurity effect. • The tunneling conductance explains the multiple peaks and dip-hump structure. • It is observed that AFM coupling enhances the superconducting transition temperature. • The low temperature specific heat anomaly due to impurity atoms. - Abstract: We present here a model Hamiltonian to study the interplay between staggered magnetic field and the superconductivity with d-wave pairing symmetry in presence of hybridization between impurity f-electrons of rare-earth ions and 3d-electrons of copper ions. The staggered field and superconducting (SC) gaps are calculated by Green’s function technique and solved self-consistently. The coupling constants are compared using s-wave and d-wave pairings. The strength of hybridization suppresses the magnitude of the gaps; while antiferromagnetic coupling enhances the superconducting transition temperature, but suppresses the Neel temperature. The density of states (DOS) representing tunneling conductance shows complex character with impurity level lying at the Fermi level. The electronic specific heat explains prototype heavy fermion behavior in cuprate systems at low temperatures.

Interplay of antiferromagnetism and superconductivity in cuprates with impurity effect and d-wave pairing

International Nuclear Information System (INIS)

Mohapatra, Rasmita; Rout, G.C.

2015-01-01

Highlights: • We considered here the interplay of antiferromagnetism (AFM) and Superconductivity (SC) with d-wave pairing symmetry in presence of impurity effect. • The tunneling conductance explains the multiple peaks and dip-hump structure. • It is observed that AFM coupling enhances the superconducting transition temperature. • The low temperature specific heat anomaly due to impurity atoms. - Abstract: We present here a model Hamiltonian to study the interplay between staggered magnetic field and the superconductivity with d-wave pairing symmetry in presence of hybridization between impurity f-electrons of rare-earth ions and 3d-electrons of copper ions. The staggered field and superconducting (SC) gaps are calculated by Green’s function technique and solved self-consistently. The coupling constants are compared using s-wave and d-wave pairings. The strength of hybridization suppresses the magnitude of the gaps; while antiferromagnetic coupling enhances the superconducting transition temperature, but suppresses the Neel temperature. The density of states (DOS) representing tunneling conductance shows complex character with impurity level lying at the Fermi level. The electronic specific heat explains prototype heavy fermion behavior in cuprate systems at low temperatures

High-temperature superconductivity in solid solutions based on mixed yttrium and barium cuprate

International Nuclear Information System (INIS)

Bazuev, G.V.; Kirsanov, N.A.; Makarova, O.V.; Zubkov, V.G.; Shveikin, G.P.

1990-01-01

The discovery of high-temperature superconductivity (T c = 30-40 K) in mixed lanthanum and alkaline earth cuprates La 2-x M x CuO 4 , where M = Ba and Ca (1-3) stimulated an extensive search for new superconducting phases based on mixed oxides of these elements. The superconducting transition temperature T c in LnBa 2 Cu 3 O 7-z phases is practically independent of the REE and lies between 90-96 K. The crystal structure of superconducting YBa 2 Cu 3 O 7-z is similar to perovskite, has orthorhombic symmetry (4,5), and is related to the lanthanum barium cuprite tetragonal defect structure La 3 Ba 3 Cu 6 O 14.1 (8). A study of possible solid solutions (SS) based on YBa 2 Cu 3 O 7-z through iso- or heterovalent substitution for Y 3+ and Ba 2+ and of their electrical properties seems warranted. In the present work, the authors report the synthesis, x-ray diffraction study, and specific electric resistivity of SS Y 1-x M x (Ba 1-y M y ') 2 Cu 3 O 7-z , where M = La, Lu, Sc, In, K, Zr, and Ce and M' = Ca, Sr, Mg, K, and La

Numerical simulations of generalized Langevin equations with deeply asymptotic parameters

International Nuclear Information System (INIS)

Bao Jingdong; Li Rongwu; Wu Wei

2004-01-01

A unified algorithm for solving Langevin equations with deeply asymptotic parameters is proposed and tested. The method consists of identifying solvable linear friction and implementing the force evaluations by use of the Runge-Kutta method. We apply the present scheme to the periodic motion of an overdamped particle subjected to a multiplicative white noise. The accurate calculations for the temporal velocity of the particle and its correlation function can be realized by introducing an inertial term. It is shown that the fluctuation around the steady quantity increases with decreasing time step in the overdamped white-noise algorithm, however, a massive white-noise technique greatly reduces this spurious drift, and the result can converge to the correct value if the added inertia approaches zero. The other application is the simulation of generalized Langevin equation with an exponential memory friction, this allows us to treat a weak non-Markovian process

One-particle inclusive processes in deeply inelastic lepton-nucleon scattering

CERN Document Server

Graudenz, Dirk

1994-01-01

Abstract: The one-particle inclusive cross section in deeply inelastic lepton--nucleon scattering, expressed in terms of parton densities and fragmentation functions being differential in the invariant mass of the observed hadron and of the incoming nucleon, diverges if this invariant mass vanishes. This divergence can be traced back to the kinematical configuration where the parent parton of the observed hadron is emitted collinearly from the incoming parton of the QCD subprocess. By using the concept of ``fracture functions'', which has recently been introduced by Trentadue and Veneziano, it is possible to absorb this divergence in these new distribution functions as long as the observed hadron is not soft. This procedure allows the determination of a finite one-particle inclusive cross section in next-to-leading order QCD perturbation theory. We give details of the calculation and the explicit form of the bare fracture functions in terms of the renormalized ones.

Deeply discounted medications: Implications of generic prescription drug wars.

Science.gov (United States)

Czechowski, Jessica L; Tjia, Jennifer; Triller, Darren M

2010-01-01

To describe the history of generic prescription pricing programs at major pharmacy chains and their potential implications on prescribing, quality of care, and patient safety. Publicly available generic prescription discount program drug lists as of May 1, 2009. Fierce competition among major pharmacy chains such as Walgreens, CVS, and Walmart has led to a generic prescription pricing war with unclear public health implications. Introduced in 2006, currently 7 of the 10 largest pharmacy chains advertise a version of a deeply discounted medication (DDM) program, accounting for more than 25,000 locations nationally. By early 2008, almost 70 million Americans had used these programs. Although DDM programs lower drug costs for many patients, DDM formularies include potentially ineffective or harmful medications, have the potential to influence physician prescribing behavior, and may impair pharmacists' ability to review complete drug-dispensing records. DDMs are widespread but have the potential for unintended consequences on patients, providers, and the health care system. A systematic review of DDMs needs to evaluate the clinical, economic, and system-level implications of such programs.

Evolution of magnetic and superconducting phases with doping and pressure in the underdoped iron-arsenide superconductor Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Hassinger, Elena [Universite de Sherbrooke, Quebec (Canada); Canadian Institute for Advanced Research, Toronto, Ontario (Canada); Max Planck Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Gredat, Gregory; Valade, Fabrice; Rene de Cotret, Samuel; Juneau-Fecteau, Alexandre; Reid, Jean-Philippe; Doiron-Leyraud, Nicolas [Universite de Sherbrooke, Quebec (Canada); Kim, H.; Tanatar, Makariy A.; Prozorov, Ruslan [Ames Laboratory, Ames, Iowa (United States); Shen, B.; Wen, H.H. [Nanjing University (China); Taillefer, Louis [Universite de Sherbrooke, Quebec (Canada); Canadian Institute for Advanced Research, Toronto, Ontario (Canada)

2015-07-01

The electrical resistivity ρ of the iron-arsenide superconductor Ba{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} was measured in applied pressures up to 2.75 GPa for seven underdoped samples. Six of them are antiferromagnetic at P = 0 with 0.16 < x < 0.24 and one is non-magnetic with x = 0.26. The stripe-like antiferromagnetic ordering temperature T{sub N}, detected as a sharp anomaly in ρ(T), decreases linearly with pressure. For every magnetic sample a second phase appears with pressure at a lower temperature T{sub 0}, which rises with pressure. The critical pressure above which this phase appears decreases with doping going to zero for x = 0.24 just below the critical doping for the magnetic phase. This behaviour is reminiscent of the second magnetic phase appearing in Ba{sub 0.76}Na{sub 0.24}Fe{sub 2}As{sub 2} where the tetragonal symmetry is restored in favour of the scenario in which the nematic order in the iron pnictides is of magnetic origin.

A comparison between Miller and five-stroke cycles for enabling deeply downsized, highly boosted, spark-ignition engines with ultra expansion

International Nuclear Information System (INIS)

Li, Tie; Wang, Bin; Zheng, Bin

2016-01-01

Highlights: • Deeply downsized, highly boosted SI engine with ultra-expansion cycle is studied. • The Miller and five stroke cycles are compared on BSFC improvements and WOT performance. • The mechanism of fuel conversion efficiency improvement at various loads is discussed. • Performance of the two-stage boosting system for the downsized SI engine is investigated. • A unique strategy using the bypass for the five-stroke engine is proposed. - Abstract: It has been well known that the engine downsizing combined with intake boosting is an effective way to improve the fuel conversion efficiency without penalizing the engine torque performance. However, the potential of engine downsizing is not yet fully explored, and the major hurdles include the knocking combustion and the pre-turbine temperature limit, owing to the aggressive intake boosting. Using the engine cycle simulation, this paper compares the effects of the Miller and five stroke cycles on the performance of the deeply downsized and highly boosted SI engine, taking the engine knock and pre-turbine temperature into consideration. In the simulation, the downsizing is implemented by reducing the combustion cylinder number from four to two, while a two stage boosting system is designed for the deeply downsized engine to ensure the wide-open-throttle (WOT) performance comparable to the original four cylinder engine. The Miller cycle is realized by varying the intake valve timing and lift, while the five stroke cycle is enabled with addition of an extra expansion cylinder between the two combustion cylinders. After calibration and validation of the engine cycle simulation models using the experimental data in the original engine, the performances of the deeply downsized engines with both the Miller and five stroke cycles are numerically studied. For the most frequently operated points on the torque-speed map, at low loads the Miller cycle exhibits superior performance over the five-stroke cycle in terms

Electronic bound states in parity-preserving QED{sub 3} applied to high-T{sub c} cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Christiansen, H.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]. E-mail: hugo@cbpf.br; Cima, O.M. Del [Universidade Catolica de Petropolis, RJ (Brazil). Grupo de Fisica Teorica]. E-mail: delcima@gft.ucp.br; Ferreira Junior, M.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]|[Maranhao Univ., Sao Luis, MA (Brazil). Dept. de Fisica]. E-mail: manojr@cbpf.br; Helayel-Neto, J.A. [Universidade Catolica de Petropolis, RJ (Brazil). Grupo de Fisica Teorica]|[Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil). Coordenacao de Teoria de Campos e Particulas]. E-mail: helayel@gft.ucp.br

2001-08-01

We consider a parity-preserving QED{sub 3} model with spontaneous breaking of the gauge symmetry as a framework for the evaluation of the electron-electron interaction potential underlying high-T{sub e} superconductivity. The fact that resulting potential, - C{sub s} K{sub o} (Mr), is non-confining and weak (in the sense of Kato) strongly suggests the mechanism of pair-condensation. This potential, compatible with an s-wave order parameters, is then applied to the Schrodinger equation for the sake of numerical calculations, thereby enforcing the existence of bound states. The results worked out by means of our theoretical framework are checked by considering a number of phenomenological data extracted from different copper oxide superconductors. The agreement may motivate a deeper analysis of our model viewing an application to quasi-planar cuprate superconductors. The data analyzed here suggest an energy scale of 1-10 meV for the breaking of the U(1)-symmetry. (author)

Deciphering the recent phylogenetic expansion of the originally deeply rooted Mycobacterium tuberculosis lineage 7.

Science.gov (United States)

Yimer, Solomon A; Namouchi, Amine; Zegeye, Ephrem Debebe; Holm-Hansen, Carol; Norheim, Gunnstein; Abebe, Markos; Aseffa, Abraham; Tønjum, Tone

2016-06-30

A deeply rooted phylogenetic lineage of Mycobacterium tuberculosis (M. tuberculosis) termed lineage 7 was discovered in Ethiopia. Whole genome sequencing of 30 lineage 7 strains from patients in Ethiopia was performed. Intra-lineage genome variation was defined and unique characteristics identified with a focus on genes involved in DNA repair, recombination and replication (3R genes). More than 800 mutations specific to M. tuberculosis lineage 7 strains were identified. The proportion of non-synonymous single nucleotide polymorphisms (nsSNPs) in 3R genes was higher after the recent expansion of M. tuberculosis lineage 7 strain started. The proportion of nsSNPs in genes involved in inorganic ion transport and metabolism was significantly higher before the expansion began. A total of 22346 bp deletions were observed. Lineage 7 strains also exhibited a high number of mutations in genes involved in carbohydrate transport and metabolism, transcription, energy production and conversion. We have identified unique genomic signatures of the lineage 7 strains. The high frequency of nsSNP in 3R genes after the phylogenetic expansion may have contributed to recent variability and adaptation. The abundance of mutations in genes involved in inorganic ion transport and metabolism before the expansion period may indicate an adaptive response of lineage 7 strains to enable survival, potentially under environmental stress exposure. As lineage 7 strains originally were phylogenetically deeply rooted, this may indicate fundamental adaptive genomic pathways affecting the fitness of M. tuberculosis as a species.

Deeply trapped electrons in imaging plates and their utilization for extending the dynamic range

International Nuclear Information System (INIS)

Ohuchi, Hiroko; Kondo, Yasuhiro

2010-01-01

The absorption spectra of deep centers in an imaging plate (IP) made of BaFBr 0:85 I 0:15 :Eu 2+ have been studied in the ultraviolet region. Electrons trapped in deep centers are considered to be the cause of unerasable and reappearing latent images in IPs over-irradiated with X-rays. Deep centers showed a dominant peak at around 320 nm, followed by two small peaks at around 345 and 380 nm. By utilizing deeply trapped electrons, we have attempted to extend the dynamic range of an IP. The IP was irradiated by 150-kV X-rays with doses from 8.07 mGy to 80.7 Gy. Reading out the latent image by the stimulation of Eu 2+ luminescence with a 633-nm He-Ne laser light from a conventional Fuji reader showed a linear relationship with irradiated dose up to 0.8 Gy, but then becoming non-linear. After fully erasing with visible light, unerasable latent images were read out using 635-nm semi-conductor laser light combined with a photon-counting detection system. The dose-response curve so obtained gave a further two orders of magnitude extending the dynamic range up to 80.7 Gy. Comprehensive results indicate that electrons supplied from deep centers to the F centers provided the extended dynamic range after the F centers became saturated. Based on these facts, a model of the excitation of deeply trapped electrons and PSL processes is proposed.

Operating experience in processing of differently sourced deeply depleted uranium oxide and production of deeply depleted uranium metal ingots

International Nuclear Information System (INIS)

Manna, S.; Ladola, Y.S.; Sharma, S.; Chowdhury, S.; Satpati, S.K.; Roy, S.B.

2009-01-01

Uranium Metal Plant (UMP) of BARC had first time experience on production of three Depleted Uranium Metal (DUM) ingots of 76kg, 152kg and 163kg during March 1991. These ingots were produced by processing depleted uranyl nitrate solution produced at Plutonium Plant (PP), Trombay. In recent past Uranium Metal Plant (UMP), Uranium Extraction Division (UED), has been assigned to produce tonnage quantity of Deeply DUM (DDUM) from its oxide obtained from PP, PREFRE and RMP, BARC. This is required for shielding the high radioactive source of BHABHATRON Tele-cobalt machine, which is used for cancer therapy. The experience obtained in processing of various DDU oxides is being utilized for design of large scale DDU-metal plant under XIth plan project. The physico- chemical characteristics like morphology, density, flowability, reactivity, particle size distribution, which are having direct effect on reactivity of the powders of the DDU oxide powder, were studied and the shop-floor operational experience in processing of different oxide powder were obtained and recorded. During campaign trials utmost care was taken to standardized all operating conditions using the same equipment which are in use for natural uranium materials processing including safety aspects both with respect to radiological safety and industrial safety. Necessary attention and close monitoring were specially arranged and maintained for the safety aspects during the trial period. In-house developed pneumatic transport system was used for powder transfer and suitable dust arresting system was used for reduction of powder carry over

Resonant inelastic x-ray scattering studies of magnons and bimagnons in the lightly doped cuprate La2 -xSrxCuO4

Science.gov (United States)

Chaix, L.; Huang, E. W.; Gerber, S.; Lu, X.; Jia, C.; Huang, Y.; McNally, D. E.; Wang, Y.; Vernay, F. H.; Keren, A.; Shi, M.; Moritz, B.; Shen, Z.-X.; Schmitt, T.; Devereaux, T. P.; Lee, W.-S.

2018-04-01

We investigated the doping dependence of magnetic excitations in the lightly doped cuprate La2 -xSrxCuO4 via combined studies of resonant inelastic x-ray scattering (RIXS) at the Cu L3 edge and theoretical calculations. With increasing doping, the magnon dispersion is found to be essentially unchanged, but the spectral width broadens and the spectral weight varies differently at different momenta. Near the Brillouin zone center, we directly observe bimagnon excitations that possess the same energy scale and doping dependence as previously observed by Raman spectroscopy. They disperse weakly in energy-momentum space, and they are consistent with a bimagnon dispersion that is renormalized by the magnon-magnon interaction at the zone center.

International Workshop on Exotic Hadronic Atoms, Deeply Bound Kaonic Nuclear States and Antihydrogen : Present Results, Future Challenges

CERN Document Server

Widmann, E; Curceanu, C; Trento 2006; Trento06

2006-01-01

These are the miniproceedings of the workshop "Exotic hadronic atoms, deeply bound kaonic nuclear states and antihydrogen: present results, future challenges," which was held at the European Centre for Theoretical Nuclear Physics and Related Studies (ECT*), Trento (Italy), June 19-24, 2006. The document includes a short presentation of the topics, the list of participants, and a short contribution from each speaker.

Beam shaping assembly of a D–T neutron source for BNCT and its dosimetry simulation in deeply-seated tumor

International Nuclear Information System (INIS)

Faghihi, F.; Khalili, S.

2013-01-01

This article involves two aims for BNCT. First case includes a beam shaping assembly estimation for a D–T neutron source to find epi-thermal neutrons which are the goal in the BNCT. Second issue is the percent depth dose calculation in the adult Snyder head phantom. Monte-Carlo simulations and verification of a suggested beam shaping assembly (including internal neutron multiplier, moderator, filter, external neutron multiplier, collimator, and reflector dimensions) for thermalizing a D–T neutron source as well as increasing neutron flux are carried out and our results are given herein. Finally, we have simulated its corresponding doses for treatment planning of a deeply-seated tumor. - Highlights: ► An assembly for the D–T neutron source including many regions is given herein. ► Dosimetry simulations in the Snyder head phantom for a deeply-seated tumor are carried out. ► Brief literatures conclusions on the recent BNCT studies are presented herein

The two-component spin-fermion model for high-Tc cuprates: its applications in neutron scattering and ARPES experiments

International Nuclear Information System (INIS)

Bang, Yunkyu

2012-01-01

Motivated by neutron scattering experiments in high-T c cuprates, we propose the two-component spin-fermion model as a minimal phenomenological model, which has both local spins and itinerant fermions as independent degrees of freedom (d.o.f.). Our calculations of the dynamic spin correlation function provide a successful description of the puzzling neutron experiment data and show that: (i) the upward dispersion branch of magnetic excitations is mostly due to local spin excitations; (ii) the downward dispersion branch is from collective particle-hole excitations of fermions; and (iii) the resonance mode is a mixture of both d.o.f. Using the same model with the same set of parameters, we calculated the renormalized quasiparticle (q.p.) dispersion and successfully reproduced one of the key features of the angle-resolved photoemission spectroscopy (ARPES) experiments, namely the high-energy kink structure in the fermion q.p. dispersion, thus supporting the two-component spin-fermion phenomenology. (paper)

Pristine Early Eocene wood buried deeply in kimberlite from northern Canada.

Science.gov (United States)

Wolfe, Alexander P; Csank, Adam Z; Reyes, Alberto V; McKellar, Ryan C; Tappert, Ralf; Muehlenbachs, Karlis

2012-01-01

We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma), revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia (Cupressaceae). The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ(18)O and δ(2)H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12-17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information.

Deeply virtual Compton scattering in the Hall A of Jefferson laboratory

International Nuclear Information System (INIS)

Munoz Camacho, C.

2005-12-01

Generalized Parton Distributions (GPDs), introduced in the late 90's, provide a universal description of hadrons in terms of the underlying degrees of freedom of Quantum Chromodynamics: quarks and gluons. GPDs appear in a wide variety of hard exclusive reactions and the advent of high luminosity accelerator facilities has made the study of GPDs accessible to experiment. Deeply Virtual Compton Scattering (DVCS) is the golden process involving GPDs. The first dedicated DVCS experiment ran in the Hall A of Jefferson Lab in Fall 2004. An electromagnetic calorimeter and a plastic scintillator detector were constructed for this experiment, together with specific electronics and acquisition system. The experiment preparation, data taking and analysis are described in this document. Results on the absolute cross section difference for opposite beam helicities provide the first measurement of a linear combination of GPDs as a function of the momentum transfer to the nucleon. (author)

More accurate X-ray scattering data of deeply supercooled bulk liquid water

Energy Technology Data Exchange (ETDEWEB)

Neuefeind, Joerg C [ORNL; Benmore, Chris J [Argonne National Laboratory (ANL); Weber, Richard [Argonne National Laboratory (ANL); Paschek, Dietmar [Rostock University, Rostock, Germany

2011-01-01

Deeply supercooled water droplets held container-less in an acoustic levitator are investigated with high energy X-ray scattering. The temperature dependence X-ray structure function is found to be non-linear. Comparison with two popular computer models reveals that structural changes are predicted too abrupt by the TIP5P model, while the rate of change predicted by TIP4P is in much better agreement with experiment. The abrupt structural changes predicted by the TIP5P model to occur in the temperature range between 260-240K as water approaches the homogeneous nucleation limit are unrealistic. Both models underestimate the distance between neighbouring oxygen atoms and overestimate the sharpness of the OO distance distribution, indicating that the strength of the H-bond is overestimated in these models.

Multiphonon contribution to the polaron formation in cuprates with strong electron correlations and strong electron-phonon interaction

Science.gov (United States)

Ovchinnikov, Sergey G.; Makarov, Ilya A.; Kozlov, Peter A.

2017-03-01

In this work dependences of the electron band structure and spectral function in the HTSC cuprates on magnitude of electron-phonon interaction (EPI) and temperature are investigated. We use three-band p-d model with diagonal and offdiagonal EPI with breathing and buckling phonon mode in the frameworks of polaronic version of the generalized tight binding (GTB) method. The polaronic quasiparticle excitation in the system with EPI within this approach is formed by a hybridization of the local multiphonon Franck-Condon excitations with lower and upper Hubbard bands. Increasing EPI leads to transfer of spectral weight to high-energy multiphonon excitations and broadening of the spectral function. Temperature effects are taken into account by occupation numbers of local excited polaronic states and variations in the magnitude of spin-spin correlation functions. Increasing the temperature results in band structure reconstruction, spectral weight redistribution, broadening of the spectral function peak at the top of the valence band and the decreasing of the peak intensity. The effect of EPI with two phonon modes on the polaron spectral function is discussed.

Pristine Early Eocene wood buried deeply in kimberlite from northern Canada.

Directory of Open Access Journals (Sweden)

Alexander P Wolfe

Full Text Available We report exceptional preservation of fossil wood buried deeply in a kimberlite pipe that intruded northwestern Canada's Slave Province 53.3±0.6 million years ago (Ma, revealed during excavation of diamond source rock. The wood originated from forest surrounding the eruption zone and collapsed into the diatreme before resettling in volcaniclastic kimberlite to depths >300 m, where it was mummified in a sterile environment. Anatomy of the unpermineralized wood permits conclusive identification to the genus Metasequoia (Cupressaceae. The wood yields genuine cellulose and occluded amber, both of which have been characterized spectroscopically and isotopically. From cellulose δ(18O and δ(2H measurements, we infer that Early Eocene paleoclimates in the western Canadian subarctic were 12-17°C warmer and four times wetter than present. Canadian kimberlites offer Lagerstätte-quality preservation of wood from a region with limited alternate sources of paleobotanical information.

Microstructural Characterisation of Cuprate/Manganate Films on (110) SrTiO3 Deposited by Laser Ablation

International Nuclear Information System (INIS)

Tse, Y Y; Chakalov, R I; Joshi, M M; Jones, I P; Muirhead, C M; Palai, R

2006-01-01

Cross-sectional TEM and microanalysis were carried out to understand at a microscopic level the effects of microstructure and chemistry on the physical properties of manganites and manganite/cuprate films. TEM observations on pure LCMO grown on a (110) STO substrate were carried out first to determine the defect structure and detect any formation of second phase precipitates, as well as microstructural changes not detectable by X-ray reflections. La 0.7 Ca 0.3 MnO 3 (LCMO) grows epitaxially on a (110) SrTiO 3 (STO) substrate. HRTEM reveals a nearly defect-free interface between LCMO and STO with a few irregularly arranged misfit dislocations. The microstructure obtained from laser ablated nanometre scaled La 0.7 Ca 0.3 MnO 3 (LCMO)/YBa 2 Cu 3 O 7 -δ (YBCO)/PrBa 2 Cu 3 O 7 (PBCO) multilayers on (110) STO was also studied. Diffraction patterns show that all films grow epitaxially on top of the (110) STO substrate, with the c-axis of YBCO in plane. There is a roughness of about 10nm between PBCO and YBCO and the roughness is increased at the YBCO - LCMO interface

A glimpse of gluons through deeply virtual compton scattering on the proton.

Science.gov (United States)

Defurne, M; Jiménez-Argüello, A Martí; Ahmed, Z; Albataineh, H; Allada, K; Aniol, K A; Bellini, V; Benali, M; Boeglin, W; Bertin, P; Brossard, M; Camsonne, A; Canan, M; Chandavar, S; Chen, C; Chen, J-P; de Jager, C W; de Leo, R; Desnault, C; Deur, A; El Fassi, L; Ent, R; Flay, D; Friend, M; Fuchey, E; Frullani, S; Garibaldi, F; Gaskell, D; Giusa, A; Glamazdin, O; Golge, S; Gomez, J; Hansen, O; Higinbotham, D; Holmstrom, T; Horn, T; Huang, J; Huang, M; Hyde, C E; Iqbal, S; Itard, F; Kang, H; Kelleher, A; Keppel, C; Koirala, S; Korover, I; LeRose, J J; Lindgren, R; Long, E; Magne, M; Mammei, J; Margaziotis, D J; Markowitz, P; Mazouz, M; Meddi, F; Meekins, D; Michaels, R; Mihovilovic, M; Camacho, C Muñoz; Nadel-Turonski, P; Nuruzzaman, N; Paremuzyan, R; Puckett, A; Punjabi, V; Qiang, Y; Rakhman, A; Rashad, M N H; Riordan, S; Roche, J; Russo, G; Sabatié, F; Saenboonruang, K; Saha, A; Sawatzky, B; Selvy, L; Shahinyan, A; Sirca, S; Solvignon, P; Sperduto, M L; Subedi, R; Sulkosky, V; Sutera, C; Tobias, W A; Urciuoli, G M; Wang, D; Wojtsekhowski, B; Yao, H; Ye, Z; Zhan, X; Zhang, J; Zhao, B; Zhao, Z; Zheng, X; Zhu, P

2017-11-10

The internal structure of nucleons (protons and neutrons) remains one of the greatest outstanding problems in modern nuclear physics. By scattering high-energy electrons off a proton we are able to resolve its fundamental constituents and probe their momenta and positions. Here we investigate the dynamics of quarks and gluons inside nucleons using deeply virtual Compton scattering (DVCS)-a highly virtual photon scatters off the proton, which subsequently radiates a photon. DVCS interferes with the Bethe-Heitler (BH) process, where the photon is emitted by the electron rather than the proton. We report herein the full determination of the BH-DVCS interference by exploiting the distinct energy dependences of the DVCS and BH amplitudes. In the regime where the scattering is expected to occur off a single quark, measurements show an intriguing sensitivity to gluons, the carriers of the strong interaction.

Pion-transfer (n,d) and (d, 3He) reactions leading to deeply bound pionic atoms

International Nuclear Information System (INIS)

Toki, H.; Hirenzaki, S.; Yamazaki, T.

1990-11-01

Theoretical studies are given on the (n,d) and (d, 3 He) reactions leading to deeply bound pionic atoms in heavy nuclei of configuration [(nl) π ·j n -1 ]J. The cross sections for various pionic and neutron-hole configurations in the case of a 208 Pb target are calculated at incident energies 300-1000 MeV/u by using the effective number approach and the eikonal approximation for distortion. The effective number with a pion in the 1s or 2p state and a neutron hole in the i 13/2 orbit peaks around the same incident energy (T n =600 MeV) as the elementary cross section n+n→d+π - , where the momentum transfer matches the angular-momentum transfer of L=5∼7. The DWIA cross section for (n,d) producing a pion in the 1s or 2p orbit at T n =600 MeV is found to be around 42 or 75 μb/sr, respectively. At T n =350 MeV, where the momentum transfer is small, quasi-substitutional states of configurations [(2p) π (3p 1/2 ) n -1 ]L=0 and [(2p) π (3p 3/2 ) n -1 ]L=0 are preferentially populated with cross sections of 190 and 380 μb/sr, respectively. The (d, 3 He) cross sections are estimated to be an order of magnitude smaller than the (n,d) cross sections. Thus, the (n,d) and (d, 3 He) reactions are found to be suited for the production of deeply bound pionic atoms. (author)

MECHANISTIC STUDIES AND DESIGN OF HIGHLY ACTIVE CUPRATE CATALYSTS FOR THE DIRECT DECOMPOSITION AND SELECTIVE REDUCTION OF NITRIC OXIDE AND HYDROCARBONS TO NITROGEN FOR ABATEMENT OF STACK EMISSIONS

Energy Technology Data Exchange (ETDEWEB)

None

1998-04-30

A flow trough type catalytic reactor system was adequately modified for NO related catalytic and adsorption measurements, including the on-line connection of a digital chemiluminescent NO-NO{sub x} analyzer to the reactor outlet system. Moreover, we have largely completed the installation of an FTIR coupled catalytic system containing a HTEC cell for high temperature DRIFT studies. Three different barium cuprate samples, Ba{sub 2}CuO{sub 3}, BaCuO{sub 2}, and Ba{sub 2}Cu{sub 3}O{sub 5} were synthesized and characterized by powder XRD for catalytic tests. Prior to catalytic studies over these cuprates, a new, liquid indium based supported molten metal catalyst (In-SMMC) was tested in the reduction of NO by various reductants. In the presence of excess O{sub 2} and H{sub 2}O, the In-SMMC proved to be more active for the selective catalytic reduction (SCR) of NO to N{sub 2} by ethanol than most other catalysts. Using C{sub 1}-C{sub 3} alcohols as reductants, self sustained periodic oscillations observed in the NO{sub x} concentrations of reactor effluents indicated the first time that radical intermediates can be involved in the SCR of NO by alcohols. Further, In-SMMC is the only effective and water tolerant SCR catalyst reported thus far which contains SiO{sub 2} support. Thus, this novel catalyst opens up a promising new alternative for developing an effective and durable catalyst for NO{sub x} abatement in stack emission.

Multilayered cuprate superconductor Ba2Ca5Cu6O12(O1-x,Fx) 2 studied by temperature-dependent scanning tunneling microscopy and spectroscopy

Science.gov (United States)

Sugimoto, Akira; Ekino, Toshikazu; Gabovich, Alexander M.; Sekine, Ryotaro; Tanabe, Kenji; Tokiwa, Kazuyasu

2017-05-01

Scanning tunneling microscopy/spectroscopy (STM/STS) measurements were carried out on a multilayered cuprate superconductor Ba2Ca5Cu6O12 (O1 -x,Fx )2. STM topography revealed random spot structures with the characteristic length ≤0.5 nm. The conductance spectra d I /d V (V ) show the coexistence of smaller gaps ΔS and large gaps (pseudogaps) ΔL. The pseudogap-related features in the superconducting state were traced with the spatial resolution of ˜0.07 nm. Here, I and V are the tunnel current and bias voltage, respectively. The temperature, T , dependence of ΔS follows the reduced Bardeen-Cooper-Schrieffer (BCS) dependence. The hallmark ratio 2 ΔS(T =0 ) /kBTc equals to 4.9, which is smaller than those of other cuprate superconductors. Here, Tc is the superconducting critical temperature and kB is the Boltzmann constant. The larger gap ΔL survives in the normal state and even increases with T above Tc. The T dependencies of the spatial distributions for both relevant gaps (Δ map), as well as for each gap separately (ΔS and ΔL), were obtained. From the histogram of Δ map, the averaged gap values were found to be Δ¯S=˜24 meV and Δ¯L=˜79 meV. The smaller gap ΔS shows a spatially homogeneous distribution while the larger gap ΔL is quite inhomogeneous, indicating that rather homogeneous superconductivity coexists with the patchy distributed pseudogap. The spatial variation length ξΔ L of ΔL correlates with the scale of the topography spot structures, being approximately 0.4 nm. This value is considerably smaller than the coherence length of this class of superconductors, suggesting that ΔL is strongly affected by the disorder of the apical O/F.

Laparoscopic excision of rectosigmoid endometriotic plaque and cul de sac obliteration in deeply infiltrating endometriosis: a case report.

Science.gov (United States)

Fragulidis, G P; Oreopulu, F V; Vezakis, A; Sofoudis, C; Kalambokas, E; Koutoulidis, V; Vlahos, N F

2016-01-01

Endometriosis represents a main cause of infertility and pelvic pain affecting 3-43% among reproductive age women. Deep pelvic endometriosis is defined as subperitoneal infiltration of endometrial implants in the uterosacral ligaments, rectum, rectovaginal septum, vagina or bladder. The authors present a case of a 29-year-old patient who underwent laparoscopic excision of extensive endometriotic plaque in rectovaginal septum accompanied with deeply infiltrating endometriosis (DIE) and chronic pelvic pain (CPP).

High energy deeply virtual Compton scattering on a photon and related meson exclusive production

International Nuclear Information System (INIS)

Machado, Magno V. T.

2007-01-01

In this work we estimate the differential cross section for the high energy deeply virtual Compton scattering on a photon target, γ*γ→γγ, within the QCD dipole-dipole scattering formalism. For the phenomenology, a saturation model for the dipole-dipole cross section for two photon scattering is considered. Its robustness is supported by a good description of current accelerator data. In addition, we consider the related exclusive vector meson production processes, γ*γ→Vγ. This analysis is focused on the light ρ and φ meson production, which produces larger cross sections. The phenomenological results are compared with the theoretical calculation using the color-dipole Balitsky-Fadin-Kuraev-Lipatov approach

Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering

International Nuclear Information System (INIS)

Airapetian, A.; Akopov, Z.

2009-11-01

The nuclear-mass dependence of azimuthal cross section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studied for hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found. (orig.)

A pseudogap model beyond BCS for the cuprates: The effect of order parameter symmetry, Debye frequency and band structure

International Nuclear Information System (INIS)

Rodriguez-Nunez, J.J.; Schmidt, A.A.; Beck, H.; Valera, M.

2005-08-01

One of the most intriguing aspects of high temperature superconductors (HTSC) is the presence of the pseudogap in the normal and the superconducting phases of the cuprate compounds. Several pseudogap models have been proposed to explain the $abnormal$ properties of the cuprates. One of the recent models relies on the assumption that the self-energy is given by Σ PG (iω n )=- E g 2 (k)G 0 (k,-iω n ) where G 0 (k,iω n is the one- particle free Green function. Going beyond this mean field model for the pseudogap we now take into account fluctuations of the pseudogap as Σ PG (iω n )=- E g 2 (k)G PG (k,-iω n ) where G PG (k,iω n is the one-particle full Green function. We study the combined effect of the band structure and the Debye frequency, ω D , on the superconducting critical temperature, T c , as a function of the number of carriers per site, n. Our conclusions are: 1) increasing the value of V/t increases the value of T c /t; 2) increasing the value of E G /t decreases the value of T c /t. By the way, one needs some critical value of V/t to have finite values of T c /t. This is the reason we have taken high values of V/ to find superconductivity; 3) decreasing the value of ω D /t decreases the value of T c /t. This is reasonable since we have less available states around the Fermi; 4) the inclusion of α', which we call the effect of the band structure, is important because it moves the center of curve of T c /t x n. The center of this curve, with respect to half-filling (n=1), is displaced to the left if α'>0.0; 5) the chemical potential is defined in the region where T c /t ≠ 0. However, in this region, it is almost identical for different values of V/t. This is due to the fact that μ is a global property; 6) our model always produces d-wave superconductivity around the Fermi level, independent whether E G (K-bar)/t is s- or d-wave symmetry. (author)

Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

International Nuclear Information System (INIS)

Kiesel, Maximilian Ludwig

2013-01-01

A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na x CoO 2 and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general considerations on

Unconventional superconductivity in cuprates, cobaltates and graphene. What is universal and what is material-dependent in strongly versus weakly correlated materials?

Energy Technology Data Exchange (ETDEWEB)

Kiesel, Maximilian Ludwig

2013-02-08

A general theory for all classes of unconventional superconductors is still one of the unsolved key issues in condensed-matter physics. Actually, it is not yet fully settled if there is a common underlying pairing mechanism. Instead, it might be possible that several distinct sources for unconventional (not phonon-mediated) superconductivity have to be considered, or an electron-phonon interaction is not negligible. The focus of this thesis is on the most probable mechanism for the formation of Cooper pairs in unconventional superconductors, namely a strictly electronic one where spin fluctuations are the mediators. Studying different superconductors in this thesis, the emphasis is put on material-independent features of the pairing mechanism. In addition, the investigation of the phase diagrams enables a view on the vicinity of superconductivity. Thus, it is possible to clarify which competing quantum fluctuations enhance or weaken the propensity for a superconducting state. The broad range of superconducting materials requires the use of more than one numerical technique to study an appropriate microscopic description. This is not a problem but a big advantage because this facilitates the approach-independent description of common underlying physics. For this evaluation, the strongly correlated cuprates are simulated with the variational cluster approach. Especially the question of a pairing glue is taken into consideration. Furthermore, it is possible to distinguish between retarded and non-retarded contributions to the gap function. The cuprates are confronted with the cobaltate Na{sub x}CoO{sub 2} and graphene. These weakly correlated materials are investigated with the functional renormalization group (fRG) and reveal a comprehensive phase diagram, including a d+id-wave superconductivity, which breaks time-reversal symmetry. The corresponding gap function is nodeless, but for NaCoO, it features a doping-dependent anisotropy. In addition, some general

Deeply virtual Compton scattering off an unpolarised hydrogen target at HERMES

Energy Technology Data Exchange (ETDEWEB)

Burns, Jonathan R.T.

2010-08-15

Deeply Virtual Compton Scattering (DVCS) i.e. ep {yields} ep{gamma} is the simplest interaction that allows access to Generalised Parton Distributions (GPDs), a theoretical framework describing nucleon structure. The strong interest in GPDs results from the fact that they can be used to determine the total angular momentum of quarks inside the nucleon and provide a 3-dimensional picture of nucleon structure. The measurement of the DVCS process is facilitated by the interference with a competing interaction known as the Bethe-Heitler process which has the same nal state. DVCS information is obtained from the asymmetrical in distribution of the real photon around the azimuthal angle {phi} at HERMES. Beam charge and beam helicity asymmetries, extracted from DVCS events with an unpolarised hydrogen target recorded during the 2006-2007 and 1996-2007 data taking periods, are presented in this thesis. The asymmetry amplitudes are presented over the range of HERMES kinematic acceptance, with their dependence on kinematic variables t, x{sub B} and Q{sup 2} also shown and compared to a phenomenological model. (orig.)

High pressure study of high-temperature superconductors

Energy Technology Data Exchange (ETDEWEB)

Souliou, Sofia-Michaela

2014-09-29

The current thesis studies experimentally the effect of high external pressure on high-T{sub c} superconductors. The structure and lattice dynamics of several members of the high-T{sub c} cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T{sub c} superconductor YBa{sub 2}Cu{sub 3}O{sub 6+x} have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa{sub 2}Cu{sub 3}O{sub 6.55} samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa{sub 2}Cu{sub 4}O{sub 8}. A clear renormalization of some of the Raman phonons is seen below T{sub c} as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B{sub 1g}-like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa{sub 2}Cu{sub 3}O{sub 6+x}. At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group

High pressure study of high-temperature superconductors

International Nuclear Information System (INIS)

Souliou, Sofia-Michaela

2014-01-01

The current thesis studies experimentally the effect of high external pressure on high-T c superconductors. The structure and lattice dynamics of several members of the high-T c cuprate and Fe-based superconductors families were investigated by means of Raman spectroscopy and X-ray diffraction under well-controlled, hydrostatic high pressure and low temperature conditions. The lattice dynamics of the high-T c superconductor YBa 2 Cu 3 O 6+x have been investigated systematically by Raman spectroscopy as a function of doping (x = 0.95, 0.75, 0.60, 0.55, and 0.45) and external pressure. Under ambient pressure conditions, in addition to the Raman modes expected from group theory, we observe new Raman active phonons upon cooling the underdoped samples, at temperatures well above the superconducting transition temperature. The doping dependence and the onset temperatures of the new Raman features suggest that they are associated with the incommensurate charge density wave (CDW) state recently discovered in underdoped cuprates using synchrotron X-ray scattering techniques. Under high pressure conditions (from 2 to 12 GPa), our Raman measurements on highly ordered underdoped YBa 2 Cu 3 O 6.55 samples do not show any of the new Raman phonons seen at ambient pressure. High pressure and low temperature Raman measurements have been performed on the underdoped superconductor YBa 2 Cu 4 O 8 . A clear renormalization of some of the Raman phonons is seen below T c as a result of the changes in the phonon self-energy upon the opening of the superconducting gap, with the most prominent one being that of the B 1g -like buckling phonon mode. The amplitude of this renormalization strongly increases with pressure, resembling the effect of hole doping in YBa 2 Cu 3 O 6+x . At ∝ 10 GPa, the system undergoes a reversible pressure-induced structural phase transition to a non-centrosymmmetric structure (space group Imm2). The structural transition is clearly reflected in the high pressure

Bimagnon studies in cuprates with resonant inelastic x-ray scattering at the O K edge. I. Assessment on La2CuO4 and comparison with the excitation at Cu L3 and Cu K edges

Science.gov (United States)

Bisogni, V.; Simonelli, L.; Ament, L. J. P.; Forte, F.; Moretti Sala, M.; Minola, M.; Huotari, S.; van den Brink, J.; Ghiringhelli, G.; Brookes, N. B.; Braicovich, L.

2012-06-01

We assess the capabilities of magnetic resonant inelastic x-ray scattering (RIXS) at the O K edge in undoped cuprates by taking La2CuO4 as a benchmark case, based on a series of RIXS measurements that we present here. By combining the experimental results with basic theory we point out the fingerprints of bimagnon excitation in the O K edge RIXS spectra. These are a dominant peak around 450 meV, the almost complete absence of dispersion both with π and σ polarization, and the almost constant intensity vs the transferred momentum with σ polarization. This behavior is quite different from Cu L3 edge RIXS giving a strongly dispersing bimagnon tending to zero at the center of the Brillouin zone. This is clearly shown by RIXS measurements at the Cu L3 edge that we present. The Cu L3 bimagnon spectra and those at the Cu K edge—both from the literature and from our data—however, have the same shape. These similarities and differences are understood in terms of different sampling of the bimagnon continuum. This panorama points out the unique possibilities offered by O K RIXS in the study of magnetic excitations in cuprates near the center of the BZ.

Measurement of Deeply Virtual Compton Scattering and its t-dependence at HERA

CERN Document Server

Aaron, F.D.; Alexa, C.; Andreev, V.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J.C.; Boenig, M.O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R.C.W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M.E.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, Andreas Werner; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Kogler, R.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Polifka, R.; Povh, B.; Preda, T.; Prideaux, P.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salek, D.; Salvaire, F.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shaw-West, R.N.; Sheviakov, I.; Shtarkov, L.N.; Sloan, T.; Smiljanic, Ivan; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stiewe, J.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y.C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

2008-01-01

A measurement of elastic deeply virtual Compton scattering gamma* p -> gamma p using e-p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 145 pb^-1. The cross section is measured as a function of the virtuality Q^2 of the exchanged photon and the centre-of-mass energy W of the gamma*p system in the kinematic domain 6.5 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2, where t denotes the squared momentum transfer at the proton vertex. The cross section is determined differentially in t for different Q^2 and W values and exponential t-slope parameters are derived. The measurements are compared to a NLO QCD calculation based on generalised parton distributions. In the context of the dipole approach, the geometric scaling property of the DVCS cross section is studied for different values of t.

Measurement of deeply virtual Compton scattering and its t-dependence at HERA

Science.gov (United States)

H1 Collaboration; Aaron, F. D.; Aktas, A.; Alexa, C.; Andreev, V.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Cantun Avila, K. B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J. G.; Coughlan, J. A.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; de Roeck, A.; de Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkiewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B. R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R. C. W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Jacquet, M.; Janssen, M. E.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, A. W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knutsson, A.; Kogler, R.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Kutak, K.; Landon, M. P. J.; Lange, W.; Laštovička-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.-U.; Maxfield, S. J.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Mudrinic, M.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G. D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Plačakytė, R.; Polifka, R.; Povh, B.; Preda, T.; Prideaux, P.; Radescu, V.; Rahmat, A. J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salek, D.; Salvaire, F.; Sankey, D. P. C.; Sauter, M.; Sauvan, E.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R. N.; Sheviakov, I.; Shtarkov, L. N.; Sloan, T.; Smiljanic, I.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stiewe, J.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Toll, T.; Tomasz, F.; Tran, T. H.; Traynor, D.; Trinh, T. N.; Truöl, P.; Tsakov, I.; Tseepeldorj, B.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Valkárová, A.; Vallée, C.; van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, Ch.; Wolf, R.; Wünsch, E.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y. C.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

2008-01-01

A measurement of elastic deeply virtual Compton scattering γp→γp using ep collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 145 pb. The cross section is measured as a function of the virtuality Q of the exchanged photon and the centre-of-mass energy W of the γp system in the kinematic domain 6.5

Fundamental studies of superconductors using scanning magnetic imaging

Energy Technology Data Exchange (ETDEWEB)

Kirtley, J R [Center for Probing the Nanoscale, Stanford University, Stanford, CA (United States)

2010-12-01

in rings of highly underdoped cuprates places limits on spin-charge separation in these materials. Studies of spontaneous generation of fluxoids upon cooling rings through the superconducting transition provide clues to dynamical processes relevant to the early development of the universe, while studies of vortex motion in cuprate grain boundaries allow the measurement of current-voltage characteristics at the femtovolt scale for these technologically important defects. Scanning SQUID susceptometry allows the measurement of superconducting fluctuations on samples comparable in size to the coherence length, revealing stripes in susceptibility believed to be associated with enhanced superfluid density on the twin boundaries in the pnictide superconductor Co doped Ba-122, and indicating the presence of spin-like excitations, which may be a source of noise in superconducting devices, in a wide variety of materials. Scanning magnetic microscopies allow the absolute value of penetration depths to be measured locally over a wide temperature range, providing clues to the symmetry of the order parameter in unconventional superconductors. Finally, MFM tips can be used to manipulate vortices, providing information on flux trapping in superconductors.

Fundamental studies of superconductors using scanning magnetic imaging

Science.gov (United States)

Kirtley, J. R.

2010-12-01

In this review I discuss the application of scanning magnetic imaging to fundamental studies of superconductors, concentrating on three scanning magnetic microscopies—scanning SQUID microscopy (SSM), scanning Hall bar microscopy (SHM) and magnetic force microscopy (MFM). I briefly discuss the history, sensitivity, spatial resolution, invasiveness and potential future developments of each technique. I then discuss a selection of applications of these microscopies. I start with static imaging of magnetic flux: an SSM study provides deeper understanding of vortex trapping in narrow strips, which are used to reduce noise in superconducting circuitry. Studies of vortex trapping in wire lattices, clusters and arrays of rings and nanoholes show fascinating ordering effects. The cuprate high-Tc superconductors are shown to have predominantly d-wave pairing symmetry by magnetic imaging of the half-integer flux quantum effect. Arrays of superconducting rings act as a physical analog for the Ising spin model, with the half-integer flux quantum effect helping to eliminate one source of disorder in antiferromagnetic arrangements of the ring moments. Tests of the interlayer tunneling model show that the condensation energy available from this mechanism cannot account for the high critical temperatures observed in the cuprates. The strong divergence in the magnetic fields of Pearl vortices allows them to be imaged using SSM, even for penetration depths of a millimeter. Unusual vortex arrangements occur in samples comparable in size to the coherence length. Spontaneous magnetization is not observed in Sr2RuO4, which is believed to have px ± ipy pairing symmetry, although effects hundreds of times bigger than the sensitivity limits had been predicted. However, unusual flux trapping is observed in this superconductor. Finally, unusual flux arrangements are also observed in magnetic superconductors. I then turn to vortex dynamics: imaging of vortices in rings of highly underdoped

Chiral plaquette polaron theory of cuprate superconductivity

Science.gov (United States)

Tahir-Kheli, Jamil; Goddard, William A., III

2007-07-01

Ab initio density functional calculations on explicitly doped La2-xSrxCuO4 find that doping creates localized holes in out-of-plane orbitals. A model for cuprate superconductivity is developed based on the assumption that doping leads to the formation of holes on a four-site Cu plaquette composed of the out-of-plane A1 orbitals apical Opz , planar Cud3z2-r2 , and planar Opσ . This is in contrast to the assumption of hole doping into planar Cudx2-y2 and Opσ orbitals as in the t-J model. Allowing these holes to interact with the d9 spin background leads to chiral polarons with either a clockwise or anticlockwise charge current. When the polaron plaquettes percolate through the crystal at x≈0.05 for La2-xSrxCuO4 , a Cudx2-y2 and planar Opσ band is formed. The computed percolation doping of x≈0.05 equals the observed transition to the “metallic” and superconducting phase for La2-xSrxCuO4 . Spin exchange Coulomb repulsion with chiral polarons leads to d -wave superconducting pairing. The equivalent of the Debye energy in phonon superconductivity is the maximum energy separation between a chiral polaron and its time-reversed partner. This energy separation is on the order of the antiferromagnetic spin coupling energy, Jdd˜0.1eV , suggesting a higher critical temperature. An additive skew-scattering contribution to the Hall effect is induced by chiral polarons and leads to a temperature dependent Hall effect that fits the measured values for La2-xSrxCuO4 . The integrated imaginary susceptibility, observed by neutron spin scattering, satisfies ω/T scaling due to chirality and spin-flip scattering of polarons along with a uniform distribution of polaron energy splittings. The derived functional form is compatible with experiments. The static spin structure factor for chiral spin coupling of the polarons to the undoped antiferromagnetic Cud9 spins is computed for classical spins on large two-dimensional lattices and is found to be incommensurate with a

Deeply virtual Compton scattering off unpolarised deuterium at HERMES

Energy Technology Data Exchange (ETDEWEB)

Hill, Gordon D.

2008-10-15

The HERMES experiment was a forward angle spectrometer on the HERA storage ring at DESY, Hamburg, Germany. HERMES successfully increased understanding of the ''spin puzzle'', the spin structure of the nucleon, by providing high precision measurements of {delta}{sigma} in the Quark Parton Model, the fraction of the spin carried by the current quarks. Following the link of another piece of the puzzle, the orbital angular momentum of quarks and gluons, to the Generalised Parton Distribution (GPD) theoretical framework, HERMES focused on measurements of the Deeply Virtual Compton Scattering (DVCS) process. These measurements are sensitive to GPDs, allowing further experimental constraints to be made on the components of nucleon spin. In the Winter shutdown period 2005-2006 HERMES was upgraded with a Recoil Detector in the target region. This allowed the experiment to make exclusive measurements of the DVCS process for the rst time, reducing background and increasing the resolution of various kinematic variables. The method for reconstructing particle tracks in the inhomogeneous magnetic eld is investigated here. DVCS o a deuterium target is measured with all available data prior to the installation of the Recoil Detector. A comparison is made to currently available models of spin-(1)/(2) GPDs. This analysis has been approved for publication by the HERMES collaboration. The data is further employed in an investigation of a model dependent constraint of the total angular momentum of up and down quarks in the nucleon. (orig.)

Deeply virtual Compton scattering off unpolarised deuterium at HERMES

International Nuclear Information System (INIS)

Hill, Gordon D.

2008-08-01

The HERMES experiment was a forward angle spectrometer on the HERA storage ring at DESY, Hamburg, Germany. HERMES successfully increased understanding of the ''spin puzzle'', the spin structure of the nucleon, by providing high precision measurements of ΔΣ in the Quark Parton Model, the fraction of the spin carried by the current quarks. Following the link of another piece of the puzzle, the orbital angular momentum of quarks and gluons, to the Generalised Parton Distribution (GPD) theoretical framework, HERMES focused on measurements of the Deeply Virtual Compton Scattering (DVCS) process. These measurements are sensitive to GPDs, allowing further experimental constraints to be made on the components of nucleon spin. In the Winter shutdown period 2005-2006 HERMES was upgraded with a Recoil Detector in the target region. This allowed the experiment to make exclusive measurements of the DVCS process for the rst time, reducing background and increasing the resolution of various kinematic variables. The method for reconstructing particle tracks in the inhomogeneous magnetic eld is investigated here. DVCS o a deuterium target is measured with all available data prior to the installation of the Recoil Detector. A comparison is made to currently available models of spin-(1)/(2) GPDs. This analysis has been approved for publication by the HERMES collaboration. The data is further employed in an investigation of a model dependent constraint of the total angular momentum of up and down quarks in the nucleon. (orig.)

Deeply virtual Compton scattering off unpolarised deuterium at HERMES

Energy Technology Data Exchange (ETDEWEB)

Hill, Gordon D

2008-10-15

The HERMES experiment was a forward angle spectrometer on the HERA storage ring at DESY, Hamburg, Germany. HERMES successfully increased understanding of the ''spin puzzle'', the spin structure of the nucleon, by providing high precision measurements of {delta}{sigma} in the Quark Parton Model, the fraction of the spin carried by the current quarks. Following the link of another piece of the puzzle, the orbital angular momentum of quarks and gluons, to the Generalised Parton Distribution (GPD) theoretical framework, HERMES focused on measurements of the Deeply Virtual Compton Scattering (DVCS) process. These measurements are sensitive to GPDs, allowing further experimental constraints to be made on the components of nucleon spin. In the Winter shutdown period 2005-2006 HERMES was upgraded with a Recoil Detector in the target region. This allowed the experiment to make exclusive measurements of the DVCS process for the rst time, reducing background and increasing the resolution of various kinematic variables. The method for reconstructing particle tracks in the inhomogeneous magnetic eld is investigated here. DVCS o a deuterium target is measured with all available data prior to the installation of the Recoil Detector. A comparison is made to currently available models of spin-(1)/(2) GPDs. This analysis has been approved for publication by the HERMES collaboration. The data is further employed in an investigation of a model dependent constraint of the total angular momentum of up and down quarks in the nucleon. (orig.)

Imaging of Au nanoparticles deeply buried in polymer matrix by various atomic force microscopy techniques

International Nuclear Information System (INIS)

Kimura, Kuniko; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

2013-01-01

Recently, some papers reported successful imaging of subsurface features using atomic force microscopy (AFM). Some theoretical studies have also been presented, however the imaging mechanisms are not fully understood yet. In the preceeding papers, imaging of deeply buried nanometer-scale features has been successful only if they were buried in a soft matrix. In this paper, subsurface features (Au nanoparticles) buried in a soft polymer matrix were visualized. To elucidate the imaging mechanisms, various AFM techniques; heterodyne force microscopy, ultrasonic atomic force microscopy (UAFM), 2nd-harmonic UAFM and force modulation microscopy (FMM) were employed. The particles buried under 960 nm from the surface were successfully visualized which has never been achieved. The results elucidated that it is important for subsurface imaging to choose a cantilever with a suitable stiffness range for a matrix. In case of using the most suitable cantilever, the nanoparticles were visualized using every technique shown above except for FMM. The experimental results suggest that the subsurface features buried in a soft matrix with a depth of at least 1 µm can affect the local viscoelasticity (mainly viscosity) detected as the variation of the amplitude and phase of the tip oscillation on the surface. This phenomenon presumably makes it possible to visualize such deeply buried nanometer-scale features in a soft matrix. - Highlights: • We visualized subsurface features buried in soft matrix, and investigated its imaging mechanism. • AFM techniques; UAFM, FMM, HFM and 2nd-harmonic UAFM were applied to elucidate the mechanism. • Au nanoparticles buried under 960 nm from surface were visualized, which has never been achieved. • Imaging at contact resonance using a cantilever of suitable stiffness is important. • Subsurface features in a soft matrix affect surface viscoelasticity, which are detected by AFM

The migration law of overlay rock and coal in deeply inclined coal seam with fully mechanized top coal caving.

Science.gov (United States)

Liu, Jian; Chen, Shan-Le; Wang, Hua-Jun; Li, Yu-Cheng; Geng, Xiaowei

2015-07-01

In a mine area, some environment geotechnics problems always occure, induced by mined-out region such as the subsidence and cracks at ground level, deformation and destruction of buildings, landslides destruction of water resources and the ecological environment. In order to research the migration of surrounding rock and coal in steeply inclined super high seams which used fully mechanized top coal caving, a working face of a certain mine was made as an example, analyzed the migration law of the overlay rock and coal under different caving ratio of fully mechanized top coal caving with numerical simulation analysis. The results suggest that the laws of overlay rock deformation caused by deeply inclined coal seam were different from horizontal coal seam. On the inclined direction, with an increase of dip angle and caving ratio, the vertical displacement of overlay rock and coal became greater, the asymmetric phenomenon of vertical displacement became obvious. On the trend direction, active region and transition region in goaf became smaller along with the increase of mining and caving ratio. On the contrary, the stable region area became greater. Therefore, there was an essential difference between the mechanism of surface movement deformation with deeply inclined coal seam and that with horizontal coal seam.

A phenomenological model for the structure-composition relationship of the high Tc cuprates based on simple chemical principles

International Nuclear Information System (INIS)

Alarco, J.A.; Talbot, P.C.

2012-01-01

A simple phenomenological model for the relationship between structure and composition of the high Tc cuprates is presented. The model is based on two simple crystal chemistry principles: unit cell doping and charge balance within unit cells. These principles are inspired by key experimental observations of how the materials accommodate large deviations from stoichiometry. Consistent explanations for significant HTSC properties can be explained without any additional assumptions while retaining valuable insight for geometric interpretation. Combining these two chemical principles with a review of Crystal Field Theory (CFT) or Ligand Field Theory (LFT), it becomes clear that the two oxidation states in the conduction planes (typically d 8 and d 9 ) belong to the most strongly divergent d-levels as a function of deformation from regular octahedral coordination. This observation offers a link to a range of coupling effects relating vibrations and spin waves through application of Hund’s rules. An indication of this model’s capacity to predict physical properties for HTSC is provided and will be elaborated in subsequent publications. Simple criteria for the relationship between structure and composition in HTSC systems may guide chemical syntheses within new material systems.

Effects of out-of-plane disorder on the superconductivity of Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}}

Energy Technology Data Exchange (ETDEWEB)

Roehler, Juergen; Trabant, Christoph; Frielingsdorf, Johanna; Djemour, Rabia [Universitaet Koeln, 50937 Koeln (Germany); Martovitsky, Victor [Lebedev-Institute, 119991 Moscow (Russian Federation); Dudy, Lenart; Dwelk, Helmut; Krapf, Alica [Humboldt Universitaet Berlin, 12489 Berlin (Germany)

2008-07-01

The effects of out-of-plane substitutional order/disorder on cuprate superconductivity remains to a large extent an unresolved issue. We have investigated the connection between superconductivity and the lattice effects arising from the heterovalent doping of Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}}, x = 0.8-0.1. Decreasing lanthanum content tunes the compound through the entire underdoped and overdoped regimes. Cu-K and La- K EXAFS served as local structural probes, and single crystal X-ray diffraction for the determination of the basic unit cell, and the symmetry of the supercell. The oxygen atoms in the CuO{sub 2} planes were found significantly disordered, dependent on doping, and to exhibit minimum disorder around x{sub opt}=0.33. But the degree of substitutional disorder in the out-of-plane La environment turned out independent on the concentration of the La dopants, the superstructure symmetry, and the crystal growth parameters, whereas T{sub c} depends sensitively on them. No evidence was found for possible concentration dependent site changes of the La dopant from the nominal Sr to the Bi sites. We discuss the probably crucial role of the interstitial oxygen atoms for the superconducting properties of the Bi{sub 2}Sr{sub 2-x}La{sub x}CuO{sub 6+{delta}} system.

Distinct charge orders in the planes and chains of ortho-III-ordered YBa2Cu3O(6+δ) superconductors identified by resonant elastic x-ray scattering.

Science.gov (United States)

Achkar, A J; Sutarto, R; Mao, X; He, F; Frano, A; Blanco-Canosa, S; Le Tacon, M; Ghiringhelli, G; Braicovich, L; Minola, M; Sala, M Moretti; Mazzoli, C; Liang, Ruixing; Bonn, D A; Hardy, W N; Keimer, B; Sawatzky, G A; Hawthorn, D G

2012-10-19

Recently, charge density wave (CDW) order in the CuO(2) planes of underdoped YBa(2)Cu(3)O(6+δ) was detected using resonant soft x-ray scattering. An important question remains: is the chain layer responsible for this charge ordering? Here, we explore the energy and polarization dependence of the resonant scattering intensity in a detwinned sample of YBa(2)Cu(3)O(6.75) with ortho-III oxygen ordering in the chain layer. We show that the ortho-III CDW order in the chains is distinct from the CDW order in the planes. The ortho-III structure gives rise to a commensurate superlattice reflection at Q=[0.33 0 L] whose energy and polarization dependence agrees with expectations for oxygen ordering and a spatial modulation of the Cu valence in the chains. Incommensurate peaks at [0.30 0 L] and [0 0.30 L] from the CDW order in the planes are shown to be distinct in Q as well as their temperature, energy, and polarization dependence, and are thus unrelated to the structure of the chain layer. Moreover, the energy dependence of the CDW order in the planes is shown to result from a spatial modulation of energies of the Cu 2p to 3d(x(2)-y(2)) transition, similar to stripe-ordered 214 cuprates.

Measurement of deeply virtual Compton scattering and its t-dependence at HERA

Energy Technology Data Exchange (ETDEWEB)

Aaron, F.D. [National Insitute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania)]|[Bucharest Univ. (Romania). Faculty of Physics; Aktas, A. [DESY Hamburg (Germany); Alexa, C. [National Insitute for Physics and Nuclear Engineering (NIPNE), Bucharest (RO)] (and others)

2007-09-15

A measurement of elastic deeply virtual Compton scattering {gamma}{sup *}p {yields} {gamma}p using e{sup -}p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 145 pb{sup -1}. The cross section is measured as a function of the virtuality Q{sup 2} of the exchanged photon and the centre-of-mass energy W of the {gamma}{sup *}p system in the kinematic domain 6.5

Deeply inelastic transfer reactions induced by heavy ions in rare earth targets. II. Interpretation of experimental data

International Nuclear Information System (INIS)

Rivet, M.F.; Bimbot, R.; Ngo, C.

1979-01-01

The experimental angular distributions and cross sections for a series of deeply inelastic transfer reactions induced by various projectiles in rare earth targets have been interpreted using a model which includes a dynamical coupling between relative motion and mass asymmetry and treats statistical fluctuations. As the transfer reactions considered correspond to an increase of the potential energy of the composite system their observation is mainly due to fluctuations. The calculation reproduces correctly the angular distributions, but the cross sections are underestimated. Several effects are discussed which may increase these cross sections and are neglected in the calculation

A measurement of the Q2, W and t dependences of deeply virtual Compton scattering at HERA

International Nuclear Information System (INIS)

2009-01-01

Deeply virtual Compton scattering, γ*p → γp, has been measured in e + p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb -1 . Cross sections are presented as a function of the photon virtuality, Q 2 , and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q 2 > 1.5 GeV 2 and 40 -1 , is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex.

A measurement of the Q2, W and t dependences of deeply virtual Compton scattering at HERA

International Nuclear Information System (INIS)

Chekanov, S.; Derrick, M.; Magill, S.

2008-12-01

Deeply virtual Compton scattering, γ * p→γp, has been measured in e + p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb -1 . Cross sections are presented as a function of the photon virtuality, Q 2 , and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q 2 >1.5 GeV 2 and 40 -1 , is used for the first direct measurement of the differential cross section as a function of t, where t is the square of the four-momentum transfer at the proton vertex. (orig.)

Deeply virtual Compton scattering off "4He

International Nuclear Information System (INIS)

Hattawy, M.

2015-01-01

The "4He nucleus is of particular interest to study nuclear GPDs (Generalized Parton Distributions) as its partonic structure is described by only one chirally-even GPD. It is also a simple few-body system and has a high density that makes it the ideal target to investigate nuclear effects on partons. The experiment described in this thesis is JLab-E08-24, which was carried out in 2009 by the CLAS collaboration during the 'EG6' run. In this experiment, a 6 GeV longitudinally-polarized electron beam was scattered onto a 6 atm "4He gaseous target. During this experiment, in addition to the CLAS detector, a Radial Time Projection Chamber (RTPC), to detect low-energy nuclear recoils, and an Inner Calorimeter (IC), to improve the detection of photons at very forward angles, were used. We carried out a full analysis on our 6 GeV dataset, showing the feasibility of measuring exclusive nuclear Deeply Virtual Compton Scattering (DVCS) reactions. The analysis included: the identification of the final-state particles, the DVCS event selection, the π"0 background subtraction. The beam-spin asymmetry was then extracted for both DVCS channels and compared to the ones of the free-proton DVCS reaction, and to theoretical predictions from two models. Finally, the real and the imaginary parts of the "4He CFF (Compton Form Factor) HA have been extracted. Different levels of agreement were found between our measurements and the theoretical calculations. This thesis is organized as follows: In chapter 1, the available theoretical tools to study hadronic structure are presented, with an emphasis on the nuclear effects and GPDs. In chapter 2, the characteristics of the CLAS spectrometer are reviewed. In chapter 3, the working principle and the calibration aspects of the RTPC are discussed. In chapter 4, the identification of the final-state particles and the Monte-Carlo simulation are presented. In chapter 5, the selection of the DVCS events, the background subtraction, and uncertainty

Relaxation phenomena in and microscopic transport theories of deeply inelastic collisions between heavy ions

International Nuclear Information System (INIS)

Noerenberg, W.

1976-01-01

Relaxation phenomena in deeply inelastic collisions are qualitatively discussed and compared with precompound reactions. Different approaches for describing these processes are reviewed, in particular the microscopic transport theories, which can be understood from a generalized master equation for macroscopic variables. The Markoff approximation and the classical limit for the relative motion lead to two coupled equations, the classical equation of relative motion with friction and a Pauli master equation for the internal degrees of freedom. The master equation approximated by the corresponding Fokker-Planck equation for mass transfer and energy dissipation is discussed in detail. Simple analytic expressions are derived for the transport coefficients as functions of excitation energy, total mass, mass fragmentation and relative angular momentum. Calculated transport coefficients are compared with experimental values. Problems and future developments in microscopic transport theories are outlined. (orig.) [de

Deeply virtual Compton scattering off longitudinally polarised protons at HERMES

International Nuclear Information System (INIS)

Mahon, David Francis

2010-03-01

This thesis details the simultaneous extraction of three polarisation-dependent asymmetries in the distribution of real photons from the ep→epγ interaction and its indistinguishable deeply virtual Compton scattering and Bethe-Heitler processes at the HERMES fixed-target experiment at Desy. The data analysed were taken using a longitudinally polarised 27.57 GeV positron beam incident on a longitudinally polarised hydrogen gas target. The extracted asymmetries include two single-spin asymmetries A UL and A LU which depend on the polarisation of the target and beam respectively, averaged over all other polarisation states. The double-spin asymmetry A LL dependent on the product of the beam and target polarisations is extracted for the first time. The asymmetry amplitudes extracted relate to combinations of Generalised Parton Distributions (GPDs), predominantly H and H. The extracted amplitudes are presented across the HERMES kinematic range alongside theoretical predictions from a GPD model based on double distributions. Large sin φ and cos(0φ) amplitudes are observed for A UL and A LL respectively, with an unexpectedly large sin(2φ) amplitude for A UL . The results for the A UL and A LL asymmetries are broadly compatible with theory predictions, and the extracted A LU amplitudes are compatible with HERMES results extracted from a significantly larger data set. It is foreseen that these results will form input to future global data-based GPD models which aim to provide a better understanding of GPDs. (orig.)

Deeply-etched micromirror with vertical slit and metallic coating enabling transmission-type optical MEMS filters

Science.gov (United States)

Othman, Muhammad A.; Sabry, Yasser M.; Sadek, Mohamed; Nassar, Ismail M.; Khalil, Diaa A.

2016-03-01

In this work we report a novel optical MEMS deeply-etched mirror with metallic coating and vertical slot, where the later allows reflection and transmission by the micromirror. The micromirror as well as fiber grooves are fabricated using deep reactive ion etching technology, where the optical axis is in-plane and the components are self-aligned. The etching depth is 150 μm chosen to improve the micromirror optical throughput. The vertical optical structure is Al metal coated using the shadow mask technique. A fiber-coupled Fabry-Pérot filter is successfully realized using the fabricated structure. Experimental measurements were obtained based on a dielectric-coated optical fiber inserted into a fiber groove facing the slotted micromirror. A versatile performance in terms of the free spectral range and 3-dB bandwidth is achieved.

Experimental and analytical studies of a deeply embedded reactor building model considering soil-building interaction. Pt. 1

International Nuclear Information System (INIS)

Tanaka, H.; Ohta, T.; Uchiyama, S.

1979-01-01

The purpose of this paper is to describe the dynamic characteristics of a deeply embedded reactor building model derived from experimental and analytical studies which considers soil-building interaction behaviour. The model building is made of reinforced concrete. It has two stories above ground level and a basement, resting on sandy gravel layer at a depth of 3 meters. The backfill around the building was made to ground level. The model building is simplified and reduced to about one-fifteenth (1/15) of the prototype. It has bearing wall system for the basement and the first story, and frame system for the second. (orig.)

Transverse Extension of Partons in the Proton probed by Deeply Virtual Compton Scattering

CERN Document Server

Akhunzyanov, R.; The COMPASS collaboration; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anfimov, N.V.; Anosov, V.; Antoshkin, A.; Augsten, K.; Augustyniak, W.; Austregesilo, A.; Azevedo, C.D.R.; Badełek, B.; Balestra, F.; Ball, M.; Barth, J.; Beck, R.; Bedfer, Y.; Bernhard, J.; Bicker, K.; Bielert, E.R.; Birsa, R.; Bodlak, M.; Bordalo, P.; Bradamante, F.; Bressan, A.; Büchele, M.; Burtin, E.; Burtsev, V.E.; Chang, W.-C.; Chatterjee, C.; Chiosso, M.; Choi, I.; Chumakov, A.G.; Chung, S.-U.; Cicuttin, A.; Crespo, M.L.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Dhara, L.; Donskov, S.V.; Doshita, N.; Dreisbach, Ch.; Dünnweber, W.; Dusaev, R.R.; Dziewiecki, M.; Efremov, A.; Eversheim, P.D.; Faessler, M.; Ferrero, A.; Finger, M.; jr., M.Finger; Fischer, H.; Franco, C.; du Fresne von Hohenesche, N.; Friedrich, J.M.; Frolov, V.; Fuchey, E.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Giarra, J.; Gnesi, I.; Gorzellik, M.; Grasso, A.; Gridin, A.; Grosse Perdekamp, M.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Hahne, D.; Hamar, G.; von Harrach, D.; Heitz, R.; Herrmann, F.; Horikawa, N.; d'Hose, N.; Hsieh, C.-Y.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jary, V.; Joosten, R.; Jörg, P.; Juraskova, K.; Kabuß, E.; Kerbizi, A.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu.A.; Kisselev, Yu.; Klein, F.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.M.; Kral, Z.; Krämer, M.; Krinner, F.; Kroumchtein, Z.V.; Kulinich, Y.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Kuznetsov, I.I.; Kveton, A.; Lednev, A.A.; Levchenko, E.A.; Levillain, M.; Levorato, S.; Lian, Y.-S.; Lichtenstadt, J.; Longo, R.; Lyubovitskij, V.E.; Maggiora, A.; Magnon, A.; Makins, N.; Makke, N.; Mallot, G.K.; Mamon, S.A.; Marianski, B.; Martin, A.; Marzec, J.; Matoušek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.V.; Meyer, M.; Meyer, W.; Mikhailov, Yu.V.; Mikhasenko, M.; Mitrofanov, E.; Mitrofanov, N.; Miyachi, Y.; Moretti, A.; Nagaytsev, A.; Nerling, F.; Neyret, D.; Nový, J.; Nowak, W.-D.; Nukazuka, G.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peng, J.-C.; Pereira, F.; Pešek, M.; Pešková, M.; Peshekhonov, D.V.; Pierre, N.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Riedl, C.; Rogacheva, N.S.; Ryabchikov, D.I.; Rybnikov, A.; Rychter, A.; Salac, R.; Samoylenko, V.D.; Sandacz, A.; Santos, C.; Sarkar, S.; Savin, I.A.; Sawada, T.; Sbrizzai, G.; Schiavon, P.; Schmieden, H.; Schönning, K.; Seder, E.; Selyunin, A.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Smolik, J.; Srnka, A.; Steffen, D.; Stolarski, M.; Subrt, O.; Sulc, M.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Tasevsky, M.; Tessaro, S.; Tessarotto, F.; Thiel, A.; Tomsa, J.; Tosello, F.; Tskhay, V.; Uhl, S.; Vasilishin, B.I.; Vauth, A.; Veit, B.M.; Veloso, J.; Vidon, A.; Virius, M.; Wallner, S.; Wilfert, M.; ter Wolbeek, J.; Zaremba, K.; Zavada, P.; Zavertyaev, M.; Zemlyanichkina, E.; Zhuravlev, N.; Ziembicki, M.

2018-01-01

We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160 GeV/$c$ polarized $\\mu^+$ and $\\mu^-$ beams of the CERN SPS impinging on a liquid hydrogen target. We determine the dependence of the average of the measured $\\mu^+$ and $\\mu^-$ cross sections for deeply virtual Compton scattering on the squared four-momentum transfer $t$ from the initial to the final final proton. The slope $B$ of the $t$-dependence is fitted with a single exponential function, which yields $B=(4.3 \\ \\pm \\ 0.6_{\\text{stat}}\\ _{- \\ 0.3}^{+ \\ 0.1}\\big\\rvert_{\\text{sys}})\\,(\\text{GeV}/c)^{-2}$. This result can be converted into an average transverse extension of partons in the proton, $\\sqrt{\\langle r_{\\perp}^2 \\rangle} = (0.58 \\ \\pm \\ 0.04_{\\text{stat}}\\ _{- \\ 0.02}^{+ \\ 0.01}\\big\\rvert_{\\text{sys}}) \\text{fm}$. For this measurement, the average virtuality of the photon mediating the interaction is $\\langle Q^2 \\rangle = 1.8\\,(\\text{GeV/}c)^2$ and the average value of the Bjorken va...

Detailed analysis of the resonant backscattering spectrum for deeply penetrating protons in carbon

International Nuclear Information System (INIS)

Tosaki, Mitsuo; Ito, Shin; Maeda, Nobuhiro

2000-01-01

In order to study the spectral response in Rutherford backscattering spectroscopy (RBS) for deeply penetrating ions in matter, the resonant backscattering spectra for 5.05-, 5.5- and 6.0-MeV proton incidence on solid carbon material have been measured at a scattering angle of 179.2 deg. (in lab.). Prominent peaks resulting from the sharp 4.8-MeV resonance in 12 C(p,p) 12 C nuclear elastic scattering are observed, even for a penetration depth of 79 μm. Detailed numerical calculations based on an algorithm of straightforward step-by-step evaluation have been made to simulate the observed spectra. The algorithm enables one to rigorously treat both the effect of sharp resonance structure and that of energy-dependent energy loss. Calculations with the SIMNRA code are also made. Through comparison of these calculations with the measured results, some conclusions on the two effects above are presented. In addition, it is demonstrated that the peak profile due to a sharp resonance is very sensitive to the degree of energy straggling

Investigation of a CDDW Hamiltonian to Explore Possibility of Magneto-Quantum Oscillations in Electronic Specific Heat of Hole-Doped Cuprates

Directory of Open Access Journals (Sweden)

Partha Goswami

2010-01-01

Full Text Available We investigate a chiral d-density wave (CDDW mean field model Hamiltonian in the momentum space suitable for the hole-doped cuprates, such as YBCO, in the pseudogap phase to obtain the Fermi surface (FS topologies, including the anisotropy parameter(́ and the elastic scattering by disorder potential (|0|. For ́=0, with the chemical potential =−0.27 eV for 10% doping level and |0|≥|| (where ||=0.25 eV is the first neighbor hopping, at zero/non-zero magnetic field (, the FS on the first Brillouin zone is found to correspond to electron pockets around antinodal regions and barely visible patches around nodal regions. For ́≠0, we find Pomeranchuk distortion of FS. We next relate our findings regarding FS to the magneto-quantum oscillations in the electronic specific heat. Since the nodal quasiparticle energy values for =0 are found to be greater than for |0|≥||, the origin of the oscillations for nonzero corresponds to the Fermi pockets around antinodal regions. The oscillations are shown to take place in the weak disorder regime (|0|=0.25eV only.

A fermi liquid electric structure and the nature of the carriers in high-T/sub c/ cuprates: A photoemission study

Energy Technology Data Exchange (ETDEWEB)

Arko, A.J.; List, R.S.; Bartlett, R.J.; Cheong, S.W.; Fisk, Z.; Thompson, J.D.; Olson, C.G.; Yang, A.B.; Liu, R.; Gu, C.; Veal, B.W.; Liu, J.Z.; Paulikas, A.P.; Vandervoort, K.; Claus, H.; Campuzano, J.C.; Schirber, J.E.; Shinn, N.D.

1989-01-01

We have performed angle-integrated and angle-resolved photoemission measurements at 20 K on well-characterized single crystals of high-T/sub c/ cuprates (both 1:2:3-type and 2:2:1:2-type) cleaved in situ, and find a relatively large, resolution limited Fermi edge which shows large amplitude variations with photon energy, indicative of band structure final state effects. The lineshapes of the spectra of the 1:2:3 materials as a function of photon energy are well reproduced by band structure predictions, indicating a correct mix of 2p and 3d orbitals on the calculations, while the energy positions of the peaks agree with calculated bands only to within /approx/0.5 eV. This may yet prove to reflect the effects of Coulomb correlation. We nevertheless conclude that a Fermi liquid approach to conductivity is appropriate. Angle-resolved data, while still incomplete, suggest agreement with the Fermi surface predicted by the LDA calculations. A BCS-like energy gap is observed in the 2:2:1:2 materials, whose magnitude is twice the weak coupling BCS value (i.e., 2/Delta/ = 7 KT/sub c/). 49 refs., 11 figs.

Land-use Scene Classification in High-Resolution Remote Sensing Images by Multiscale Deeply Described Correlatons

Science.gov (United States)

Qi, K.; Qingfeng, G.

2017-12-01

With the popular use of High-Resolution Satellite (HRS) images, more and more research efforts have been placed on land-use scene classification. However, it makes the task difficult with HRS images for the complex background and multiple land-cover classes or objects. This article presents a multiscale deeply described correlaton model for land-use scene classification. Specifically, the convolutional neural network is introduced to learn and characterize the local features at different scales. Then, learnt multiscale deep features are explored to generate visual words. The spatial arrangement of visual words is achieved through the introduction of adaptive vector quantized correlograms at different scales. Experiments on two publicly available land-use scene datasets demonstrate that the proposed model is compact and yet discriminative for efficient representation of land-use scene images, and achieves competitive classification results with the state-of-art methods.

Deeply virtual Compton scattering off longitudinally polarised protons at HERMES

Energy Technology Data Exchange (ETDEWEB)

Mahon, David Francis

2010-06-15

This thesis details the simultaneous extraction of three polarisation-dependent asymmetries in the distribution of real photons from the ep{yields}ep{gamma} interaction and its indistinguishable deeply virtual Compton scattering and Bethe-Heitler processes at the HERMES fixed-target experiment at Desy. The data analysed were taken using a longitudinally polarised 27.57 GeV positron beam incident on a longitudinally polarised hydrogen gas target. The extracted asymmetries include two single-spin asymmetries A{sub UL} and A{sub LU} which depend on the polarisation of the target and beam respectively, averaged over all other polarisation states. The double-spin asymmetry A{sub LL} dependent on the product of the beam and target polarisations is extracted for the first time. The asymmetry amplitudes extracted relate to combinations of Generalised Parton Distributions (GPDs), predominantly H and H. The extracted amplitudes are presented across the HERMES kinematic range alongside theoretical predictions from a GPD model based on double distributions. Large sin {phi} and cos(0{phi}) amplitudes are observed for A{sub UL} and A{sub LL} respectively, with an unexpectedly large sin(2{phi}) amplitude for A{sub UL}. The results for the A{sub UL} and A{sub LL} asymmetries are broadly compatible with theory predictions, and the extracted A{sub LU} amplitudes are compatible with HERMES results extracted from a significantly larger data set. It is foreseen that these results will form input to future global data-based GPD models which aim to provide a better understanding of GPDs. (orig.)

Deeply Virtual Compton scattering at CERN. What is the size of the proton?

Energy Technology Data Exchange (ETDEWEB)

Joerg, Philipp

2017-04-27

Tremendous efforts have been made to understand the Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism, which led to the successful discovery of the Higgs Boson and the clarification of the origin of the mass of fundamental particles. However, it is often forgotten that the vast majority of visible matter is given by baryons, which gain most of their mass dynamically within poorly known non-perturbative quantum chromodynamics processes. The best laboratory to study the underlying mechanisms of non-perturbative quantum chromodynamics is still given by the nucleon and the central question of how the macroscopic properties of a nucleon like its mass, spin and size can be comprehensively decomposed into the microscopic description in terms of quarks, antiquarks and gluons remains still open. A major part of the COMPASS-II program is dedicated to the investigation of Generalized Parton Distributions (GPDs), which aim for the most complete description of the partonic structure of the nucleon, comprising both, spacial and kinematic distributions. By including transverse degrees of freedom, a three dimensional picture of baryonic matter is created, which will revolutionise our understanding of what comprises 99 percent of the visible matter. GPDs are experimentally accessible via lepton-induced exclusive reactions, in particular the Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). At COMPASS, those processes are investigated using a high intensity muon beam of 160 GeV/c together with a 2.5 m-long liquid hydrogen target and an open field two stage spectrometer, to detect and identify charged and neutral particles. In order to optimize the selection of exclusive reactions at those energies, the target is surrounded by a new barrel-shaped time-of-flight system, which detects the recoiling target particles. A pilot run dedicated to the measurement of Generalized Parton distributions performed in 2012 allows for detailed performance studies

Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction

International Nuclear Information System (INIS)

Airapetian, A.; Akopov, Z.

2012-06-01

The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized HERA positron beam scattering off an unpolarized hydrogen target is measured at HERMES. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe-Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of ep→epγ events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of resonant background that was estimated to contribute an average of about 12% to the signal in previous HERMES publications. The removal of the resonant background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0.054±0.016 to -0.328±0.027(stat.)±0.045(syst.).

Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction

Energy Technology Data Exchange (ETDEWEB)

Airapetian, A. [Giessen Univ. (Germany). Physikalisches Inst.; Michigan Univ., Ann Arbor, MI (United States). Randall Lab. of Physics; Akopov, N. [Yerevan Physics Inst. (Armenia); Akopov, Z. [DESY, Hamburg (DE)] (and others)

2012-06-15

The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized HERA positron beam scattering off an unpolarized hydrogen target is measured at HERMES. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe-Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of ep{yields}ep{gamma} events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of resonant background that was estimated to contribute an average of about 12% to the signal in previous HERMES publications. The removal of the resonant background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0.054{+-}0.016 to -0.328{+-}0.027(stat.){+-}0.045(syst.).

Strong Energy-momentum Dispersion of Phonon Dressed Carriers in the Lightly Doped Band Insulator SrTiO3

International Nuclear Information System (INIS)

Meevasana, Warawat

2010-01-01

Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is the perovskite SrTiO 3 (STO), well known for its giant dielectric constant of 10000 at low temperature, exceeding that of La 2 CuO 4 by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped SrTiO 3 . Comparing to lightly doped Mott insulators, we find the signatures of only moderate electron-phonon coupling: a dispersion anomaly associated with the low frequency optical phonon with a λ(prime) ∼ 0.3 and an overall bandwidth renormalization suggesting an overall λ(prime) ∼ 0.7 coming from the higher frequency phonons. Further, we find no clear signatures of the large pseudogap or small polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.

IPHAS J062746.41+014811.3: A DEEPLY ECLIPSING INTERMEDIATE POLAR

International Nuclear Information System (INIS)

Aungwerojwit, A.; Gänsicke, B. T.; Wheatley, P. J.; Pyrzas, S.; Staels, B.; Krajci, T.; Rodríguez-Gil, P.

2012-01-01

We present time-resolved photometry of a cataclysmic variable discovered in the Isaac Newton Telescope Photometric Hα Survey of the northern galactic plane, IPHAS J062746.41+014811.3, and classify the system as the fourth deeply eclipsing intermediate polar known with an orbital period of P orb = 8.16 hr and a spin period of P spin = 2210 s. The system shows mild variations of its brightness that appear to be accompanied by a change in the amplitude of the spin modulation at optical wavelengths and a change in the morphology of the eclipse profile. The inferred magnetic moment of the white dwarf is μ wd ∼ (6-7) × 10 33 G cm 3 , and in this case IPHAS J062746.41+014811.3 will evolve either into a short-period EX Hya-like intermediate polar with a large P spin /P orb ratio or, perhaps more likely, into a synchronized polar. Swift observations show that the system is an ultraviolet and X-ray source, with a hard X-ray spectrum that is consistent with those seen in other intermediate polars. The ultraviolet light curve shows orbital modulation and an eclipse, while the low signal-to-noise ratio X-ray light curve does not show a significant modulation on the spin period. The measured X-ray flux is about an order of magnitude lower than would be expected from scaling by the optical fluxes of well-known X-ray-selected intermediate polars.

Two-particle excitations in the Hubbard model for high-temperature superconductors. A quantum cluster study

International Nuclear Information System (INIS)

Brehm, Sascha

2009-01-01

Two-particle excitations, such as spin and charge excitations, play a key role in high-T c cuprate superconductors (HTSC). Due to the antiferromagnetism of the parent compound the magnetic excitations are supposed to be directly related to the mechanism of superconductivity. In particular, the so-called resonance mode is a promising candidate for the pairing glue, a bosonic excitation mediating the electronic pairing. In addition, its interactions with itinerant electrons may be responsible for some of the observed properties of HTSC. Hence, getting to the bottom of the resonance mode is crucial for a deeper understanding of the cuprate materials. To analyze the corresponding two-particle correlation functions we develop in the present thesis a new, non-perturbative and parameter-free technique for T=0 which is based on the Variational Cluster Approach (VCA, an embedded cluster method for one-particle Green's functions). Guided by the spirit of the VCA we extract an effective electron-hole vertex from an isolated cluster and use a fully renormalized bubble susceptibility χ 0 including the VCA one-particle propagators. Within our new approach, the magnetic excitations of HTSC are shown to be reproduced for the Hubbard model within the relevant strong-coupling regime. Exceptionally, the famous resonance mode occurring in the underdoped regime within the superconductivity-induced gap of spin-flip electron-hole excitations is obtained. Its intensity and hourglass dispersion are in good overall agreement with experiments. Furthermore, characteristic features such as the position in energy of the resonance mode and the difference of the imaginary part of the susceptibility in the superconducting and the normal states are in accord with Inelastic Neutron Scattering (INS) experiments. For the first time, a strongly-correlated parameter-free calculation revealed these salient magnetic properties supporting the S=1 magnetic exciton scenario for the resonance mode. Besides

The HERMES recoil photon detector and the study of deeply virtual Compton scattering

Energy Technology Data Exchange (ETDEWEB)

Hulse, Charlotte van

2011-03-15

The study of deeply virtual Compton scattering (DVCS) gives information about the contribution of the quark orbital angular momentum to the spin of the proton. DVCS has been studied at the HERMES experiment at DESY in Hamburg. Here 27.6 GeV longitudinally polarized electrons and positrons were scattered off a gaseous proton target. For the analysis of DVCS the recoiling proton could not be detected, but was reconstructed via its missing mass. This method suffers, however, from a 14% background contribution, mainly originating from associated DVCS. In this process the proton does not stay in its ground state but is excited to a {delta}{sup +} resonance. In order to reduce the background contribution down to less than 1%, a recoil detector was installed in the HERMES experiment beginning of 2006. This detector consists of three subcomponents, of which one is the photon detector. The main function of the photon detector is the detection of {delta}{sup +} decay photons. The photon detector was started up and commissioned for the analysis of (associated) DVCS. Subsequently DVCS and associated DVCS were analyzed using the recoil detector. (orig.)

Investigation into magnetic correlations in cuprates by means of neutron scattering experiments

International Nuclear Information System (INIS)

Henggeler, W.

1996-01-01

This thesis shows the results of our investigation on cuprate materials containing rare earth ions. The main experimental tools were inelastic and elastic neutron scattering techniques. In some cases we also performed μSR, susceptibility and specific heat measurements. One aim was to learn more about the crystalline environment of the rare earth ions in these substances via the crystalline electric field (CEF) interaction. Furthermore, we investigated the correlations of the magnetic moments of these ions by a determination of the dispersion of the CEF excitations. The theory that is essential for the understanding of this work is outlined. The instruments on which the experiments have been performed are presented in the third chapter. In the fourth chapter we show the measurements of the CEF excitations of Ho 3+ in Y 0.99 Ho 0.01 Ba 2 Cu 3 O 6+x . The Ho ions represent ideal local probes to examine changes of the charge distribution in the copper oxide planes upon doping with oxygen. To prevent any influence of the Ho-Ho exchange interaction on the CEF excitations we performed the experiments on substances containing only one percent of Ho. Our results show that for all the intermediately doped compounds the charge distribution is very inhomogeneous. For all the highly doped samples we observe a line asymmetry for which several possible origins are discussed. In the fifth chapter we examine the Pr 3+ CEF excitations in the Pr 2-x Ce x CuO 4(-δ) (0≤x≤0.2)-substances. Our results show a coexistence of different environments of the Pr ions in all the doped compounds. We try to describe these inhomogeneities with the help of a model. We used the μSR-technique on some of these samples in order to learn more about the oxygen reduction process. Finally, we performed inelastic neutron scattering experiments on Pr 1.86 Ce 0.14 CuO 4 single crystal, which allowed a direct determination of the coupling constants between the magnetic moments of the Pr ions. (author

Extraction of Generalized Parton Distributions from combined Deeply Virtual Compton Scattering and Timelike Compton scattering fits

Science.gov (United States)

Boer, Marie

2017-09-01

Generalized Parton Distributions (GPDs) contain the correlation between the parton's longitudinal momentum and their transverse distribution. They are accessed through hard exclusive processes, such as Deeply Virtual Compton Scattering (DVCS). DVCS has already been measured in several experiments and several models allow for extracting GPDs from these measurements. Timelike Compton Scattering (TCS) is, at leading order, the time-reversal equivalent process to DVCS and accesses GPDs at the same kinematics. Comparing GPDs extracted from DVCS and TCS is a unique way for proving GPD universality. Combining fits from the two processes will also allow for better constraining the GPDs. We will present our method for extracting GPDs from DVCS and TCS pseudo-data. We will compare fit results from the two processes in similar conditions and present what can be expected in term of contraints on GPDs from combined fits.

High-resolution spectroscopy of deeply-bound pionic atoms in heavy nuclei by pion-transfer reactions of inverse kinematics using the GSI cooler ring ESR

International Nuclear Information System (INIS)

Yamazaki, Toshimitsu.

1991-02-01

Many studies published in the past are reviewed first in relation to high-resolution spectroscopy of deeply-bound pionic atoms in heavy nuclei. The report then describes a procedure for applying the method of inverse kinematics to the case of (d, 3 He) reactions. The (d, 3 He) reaction in inverse kinematics is feasible from practical viewpoints. Thus a discussion is made of the inverse kinematics in which a heavy-ion beam ( 208 Pb for instance) with a projectile kinetic energy hits a deuteron target and ejected recoil 3 He nuclei are measured in the forward direction. The recoil momentum is calculated as a function of the Q value. Analysis shows that the recoil spectroscopy with inverse kinematics can be applied to the case of (d, 3 He) reaction, which will yield a very high mass resolution. The experimental setup for use in the first stage is then outlined, and a simple detector configuration free of magnetic field is discussed. These investigations demonstrate that the (d, 3 He) reaction in inverse kinematics provides a promising tool for obtaining high-resolution spectra of deeply-bound pionic atoms. (N.K.)

Beam shaping assembly of a D-T neutron source for BNCT and its dosimetry simulation in deeply-seated tumor

Science.gov (United States)

Faghihi, F.; Khalili, S.

2013-08-01

This article involves two aims for BNCT. First case includes a beam shaping assembly estimation for a D-T neutron source to find epi-thermal neutrons which are the goal in the BNCT. Second issue is the percent depth dose calculation in the adult Snyder head phantom. Monte-Carlo simulations and verification of a suggested beam shaping assembly (including internal neutron multiplier, moderator, filter, external neutron multiplier, collimator, and reflector dimensions) for thermalizing a D-T neutron source as well as increasing neutron flux are carried out and our results are given herein. Finally, we have simulated its corresponding doses for treatment planning of a deeply-seated tumor.

Single and Double Spin Asymmetries for Deeply Virtual Exclusive π⁰ Production on Longitudinally Polarized Proton Target with CLAS

Energy Technology Data Exchange (ETDEWEB)

Kim, Andrew [Kyungpook National Univ., Daegu (Korea, Republic of)

2013-12-01

Deeply virtual exclusive processes probe the internal structure of nucleons through measurements of structure functions and their ratios, which are sensitive to the chiral-even generalized parton distributions (GPDs) and the chiral-odd transversity GPDs. The GPDs encode correlations of parton distributions in longitudinal momentum space and transverse impact parameter space and are accessible through the measurements of the _xB and _t dependence of meson production. The wide kinematic coverage of CLAS detector allowed measurements of exclusive π⁰ electroproduction in full azimuthal range. The target and double spin asymmetries for the deeply virtual exclusive π⁰ electroproduction were measured for the first time in the DIS region. The experiment was carried out at Hall B, Jefferson Lab using the longitudinally polarized electron beam with energy of up to 6 GeV and a dynamically polarized NH₃ target with spins of free protons aligned along the beam axis. All four final-state particles from exclusive channel, electron, proton and two photons from π⁰ decay, were identified. The asymmetries were fitted according to their angular modulations in the hadronic center-of-mass system, and their moments were extracted. The data comparison with two handbag-based calculations involving the contribution from both chiral-even and chiral-odd GPDs was performed in wide kinematic range. The applicability of a formalism based on generalized parton distributions within the framework of modified perturbative approach is discussed.

Study by neutrons diffusion and X-rays of structural and magnetic properties of Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}} type superconductive cuprates; Etude par diffusion des neutrons et des rayons X des proprietes structurales et magnetiques des cuprates supraconducteurs de type Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}}

Energy Technology Data Exchange (ETDEWEB)

Vasiliu-Doloc, L

1995-09-22

In this work we have used inelastic and elastic neutron and X-ray scattering techniques for characterizing the incommensurate structural distortions in compounds belonging to the family Bi{sub 2}Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub 2n+4+{delta}} of high-Tc superconducting cuprates. We have searched the existence of structural instabilities specific of the CuO{sub 2} planes and of magnetic instabilities. The modulated structure of the 2212 phase has been refined from single-crystal neutron diffraction results and importance of distortion of CuO{sub 2} planes has thus been determined. It is shown that the additional oxygen is not ordered three-dimensionally within the modulated structure and that the information about it is contained in diffuse scattering results. A model of the short-range order associated with additional oxygen atoms is proposed and discussed. The temperature studies of the long-range order have shown a great stability of the amplitude and period of the incommensurate distortion wave in the one-layer, as well as in the double-layer compounds, either superconducting or insulating. We find such a behaviour to be highly incompatible with a distortion resulting from a charge-density-wave instability. The results we have obtained indicate that the bismuth-based high-Tc superconducting cuprates have essentially the same physics of the CuO{sub 2} planes as the previous two families, La{sub 2-x}Sr{sub x}CuO{sub 4} and YBa{sub 2}Cu{sub 3}O{sub 6+{delta}}, being at the proximity of three instabilities: a metal-insulator transition, an antiferromagnetic instability and a structural instability specific of the CuO{sub 2} planes. (author).

Scanning tunneling microscopy/spectroscopy on multi-layered cuprate superconductor Ba2Ca5Cu6O12 (O1-x Fx)2

International Nuclear Information System (INIS)

Sugimoto, A.; Shohara, K.; Ekino, T.; Watanabe, Y.; Harada, Y.; Mikusu, S.; Tokiwa, K.; Watanabe, T.

2009-01-01

Scanning tunneling microscopy/spectroscopy (STM/STS) measurements on multi-layered cuprate superconductor Ba 2 Ca 5 Cu 6 O 12 (O 1-x F x ) 2 are carried out. STM topographies show randomly distributed bright spot structures with a typical spot size of ∼0.8 nm. These bright spots are occupied about 28% per one unit cell of c-plane, which is comparable to the regular amount of apical oxygen of 20% obtained from element analysis. Tunneling spectra simultaneously show both the small and the large gap structures. These gap sizes at 4.9 K are about Δ ∼15 meV and ∼90 meV, respectively. The small gap structure disappears at the temperature close to T C , while the large gap persists up to ∼200 K. Therefore, these features correspond to the superconducting gap and pseudogap, respectively. These facts give evidence for some ordered state with large energy scale even in the superconducting state. For the superconducting gap, the ratio of 2Δ/K B T C = 4.9 is obtained with T C = 70 K, which is determined from temperature dependence of the tunneling spectra.

Anisotropy of the Seebeck Coefficient in the Cuprate Superconductor YBa_{2}Cu_{3}O_{y}: Fermi-Surface Reconstruction by Bidirectional Charge Order

Directory of Open Access Journals (Sweden)

O. Cyr-Choinière

2017-09-01

Full Text Available The Seebeck coefficient S of the cuprate YBa_{2}Cu_{3}O_{y} is measured in magnetic fields large enough to suppress superconductivity, at hole dopings p=0.11 and p=0.12, for heat currents along the a and b directions of the orthorhombic crystal structure. For both directions, S/T decreases and becomes negative at low temperature, a signature that the Fermi surface undergoes a reconstruction due to broken translational symmetry. Above a clear threshold field, a strong new feature appears in S_{b}, for conduction along the b axis only. We attribute this feature to the onset of 3D-coherent unidirectional charge-density-wave modulations seen by x-ray diffraction, also along the b axis only. Because these modulations have a sharp onset temperature well below the temperature where S/T starts to drop towards negative values, we infer that they are not the cause of Fermi-surface reconstruction. Instead, the reconstruction must be caused by the quasi-2D bidirectional modulations that develop at significantly higher temperature. The unidirectional order only confers an additional anisotropy to the already reconstructed Fermi surface, also manifest as an in-plane anisotropy of the resistivity.

Cu k-edge studies of the charge carries in Th-doped cuprate system R2-xThxCuO4-δ (R = Nd, Sm and Gd)

International Nuclear Information System (INIS)

Liang, G.; Yi, Y.; Jardim, R.F.; Wang, L.V.

1999-01-01

To further study the charge carrier concentration in electron doped cuprate superconductors, a systematic x-ray absorption near edge structure (XANES) measurement has been carried out on Th-doped superconductor system R 2-x Th x CuO 4-δ (R = Nd, Sm, and Gd). The XANES results show that, similar to the Ce-doped compounds, while the intensity of the Cu 1+ 4p π feature increase with the increase of the Th doping level x, the intensities of the Cu 2+ 4p π and 4p σ features decreases. This clearly indicates that the electrons doped by the Th atoms are injected into the local Cu 3d-orbitals. The normalized Cu 1+ 4p π intensity data show that the Cu 1+ concentration in the Th-doped compound series with different R-elements is linearly proportional to the Th doping-level x. The data suggest that both Ce and Th donate the same fraction of electrons into the Cu sites

Coherent deeply virtual Compton scattering off 3He and neutron generalized parton distributions

Directory of Open Access Journals (Sweden)

Rinaldi Matteo

2014-06-01

Full Text Available It has been recently proposed to study coherent deeply virtual Compton scattering (DVCS off 3He nuclei to access neutron generalized parton distributions (GPDs. In particular, it has been shown that, in Impulse Approximation (IA and at low momentum transfer, the sum of the quark helicity conserving GPDs of 3He, H and E, is dominated by the neutron contribution. This peculiar result makes the 3He target very promising to access the neutron information. We present here the IA calculation of the spin dependent GPD H See Formula in PDF of 3He. Also for this quantity the neutron contribution is found to be the dominant one, at low momentum transfer. The known forward limit of the IA calculation of H See Formula in PDF , yielding the polarized parton distributions of 3He, is correctly recovered. The extraction of the neutron information could be anyway non trivial, so that a procedure, able to take into account the nuclear effects encoded in the IA analysis, is proposed. These calculations, essential for the evaluation of the coherent DVCS cross section asymmetries, which depend on the GPDs H,E and H See Formula in PDF , represent a crucial step for planning possible experiments at Jefferson Lab.

Deeply virtual Compton scattering with the CLAS detector for the study of generalized parton distributions

International Nuclear Information System (INIS)

Girod, F.X.

2006-12-01

The structure of the nucleon, among the first fundamental problems in hadronic physics, is the subject of a renewed interest. The lightest baryonic state has historically been described in two complementary approaches: through elastic scattering, measuring form factors which reflect the spatial shape of charge distributions, and through deep inelastic scattering, providing access to parton distribution functions which encode the momentum content carried by the constituents. The recently developed formalism of Generalized Parton Distributions unifies those approaches and provides access to new informations. The cleanest process sensitive to GPDs is the deeply virtual Compton scattering (DVCS) contributing to the ep → epγ reaction. This work deals with a dedicated experiment accomplished with the CLAS detector, completed with two specific equipments: a lead tungstate calorimeter covering photon detection at small angles, and a superconducting solenoid actively shielding the electromagnetic background. The entire project is covered: from the upgrade of the experimental setup, through the update of the software, data taking and analysis, up to a first comparison of the beam spin asymmetry to model predictions. (author)

Experimental setup for deeply virtual Compton scattering (DVCS) experiment in hall A at Jefferson Laboratory

International Nuclear Information System (INIS)

Camsonne, A.

2005-11-01

The Hall A Deeply Virtual Compton Scattering (DVCS) experiment used the 5.757 GeV polarized electron beam available at Jefferson Laboratory and ran from september until december 2004. Using the standard Hall A left high resolution spectrometer three kinematical points were taken at a fixed x b (jorken) = 0.32 value for three Q 2 values: 1.5 GeV 2 , 1.91 GeV 2 , 2.32 GeV 2 . An electromagnetic Lead Fluoride calorimeter and a proton detector scintillator array designed to work at a luminosity of 10 37 cm -2 s -1 were added to ensure the exclusivity of the DVCS reaction. In addition to the new detectors new custom electronics was used: a calorimeter trigger module which determines if an electron photon coincidence has occurred and a sampling system allowing to deal with pile-up events during the offline analysis. Finally the data from the kinematic at Q 2 = 2.32 GeV 2 and s = 5.6 GeV 2 allowed to get a preliminary result for the exclusive π 0 electroproduction on the proton. (author)

Growth of superconductor material in a fluxed melt, and article of manufacture

International Nuclear Information System (INIS)

Jackson, K.A.; Schneemeyer, L.F.

1991-01-01

This patent describes a method for making a body of bismuth-strontium calcium cuprate, lead-substituted bismuth strontium calcium cuprate, or thallium-barium calcium cuprate superconductor material. It comprises cooling a melt at least locally, the melt comprising constituents of the material, characterized in that the melts further comprises a flux component comprising at least one fluxing agent selected from the group consisting of sodium chloride and potassium chloride, such that the cuprate body has superconductor properties at a temperature of 77 K

Effect of interlayer tunneling on the electronic structure of bilayer cuprates and quantum phase transitions in carrier concentration and high magnetic field

International Nuclear Information System (INIS)

Ovchinnikov, S. G.; Makarov, I. A.; Shneyder, E. I.

2011-01-01

We present a theoretical study of the electronic structure of bilayer HTSC cuprates and its evolution under doping and in a high magnetic field. Analysis is based on the t-t′-t″-J* model in the generalized Hartree-Fock approximation. Possibility of tunneling between CuO2 layers is taken into account in the form of a nonzero integral of hopping between the orbitals of adjacent planes and is included in the scheme of the cluster form of perturbation theory. The main effect of the coupling between two CuO 2 layers in a unit cell is the bilayer splitting manifested in the presence of antibonding and bonding bands formed by a combination of identical bands of the layers themselves. A change in the doping level induces reconstruction of the band structure and the Fermi surface, which gives rise to a number of quantum phase transitions. A high external magnetic field leads to a fundamentally different form of electronic structure. Quantum phase transitions in the field are observed not only under doping, but also upon a variation of the field magnitude. Because of tunneling between the layers, quantum transitions are also split; as a result, a more complex sequence of the Lifshitz transitions than in single-layer structures is observed.

A measurement of the Q{sup 2}, W and t dependences of deeply virtual Compton scattering at HERA

Energy Technology Data Exchange (ETDEWEB)

Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Lab., Argonne, IL (US)] (and others)

2008-12-15

Deeply virtual Compton scattering, {gamma}{sup *}p{yields}{gamma}p, has been measured in e{sup +}p collisions at HERA with the ZEUS detector using an integrated luminosity of 61.1 pb{sup -1}. Cross sections are presented as a function of the photon virtuality, Q{sup 2}, and photon-proton centre-of-mass energy, W, for a wide region of the phase space, Q{sup 2}>1.5 GeV{sup 2} and 40

Positron Annihilation Studies of the Electronic Structure of Selected High-Temperature Cuprate and Organic Superconductors.

Science.gov (United States)

Chan, Lie Ping

The understanding of the electronic structure of the high-T_{c} superconductors could be important for a full theoretical description of the mechanism behind superconductivity in these materials. In this thesis, we present our measurements of the positron -electron momentum distributions of the cuprate superconductors Bi_2Sr_2CaCu _2O_8, Tl _2Ba_2Ca _2Cu_3O_ {10}, and the organic superconductor kappa-(BEDT)_2Cu(NCS) _2. We use the positron Two-dimensional Angular Correlation of Annihilation Radiation technique to make the measurements on single crystals and compare our high-statistics data with band structure calculations to determine the existence and nature of the respective Fermi surfaces. The spectra from unannealed Bi _2Sr_2CaCu _2O_8 exhibit effects of the superlattice modulation in the BiO_2 layers, and a theoretical understanding of the modulation effects on the electronic band structure is required to interpret these spectra. Since the present theory does not consider the modulation, we have developed a technique to remove the modulation effects from our spectra, and the resultant data when compared with the positron -electron momentum distribution calculation, yield features consistent with the predicted CuO_2 and BiO_2 Fermi surfaces. In the data from unannealed Tl_2Ba _2Ca_2Cu_3 O_{10}, we only observe indications of the TlO Fermi surfaces, and attribute the absence of the predicted CuO_2 Fermi surfaces to the poor sample quality. In the absence of positron-electron momentum calculations for kappa-(BEDT)_2Cu(NCS) _2, we compare our data to electronic band structure calculations, and observed features suggestive of the predicted Fermi surface contributions from the BEDT cation layers. A complete positron-electron calculation for kappa-(BEDT)_2 Cu(NCS)_2 is required to understand the positron wavefunction effects in this material.

Separation of contributions from deeply virtual Compton scattering and its interference with the Bethe-Heitler process in measurements on a hydrogen target

International Nuclear Information System (INIS)

Airapetian, A.; Akopov, Z.

2009-09-01

Hard exclusive leptoproduction of real photons from an unpolarized proton target is studied in an effort to elucidate generalized parton distributions. The data accumulated during the years 1996-2005 with the HERMES spectrometer are analyzed to yield asymmetries with respect to the combined dependence of the cross section on beam helicity and charge, thereby revealing previously unseparated contributions from deeply virtual Compton scattering and its interference with the Bethe-Heitler process. The integrated luminosity is sufficient to show correlated dependences on two kinematic variables, and provides the most precise determination of the dependence on only the beam charge. (orig.)

The interventional diagnosis and therapy for thyroid disease should be studied deeply and developed prudently

International Nuclear Information System (INIS)

Zhao Wei; Cheng Yongde

2007-01-01

Many details concerning the interventional diagnosis and therapy of thyroid disease need to be studied deeply and carefully; for example, the thyroid applied anatomy, especially the anatomical imageology study of the thyroid arterial anastomosis involving the therapeutic effects and complications, the thyroid artery embolization treatment, presently as a substitution or the supplement therapy for the traditional classical therapy of Graves disease. There are many exploration to extend the indication scope, the therapeutic effect, embolization scope in intervention for Graves disease due to having no accurate individual quantification standard, and so on. The thyroid arterial embolization for Graves disease is to reduce the main cause of thyroxin secretion. Simultaneously, the comprehensive therapeutic effects might have possibly produce the thyroidcytic apoptosis and immune adjustments. Serious complications such as the cerebral infarction, the hyperthyroidism crisis, the hypocalcemia, the periodic paralysis, and so on commonly occured in thyroid arterial embolization. It is necessary to keep strictly the procedure rule and the indication. The mid-and long- term therapeutic effect of thyroid artery embolization for Graves disease is good, but still need more extensive and prudent research for the prospective achievement. (authors)

Method of recovering deeply submerged support strings of a self-lifting floating unit from the ground

Energy Technology Data Exchange (ETDEWEB)

Dzhafarov, A M; Leybenzon, S R; Sarkisov, V G

1982-01-01

A method is proposed for recovering from the ground deeply submerged strings of self-lifting floating unit consisting of application of vertical forces through a lifter to the support string from surplus buoyancy of the housing submerged into the water. It is distinguished by the fact that in order to improve reliability and to expand the area of operation in water areas with deep occurrence of the bearing ground, submersion of the housing is done with its inclination. This applies to the support string or a group of support strings a permissible momentum, after which water ballast is used towards the housing opposite the inclined, with simultaneous preservation of the permissible moment applied to the support string or group of support strings, and the permissible momentum is determined from the formula-..mu.. = ..sqrt..theta/sup 2/ + /PSI//sup 2//A where M--momentum permitted according to the conditions of strength of the support string; /PSI/--angle of trim; /ETA/-- angle of list; A--coefficient of flexibility of the string submerged into the ground.

Characterization of the island divertor plasma of W7-AS stellarator in the deeply detached state with volume recombination

International Nuclear Information System (INIS)

Ramasubramanian, N.; Koenig, R.; Feng, Y.; Giannone, L.; Grigull, P.; Klinger, T.; McCormick, K.; Thomsen, H.; Wenzel, U.

2004-01-01

In the high-density H-mode of the Stellarator Wendelstein 7-AS, the plasma detaches from the island divertor targets when the line-averaged density exceeds a critical value. This quasi-stationary detachment is found to be partial and shows edge-localized, poloidally asymmetric radiation. The spectroscopic characteristics of the deeply detached plasma are reported, including evidence for volume recombination. The detached plasma radiates up to 90% of the absorbed power with larger contributions from the locations close to magnetic X-points outside the divertor region. The spectral analysis of the Balmer series indicate very high densities and low temperatures at the detached regions. The results of the spectral analysis underline the importance of three-dimensional modelling. An initial comparison is made with the latest results from EMC3-EIRENE modelling. (author)

Deeply reinverted T wave at 14 days after the onset of first anterior acute myocardial infarction predicts improved left ventricular function at 6 months.

Science.gov (United States)

Yokoyama, Hiroaki; Tomita, Hirofumi; Nishizaki, Fumie; Hanada, Kenji; Shibutani, Shuji; Yamada, Masahiro; Abe, Naoki; Higuma, Takumi; Osanai, Tomohiro; Okumura, Ken

2015-03-01

Changes in electrocardiogram (ECG), especially in the ST segment and T wave, have been recognized as a noninvasive diagnostic tool for coronary flow or myocardial injury. A deeply inverted T wave at 14 days after successful percutaneous coronary intervention (PCI) in patients with ST-segment elevation acute myocardial infarction (STEMI) predicts improved left ventricular (LV) function at 6 months. We enrolled 112 consecutive patients (88 men, 63 ± 11 years) with first anterior STEMI who underwent successful PCI. A 12-lead ECG was recorded everyday from admission through 14 days. After PCI, the first T-wave inversion was observed within 2 days, and the second occurred at 14 days. We measured the maximum depth of the reinverted T wave (Neg-T) and divided the patients into 2 groups based on the median value of Neg-T: the deep group (≥0.6 mV, n = 62) and the nondeep group (wave in precordial leads at 6 months was more frequently observed in the deep than in the nondeep group (68% vs 46%, P = 0.02). Multivariate regression analysis showed that the Neg-T and max CPK-MB were independent contributors to LVEF at 6 months. A deeply reinverted T wave at 14 days after onset of first anterior STEMI can be a useful predictive marker for improved LV function at 6 months. © 2015 Wiley Periodicals, Inc.

Longitudinal target-spin azimuthal asymmetry in Deeply-Virtual Compton Scattering

Energy Technology Data Exchange (ETDEWEB)

Kopytin, M.

2006-08-22

As a generalization of the usual Parton Distribution Functions (PDFs) Generalized Parton Distributions (GPDs), introduced a decade ago, contain additional information about quark and gluon distributions in the plane transverse to the direction of motion of the nucleon. Strong interest in GPDs was triggered by the work of X. Ji who demonstrated that in the forward limit GPDs can give information about the total angular momentum carried by quarks (gluons) in the nucleon. The hard exclusive electroproduction of a real photon, called Deeply Virtual Compton Scattering (DVCS), appears to be the theoretically cleanest way to access GPDs experimentally. This process has a final state identical to that of the Bethe-Heitler (BH) process where the photon is radiated from either incoming or outgoing lepton. Both processes are experimentally indistinguishable as their amplitudes interfere. The interference term involves linearly the amplitudes of the DVCS process giving access to GPDs. In this thesis results from HERMES are reported on an azimuthal asymmetry with respect to the spin of the proton target, which is attributed to the interference between the Bethe-Heitler process and the DVCS process. The asymmetry, also referred to as the longitudinal target-spin asymmetry (LTSA), gives access mainly to the polarized GPD H. The kinematic dependences of the LTSA on t, x{sub B} and Q{sup 2} are measured and compared with the corresponding measurements on the deuteron. The results are compared with theoretical calculations and with the recent CLAS measurements. The data, used for analysis in this thesis, have been accumulated by the HERMES experiment at DESY scattering the HERA 27.6 GeV positron beam off hydrogen and deuterium gas targets. Additionally, production tests of the HELIX128 3.0 chip are discussed. The chip is the frontend readout chip of the silicon recoil detector. The latter is a part of the HERMES recoil detector, which is built around the target area in order to

Longitudinal target-spin azimuthal asymmetry in Deeply-Virtual Compton Scattering

International Nuclear Information System (INIS)

Kopytin, M.

2006-01-01

As a generalization of the usual Parton Distribution Functions (PDFs) Generalized Parton Distributions (GPDs), introduced a decade ago, contain additional information about quark and gluon distributions in the plane transverse to the direction of motion of the nucleon. Strong interest in GPDs was triggered by the work of X. Ji who demonstrated that in the forward limit GPDs can give information about the total angular momentum carried by quarks (gluons) in the nucleon. The hard exclusive electroproduction of a real photon, called Deeply Virtual Compton Scattering (DVCS), appears to be the theoretically cleanest way to access GPDs experimentally. This process has a final state identical to that of the Bethe-Heitler (BH) process where the photon is radiated from either incoming or outgoing lepton. Both processes are experimentally indistinguishable as their amplitudes interfere. The interference term involves linearly the amplitudes of the DVCS process giving access to GPDs. In this thesis results from HERMES are reported on an azimuthal asymmetry with respect to the spin of the proton target, which is attributed to the interference between the Bethe-Heitler process and the DVCS process. The asymmetry, also referred to as the longitudinal target-spin asymmetry (LTSA), gives access mainly to the polarized GPD H. The kinematic dependences of the LTSA on t, x B and Q 2 are measured and compared with the corresponding measurements on the deuteron. The results are compared with theoretical calculations and with the recent CLAS measurements. The data, used for analysis in this thesis, have been accumulated by the HERMES experiment at DESY scattering the HERA 27.6 GeV positron beam off hydrogen and deuterium gas targets. Additionally, production tests of the HELIX128 3.0 chip are discussed. The chip is the frontend readout chip of the silicon recoil detector. The latter is a part of the HERMES recoil detector, which is built around the target area in order to detect the

Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory

Energy Technology Data Exchange (ETDEWEB)

Guegan, Baptiste [Rensselaer Polytechnic Inst., Troy, NY (United States)

2012-11-01

The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.

Oxygen stoichiometry and the high Tc superconducting oxides

International Nuclear Information System (INIS)

Tarascon, J.M.; Bagley, B.G.

1989-01-01

Methods for determining the oxygen content in high Tc materials, such as thermogravimetric analysis and chemical analysis, are discussed. Consideration is given to La-based cuprates, Y-based cuprates, and Bi-based cuprates. Superconducting transition temperatures are analyzed as a function of the Cu(1)-O(4) bond lengths for several different compositions in the Y-based system. 28 references

OVERVIEW ON BNL ASSESSMENT OF SEISMIC ANALYSIS METHODS FOR DEEPLY EMBEDDED NPP STRUCTURES

International Nuclear Information System (INIS)

XU, J.; COSTANTINO, C.; HOFMAYER, C.; GRAVES, H.

2007-01-01

A study was performed by Brookhaven National Laboratory (BNL) under the sponsorship of the U. S. Nuclear Regulatory Commission (USNRC), to determine the applicability of established soil-structure interaction analysis methods and computer programs to deeply embedded and/or buried (DEB) nuclear power plant (NPP) structures. This paper provides an overview of the BNL study including a description and discussions of analyses performed to assess relative performance of various SSI analysis methods typically applied to NPP structures, as well as the importance of interface modeling for DEB structures. There are four main elements contained in the BNL study: (1) Review and evaluation of existing seismic design practice, (2) Assessment of simplified vs. detailed methods for SSI in-structure response spectrum analysis of DEB structures, (3) Assessment of methods for computing seismic induced earth pressures on DEB structures, and (4) Development of the criteria for benchmark problems which could be used for validating computer programs for computing seismic responses of DEB NPP structures. The BNL study concluded that the equivalent linear SSI methods, including both simplified and detailed approaches, can be extended to DEB structures and produce acceptable SSI response calculations, provided that the SSI response induced by the ground motion is very much within the linear regime or the non-linear effect is not anticipated to control the SSI response parameters. The BNL study also revealed that the response calculation is sensitive to the modeling assumptions made for the soil/structure interface and application of a particular material model for the soil

Suggestions for locations for the surface installations required for deep-lying repositories; standortareale fuer die oberflaechenanlage von tiefenlagern -- vorschlaege zur diskussion

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-01-15

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the various factors involved in the selection of locations for surface installations that are required for the operation of deep-lying nuclear waste repositories. The method chosen for the selection of possible locations for surface installations is explained and the necessity for such installations is discussed. The requirements placed on such a location are discussed and the various locations chosen for further consideration are noted. The evaluation phases involved in the selection of sites are described. The proposed surface installations are noted and the proposed structures for both repository types - for highly radioactive wastes and for low and medium active wastes - are described.

Spin fluctuations in iron based superconductors probed by NMR relaxation rate

Energy Technology Data Exchange (ETDEWEB)

Graefe, Uwe; Kuehne, Tim; Wurmehl, Sabine; Buechner, Bernd; Grafe, Hans-Joachim [IFW Dresden, Institute for Solid State Research, PF 270116, 01171 Dresden (Germany); Hammerath, Franziska [IFW Dresden, Institute for Solid State Research, PF 270116, 01171 Dresden (Germany); Department of Physics ' ' A. Volta' ' , University of Pavia-CNISM, I-27100 Pavia (Italy); Lang, Guillaume [3LPEM-UPR5, CNRS, ESPCI Paris Tech, 10 Rue Vauquelin, 75005 Paris (France)

2013-07-01

We present {sup 75}As nuclear magnetic resonance (NMR) results in F doped LaOFeAs iron pnictides. In the underdoped superconducting samples, pronounced spin fluctuations lead to a peak in the NMR spin lattice relaxation rate, (T{sub 1}T){sup -1}. The peak shows a typical field dependence that indicates a critical slowing of spin fluctuations: it is reduced in height and shifted to higher temperatures. In contrast, a similar peak in the underdoped magnetic samples at the ordering temperature of the spin density wave does not show such a field dependence. Furthermore, the peak is absent in optimally and overdoped samples, suggesting the absence of strong spin fluctuations. Our results indicate a glassy magnetic ordering in the underdoped samples that is in contrast to the often reported Curie Weiss like increase of spin fluctuations towards T{sub c}. Additional measurements of the linewidth and the spin spin relaxation rate are in agreement with such a glassy magnetic ordering that is most likely competing with superconductivity. Our results will be compared to Co doped BaFe{sub 2}As{sub 2}, where a similar peak in (T{sub 1}T){sup -1} has been observed.

Correlation of tunneling spectra with surface nanomorphology and doping in thin YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films

Energy Technology Data Exchange (ETDEWEB)

Sharoni, A.; Millo, O. [Hebrew Univ., Jerusalem (Israel). Racah Inst. of Physics; Koren, G. [Technion-Israel Inst. of Tech., Haifa (Israel). Dept. of Physics

2001-06-01

Tunneling spectra measured on thin epitaxial YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} films are found to exhibit strong spatial variations, showing U- and V-shaped gaps as well as zero-bias conductance peaks typical of a d-wave superconductor. A full correspondence is found between the tunneling spectra and the surface morphology down to a level of a unit-cell step. Splitting of the zero-bias conductance peak is seen in optimally-doped and overdoped films, but not in the underdoped ones, suggesting that there is no transition to a state of broken time-reversal symmetry in the underdoped regime. (orig.)

Stripe order from the perspective of the Hubbard model

Energy Technology Data Exchange (ETDEWEB)

Devereaux, Thomas Peter

2018-03-01

A microscopic understanding of the strongly correlated physics of the cuprates must account for the translational and rotational symmetry breaking that is present across all cuprate families, commonly in the form of stripes. Here we investigate emergence of stripes in the Hubbard model, a minimal model believed to be relevant to the cuprate superconductors, using determinant quantum Monte Carlo (DQMC) simulations at finite temperatures and density matrix renormalization group (DMRG) ground state calculations. By varying temperature, doping, and model parameters, we characterize the extent of stripes throughout the phase diagram of the Hubbard model. Our results show that including the often neglected next-nearest-neighbor hopping leads to the absence of spin incommensurability upon electron-doping and nearly half-filled stripes upon hole-doping. The similarities of these findings to experimental results on both electron and hole-doped cuprate families support a unified description across a large portion of the cuprate phase diagram.

Charge density waves as the origin of dip-hump structures in the differential tunneling conductance of cuprates: The case of d-wave superconductivity

Energy Technology Data Exchange (ETDEWEB)

Gabovich, Alexander M., E-mail: gabovich@iop.kiev.ua; Voitenko, Alexander I., E-mail: voitenko@iop.kiev.ua

2014-08-15

Highlights: • d-Wave superconductivity and charge-density waves compete for the Fermi surface. • Charge-density waves induce pseudogaps and peak-dip-hump structures in cuprates. • Tunnel spectra are non-symmetric due to the dielectric order-parameter phase fixation. • Scatter of the dielectric order parameter smears the tunnel spectra peculiarities. - Abstract: Quasiparticle differential current–voltage characteristics (CVCs) G(V) of non-symmetric tunnel junctions between d-wave superconductors with charge-density waves (CDWs) and normal metals were calculated. The dependences G(V) were shown to have a V-like form at small voltages V and low temperatures, and to be asymmetric at larger V owing to the presence of CDW peak in either of the V-branches. The spatial scatter of the dielectric (CDW) order parameter smears the CDW peak into a hump and induces a peak-dip-hump structure (PDHS) typical of CVCs observed for such junctions. At temperatures larger than the superconducting critical one, the PDHS evolves into a pseudogap depression. The results agree well with the scanning tunneling microscopy data for Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} and YBa{sub 2}Cu{sub 3}O{sub 7−δ}. The results differ substantially from those obtained earlier for CDW s-wave superconductors.

Symmetry-Breaking Orbital Anisotropy Observed for Detwinned Ba(Fe1-xCox)2As2 above the Spin Density Wave Transition

International Nuclear Information System (INIS)

Yi, Ming

2011-01-01

Nematicity, defined as broken rotational symmetry, has recently been observed in competing phases proximate to the superconducting phase in the cuprate high temperature superconductors. Similarly, the new iron-based high temperature superconductors exhibit a tetragonal to orthorhombic structural transition (i.e. a broken C 4 symmetry) that either precedes or is coincident with a collinear spin density wave (SDW) transition in undoped parent compounds, and superconductivity arises when both transitions are suppressed via doping. Evidence for strong in-plane anisotropy in the SDW state in this family of compounds has been reported by neutron scattering, scanning tunneling microscopy, and transport measurements. Here we present an angle resolved photoemission spectroscopy study of detwinned single crystals of a representative family of electron-doped iron-arsenide superconductors, Ba(Fe 1-x Co x ) 2 As 2 in the underdoped region. The crystals were detwinned via application of in-plane uniaxial stress, enabling measurements of single domain electronic structure in the orthorhombic state. At low temperatures, our results clearly demonstrate an in-plane electronic anisotropy characterized by a large energy splitting of two orthogonal bands with dominant d xz and d yz character, which is consistent with anisotropy observed by other probes. For compositions x > 0, for which the structural transition (T S ) precedes the magnetic transition (T SDW ), an anisotropic splitting is observed to develop above T SDW , indicating that it is specifically associated with T S . For unstressed crystals, the band splitting is observed close to T S , whereas for stressed crystals the splitting is observed to considerably higher temperatures, revealing the presence of a surprisingly large in-plane nematic susceptibility in the electronic structure.

A Simple Model Framework to Explore the Deeply Uncertain, Local Sea Level Response to Climate Change. A Case Study on New Orleans, Louisiana

Science.gov (United States)

Bakker, Alexander; Louchard, Domitille; Keller, Klaus

2016-04-01

Sea-level rise threatens many coastal areas around the world. The integrated assessment of potential adaptation and mitigation strategies requires a sound understanding of the upper tails and the major drivers of the uncertainties. Global warming causes sea-level to rise, primarily due to thermal expansion of the oceans and mass loss of the major ice sheets, smaller ice caps and glaciers. These components show distinctly different responses to temperature changes with respect to response time, threshold behavior, and local fingerprints. Projections of these different components are deeply uncertain. Projected uncertainty ranges strongly depend on (necessary) pragmatic choices and assumptions; e.g. on the applied climate scenarios, which processes to include and how to parameterize them, and on error structure of the observations. Competing assumptions are very hard to objectively weigh. Hence, uncertainties of sea-level response are hard to grasp in a single distribution function. The deep uncertainty can be better understood by making clear the key assumptions. Here we demonstrate this approach using a relatively simple model framework. We present a mechanistically motivated, but simple model framework that is intended to efficiently explore the deeply uncertain sea-level response to anthropogenic climate change. The model consists of 'building blocks' that represent the major components of sea-level response and its uncertainties, including threshold behavior. The framework's simplicity enables the simulation of large ensembles allowing for an efficient exploration of parameter uncertainty and for the simulation of multiple combined adaptation and mitigation strategies. The model framework can skilfully reproduce earlier major sea level assessments, but due to the modular setup it can also be easily utilized to explore high-end scenarios and the effect of competing assumptions and parameterizations.

High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

International Nuclear Information System (INIS)

Salvador, R; Miranda, P C; Roth, Y; Zangen, A

2009-01-01

Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/√2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

Science.gov (United States)

Salvador, R.; Miranda, P. C.; Roth, Y.; Zangen, A.

2009-05-01

Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/\\sqrt 2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

High permeability cores to optimize the stimulation of deeply located brain regions using transcranial magnetic stimulation

Energy Technology Data Exchange (ETDEWEB)

Salvador, R; Miranda, P C [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon (Portugal); Roth, Y [Advanced Technology Center, Sheba Medical Center, Tel-Hashomer (Israel); Zangen, A [Neurobiology Department, Weizmann Institute of Science, Rehovot 76100 (Israel)], E-mail: rnsalvador@fc.ul.pt

2009-05-21

Efficient stimulation of deeply located brain regions with transcranial magnetic stimulation (TMS) poses many challenges, arising from the fact that the induced field decays rapidly and becomes less focal with depth. We propose a new method to improve the efficiency of TMS of deep brain regions that combines high permeability cores, to increase focality and field intensity, with a coil specifically designed to induce a field that decays slowly with increasing depth. The performance of the proposed design was investigated using the finite element method to determine the total electric field induced by this coil/core arrangement on a realistically shaped homogeneous head model. The calculations show that the inclusion of the cores increases the field's magnitude by as much as 25% while also decreasing the field's decay with depth along specific directions. The focality, as measured by the area where the field's norm is greater than 1/{radical}2 of its maximum value, is also improved by as much as 15% with some core arrangements. The coil's inductance is not significantly increased by the cores. These results show that the presence of the cores might make this specially designed coil even more suited for the effective stimulation of deep brain regions.

Overburden stripping from deeply buried orebodies by controlled nuclear explosive casting

Energy Technology Data Exchange (ETDEWEB)

Saperstein, L W; Mishra, R [Department of Mining, The Pennsylvania State University, University Park, PA (United States)

1970-05-15

Previous schemes to strip the overburden from a deeply-buried orebody by nuclear explosives have been hampered by various constraints. These are the notions that surface topography should slope in the desired direction to facilitate casting; that the orebody should be stripped all at once, meaning that an unsafe and unnaturally high yield will be detonated; or that the overburden be broken and cast, in a manner akin to conventional blasting, with a series of explosions linked by milli-second delays, such delays being an unproven and, perhaps non-permissible technology; and, finally, that the schemes leave an excessive amount of overburden to be removed by conventional means. It is proposed that deep orebodies, idealized by a 250-ft. thick copper porphyry under 600 feet of cover, be stripped in successive rows, using available row-charge technology. A first row, of greater magnitude than those succeeding, is used to expose the orebody. The second row is placed so as to throw overburden into the void created by the first. All rows are placed so as not to damage the ore. Except for the first row, all rows utilize directed throwing. After a row is detonated, the ore beneath it would be removed by conventional means. The void thus created would provide space for the successive row to fire into. Further, the additional free-face provided by the void imparts a major direction to the ejecta. Because of the directed nature of the throw, ore removal does not have to proceed directly beneath the row slope. Advantages to this scheme are its adaptability to terrain; its reduction in overburden to be removed by conventional methods; its increased speed in uncovering ore; its reduction of unit costs; audits adaptability to production rates. An example, utilizing the idealized orebody shows that production of ore can begin within a year of project approval versus four or five years for the same orebody developed conventionally; that no more than eight percent of the overburden has

Overburden stripping from deeply buried orebodies by controlled nuclear explosive casting

International Nuclear Information System (INIS)

Saperstein, L.W.; Mishra, R.

1970-01-01

Previous schemes to strip the overburden from a deeply-buried orebody by nuclear explosives have been hampered by various constraints. These are the notions that surface topography should slope in the desired direction to facilitate casting; that the orebody should be stripped all at once, meaning that an unsafe and unnaturally high yield will be detonated; or that the overburden be broken and cast, in a manner akin to conventional blasting, with a series of explosions linked by milli-second delays, such delays being an unproven and, perhaps non-permissible technology; and, finally, that the schemes leave an excessive amount of overburden to be removed by conventional means. It is proposed that deep orebodies, idealized by a 250-ft. thick copper porphyry under 600 feet of cover, be stripped in successive rows, using available row-charge technology. A first row, of greater magnitude than those succeeding, is used to expose the orebody. The second row is placed so as to throw overburden into the void created by the first. All rows are placed so as not to damage the ore. Except for the first row, all rows utilize directed throwing. After a row is detonated, the ore beneath it would be removed by conventional means. The void thus created would provide space for the successive row to fire into. Further, the additional free-face provided by the void imparts a major direction to the ejecta. Because of the directed nature of the throw, ore removal does not have to proceed directly beneath the row slope. Advantages to this scheme are its adaptability to terrain; its reduction in overburden to be removed by conventional methods; its increased speed in uncovering ore; its reduction of unit costs; audits adaptability to production rates. An example, utilizing the idealized orebody shows that production of ore can begin within a year of project approval versus four or five years for the same orebody developed conventionally; that no more than eight percent of the overburden has

Serum and peritoneal interleukin-33 levels are elevated in deeply infiltrating endometriosis.

Science.gov (United States)

Santulli, Pietro; Borghese, Bruno; Chouzenoux, Sandrine; Vaiman, Daniel; Borderie, Didier; Streuli, Isabelle; Goffinet, François; de Ziegler, Dominique; Weill, Bernard; Batteux, Frédéric; Chapron, Charles

2012-07-01

Interleukin 33 (IL-33) is a cytokine involved in fibrotic disorders. We have analyzed IL-33 levels in the sera and peritoneal fluids of women with various forms of endometriosis and investigated the correlation with disease activity. We conducted a prospective laboratory study in a tertiary-care university hospital between January 2005 and December 2010. Five hundred and ten women with histologically proven endometriosis and 132 endometriosis-free controls were enrolled in this study. Complete surgical exploration of the abdominopelvic cavity was performed in each patient. Blood samples and peritoneal fluids were obtained before and during surgical procedures, respectively. IL-33 was measured by an enzyme-linked immunosorbent assay in sera and peritoneal fluids, and the concentrations correlated with the extent and the severity of endometriotic lesions. IL-33 was detectable in 23.1% of serum samples from all 642 women studied and 75.0% of peritoneal fluid samples studied (44 women with endometriosis and 36 controls). Serum IL-33 was higher in deeply infiltrating endometriosis (DIE) (median, 104.9 pg/ml; range, 8.0-104.9) than in endometriosis-free women (median, 61.3 pg/ml; range, 7.5-526.0; P = 0.022) or in women affected by superficial endometriosis (median, 36.8 pg/ml; range, 7.5-179.0; P Peritoneal IL-33 was higher in DIE than in endometriosis-free women (median, 642.0 pg/ml; range, 25.9-3350.6 versus median, 194.2 pg/ml; range, 12.7-1818.2, respectively; P = 0.003). We found positive correlations between serum IL-33 concentration and intensity of dysmenorrhea (r = 0.174; P = 0.028) and gastrointestinal symptoms (r = 0.199; P = 0.027), total number of DIE lesions (r = 0.224; P = 0.016) and the worst DIE lesion (r = 0.299; P endometriosis and principally in DIE. Elevated serum IL-33 is correlated with the intensity of preoperative painful symptoms, and with the extent and severity of the DIE. IL-33 may be considered as a novel cytokine involved in the

Many-Objective Robust Decision Making: Managing Water in a Deeply Uncertain World of Change (Invited)

Science.gov (United States)

Reed, P. M.

2013-12-01

Water resources planning and management has always required the consideration of uncertainties and the associated system vulnerabilities that they may cause. Despite the long legacy of these issues, our decision support frameworks that have dominated the literature over the past 50 years have struggled with the strongly multiobjective and deeply uncertain nature of water resources systems. The term deep uncertainty (or Knightian uncertainty) refers to factors in planning that strongly shape system risks that maybe unknown and even if known there is a strong lack of consensus on their likelihoods over decadal planning horizons (population growth, financial stability, valuation of resources, ecosystem requirements, evolving water institutions, regulations, etc). In this presentation, I will propose and demonstrate the many-objective robust decision making (MORDM) framework for water resources management under deep uncertainty. The MORDM framework will be demonstrated using an urban water portfolio management test case. In the test case, a city in the Lower Rio Grande Valley managing population and drought pressures must cost effectively maintain the reliability of its water supply by blending permanent rights to reservoir inflows with alternative strategies for purchasing water within the region's water market. The case study illustrates the significant potential pitfalls in the classic Cost-Reliability conception of the problem. Moreover, the proposed MORDM framework exploits recent advances in multiobjective search, visualization, and sensitivity analysis to better expose these pitfalls en route to identifying highly robust water planning alternatives.

New world of Gossamer superconductivity

International Nuclear Information System (INIS)

Maki, Kazumi; Haas, Stephan; Parker, David; Won, Hyekyung; Dora, Balazs; Virosztek, Attila

2006-01-01

Since the discovery of the high-T c cuprate superconductor La 2-x BaCuO 4 in 1986 by Bednorz and Mueller, controversy regarding the nature or origin of this remarkable superconductivity has continued. However, d-wave superconductivity in the hole-doped cuprates, arising due to the anti-paramagnon exchange, was established around 1994. More recently we have shown that the mean field theory, like the BCS theory of superconductivity and Landau's Fermi liquid theory are adequate to describe the cuprates. The keys for this development are the facts that a) the pseudogap phase is d-wave density wave (dDW) and that the high-T c cuprate superconductivity is gossamer (i.e. it exists in the presence of dDW). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Effective inelastic scattering cross-sections for background analysis in HAXPES of deeply buried layers

Energy Technology Data Exchange (ETDEWEB)

Risterucci, P., E-mail: paul.risterucci@gmail.com [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Renault, O., E-mail: olivier.renault@cea.fr [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Zborowski, C. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark); Bertrand, D.; Torres, A. [Univ. Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Rueff, J.-P. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005, Paris (France); Ceolin, D. [Synchrotron SOLEIL, L' Orme des Merisiers Saint-Aubin, BP 48 91192, Gif-sur-Yvette Cedex (France); Grenet, G. [Université de Lyon, Institut des Nanotechnologies de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

2017-04-30

Highlights: • An effective approach for quantitative background analysis in HAXPES spectra of buried layer underneath complex overlayer structures is proposed. • The approach relies on using a weighted sum of inelastic scattering cross section of the pure layers. • The method is validated by the study of an advanced power transistor stack after successive annealing steps. • The depth distribution of crucial elements (Ti, Ga) is determined reliably at depths up to nearly 50 nm. - Abstract: Inelastic background analysis of HAXPES spectra was recently introduced as a powerful method to get access to the elemental distribution in deeply buried layers or interfaces, at depth up to 60 nm below the surface. However the accuracy of the analysis highly relies on suitable scattering cross-sections able to describe effectively the transport of photoelectrons through overlayer structures consisting of individual layers with potentially very different scattering properties. Here, we show that within Tougaard’s practical framework as implemented in the Quases-Analyze software, the photoelectron transport through thick (25–40 nm) multi-layer structures with widely different cross-sections can be reliably described with an effective cross-section in the form of a weighted sum of the individual cross-section of each layer. The high-resolution core-level analysis partly provides a guide for determining the nature of the individual cross-sections to be used. We illustrate this novel approach with the practical case of a top Al/Ti bilayer structure in an AlGaN/GaN power transistor device stack before and after sucessive annealing treatments. The analysis provides reliable insights on the Ti and Ga depth distributions up to nearly 50 nm below the surface.

Angle-resolved photoemission spectroscopy of strontium lanthanum copper oxide thin films grown by molecular-beam epitaxy

Science.gov (United States)

Harter, John Wallace

Among the multitude of known cuprate material families and associated structures, the archetype is "infinite-layer" ACuO2, where perfectly square and flat CuO2 planes are separated by layers of alkaline earth atoms. The infinite-layer structure is free of magnetic rare earth ions, oxygen chains, orthorhombic distortions, incommensurate superstructures, ordered vacancies, and other complications that abound among the other material families. Furthermore, it is the only cuprate that can be made superconducting by both electron and hole doping, making it a potential platform for decoding the complex many-body interactions responsible for high-temperature superconductivity. Research on the infinite-layer compound has been severely hindered by the inability to synthesize bulk single crystals, but recent progress has led to high-quality superconducting thin film samples. Here we report in situ angle-resolved photoemission spectroscopy measurements of epitaxially-stabilized Sr1-chiLa chiCuO2 thin films grown by molecular-beam epitaxy. At low doping, the material exhibits a dispersive lower Hubbard band typical of other cuprate parent compounds. As carriers are added to the system, a continuous evolution from Mott insulator to superconducting metal is observed as a coherent low-energy band develops on top of a concomitant remnant lower Hubbard band, gradually filling in the Mott gap. For chi = 0.10, our results reveal a strong coupling between electrons and (pi,pi) anti-ferromagnetism, inducing a Fermi surface reconstruction that pushes the nodal states below the Fermi level and realizing nodeless superconductivity. Electron diffraction measurements indicate the presence of a surface reconstruction that is consistent with the polar nature of Sr1-chiLachiCuO2. Most knowledge about the electron-doped side of the cuprate phase diagram has been deduced by generalizing from a single material family, Re2-chi CechiCuO4, where robust antiferromagnetism has been observed past chi �

New world of Gossamer superconductivity

Energy Technology Data Exchange (ETDEWEB)

Maki, Kazumi; Haas, Stephan; Parker, David [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-0484 (United States); Won, Hyekyung [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Str. 38, 01187, Dresden (Germany); Department of Physics, Hallym University, Chuncheon 200-702 (Korea); Dora, Balazs; Virosztek, Attila [Department of Physics, Budapest University of Technology and Economics, 1521 Budapest (Hungary)

2006-09-15

Since the discovery of the high-T {sub c} cuprate superconductor La{sub 2-x}BaCuO{sub 4} in 1986 by Bednorz and Mueller, controversy regarding the nature or origin of this remarkable superconductivity has continued. However, d-wave superconductivity in the hole-doped cuprates, arising due to the anti-paramagnon exchange, was established around 1994. More recently we have shown that the mean field theory, like the BCS theory of superconductivity and Landau's Fermi liquid theory are adequate to describe the cuprates. The keys for this development are the facts that a) the pseudogap phase is d-wave density wave (dDW) and that the high-T{sub c} cuprate superconductivity is gossamer (i.e. it exists in the presence of dDW). (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Minimizing the regrets of long-term urban floodplain management decisions under deeply uncertain climate change

Science.gov (United States)

Hecht, J. S.; Kirshen, P. H.; Vogel, R. M.

2016-12-01

Making long-term floodplain management decisions under uncertain climate change is a major urban planning challenge of the 21stcentury. To support these efforts, we introduce a screening-level optimization model that identifies adaptation portfolios by minimizing the regrets associated with their flood-control and damage costs under different climate change trajectories that are deeply uncertain, i.e. have probabilities that cannot be specified plausibly. This mixed integer program explicitly considers the coupled damage-reduction impacts of different floodwall designs and property-scale investments (first-floor elevation, wet floodproofing of basements, permanent retreat and insurance), recommends implementation schedules, and assesses impacts to stakeholders residing in three types of homes. An application to a stylized municipality illuminates many nonlinear system dynamics stemming from large fixed capital costs, infrastructure design thresholds, and discharge-depth-damage relationships. If stakeholders tolerate mild damage, floodwalls that fully protect a community from large design events are less cost-effective than portfolios featuring both smaller floodwalls and property-scale measures. Potential losses of property tax revenue from permanent retreat motivate municipal property-tax initiatives for adaptation financing. Yet, insurance incentives for first-floor elevation may discourage locally financed floodwalls, in turn making lower-income residents more vulnerable to severe flooding. A budget constraint analysis underscores the benefits of flexible floodwall designs with low incremental expansion costs while near-optimal solutions demonstrate the scheduling flexibility of many property-scale measures. Finally, an equity analysis shows the importance of evaluating the overpayment and under-design regrets of recommended adaptation portfolios for each stakeholder and contrasts them to single-scenario model results.

Theoretical studies of unconventional superconductors

Energy Technology Data Exchange (ETDEWEB)

Groensleth, Martin Sigurd

2008-07-01

This thesis presents four research papers. In the first three papers we have derived analytical results for the transport properties in unconventional superconductors and ferromagnetic systems with multiple broken symmetries. In Paper I and parts of Paper II we have studied tunneling transport between two non-unitary ferromagnetic spin-triplet superconductors, and found a novel interplay between ferromagnetism and superconductivity manifested in the Josephson effect as a spin- and charge-current in the absence of an applied voltage across the junction. The critical amplitudes of these currents can be adjusted by the relative magnetization direction on each side of the junction. Furthermore, in Paper II, we have found a way of controlling a spin-current between two ferromagnets with spin-orbit coupling. Paper III considers a junction consisting of a ferromagnet and a non-unitary ferromagnetic superconductor, and we show that the conductance spectra contains detailed information about the superconducting gaps and pairing symmetry of the Cooper-pairs. In the last paper we present a Monte Carlo study of an effective Hamiltonian describing orbital currents in the CuO2 layers of high-temperature superconductive cuprates. The model features two intrinsically anisotropic Ising models, coupled through an anisotropic next-nearest neighbor interaction, and an Ashkin-Teller nearest neighbor fourth order coupling. We have studied the specific heat anomaly, as well as the anomaly in the staggered magnetization associated with the orbital currents and its susceptibility. We have found that in a limited parameter regime, the specific heat anomaly is substantially suppressed, while the susceptibility has a non-analytical peak across the order-disorder transition. The model is therefore a candidate for describing the breakup of hidden order when crossing the pseudo-gap line on the under-doped side in the phase diagram of high-temperature superconductors. (Author) 64 refs., figs

Microscopic calculation of the form factors for deeply inelastic heavy-ion collisions within the statistical model

International Nuclear Information System (INIS)

Barrett, B.R.; Shlomo, S.; Weidenmueller, H.A.

1978-01-01

Agassi, Ko, and Weidenmueller have recently developed a transport theory of deeply inelastic heavy-ion collisions based on a random-matrix model. In this work it was assumed that the reduced form factors, which couple the relative motion with the intrinsic excitation of either fragment, represent a Gaussian stochastic process with zero mean and a second moment characterized by a few parameters. In the present paper, we give a justification of the statistical assumptions of Agassi, Ko, and Weidenmueller and of the form of the second moment assumed in their work, and calculate the input parameters of their model for two cases: 40 Ar on 208 Pb and 40 Ar on 120 Sn. We find values for the strength, correlation length, and angular momentum dependence of the second moment, which are consistent with those estimated by Agassi, Ko, and Weidenmueller. We consider only inelastic excitations (no nucleon transfer) caused by the penetration of the single-particle potential well of the light ion into the mass distribution of the heavy one. This is combined with a random-matrix model for the high-lying excited states of the heavy ion. As a result we find formulas which relate simply to those of Agassi, Ko, and Weidenmueller, and which can be evaluated numerically, yielding the results mentioned above. Our results also indicate for which distances of closest approach the Agassi-Ko-Weidenmueller theory breaks down

Deeply virtual Compton scattering in the Hall A of Jefferson laboratory; Diffusion Compton profondement virtuelle dans le Hall A au Jefferson laboratory

Energy Technology Data Exchange (ETDEWEB)

Munoz Camacho, C

2005-12-15

Generalized Parton Distributions (GPDs), introduced in the late 90's, provide a universal description of hadrons in terms of the underlying degrees of freedom of Quantum Chromodynamics: quarks and gluons. GPDs appear in a wide variety of hard exclusive reactions and the advent of high luminosity accelerator facilities has made the study of GPDs accessible to experiment. Deeply Virtual Compton Scattering (DVCS) is the golden process involving GPDs. The first dedicated DVCS experiment ran in the Hall A of Jefferson Lab in Fall 2004. An electromagnetic calorimeter and a plastic scintillator detector were constructed for this experiment, together with specific electronics and acquisition system. The experiment preparation, data taking and analysis are described in this document. Results on the absolute cross section difference for opposite beam helicities provide the first measurement of a linear combination of GPDs as a function of the momentum transfer to the nucleon. (author)

Study of angular momentum transfer from sequential fission in deeply inelastic collisions 40Ar-209Bi at 255 MeV

International Nuclear Information System (INIS)

Le Brun, C.; Lecolley, J.F.; Lefebvres, F.; L'Haridon, M.; Osmont, A.; Patry, J.P.; Steckmeyer, J.C.; Chechik, R.; Guilbault, F.

We have measured the angular distribution of the target-like reaction product fission fragments emitted in coincidence with the light projectile like reaction product. For the first time, a sequential fission experiment in deeply inelastic collisions has observed an increase of the width of the out of plane angular distributions with the in-plane angle phi. The in-plane distribution exhibits an anisotropy centered in the recoil direction of the heavy fissionning nucleus, and shows up a dealignment mechanism of the transferred angular comparatively to the normal to the reaction plane. The de-aligned spin components have a gaussian distribution with a r.m.s width of about 10h and are lying preferentially in a plane perpendicular to the recoil direction. The mean value of the aligned component is of about 45h in agreement with the sticking limit with deformed nuclei. The dependence of the target-like reaction product fission probabilities on the total kinetic energy loss and Z of the projectile-like reaction product have been measured [fr

VISTA Stares Deeply into the Blue Lagoon

Science.gov (United States)

2011-01-01

This new infrared image of the Lagoon Nebula was captured as part of a five-year study of the Milky Way using ESO's VISTA telescope at the Paranal Observatory in Chile. This is a small piece of a much larger image of the region surrounding the nebula, which is, in turn, only one part of a huge survey. Astronomers are currently using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) to scour the Milky Way's central regions for variable objects and map its structure in greater detail than ever before. This huge survey is called VISTA Variables in the Via Lactea (VVV) [1]. The new infrared image presented here was taken as part of this survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8, see eso0936), which lies about 4000-5000 light-years away in the constellation of Sagittarius (the Archer). Infrared observations allow astronomers to peer behind the veil of dust that prevents them from seeing celestial objects in visible light. This is because visible light, which has a wavelength that is about the same size as the dust particles, is strongly scattered, but the longer wavelength infrared light can pass through the dust largely unscathed. VISTA, with its 4.1-metre diameter mirror - the largest survey telescope in the world - is dedicated to surveying large areas of the sky at near-infrared wavelengths deeply and quickly. It is therefore ideally suited to studying star birth. Stars typically form in large molecular clouds of gas and dust, which collapse under their own weight. The Lagoon Nebula, however, is also home to a number of much more compact regions of collapsing gas and dust, called Bok globules [2]. These dark clouds are so dense that, even in the infrared, they can block the starlight from background stars. But the most famous dark feature in the nebula, for which it is named, is the lagoon-shaped dust lane that winds its way through the glowing cloud of gas. Hot, young stars, which give off intense

Thermodynamic efficiency analysis and cycle optimization of deeply precooled combined cycle engine in the air-breathing mode

Science.gov (United States)

Zhang, Jianqiang; Wang, Zhenguo; Li, Qinglian

2017-09-01

The efficiency calculation and cycle optimization were carried out for the Synergistic Air-Breathing Rocket Engine (SABRE) with deeply precooled combined cycle. A component-level model was developed for the engine, and exergy efficiency analysis based on the model was carried out. The methods to improve cycle efficiency have been proposed. The results indicate cycle efficiency of SABRE is between 29.7% and 41.7% along the flight trajectory, and most of the wasted exergy is occupied by the unburned hydrogen in exit gas. Exergy loss exists in each engine component, and the sum losses of main combustion chamber(CC), pre-burner(PB), precooler(PC) and 3# heat exchanger(HX3) are greater than 71.3% of the total loss. Equivalence ratio is the main influencing factor of cycle, and it can be regulated by adjusting parameters of helium loop. Increase the maximum helium outlet temperature of PC by 50 K, the total assumption of hydrogen will be saved by 4.8%, and the cycle efficiency is advanced by 3% averagely in the trajectory. Helium recirculation scheme introduces a helium recirculation loop to increase local helium flow rate of PC. It turns out the total assumption of hydrogen will be saved by 9%, that's about 1740 kg, and the cycle efficiency is advanced by 5.6% averagely.

Theoretical analysis and simulation study of low-power CMOS electrochemical impedance spectroscopy biosensor in 55 nm deeply depleted channel technology for cell-state monitoring

Science.gov (United States)

Itakura, Keisuke; Kayano, Keisuke; Nakazato, Kazuo; Niitsu, Kiichi

2018-01-01

We present an impedance-detection complementary metal oxide semiconductor (CMOS) biosensor circuit for cell-state observation. The proposed biosensor can measure the expected impedance values encountered by a cell-state observation measurement system within a 0.1-200 MHz frequency range. The proposed device is capable of monitoring the intracellular conditions necessary for real-time cell-state observation, and can be fabricated using a 55 nm deeply depleted channel CMOS process. Operation of the biosensor circuit with 0.9 and 1.7 V supply voltages is verified via a simulated program with integrated circuit emphasis (SPICE) simulation. The power consumption is 300 µW. Further, the standby power consumption is 290 µW, indicating that this biosensor is a low-power instrument suitable for use in Internet of Things (IoT) devices.

In situ deposition of thallium-containing oxides

International Nuclear Information System (INIS)

Myers, K.E.

1996-01-01

The number and variety of thallium based materials that can be made by in situ methods have grown consistently since the first report of successful thallium cuprate deposition by Face and Nestlerode in 1992. Processes for the deposition of superconductors, normal metals, and insulators have been developed. Most work to date has been done on the Tl-1212 phases, TlBa 2 CaCu 2 O 7 and (Tl,Pb)Sr 2 CaCu 2 O 7 . Recently however, the in situ thallium technique has been extended to other materials. For example, epitaxial thin films of thallium tantalate, an insulator of the pyrochlore structure and a potential buffer layer for thallium cuprate films, have been grown. Multilayers, important in the fabrication of Josephson junctions, have been demonstrated with the thallium lead cuprates. This paper reviews progress in the area of in situ thallium deposition technology which will make more complex thallium cuprate multilayer structures and devices possible