Spin, charge, and orbital orderings in iron-based superconductors
Institute of Scientific and Technical Information of China (English)
Jiang Qing; Kang Yao-Tai; Yao Dao-Xin
2013-01-01
In this article,we briefly review spin,charge,and orbital orderings in iron-based superconductors,as well as the multi-orbital models.The interplay of spin,charge,and orbital orderings is a key to understand the high temperature superconductivity.As an illustration,we use the two-orbital model to show the spin and charge orderings in iron-based superconductors based on the mean-field approximation in real space.The typical spin and charge orderings are shown by choosing appropriate parameters,which are in good agreement with experiments.We also show the effect of Fe vacancies,which can introduce the nematic phase and interesting magnetic ground states.The orbital ordering is also discussed in iron-based superconductors.It is found that disorder may play a role to produce the superconductivity.
Charge Order Induced in an Orbital Density-Wave State
Singh, Dheeraj Kumar; Takimoto, Tetsuya
2016-04-01
Motivated by recent angle resolved photoemission measurements [D. V. Evtushinsky et al., Phys. Rev. Lett. 105, 147201 (2010)] and evidence of the density-wave state for the charge and orbital ordering [J. García et al., Phys. Rev. Lett. 109, 107202 (2012)] in La0.5Sr1.5MnO4, the issue of charge and orbital ordering in a two-orbital tight-binding model for layered manganite near half doping is revisited. We find that the charge order with the ordering wavevector 2{Q} = (π ,π ) is induced by the orbital order of d-/d+-type having B1g representation with a different ordering wavevector Q, where the orbital order as the primary order results from the strong Fermi-surface nesting. It is shown that the induced charge order parameter develops according to TCO - T by decreasing the temperature below the orbital ordering temperature TCO, in addition to the usual mean-field behavior of the orbital order parameter. Moreover, the same orbital order is found to stabilize the CE-type spin arrangement observed experimentally below TCE < TCO.
Charge-ordering cascade with spin-orbit Mott dimer states in metallic iridium ditelluride.
Ko, K-T; Lee, H-H; Kim, D-H; Yang, J-J; Cheong, S-W; Eom, M J; Kim, J S; Gammag, R; Kim, K-S; Kim, H-S; Kim, T-H; Yeom, H-W; Koo, T-Y; Kim, H-D; Park, J-H
2015-01-01
Spin-orbit coupling results in technologically-crucial phenomena underlying magnetic devices like magnetic memories and energy-efficient motors. In heavy element materials, the strength of spin-orbit coupling becomes large to affect the overall electronic nature and induces novel states such as topological insulators and spin-orbit-integrated Mott states. Here we report an unprecedented charge-ordering cascade in IrTe2 without the loss of metallicity, which involves localized spin-orbit Mott states with diamagnetic Ir(4+)-Ir(4+) dimers. The cascade in cooling, uncompensated in heating, consists of first order-type consecutive transitions from a pure Ir(3+) phase to Ir(3+)-Ir(4+) charge-ordered phases, which originate from Ir 5d to Te 5p charge transfer involving anionic polymeric bond breaking. Considering that the system exhibits superconductivity with suppression of the charge order by doping, analogously to cuprates, these results provide a new electronic paradigm of localized charge-ordered states interacting with itinerant electrons through large spin-orbit coupling. PMID:26059464
Charge order from orbital-dependent coupling evidenced by NbSe2.
Flicker, Felix; van Wezel, Jasper
2015-01-01
Niobium diselenide has long served as a prototype of two-dimensional charge ordering, believed to arise from an instability of the electronic structure analogous to the one-dimensional Peierls mechanism. Despite this, various anomalous properties have recently been identified experimentally, which cannot be explained by Peierls-like weak-coupling theories. Here, we consider instead a model with strong electron-phonon coupling, taking into account both the full momentum and orbital dependence of the coupling matrix elements. We show that both are necessary for a consistent description of the full range of experimental observations. We argue that NbSe2 is typical in this sense, and that any charge-ordered material in more than one dimension will generically be shaped by the momentum and orbital dependence of its electron-phonon coupling as well as its electronic structure. The consequences will be observable in many charge-ordered materials, including cuprate superconductors. PMID:25948390
Staircase effect in metamagnetic transitions of charge and orbitally ordered manganites
International Nuclear Information System (INIS)
This paper reports on peculiar metamagnetic transitions which take place in antiferromagnetic, charge and orbitally ordered manganites. At very low temperatures, the virgin magnetization curves of some of these compounds exhibit several, sharp steps giving rise to a staircase-like shape. This staircase effect is shown to be sensitive to various experimental parameters. Several potential interpretations of the staircase effect are discussed in relation to this set of results. A martensitic-like scenario, involving a leading role of the structural distortions associated to the collapse of the orbital ordering, is found to be the most plausible interpretation
RESONANT X-RAY SCATTERING AS A PROBE OF ORBITAL AND CHARGE ORDERING
International Nuclear Information System (INIS)
Resonant x-ray scattering is a powerful experimental technique for probing orbital and charge ordering. It involves tuning the incident photon energy to an absorption edge of the relevant ion and observing scattering at previously 'forbidden' Bragg peaks, and it allows high-resolution, quantitative studies of orbital and charge order--even from small samples. Further, resonant x-ray scattering from orbitally ordered systems exhibits polarization- and azimuthal-dependent properties that provide additional information about the details of the orbital order that is difficult, or impossible, to obtain with any other technique. In the manganites, the sensitivity to charge and orbital ordering is enhanced when the incident photon energy is tuned near the Mn K absorption edge (6.539 keV), which is the lowest energy at which a 1s electron can be excited into an unoccupied state. In this process, the core electron is promoted to an intermediate excited state, which decays with the emission of a photon. The sensitivity to charge ordering is believed to be due to the small difference in K absorption edges of the Mn3+ and Mn4+ sites. For orbital ordering, the sensitivity arises from a splitting--or difference in the weight of the density of states [239]--of the orbitals occupied by the excited electron in the intermediate state. In the absence of such a splitting, there is no resonant enhancement of the scattering intensity. In principle, other absorption edges in which the intermediate state is anisotropic could be utilized, but the strong dipole transition to the Mn 4p levels--and their convenient energies for x-ray diffraction--make the K edge well-suited to studies of manganites. The Mn 4p levels are affected by the symmetry of the orbital ordering, which makes the technique sensitive to the orbital degree of freedom. Therefore resonant x-ray scattering can be used to obtain important quantitative information concerning the details of this electronic order. Two mechanisms
Intramolecular charge ordering in the multi molecular orbital system (TTM-TTP)I3
Bonnet, Marie-Laure; Robert, Vincent; Tsuchiizu, Masahisa; Omori, Yukiko; Suzumura, Yoshikazu
2010-06-01
Starting from the structure of the (TTM-TTP)I3 molecular-based material, we examine the characteristics of frontier molecular orbitals using ab initio (CASSCF/CASPT2) configurations interaction calculations. It is shown that the singly occupied and second-highest-occupied molecular orbitals are close to each other, i.e., this compound should be regarded as a two-orbital system. By dividing virtually the [TTM-TTP] molecule into three fragments, an effective model is constructed to rationalize the origin of this picture. In order to investigate the low-temperature, symmetry breaking experimentally observed in the crystal, the electronic distribution in a pair of [TTM-TTP] molecules is analyzed from CASPT2 calculations. Our inspection supports and explains the speculated intramolecular charge ordering which is likely to give rise to low-energy magnetic properties.
SHVETS, IGOR
2013-01-01
PUBLISHED Charge-orbital ordering is commonly present in complex transition metal oxides and offers interesting opportunities for novel electronic devices. In this work, we demonstrate for the first time that the magnetization states of the spin valve can be directly manipulated by charge-orbital ordering. We investigate the interlayer exchange coupling (IEC) between two epitaxial magnetite layers separated by a nonmagnetic epitaxial MgO dielectric. We find that the state of the charge-orb...
Charge, spin and orbital order in the candidate multiferroic material LuFe2O4
International Nuclear Information System (INIS)
This thesis is a detailed study of the magnetic, structural and orbital order parameters of the candidate multiferroic material LuFe2O4. Multiferroic oxides with a strong magnetoelectric coupling are of high interest for potential information technology applications, but they are rare because the traditional mechanism of ferroelectricity is incompatible with magnetism. Consequently, much attention is focused on various unconventional mechanisms of ferroelectricity. Of these, ferroelectricity originating from charge ordering (CO) is particularly intriguing because it potentially combines large electric polarizations with strong magneto-electric coupling. However, examples of oxides where this mechanism occurs are exceedingly rare and none is really well understood. LuFe2O4 is often cited as the prototypical example of CO-based ferroelectricity. In this material, the order of Fe valences has been proposed to render the triangular Fe/O bilayers polar by making one of the two layers rich in Fe2+ and the other rich in Fe3+, allowing for a possible ferroelectric stacking of the individual bilayers. Because of this new mechanism for ferroelectricity, and also because of the high transition temperatures of charge order (TCO ∝320K) and ferro magnetism (TN∝240 K) LuFe2O4 has recently attracted increasing attention. Although these polar bilayers are generally accepted in the literature for LuFe2O4, direct proof is lacking. An assumption-free experimental determination of whether or not the CO in the Fe/O bilayers is polar would be crucial, given the dependence of the proposed mechanism of ferroelectricity from CO in LuFe2O4 on polar bilayers. This thesis starts with a detailed characterization of the macroscopic magnetic properties, where growing ferrimagnetic contributions observed in magnetization could be ascribed to increasing oxygen off-stoichiometry. The main focus is on samples exhibiting a sharp magnetic transition to long-range spin order at TN∝240 K
Charge, orbital and magnetic ordering in La0.4Sr1.6MnO4
International Nuclear Information System (INIS)
The coupled ordering of charge orbital and spin (COS) degrees of freedom in the manganites constitutes a key element to understand the mechanism of CMR. 214 manganites are well-suited to study the COS state. The COS state of the half-doped layered material La0.5Sr1.5MnO4 can be described by the Goodenough model. The over-doped La0.4Sr1.6MnO4 consists of 60% Mn4+ ions and 40% Mn3+ ions. Consequently there is no optimal checkerboard charge ordering possible. We suggest to put these excess of Mn4+ ions into stripes cutting the zig-zag chains. Investigations by neutron scattering emphasize this idea as incommensurable superstructure reflections of charges and orbitals could be found. The reflections of the magnetic ordering of Mn3+ are incommensurable as well, while the magnetic ordering of Mn4+ yields scattering at commensurable positions. Stripe-like arrangement of Mn4+ ions are similar to the stripe phases in nickelates and cuprates. The order, however, is quite complex involving incommensurate ordering of orbitals, charges and Mn3+-magnetic moments.
Uchida, M; Akahoshi, D; Kumai, R; Tomioka, Y; Tokura, Y; Arima, T H
2002-01-01
In an A-site ordered perovskite manganite Sm sub 1 sub / sub 2 Ba sub 1 sub / sub 2 MnO sub 3 , a new charge/orbital ordering pattern was found at room temperature. Electron diffraction studies revealed a series of superlattice reflections with modulation vectors at q sub 2 =(1/2, 1/2, 1/2) as well as at q sub 1 =(1/4, 1/4, 0) in the tetragonal setting (a sub p x a sub p x 2a sub p , a sub p being the cubic perovskite lattice parameter). Together with the results of the resonant X-ray scattering and the charge-transport and magnetization measurements, a new model for the three-dimensional charge/orbital ordering in the ordered perovskite is proposed. (author)
Re-examination of charge and orbital ordering in lightly doped La1-xSrxMnO3 by X-ray scattering
International Nuclear Information System (INIS)
We report on the new synchrotron X-ray scattering results from the re-investigation of charge and orbital ordering in lightly doped La1-xSrxMnO3. The resonant X-ray scattering from forbidden Bragg reflections was observed not only in the ferromagnetic insulating phase, but also in strongly Jahn-Teller distorted regime. Some of characteristic superstructure reflections were also found to show a clear resonant behavior at the Mn K absorption edge. It can be argued that the exact pattern of charge and orbital ordering should be much more complicated
Kuepper, K.; Raekers, M.; Taubitz, C.; Prinz, M.; Derks, C.; Neumann, M.; Postnikov, A. V.; de Groot, F. M. F.; Piamonteze, C.; Prabhakaran, D.; Blundell, S. J.
2009-01-01
Electronic and magnetic properties of the charge ordered phase of LuFe2O4 are investigated by means of x-ray spectroscopic and theoretical electronic structure approaches. LuFe2O4 is a compound showing fascinating magnetoelectric coupling via charge ordering. Here, we identify the spin ground state
Charge, spin and orbital order in the candidate multiferroic material LuFe{sub 2}O{sub 4}
Energy Technology Data Exchange (ETDEWEB)
Groot, Joost de
2012-06-28
This thesis is a detailed study of the magnetic, structural and orbital order parameters of the candidate multiferroic material LuFe{sub 2}O{sub 4}. Multiferroic oxides with a strong magnetoelectric coupling are of high interest for potential information technology applications, but they are rare because the traditional mechanism of ferroelectricity is incompatible with magnetism. Consequently, much attention is focused on various unconventional mechanisms of ferroelectricity. Of these, ferroelectricity originating from charge ordering (CO) is particularly intriguing because it potentially combines large electric polarizations with strong magneto-electric coupling. However, examples of oxides where this mechanism occurs are exceedingly rare and none is really well understood. LuFe{sub 2}O{sub 4} is often cited as the prototypical example of CO-based ferroelectricity. In this material, the order of Fe valences has been proposed to render the triangular Fe/O bilayers polar by making one of the two layers rich in Fe{sup 2+} and the other rich in Fe{sup 3+}, allowing for a possible ferroelectric stacking of the individual bilayers. Because of this new mechanism for ferroelectricity, and also because of the high transition temperatures of charge order (T{sub CO} {proportional_to}320K) and ferro magnetism (T{sub N}{proportional_to}240 K) LuFe{sub 2}O{sub 4} has recently attracted increasing attention. Although these polar bilayers are generally accepted in the literature for LuFe{sub 2}O{sub 4}, direct proof is lacking. An assumption-free experimental determination of whether or not the CO in the Fe/O bilayers is polar would be crucial, given the dependence of the proposed mechanism of ferroelectricity from CO in LuFe{sub 2}O{sub 4} on polar bilayers. This thesis starts with a detailed characterization of the macroscopic magnetic properties, where growing ferrimagnetic contributions observed in magnetization could be ascribed to increasing oxygen off-stoichiometry. The
Epitaxial-strain effect on charge/orbital order in Pr0.5Ca0.5MnO3 films
Okuyama, D.; Nakamura, M.; Wakabayashi, Y.; Itoh, H.; Kumai, R.; Yamada, H.; TAGUCHI, Y.; Arima, T.; M. Kawasaki; Tokura, Y.
2009-01-01
Effect of growth orientation on charge- and orbital-ordering (CO-OO) phenomena has been studied for Pr0.5Ca0.5MnO3 epitaxial thin films fabricated on (LaAlO3)0.3-(SrAl0.5Ta0.5O3)0.7 (LSAT) substrates by means of resistivity, synchrotron x-ray diffraction, and polarized optical microscopy measurements. CO-OO transition is observed around 220 K for a film grown on an LSAT (011) substrate ((011)-film), similarly to a bulk sample, while a film grown on a (001) plane of LSAT ((001)-film) shows muc...
Charge states of ions, and mechanisms of charge ordering transitions
International Nuclear Information System (INIS)
To gain insight into the mechanism of charge ordering transitions, which conventionally are pictured as a disproportionation of an ion M as 2Mn+→M(n+1)+ + M(n−1)+, we (1) review and reconsider the charge state (or oxidation number) picture itself, (2) introduce new results for the putative charge ordering compound AgNiO2 and the dual charge state insulator AgO, and (3) analyze the cationic occupations of the actual (not formal) charge, and work to reconcile the conundrums that arise. We establish that several of the clearest cases of charge ordering transitions involve no disproportion (no charge transfer between the cations, and hence no charge ordering), and that the experimental data used to support charge ordering can be accounted for within density functional-based calculations that contain no charge transfer between cations. We propose that the charge state picture retains meaning and importance, at least in many cases, if one focuses on Wannier functions rather than atomic orbitals. The challenge of modeling charge ordering transitions with model Hamiltonians isdiscussed. (paper)
Rational Orbits around Charged Black Holes
Misra, Vedant
2010-01-01
We show that all eccentric timelike orbits in Reissner-Nordstr\\"{o}m spacetime can be classified using a taxonomy that draws upon an isomorphism between periodic orbits and the set of rational numbers. By virtue of the fact that the rationals are dense, the taxonomy can be used to approximate aperiodic orbits with periodic orbits. This may help reduce computational overhead for calculations in gravitational wave astronomy. Our dynamical systems approach enables us to study orbits for both charged and uncharged particles in spite of the fact that charged particle orbits around a charged black hole do not admit a simple one-dimensional effective potential description. Finally, we show that comparing periodic orbits in the RN and Schwarzschild geometries enables us to distinguish charged and uncharged spacetimes by looking only at the orbital dynamics.
Engineering charge ordering into multiferroicity
He, Xu; Jin, Kui-juan
2016-01-01
Multiferroic materials have attracted great interests but are rare in nature. In many transitional metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superla...
Energy Technology Data Exchange (ETDEWEB)
Su, Y. E-mail: y.su@fz-juelich.de; Istomin, K.; Wermeille, D.; Fattah, A.; Foucart, P.; Meuffels, P.; Hupfeld, D.; Brueckel, Th
2004-05-01
We report on the new synchrotron X-ray scattering results from the re-investigation of charge and orbital ordering in lightly doped La{sub 1-x}Sr{sub x}MnO{sub 3}. The resonant X-ray scattering from forbidden Bragg reflections was observed not only in the ferromagnetic insulating phase, but also in strongly Jahn-Teller distorted regime. Some of characteristic superstructure reflections were also found to show a clear resonant behavior at the Mn K absorption edge. It can be argued that the exact pattern of charge and orbital ordering should be much more complicated.
Symmetry of charge order in cuprates
Comin, R.; Sutarto, R.; He, F.; da Silva Neto, E. H.; Chauviere, L.; Fraño, A.; Liang, R.; Hardy, W. N.; Bonn, D. A.; Yoshida, Y.; Eisaki, H.; Achkar, A. J.; Hawthorn, D. G.; Keimer, B.; Sawatzky, G. A.; Damascelli, A.
2015-08-01
Charge-ordered ground states permeate the phenomenology of 3d-based transition metal oxides, and more generally represent a distinctive hallmark of strongly correlated states of matter. The recent discovery of charge order in various cuprate families has fuelled new interest into the role played by this incipient broken symmetry within the complex phase diagram of high-Tc superconductors. Here, we use resonant X-ray scattering to resolve the main characteristics of the charge-modulated state in two cuprate families: Bi2Sr2-xLaxCuO6+δ (Bi2201) and YBa2Cu3O6+y (YBCO). We detect no signatures of spatial modulations along the nodal direction in Bi2201, thus clarifying the inter-unit-cell momentum structure of charge order. We also resolve the intra-unit-cell symmetry of the charge-ordered state, which is revealed to be best represented by a bond order with modulated charges on the O-2p orbitals and a prominent d-wave character. These results provide insights into the origin and microscopic description of charge order in cuprates, and its interplay with superconductivity.
Engineering charge ordering into multiferroicity
He, Xu; Jin, Kui-juan
2016-04-01
Multiferroic materials have attracted great interest but are rare in nature. In many transition-metal oxides, charge ordering and magnetic ordering coexist, so that a method of engineering charge-ordered materials into ferroelectric materials would lead to a large class of multiferroic materials. We propose a strategy for designing new ferroelectric or even multiferroic materials by inserting a spacing layer into each two layers of charge-ordered materials and artificially making a superlattice. One example of the model demonstrated here is the perovskite (LaFeO3)2/LaTiO3 (111) superlattice, in which the LaTiO3 layer acts as the donor and the spacing layer, and the LaFeO3 layer is half doped and performs charge ordering. The collaboration of the charge ordering and the spacing layer breaks the space inversion symmetry, resulting in a large ferroelectric polarization. As the charge ordering also leads to a ferrimagnetic structure, (LaFeO3)2/LaTiO3 is multiferroic. It is expected that this work can encourage the designing and experimental implementation of a large class of multiferroic structures with novel properties.
Orbital symmetry of charge-density-wave order in La1.875Ba0.125CuO4 and YBa2Cu3O6.67
Achkar, A. J.; He, F.; Sutarto, R.; McMahon, Christopher; Zwiebler, M.; Hücker, M.; Gu, G. D.; Liang, Ruixing; Bonn, D. A.; Hardy, W. N.; Geck, J.; Hawthorn, D. G.
2016-06-01
Recent theories of charge-density-wave (CDW) order in high-temperature superconductors have predicted a primarily d CDW orbital symmetry. Here, we report on the orbital symmetry of CDW order in the canonical cuprate superconductors La1.875Ba0.125CuO4 (LBCO) and YBa2Cu3O6.67 (YBCO), using resonant soft X-ray scattering and a model mapped to the CDW orbital symmetry. From measurements sensitive to the O sublattice, we conclude that LBCO has predominantly s' CDW orbital symmetry, in contrast to the d orbital symmetry recently reported in other cuprates. Furthermore, we show for YBCO that the CDW orbital symmetry differs along the a and b crystal axes and that these both differ from LBCO. This work highlights CDW orbital symmetry as an additional key property that distinguishes the different cuprate families. We discuss how the CDW symmetry may be related to the `1/8-anomaly’ and to static spin ordering.
Electromagnetic effects on the orbital motion of a charged spacecraft
Abdel-Aziz, Yehia Ahmed; Khalil, Khalil Ibrahim
2014-05-01
This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth's magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft's orbits. Lagrange's planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numerical results of Lagrange's planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturbation for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft.
Electromagnetic effects on the orbital motion of a charged spacecraft
International Nuclear Information System (INIS)
This paper deals with the effects of electromagnetic forces on the orbital motion of a spacecraft. The electrostatic charge which a spacecraft generates on its surface in the Earth's magnetic field will be subject to a perturbative Lorentz force. A model incorporating all Lorentz forces as a function of orbital elements has been developed on the basis of magnetic and electric fields. This Lorentz force can be used to modify or perturb the spacecraft's orbits. Lagrange's planetary equations in the Gauss variational form are derived using the Lorentz force as a perturbation to a Keplerian orbit. Our approach incorporates orbital inclination and the true anomaly. The numerical results of Lagrange's planetary equations for some operational satellites show that the perturbation in the orbital elements of the spacecraft is a second order perturbation for a certain value of charge. The effect of the Lorentz force due to its magnetic component is three times that of the Lorentz force due to its electric component. In addition, the numerical results confirm that the strong effects are due to the Lorentz force in a polar orbit, which is consistent with realistic physical phenomena that occur in polar orbits. The results confirm that the magnitude of the Lorentz force depends on the amount of charge. This means that we can use artificial charging to create a force to control the attitude and orbital motion of a spacecraft
Two-Centered Magical Charge Orbits
Andrianopoli, Laura; Ferrara, Sergio; Marrani, Alessio; Trigiante, Mario
2011-01-01
We determine the two-centered generic charge orbits of magical N = 2 and maximal N = 8 supergravity theories in four dimensions. These orbits are classified by seven U-duality invariant polynomials, which group together into four invariants under the horizontal symmetry group SL(2,R). These latter are expected to disentangle different physical properties of the two-centered black-hole system. The invariant with the lowest degree in charges is the symplectic product (Q1,Q2), known to control the mutual non-locality of the two centers.
Orbital Ordering Induced by Direct Coulomb Repulsion
Institute of Scientific and Technical Information of China (English)
HUANG Yuan-Yie; ZHANG Yu-Heng
2011-01-01
We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering (OO) based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction (OO-I) between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.
Charge order and phase segregation in overdoped bilayer manganites
Energy Technology Data Exchange (ETDEWEB)
Maitra, T [Institut fuer Theoretische Physik, J W Goethe Universitaet, Max-von-Laue-Strasse 1, 60438 Frankfurt (Germany); Taraphder, A [Department of Physics and Meteorology and Centre for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302 (India); Beck, H [Institute of Physics, University of Neuchatel, rue de Breguet 1, CH-2000 (Switzerland)
2005-07-13
There have been recent reports of charge ordering around x = 0.5 in the bilayer manganites like La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7}. At x = 0.5, there appears to be a coexistence region of layered A-type antiferromagnetic order and charge order. There are also reports of orbital order in this region without any Jahn-Teller effect. Based on physical grounds, this region is investigated from a model that incorporates the two e{sub g} orbitals at each Mn site and a near-neighbour Coulomb repulsion. It is shown that there indeed both charge and orbital order close to the half-doped region coincident with a layered magnetic structure. Although the orbital order is known to drive the magnetic order, the layered magnetic structure is also favoured in this system by the lack of coherent transport across the planes and the reduced dimensionality of the lattice. The anisotropic hopping across the e{sub g} orbitals and the underlying layered structure largely determine the orbital arrangements in this region, while the charge order is primarily due to the long-range interactions.
The Orbit of Water Droplets around Charged Rod
Ferstl, Andrew; Burns, Andrew
2013-01-01
The motion of charges around a centrally charged object is often compared to gravitational orbits (such as satellites around planets). Recently, a video taken by astronaut Don Pettit onboard the International Space Station shows water droplets orbiting a charged knitting needle. Here we attempt to model this motion and estimate the charges on the…
Zhao, Y. Y.; Wang, J.; Hu, F. X.; Kuang, H.; Wu, R. R.; Zheng, X. Q.; Sun, J. R.; Shen, B. G.
2014-05-01
The static and dynamic lattice strain effects on the competition between ferromagnetic and charge/orbital ordering (COO) phase, phase separation (PS) and transport properties were studied in Pr0.7(Ca0.6Sr0.4)0.3MnO3 (PCSMO) films. It is found that the tensile strained films show pronounced percolative transport behaviors with increased hysteresis, indicating that the stability of the long-range COO is enhanced by the tensile strain. On the other hand, a nearly reversible insulator-metal transition was observed in the compressive strained films, suggesting a strong suppression of the long-range COO. The experiment of dynamic strain effect induced by the bias electric field further verifies the conclusion. Moreover, coactions of the ferroelectric polarization of the substrate and the dynamic strain effect on the PS were found in present PCSMO/PMN-PT film.
The search for competing charge orders in frustrated ladder systems
International Nuclear Information System (INIS)
A recent study revealed the dynamics of the charge sector of a one-dimensional quarter- filled electronic system with extended Hubbard interactions to be that of an effective pseudospin transverse-field Ising model (TFIM) in the strong coupling limit. With the twin motivations of studying the co-existing charge and spin order found in strongly correlated chain systems and the effects of inter-chain couplings, we investigate the phase diagram of coupled effective (TFIM) systems. A bosonisation and RG analysis for a two-leg TFIM ladder yields a rich phase diagram showing Wigner/Peierls charge order and Neel/dimer spin order. In a broad parameter regime, the orbital antiferromagnetic phase is found to be stable. An intermediate gapless phase of finite width is found to lie in between two charge-ordered gapped phases. Kosterlitz-Thouless transitions are found to lead from the gapless phase to either of the charge-ordered phases. Low energy effective Hamiltonian analyses of a strongly coupled 2-chain ladder system confirm a phase diagram with in-chain CO, rung-dimer, and orbital antiferromagnetic ordered phases with varying interchain couplings as well as superconductivity upon hole-doping. Our work is potentially relevant for a unified description of a class of strongly correlated, quarter-filled chain and ladder systems. (autor)
Charge order, superconducting correlations, and positive muons
Energy Technology Data Exchange (ETDEWEB)
Sonier, J.E., E-mail: jsonier@sfu.ca
2015-02-15
The recent discoveries of short-range charge-density wave order in the normal state of several hole-doped cuprate superconductors constitute a significant addition to the known intrinsic properties of these materials. Besides likely being associated with the normal-state pseudogap, the charge-density wave order presumably influences the build-up of known superconducting correlations as the temperature is lowered toward the superconducting state. As a pure magnetic probe, muon spin rotation (μ SR) is not directly sensitive to charge order, but may sense its presence via the effect it has on the magnetic dipolar coupling of the muon with the host nuclei at zero or low magnetic field. At higher field where μ SR is completely blind to the effects of charge order, experiments have revealed a universal inhomogeneous normal-state response extending to temperatures well above T{sub c}. The measured inhomogeneous line broadening has been attributed to regions of superconducting correlations that exhibit varying degrees of fluctuation diamagnetism. Here, the compatibility of these results with other measurements showing charge order correlations or superconducting fluctuations above T{sub c} is discussed. - Highlights: • Superconducting fluctuations in high-T cuprates probed by positive muons are discussed. • Superconducting fluctuations are detected at higher temperatures than by other methods. • The muon experiments indicate that the superconducting fluctuations are inhomogeneous. • The compatibility with short-range charge order in the normal state is considered.
An Investigation of Low Earth Orbit Internal Charging
NeergaardParker, Linda; Minow, Joseph I.; Willis, Emily M.
2014-01-01
Low Earth orbit is usually considered a relatively benign environment for internal charging threats due to the low flux of penetrating electrons with energies of a few MeV that are encountered over an orbit. There are configurations, however, where insulators and ungrounded conductors used on the outside of a spacecraft hull may charge when exposed to much lower energy electrons of some 100's keV in a process that is better characterized as internal charging than surface charging. For example, the minimal radiation shielding afforded by thin thermal control materials such as metalized polymer sheets (e.g., aluminized Kapton or Mylar) and multilayer insulation may allow electrons of 100's of keV to charge underlying materials. Yet these same thermal control materials protect the underlying insulators and ungrounded conductors from surface charging currents due to electrons and ions at energies less than a few keV as well as suppress the photoemission, secondary electron, and backscattered electron processes associated with surface charging. We investigate the conditions required for this low Earth orbit "internal charging" to occur and evaluate the environments for which the process may be a threat to spacecraft. First, we describe a simple one-dimensional internal charging model that is used to compute the charge accumulation on materials under thin shielding. Only the electron flux that penetrates exposed surface shielding material is considered and we treat the charge balance in underlying insulation as a parallel plate capacitor accumulating charge from the penetrating electron flux and losing charge due to conduction to a ground plane. Charge dissipation due to conduction can be neglected to consider the effects of charging an ungrounded conductor. In both cases, the potential and electric field is computed as a function of time. An additional charge loss process is introduced due to an electrostatic discharge current when the electric field reaches a
Charged dust dynamics - Orbital resonance due to planetary shadows
Horanyi, M.; Burns, J. A.
1991-01-01
The dynamics of a weakly charged dust grain orbiting in the equatorial plane of a planet surrounded by a rigidly corotating magnetospehre is examined. It is shown that an introduction of an effectilve 1D potential causes a perturbation due to electrostatic forces, which induces a motion of the pericenter, similar to the effect of the planetary oblateness. A case is examined where the charge varies periodically due to the modulation of the photoelectron current occurring as the grain enters and leaves the planetary shadow, causing the electromagnetic perturbation to resonate with the orbital period and to modify the size and eccentricity of the orbit. This effect is demonstrated both numerically and analytically for small grains comprising the Jovian ring, showing that their resulting changes are periodic, and their amplitude is much larger than that of the periodic changes due to light-pressure perturbation or the secular changes due to resonant charge variations that develop over a comparable time span.
Interaction induced staggered spin-orbit order in two-dimensional electron gas
Energy Technology Data Exchange (ETDEWEB)
Das, Tanmoy [Los Alamos National Laboratory
2012-06-05
Decoupling spin and charge transports in solids is among the many prerequisites for realizing spin electronics, spin caloritronics, and spin-Hall effect. Beyond the conventional method of generating and manipulating spin current via magnetic knob, recent advances have expanded the possibility to optical and electrical method which are controllable both internally and externally. Yet, due to the inevitable presence of charge excitations and electrical polarizibility in these methods, the separation between spin and charge degrees of freedom of electrons remains a challenge. Here we propose and formulate an interaction induced staggered spin-orbit order as a new emergent phase of matter. We show that when some form of inherent spin-splitting via Rashba-type spin-orbit coupling renders two helical Fermi surfaces to become significantly nested, a Fermi surface instability arises. To lift this degeneracy, a spontaneous symmetry breaking spin-orbit density wave develops, causing a surprisingly large quasiparticle gapping with chiral electronic states, with no active charge excitations. Since the staggered spin-orbit order is associated with a condensation energy, quantified by the gap value, destroying such spin-orbit interaction costs sufficiently large perturbation field or temperature or de-phasing time. BiAg2 surface state is shown to be a representative system for realizing such novel spin-orbit interaction with tunable and large strength, and the spin-splitting is decoupled from charge excitations.
High-order harmonic generation from eld-distorted orbitals
DEFF Research Database (Denmark)
Spiewanowski, Maciek; Etches, Adam; Madsen, Lars Bojer
We investigate the eect on high-order harmonic generation of the distortion of molecular orbitals by the driving laser eld. Calculations for high-order harmonic generation including orbital distortion are performed for N2 (high polarizability). Our results allow us to suggest that field...
Second order Born calculation for charge transfer
International Nuclear Information System (INIS)
Charge transfer cross sections, from the ground state of the target to the ground state of the projectile, have been computed in a second order Born approximation for protons incident upon hydrogen at energies of 1, 10, and 50 MeV. The exact second order matrix element is evaluated numerically, and the results are compared to a standard peaking approximation (SP), as well as to a new peaking approximation (LP) developed herein. At 50 MeV two distinct second order effects are evident in the differential cross section. For very small (center of mass) scattering angles (THETA approx. = .0320) the second order cross section is smaller than the first order cross section, while at larger angles (THETA approx. = .0540) a second Born peak occurs. This peak can be kinematically associated with a classical two step process which gives rise to the well known dominating v-11 asymptotic velocity dependence of the total cross section. The reduction of the differential cross section at smaller angles serves to decrease the total cross section, as is predicted by the asymptotic expression. At 10 MeV second order effects become less important, and at 1 MeV the kinematic peak has all but disappeared, while the second order cross section has here become larger than the first order cross section. At intermediate energies experimental results indicate that the first order cross section used here is itself too large
Ribeiro, J. L.
2016-07-01
The complex interplay between order parameters of different nature that dominates the physics of colossal magnetoresistance manganites is analysed from a symmetry based perspective. Phenomenological energies are given for the different competing phases. It is shown that the general trends observed in different systems, such as the mutual exclusion of orbital order and A-AFM order and the related stabilization of the CE-AFM order, stem to large extend from the symmetry of the parameters involved. The possible stabilization of complex phases where charge and orbital order coexist with magnetic and ferroelectric states is also anticipated.
International Nuclear Information System (INIS)
In this paper, the quasi-Keplerian parameterization for the case that spins and orbital angular momentum in a compact binary system are aligned or anti-aligned with the orbital angular momentum vector is extended to 3PN point-mass, next-to-next-to-leading order spin–orbit, next-to-next-to-leading order spin(1)–spin(2) and next-to-leading order spin-squared dynamics in the conservative regime. In a further step, we use the expressions for the radiative multipole moments with spin to leading order linear and quadratic in both spins to compute radiation losses of the orbital binding energy and angular momentum. Orbital averaged expressions for the decay of energy and eccentricity are provided. An expression for the last stable circular orbit is given in terms of the angular velocity-type variable x. (paper)
Tessmer, Manuel; Schäfer, Gerhard
2012-01-01
In this article the quasi-Keplerian parameterisation for the case that spins and orbital angular momentum in a compact binary system are aligned or anti-aligned with the orbital angular momentum vector is extended to 3PN point-mass, next-to-next-to-leading order spin-orbit, next-to-next-to-leading order spin(1)-spin(2), and next-to-leading order spin-squared dynamics in the conservative regime. In a further step, we use the expressions for the radiative multipole moments with spin to leading order linear and quadratic in both spins to compute radiation losses of the orbital binding energy and angular momentum. Orbital averaged expressions for the decay of energy and eccentricity are provided. An expression for the last stable circular orbit is given in terms of the angular velocity type variable $x$.
Complex Kepler Orbits and Particle Aggregation in Charged Microscopic Grains
Lee, Victor; Waitukaitis, Scott; Miskin, Marc; Jaeger, Heinrich
2015-03-01
Kepler orbits are usually associated with the motion of astronomical objects such as planets or comets. Here we observe such orbits at the microscale in a system of charged, insulating grains. By letting the grains fall freely under vacuum, we eliminate the effects of air drag and gravity, and by imaging them with a co-falling high-speed camera we track the relative positions of individual particles with high spatial and temporal precision. This makes it possible to investigate the behaviors caused by the combination of long-range electrostatic interactions and short-range, dissipative, contact interactions in unprecedented detail. We make the first direct observations of microscopic elliptical and hyperbolic Kepler orbits, collide-and-capture events between pairs of charged grains, and particle-by-particle aggregation into larger clusters. Our findings provide experimental evidence for electrostatic mechanisms that have been suspected, but not previously observed at the single-event level, as driving the early stages of particle aggregation in systems ranging from fluidized particle bed reactors to interstellar protoplanetary disks. Furthermore, since particles of different net charge and size are seen to aggregate into characteristic spatial configurations, our results suggest new possibilities for the formation of charge-stabilized ``granular molecules''. We can reproduce the observed molecule configurations by taking many-body, dielectric polarization effects into account.
Orbital nematic order and interplay with magnetism in the two-orbital Hubbard model
International Nuclear Information System (INIS)
Motivated by the recent angle-resolved photoemission spectroscopy (ARPES) on FeSe and iron pnictide families of iron-based superconductors, we have studied the orbital nematic order and its interplay with antiferromagnetism within the two-orbital Hubbard model. We used random phase approximation (RPA) to calculate the dependence of the orbital and magnetic susceptibilities on the strength of interactions and electron density (doping). To account for strong electron correlations not captured by RPA, we further employed non-perturbative variational cluster approximation (VCA) capable of capturing symmetry broken magnetic and orbitally ordered phases. Both approaches show that the electron and hole doping affect the two orders differently. While hole doping tends to suppress both magnetism and orbital ordering, the electron doping suppresses magnetism faster. Crucially, we find a realistic parameter regime for moderate electron doping that stabilizes orbital nematicity in the absence of long-range antiferromagnetic order. This is reminiscent of the non-magnetic orbital nematic phase observed recently in FeSe and a number of iron pnictide materials and raises the possibility that at least in some cases, the observed electronic nematicity may be primarily due to orbital rather than magnetic fluctuations. (paper)
Strain-mediated control of orbital ordering planes in heteroepitaxial lanthanum manganite thin films
Kim, Yong-Jin; Lee, Jin Hong; Koo, Tae Yeong; Yang, Chan-Ho
Strain engineering which controls the misfit strain of heteroepitaxial thin films leads to distinctive physical properties in contrast to the intrinsic properties of unstrained bulk materials Perovskite LaMnO3 (LMO) has attracted considerable attention due to strong coupling among the lattice, charge, spin and orbital degrees of freedom. Bulk LMO is known to be an A-type antiferromagnetic (TN~140 K) Mott insulator, and its orbital ordering plane is established due to cooperative Jahn-Teller distortion below ~750 K. Previous studies have focused on the orbital ordering planes of the bulk LMO but not researched on correlation between orbital planes and misfit stain. To figure out the strain dependence of orbital ordering planes, we have grown LMO thin films on four different substrates, i . e . , DyScO3(110), GaScO3(110), SrTiO3(001), and LSAT(001), using the pulsed laser deposition technique. The films have been characterized by atomic force microscopy and x-ray diffraction. We have performed resonant x-ray scattering to identify orbital ordering plane on each film. We have found that orbital ordering planes can be modulated depending on the misfit strain.
Orbital-frustration-induced ordering in semiconductor alloys
Liu, Kai; Yin, Wanjian; Chen, Shiyou; Gong, X. G.; Wei, S.-H.; Xiang, H. J.
2016-05-01
It is well known that ternary zinc-blende semiconductors are always more stable in the chalcopyrite (CH) structure than the Cu-Au (CA) structure because the CH structure has a large Coulomb interaction and a reduced strain energy. Surprisingly, an experimental study showed that the ZnFeS e2 alloy takes the CA order as the ground-state structure, which is consistent with our density functional theory calculations showing that the CA order has lower energy than the CH order for ZnFeS e2 . We reveal that the orbital degree of freedom of a high-spin F e2 + ion (d6) in the tetrahedral crystal field plays a key role in stabilizing the CA order. First, the spin-minority d electron of the F e2 + ion tends to occupy the dx2-y2-like orbital instead of the d3 z2-r2-like orbital because of its large negative Coulomb energy. Second, for a nearest-neighboring F e2 + pair, two spin-minority d electrons with occupied dx2-y2-like orbitals on the plane containing the Fe-Fe bond have lower electronic kinetic energies. Both conditions can be satisfied in the CA ordered ZnFeS e2 alloy, whereas there is an orbital frustration in the CH structure. Our results suggest that the orbital degree of freedom provides a new way to manipulate the structure and properties of alloys.
Particle beams carrying orbital angular momentum, charge, mass and spin
Tijssen, Teuntje; Hayrapetyan, Armen; Goette, Joerg; Dennis, Mark
Electron beams carrying vortices and angular momentum have been of much experimental and theoretical interest in recent years. In addition, optical vortex beams are a well-established field in optics and photonics. In both cases, the orbital angular momentum associated with the beam's axial vortex has effects on the overall spin of the beam, due to spin-orbit interactions. A simple model of these systems are Bessel beam solutions (of either the Dirac equation or Maxwell equations) with a nonzero azimuthal quantum number, which are found by separation in cylindrical coordinates. Here, we generalize this approach, considering the classical field theory of Bessel beams for particles which are either massive or massless, uncharged or charged and of a variety of different spins (0, 1/2, 1, ⋯). We regard the spin and helicity states and different forms of spin-orbit terms that arise. Moreover, we analyse the induced electromagnetic field when the particles carry charge. Most importantly, this unified field theory approach leads to the prediction of effects for vortex beams of neutrons, mesons and neutrinos.
Magnetic ordering in fullerene charge-transfer complexes
Sato, Tohru; Yamabe, Tokio; Tanaka, Kazuyoshi
1997-07-01
We have determined the ground states of the charge-transfer (CT) complexes in which the energy levels of the highest occupied molecular orbital (HOMO) of donors and the lowest unoccupied MO (LUMO) of acceptors are closely located, and examined some fullerene complexes consisting of C60, C70, tetrakis(dimethylamino)ethylene (TDAE), and 1,1',3,3'-tetramethyl-Δ2,2'-bi(imidazolidine) (TMBI). The observed magnetic properties of TDAE-C60, TMBI-C60, and TDAE-C70 can be accounted for by employing realistic parameters. The effective Hamiltonian including up to the fourth-order perturbation has also been derived in the fourfold degenerate model space. The effective Hamiltonian can plausibly reproduce the magnetic phase diagram obtained by the variational treatment of TDAE-C60. It has been shown that the third and the fourth processes contribute to the stabilization of the antiferromagnetic state.
Twist number and order properties of periodic orbits
Petrisor, Emilia
2011-01-01
A less studied numerical characteristic of periodic orbits of area preserving twist maps of the annulus is the twist or torsion number, called initially the amount of rotation [Mather]. It measures the average rotation of tangent vectors under the action of the derivative of the map along that orbit, and characterizes the degree of complexity of the dynamics. The aim of this paper is to give new insights into the definition and properties of the twist number, and to relate its range to the order properties of periodic orbits. We derive an algorithm to deduce the exact value or a demi--unit interval containing the exact value of the twist number. We prove that at a period--doubling bifurcation threshold of a mini-maximizing periodic orbit, the new born doubly periodic orbit has the absolute twist number larger than the absolute twist of the original orbit after bifurcation. We also show that the periodic orbits of absolute twist number at least 1/2, that are born through a saddle--center bifurcation, are badly...
Phase separation, orbital ordering and magnetism in (La0.375Ca0.625)MnO3
Martinelli, A.; Ferretti, M.; Ritter, C.
2016-07-01
At 300 K (La0.375Ca0.625)MnO3 crystallizes in the orthorhombic Pnma space group; on cooling a Pnma → Pnma structural transition occurs due to charge-orbital ordering within the Mn sub-lattice, producing a superstructure consistent with a Wigner-crystal model with a tripling of the cell parameter a. The primary active mode yielding the observed ordered structure corresponds to the irreducible representation labelled Σ3, with wave vector (⅓,0,0). Nevertheless, the disordered polymorph stable at room temperature is retained at low temperature as a secondary phase, coexisting with the charge-orbital ordered structure. These two phases display different spin orderings; the antiferromagnetic structure associated to the charge-orbital ordered phase is characterized by a magnetic propagation wave vector k=(0,0,½), with a canted spin ordering in the ac plane, whereas a Cy-type arrangement develops within the disordered polymorph.
From order to chaos in Earth satellite orbits
Gkolias, Ioannis; Gachet, Fabien; Rosengren, Aaron J
2016-01-01
We consider Earth satellite orbits in the range of semi-major axes where the perturbing effects of Earth's oblateness and lunisolar gravity are of comparable order. This range covers the medium-Earth orbits (MEO) of the Global Navigation Satellite Systems and the geosynchronous orbits (GEO) of the communication satellites. We recall a secular and quadrupolar model, based on the Milankovitch vector formulation of perturbation theory, which governs the long-term orbital evolution subject to the predominant gravitational interactions. We study the global dynamics of this two-and-a-half degrees of freedom Hamiltonian system by means of the fast Lyapunov indicator (FLI), used in a statistical sense. Specifically, we characterize the degree of chaoticity of the action space using angles-averaged normalized FLI maps, thereby overcoming the angle dependencies of the conventional stability maps. Emphasis is placed upon the phase-space structures near secular resonances which are of first importance to the space debris...
Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation
Strohaber, J; Sokolov, A V; Kolomenskii, A A; Paulus, G G; Schuessler, H A
2012-01-01
Experimental results from the generation of Raman sidebands using optical vortices are presented. By generating two sets of sidebands originating from different locations in a Raman active crystal, one set containing optical orbital angular momentum and the other serving as a reference, a Young's double slit experiment was simultaneously realized for each sideband. The interference between the two sets of sidebands was used to determine the helicity and topological charge in each order. Topological charges in all orders were found to be discrete and follow selection rules predicted by a cascaded Raman process.
Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation.
Strohaber, J; Zhi, M; Sokolov, A V; Kolomenskii, A A; Paulus, G G; Schuessler, H A
2012-08-15
Experimental results from the generation of Raman sidebands using optical vortices are presented. By generating two sets of sidebands originating from different locations in a Raman-active crystal, one set containing optical orbital angular momentum and the other serving as a reference, Young's double slit experiment was simultaneously realized for each sideband. The interference between the two sets of sidebands was used to determine the helicity and topological charge in each order. Topological charges in all orders were found to be discrete and follow selection rules predicted by a cascaded Raman process. PMID:23381274
A Duality Between Unidirectional Charge Density Wave Order and Superconductivity
Lee, Dung-Hai
2001-01-01
This paper shows the existence of a duality between an unidirectional charge density wave order and a superconducting order. This duality predicts the existence of charge density wave near a superconducting vortex, and the existence of superconductivity near a charge density wave dislocation.
Charge ordering in perovskite rare-earth titanate compounds
International Nuclear Information System (INIS)
Having a single electron in the 3d shell, the rare-earth (RE) titanates RETiO3 have attracted strong interest to study the complex interplay of charge, orbital and magnetic degrees of freedom. Substituting divalent earth-alkali for the RE, a metal-insulator transition is induced, which in case of Y1-xCaxTiO3 occurs only at rather high doping. We have studied the hole-doped system (Y,Er,Lu)1-xCaxTiO3 by various diffraction techniques, by resistivity and by magnetic susceptibility measurements. This system shows a complex phase diagram of structural distortions accompanied by a metal-insulator transition. We ascribe the complex behavior to the coexistence of an insulating monoclinic phase with a metallic low-temperature orthorhombic phase. Our neutron diffraction data show that charge ordering occurs in the monoclinic phase. Even away from half-doping, we find two distinct Ti sites in a checkerboard arrangement, with significantly different TiO6 coordination
Controlling Charging and Arcing on a Solar Powered Auroral Orbiting Spacecraft
Ferguson, Dale C.; Rhee, Michael S.
2008-01-01
The Global Precipitation Measurement satellite (GPM) will be launched into a high inclination (65 degree) orbit to monitor rainfall on a global scale. Satellites in high inclination orbits have been shown to charge to high negative potentials, with the possibility of arcing on the solar arrays, when three conditions are met: a drop in plasma density below approximately 10,000 cm(exp -3), an injection of energetic electrons of energy more that 7-10 keV, and passage through darkness. Since all of these conditions are expected to obtain for some of the GPM orbits, charging calculations were done using first the Space Environment and Effects (SEE) Program Interactive Spacecraft Charging Handbook, and secondly the NASA Air-force Spacecraft Charging Analyzer Program (NASCAP-2k). The object of the calculations was to determine if charging was likely for the GPM configuration and materials, and specifically to see if choosing a particular type of thermal white paint would help minimize charging. A detailed NASCAP-2k geometrical model of the GPM spacecraft was built, with such a large number of nodes that it challenged the capability of NASCAP-2k to do the calculations. The results of the calculations were that for worst-case auroral charging conditions, charging to levels on the order of -120 to -230 volts could occur on GPM during night-time, with differential voltages on the solar arrays that might lead to solar array arcing. In sunlit conditions, charging did not exceed -20 V under any conditions. The night-time results were sensitive to the spacecraft surface materials chosen. For non-conducting white paints, the charging was severe, and could continue unabated throughout the passage of GPM through the auroral zone. Somewhat conductive (dissipative) white paints minimized the night-time charging to levels of -120 V or less, and thus were recommended for GPM thermal control. It is shown that the choice of thermal control paints is important to prevent arcing on high
Hybrid DFT calculation of Fe57 NMR resonances and orbital order in magnetite
Patterson, C. H.
2014-08-01
The crystal structure and charge and orbital order of magnetite below the Verwey temperature are calculated using a first-principles hybrid density functional theory (DFT) method. The initial atomic positions in the crystal-structure calculation are those recently refined from x-ray diffraction data for the Cc space-group unit cell [Senn, Wright, and Attfield, Nature (London) 481, 173 (2012), 10.1038/nature10704]. Fermi contact and magnetic dipolar contributions to hyperfine fields at Fe57 nuclei obtained from hybrid DFT calculations are used to obtain NMR resonance frequencies for magnetite for a range of external magnetic field directions in a relatively weak field. NMR frequencies from hybrid density functional theory calculations are compared to NMR data [M. Mizoguchi, J. Phys. Soc. Jpn. 70, 2333 (2001), 10.1143/JPSJ.70.2333] for a range of applied magnetic field directions. NMR resonance frequencies of B-site Fe ions show large relative variations with applied field direction owing to anisotropic hyperfine fields from charge and orbital ordered Fe 3d minority-spin electrons at those sites. Good agreement between computed and measured NMR resonance frequencies confirms the pattern of charge and orbital order obtained from calculations. The charge and orbital order of magne-tite in its low-temperature phase obtained from hybrid DFT calculations is analyzed in terms of one-electron bonds between Fe ions. The Verwey transition in magnetite therefore resembles Mott-Peierls transitions in vanadium oxides which undergo symmetry-breaking transitions owing to electron-pair bond formation.
Orbital-motion-limited theory of dust charging and plasma response
International Nuclear Information System (INIS)
The foundational theory for dusty plasmas is the dust charging theory that provides the dust potential and charge arising from the dust interaction with a plasma. The most widely used dust charging theory for negatively charged dust particles is the so-called orbital motion limited (OML) theory, which predicts the dust potential and heat collection accurately for a variety of applications, but was previously found to be incapable of evaluating the dust charge and plasma response in any situation. Here, we report a revised OML formulation that is able to predict the plasma response and hence the dust charge. Numerical solutions of the new OML model show that the widely used Whipple approximation of dust charge-potential relationship agrees with OML theory in the limit of small dust radius compared with plasma Debye length, but incurs large (order-unity) deviation from the OML prediction when the dust size becomes comparable with or larger than plasma Debye length. This latter case is expected for the important application of dust particles in a tokamak plasma
Orbital-motion-limited theory of dust charging and plasma response
Energy Technology Data Exchange (ETDEWEB)
Tang, Xian-Zhu, E-mail: xtang@lanl.gov; Luca Delzanno, Gian, E-mail: delzanno@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-12-15
The foundational theory for dusty plasmas is the dust charging theory that provides the dust potential and charge arising from the dust interaction with a plasma. The most widely used dust charging theory for negatively charged dust particles is the so-called orbital motion limited (OML) theory, which predicts the dust potential and heat collection accurately for a variety of applications, but was previously found to be incapable of evaluating the dust charge and plasma response in any situation. Here, we report a revised OML formulation that is able to predict the plasma response and hence the dust charge. Numerical solutions of the new OML model show that the widely used Whipple approximation of dust charge-potential relationship agrees with OML theory in the limit of small dust radius compared with plasma Debye length, but incurs large (order-unity) deviation from the OML prediction when the dust size becomes comparable with or larger than plasma Debye length. This latter case is expected for the important application of dust particles in a tokamak plasma.
Orbital-motion-limited theory of dust charging and plasma response
Tang, Xian-Zhu
2015-01-01
The foundational theory for dusty plasmas is the dust charging theory that provides the dust potential and charge arising from the dust interaction with a plasma. The most widely used dust charging theory for negatively charged dust particles is the so-called orbital motion limited (OML) theory, which predicts the dust potential and heat collection accurately for a variety of applications, but was previously found to be incapable of evaluating the dust charge and plasma response in any situation. Here we report a revised OML formulation that is able to predict the plasma response and hence the dust charge. Numerical solutions of the new OML model show that the widely-used Whipple approximation of dust charge-potential relationship agrees with OML theory in the limit of small dust radius compared with plasma Debye length, but incurs large (order-unity) deviation from the OML prediction when the dust size becomes comparable with or larger than plasma Debye length. This latter case is expected for the important ...
Mean-Field Theory of Intra-Molecular Charge Ordering in (TTM--TTP)I3
Omori, Yukiko; Tsuchiizu, Masahisa; Suzumura, Yoshikazu
2011-02-01
We examine an intra-molecular charge-ordered (ICO) state in the multi-orbital molecular compound (TTM--TTP)I3 on the basis of an effective two-orbital model derived from ab initio calculations. Representing the model in terms of the fragment molecular-orbital (MO) picture, the ICO state is described as the charge disproportionation on the left and right fragment MOs. By applying the mean-field theory, the phase diagram of the ground state is obtained as a function of the inter-molecular Coulomb repulsion and the intra-molecular transfer integral. The ICO state is stabilized by large inter-fragment Coulomb interactions, and the small intra-molecular transfer energy between two fragment MOs. Furthermore, we examine the finite-temperature phase diagram. The relevance to the experimental observations in the molecular compound of (TTM--TTP)I3 is also discussed.
Microscopic analysis of resonant inelastic x-ray scattering in orbital-ordered KCuF3
International Nuclear Information System (INIS)
We analyze resonant inelastic x-ray scattering (RIXS) at the Cu K edge in a typical orbital-ordered compound KCuF3 on the basis of a microscopic theory. Spectral shape and its dependence on polarization direction and momentum transfer of photons are explained consistently with experimental data within our microscopic calculation. According to our microscopic orbital-resolving analysis, high-energy spectral weights (above 5 eV) originate from charge-transfer excitations related to the Cu-dγ orbitals, while the low-energy weights (below 2 eV) originate from the d–d orbital excitations among the five Cu-d orbitals. We assign specifically the RIXS weights to microscopic orbital-excitation processes, beyond the previous phenomenological assignment based on symmetry properties. (author)
Self-Force on a Scalar Charge in Circular Orbit around a Schwarzschild Black Hole
Nakano, Hiroyuki; Mino, Yasushi; Sasaki, Misao
2001-01-01
In an accompanying paper, we have formulated two types of regulariz_ation methods to calculate the scalar self-force on a particle of charge $q$ moving around a black hole of mass $M$, one of which is called the ``power expansion regularization''. In this paper, we analytically evaluate the self-force (which we also call the reaction force) to the third post-Newtonian (3PN) order on the scalar particle in circular orbit around a Schwarzschild black hole by using the power expansion regulariza...
Terao, Jun; Wadahama, Akihisa; Matono, Akitoshi; Tada, Tomofumi; Watanabe, Satoshi; Seki, Shu; Fujihara, Tetsuaki; Tsuji, Yasushi
2013-01-01
The feasibility of using π-conjugated polymers as next-generation electronic materials is extensively studied; however, their charge mobilities are lower than those of inorganic materials. Here we demonstrate a new design principle for increasing the intramolecular charge mobility of π-conjugated polymers by covering the π-conjugated chain with macrocycles and regularly localizing π-molecular orbitals to realize an ideal orbital alignment for charge hopping. Based on theoretical predictions, ...
Tuning the topological charge of laser high-order harmonics
Gauthier, D; Adhikary, G; Camper, A; Chappuis, C; Cucini, R; Dovillaire, G; Géneaux, R; Poletto, L; Ressel, B; Ruchon, T; Spezzani, C; Stupar, M; De Ninno, G
2016-01-01
We report on the generation of optical vortices carrying a controllable amount of orbital angular momentum in laser high-order harmonics in gas. The experiment is based on two-color wave mixing, where a vortex and a Gaussian beam are spatially overlapped in the generation medium. Such a setup allows efficient and robust generation of lower order orbital angular momentum modes. The results constitute the first experimental verification of the conservation rule for orbital angular momentum in high-harmonic generation using two driving beams. Our findings significantly extend the capability of controlling the spatial properties of femtosecond extreme-ultraviolet pulses and could lead to entirely new experiments in the field of light-matter interactions.
Bond centered vs. site-centered charge ordering: ferroelectricity in oxides
International Nuclear Information System (INIS)
We show that in manganites close to half-doping, novel non-bipartite magnetic phases appear due to the interplay between double exchange, superexchange and orbital ordering. In considerable part of the phase diagram the ground state has a magnetic order that is intermediate between the canonical magnetic CE phase and a state that we identify as the recently observed Zener polaron state. The intermediate phase shows a type of charge ordering that breaks inversion symmetry and is therefore predicted to be ferroelectric
Minow, Joseph I.; Coffey, Victoria N.; Parker, Linda N.; Blackwell, William C., Jr.; Jun, Insoo; Garrett, Henry B.
2007-01-01
The NUMIT 1-dimensional bulk charging model is used as a screening to ol for evaluating time-dependent bulk internal or deep dielectric) ch arging of dielectrics exposed to penetrating electron environments. T he code is modified to accept time dependent electron flux time serie s along satellite orbits for the electron environment inputs instead of using the static electron flux environment input originally used b y the code and widely adopted in bulk charging models. Application of the screening technique ts demonstrated for three cases of spacecraf t exposure within the Earth's radiation belts including a geostationa ry transfer orbit and an Earth-Moon transit trajectory for a range of orbit inclinations. Electric fields and charge densities are compute d for dielectric materials with varying electrical properties exposed to relativistic electron environments along the orbits. Our objectiv e is to demonstrate a preliminary application of the time-dependent e nvironments input to the NUMIT code for evaluating charging risks to exposed dielectrics used on spacecraft when exposed to the Earth's ra diation belts. The results demonstrate that the NUMIT electric field values in GTO orbits with multiple encounters with the Earth's radiat ion belts are consistent with previous studies of charging in GTO orb its and that potential threat conditions for electrostatic discharge exist on lunar transit trajectories depending on the electrical proper ties of the materials exposed to the radiation environment.
Dynamics of Charge Transfer in Ordered and Chaotic Nucleotide Sequences
Fialko, N S
2013-01-01
Charge transfer is considered in systems composed of a donor, an acceptor and bridge sites of (AT) nucleotide pairs. For a bridge consisting of 180 (AT) pairs, three cases are dealt with: a uniform case, when all the nucleotides in each strand are identical; an ordered case, when nucleotides in each DNA strand are arranged in an orderly fashion; a chaotic case, when (AT) and (TA) pairs are arranged randomly. It is shown that in all the cases a charge transfer from a donor to an acceptor can take place. All other factors being equal, the transfer is the most efficient in the uniform case, the ordered and chaotic cases are less and the least efficient, accordingly. The results obtained are in agreement with experimental data on long-range charge transfer in DNA.
Superconductivity and spin excitations in orbitally ordered FeSe
Kreisel, Andreas; Mukherjee, Shantanu; Hirschfeld, P. J.; Andersen, B. M.
We provide a band-structure with low-energy properties consistent with recent photoemission and quantum oscillations measurements on the Fe-based superconductor FeSe, including a mean-field like orbital ordering in the dxz /dyz channel, and show that this model also accounts for the temperature dependence of the measured Knight shift and the spin-relaxation rate. An RPA calculation of the dynamical spin susceptibility yields spin excitations which are peaked at wave vector (π , 0) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. Furthermore, the superconducting gap structure obtained from spin fluctuation theory exhibits nodes on the electron pockets, consistent with the 'V'-shaped density of states measured by tunneling spectroscopy on this material. The redistribution of spectral weight in the superconducting state creates a (π , 0) ''neutron resonance'' as seen in recent experiments. Comparing to various experimental results, we give predictions for further studies A.K. and B.M.A. acknowledge financial support from a Lundbeckfond fellowship (Grant No. A9318). P.J.H. was partially supported by the Department of Energy under Grant No. DE-FG02-05ER46236.
Genesis of charge orders in high temperature superconductors
Tu, Wei-Lin; Lee, Ting-Kuo
2016-01-01
One of the most puzzling facts about cuprate high-temperature superconductors in the lightly doped regime is the coexistence of uniform superconductivity and/or antiferromagnetism with many low-energy charge-ordered states in a unidirectional charge density wave or a bidirectional checkerboard structure. Recent experiments have discovered that these charge density waves exhibit different symmetries in their intra-unit-cell form factors for different cuprate families. Using a renormalized mean-field theory for a well-known, strongly correlated model of cuprates, we obtain a number of charge-ordered states with nearly degenerate energies without invoking special features of the Fermi surface. All of these self-consistent solutions have a pair density wave intertwined with a charge density wave and sometimes a spin density wave. Most of these states vanish in the underdoped regime, except for one with a large d-form factor that vanishes at approximately 19% doping of the holes, as reported by experiments. Furthermore, these states could be modified to have a global superconducting order, with a nodal-like density of states at low energy.
Coexistence of charge and ferromagnetic order in fcc Fe
Hsu, Pin-Jui; Kügel, Jens; Kemmer, Jeannette; Parisen Toldin, Francesco; Mauerer, Tobias; Vogt, Matthias; Assaad, Fakher; Bode, Matthias
2016-01-01
Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states...
Charge orders, magnetism and pairings in the cuprate superconductors
Kloss, T.; Montiel, X.; de Carvalho, V. S.; Freire, H.; Pépin, C.
2016-08-01
We review the recent developments in the field of cuprate superconductors with special focus on the recently observed charge order in the underdoped compounds. We introduce new theoretical developments following the study of the antiferromagnetic quantum critical point in two dimensions, in which preemptive orders in both charge and superconducting (SC) sectors emerge, that are in turn related by an SU(2) symmetry. We consider the implications of this proliferation of orders in the underdoped region, and provide a study of the type of fluctuations which characterize the SU(2) symmetry. We identify an intermediate energy scale where the SC fluctuations are dominant and argue that they are unstable towards the formation of a resonant excitonic state at the pseudogap temperature T *. We discuss the implications of this scenario for a few key experiments.
Effects of charging and doping on orbital hybridizations and distributions in TiO2 clusters
Zhao, Hong Min; Wu, Miao Miao; Wang, Qian; Jena, Puru
2011-11-01
Charging and doping are two important strategies used in TiO2 quantum dots for photocatalysis and photovoltaics. Using small clusters as the prototypes for quantum dots, we have carried out density functional calculations to study the size-specific effects of charging and doping on geometry, electronic structure, frontier orbital distribution, and orbital hybridization. We find that in neutral (TiO2)n clusters the charge transfer from Ti to O is almost size independent, while for the anionic (TiO2)n clusters the corresponding charge transfer is reduced but it increases with size. When one O atom is substituted with N, the charge transfer is also reduced due to the smaller electron affinity of N. As the cluster size increases, the populations of 3d and 4s orbitals of Ti decrease with size, while the populations of the 4p orbital increase, suggesting size dependence of spd hybridizations. The present study clearly shows that charging and doping are effective ways for tailoring the energy gap, orbital distributions, and hybridizations.
Magnonic charge pumping via spin-orbit coupling
Czech Academy of Sciences Publication Activity Database
Ciccarelli, C.; Hals, K.M.D.; Irvine, A.; Novák, Vít; Tserkovnyak, Y.; Kurebayashi, H.; Brataas, A.; Ferguson, A.
2015-01-01
Roč. 10, č. 1 (2015), 50-54. ISSN 1748-3387 R&D Projects: GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : spintronics * spin-orbit torque * GaMnAs Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 34.048, year: 2014
Yoshida, M.; Ishii, K.; Naka, M.; Ishihara, S.; Jarrige, I.; Ikeuchi, K.; Murakami, Y.; Kudo, K.; Koike, Y.; Nagata, T.; Fukada, Y.; Ikeda, N.; Mizuki, J.
2016-01-01
In strongly correlated electron systems, enhanced fluctuations in the proximity of the ordered states of electronic degrees of freedom often induce anomalous electronic properties such as unconventional superconductivity. While spin fluctuations in the energy-momentum space have been studied widely using inelastic neutron scattering, other degrees of freedom, i.e., charge and orbital, have hardly been explored thus far. Here, we use resonant inelastic x-ray scattering to observe charge fluctuations proximate to the charge-order phase in transition metal oxides. In the two-leg ladder of Sr14−xCaxCu24O41, charge fluctuations are enhanced at the propagation vector of the charge order (qCO) when the order is melted by raising temperature or by doping holes. In contrast, charge fluctuations are observed not only at qCO but also at other momenta in a geometrically frustrated triangular bilayer lattice of LuFe2O4. The observed charge fluctuations have a high energy (~1 eV), suggesting that the Coulomb repulsion between electrons plays an important role in the formation of the charge order. PMID:27021464
Tursunov, Arman; Stuchlík, Zdeněk; Kološ, Martin
2016-04-01
We study the motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasicircular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyze the circular orbits using the so-called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum, and specific energy of the circular orbits in dependence on the black-hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with an outward-oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged particles in the radial and vertical directions related to the equatorial circular orbits and study the radial profiles of the radial, ωr; vertical, ωθ; and orbital, ωϕ, frequencies, finding significant differences in comparison to the epicyclic geodesic circular motion. The most important new phenomenon is the existence of toroidal charged particle epicyclic motion with ωr˜ωθ≫ωϕ that could occur around retrograde circular orbits with an outward-oriented Lorentz force. We demonstrate that for the rapidly rotating black holes the role of the "Wald induced charge" can be relevant.
Perfect optical vortex array with controllable diffraction order and topological charge.
Fu, Shiyao; Wang, Tonglu; Gao, Chunqing
2016-09-01
We have demonstrated a holographic grating, the far-field diffraction pattern of which is a perfect optical vortex (POV) array. The diffraction order, as well as the topological charge of each spot in the array, is controllable. By setting different parameters when designing the hologram, the spot in different diffraction orders will be changed, resulting in the variance of the POV array. During the experiment, we uploaded holograms of different design on a phase-only spatial light modulator. We then observed POV arrays with different dimensions and topological charges using a CCD camera, which fit well with the simulation. This technique provides the possibility to generate multiple POVs simultaneously, and can be used in domains where multiple POVs are of high interest such as orbital angular momentum multiplexed fiber data transmission systems. PMID:27607508
Energy Technology Data Exchange (ETDEWEB)
Takubo, K; Mizokawa, T [Department of Physics and Department of Complexity Science and Engineering, University of Tokyo, Kashiwa, Chiba 277-8561 (Japan); Takubo, N; Miyano, K [Research Center for Advanced Science and Technology (RCAST), University of Tokyo, Tokyo 153-8904 (Japan); Matsumoto, N; Nagata, S, E-mail: takubo@sces.k.u-tokyo.ac.j [Department of Materials Science and Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, Muroran, Hokkaido, 050-8585 Japan (Japan)
2009-02-01
Transition-metal compounds with spin, charge, and orbital degrees of freedom tend to have frustrated electronic states coupled with local lattice distortions and to show drastic response to external stimuli such as photo-excitation. We have studied the charge-orbital states in perovskite-type Pr{sub 0.55}(Ca{sub 1-y}Sr{sub y}){sub 0.45}MnO{sub 3} thin films (PCSMO) and spinel-type CuIr{sub 2}S{sub 4} using photoemission spectroscopy combined with additional laser illumination. PCSMO and CuIr{sub 2}S{sub 4} are clear-cut examples of transition-metal compounds showing photo-induced metallic conductivities but the charge-orbital states in the two systems show contrasting responses to the photo-excitation. The charge-orbital states in PCSMO are stabilized by Jahn-Teller or Breathing-type lattice distortions and can be destroyed by photo-excitation. On the other hand, the charge-orbital states in CuIr{sub 2}S{sub 4} are stabilized by dimer formation and tend to be robust against photo-excitation.
Charge ordering phenomena and superconductivity in underdoped cuprates
International Nuclear Information System (INIS)
In this thesis electronic properties of two prototypical copper-oxygen superconductors were studied with Raman scattering. The underdoped regime including the onset point of superconductivity psc1 was investigated. Evidence of quasi one-dimensional (1D) dynamical stripes was found. The 1D structures have a universal preferential orientation along the diagonals of the CuO2 planes below psc1. At psc1, lattice and electron dynamics change discontinuously. The results show that charge ordering drives the transition at psc1 and that the maximal transition temperature to superconductivity at optimal doping TcMAX depends on the type of ordering at psc1. (orig.)
International Nuclear Information System (INIS)
A review of tracking charged particle motion in an axisymmetric toroidal plasma and of Monte Carlo modelling of particle-background interactions is given. Computational methods for efficient modelling of electron and ion guiding center orbits in tokamaks are described and the Monte Carlo orbit-following code ASCOT is reviewed. The efficiency of the code is based on the use of a coordinate system specifically designed for a toroidal system, on preventing numerical error accumulation, and on accelerating interaction time scales. Solutions for enhancing the computational efficiency of the Monte Carlo operators without deterioration of accuracy are described. Applications of the ASCOT code to studies of reverse runaway electrons, lower hybrid (LH) and ion cyclotron (IC) heating and current drive are presented. Relativistic effects are found to increase the reverse runaway probability of fast electrons during current ramp-up. Collisions, acting to diminish the total energy of the electrons towards thermal energy, have a lesser effect on the velocity of the test electron at relativistic energies. Combined to the effect of pitch collisions which bring the electrons towards the trapping cone, this relativistic effect enables the electrons to reach the trapping cone at a large total velocity, where the trapping cone is wide and the region traversed during trapped orbit motion is larger. This brings forth a notable increase in the reverse runaway probability. In a realistic tokamak configuration with smooth wave diffusion and fusion reactivity profiles, fusion-born alpha particles are found to interact with lower hybrid waves by absorbing energy from the wave. Special absorbing boundary conditions must be applied at the perpendicular energy boundary of the wave region in order to reverse the direction of energy transfer. A parameter study of ion cyclotron heating and current drive indicates that the power efficiency of minority ion current generation by IC waves is optimized
15th order resonance terms using the decaying orbit of TETR-3. [perturbation due to gravitation
Wagner, C. A.; Klosko, S. M.
1975-01-01
Fifteenth-order commensurability of the orbit of TETR-3 (1971-83B) is studied. The study is designed to obtain good discrimination of 15th-order resonances through a better range of inclinations. The first low inclination orbit, 33 deg, is used for this purpose; it is very sensitive to the high degree terms which were rather poorly represented by previously analyzed orbits.
Self-consistent coupling of atomic orbitals to a moving charge
International Nuclear Information System (INIS)
The authors describe the time evolution of hydrogenic orbitals perturbed by a moving charge. Starting with the equation for an atom interacting with a charge, the authors use an eikonal representation of the total wave-function, followed by an eikonal approximation, to derive coupled differential equations for the temporal change of the orbitals and the charge's trajectory. The orbitals are represented by functions with complex exponents changing with time, describing electronic density and flux changes. For each orbital, they solve a set of six coupled differential equations; two of them are derived with a time-dependent variational procedure for the real and imaginary parts of the exponents, and the other four are the Hamilton equations of the positions and momenta of the moving charge. The molecular potentials are derived from the exact expressions for the electronic energies. Results of calculations for 1s and 2s orbitals show large variation of the real exponent parts over time, with respect to asymptotic values, and that imaginary parts remain small
Critical competition between two distinct orbital-spin ordered states in perovskite vanadates
Fujioka, J.; Yasue, T.; Miyasaka, S.; Yamasaki, Y.; Arima, T.; Sagayama, H.; Inami, T.; Ishii, K.; Tokura, Y.
2010-10-01
We have investigated the spin/orbital phase diagram in the perovskite orthovanadate RVO3 ( R=Eu , Y, Dy, and Ho) by measurements of magnetization, dielectric constant, specific heat, Raman scattering spectra, and x-ray diffraction, focusing on the interplay between the V3d spin and the 4f moment of the R ion. The thermally induced phase transition between the C-type spin/G-type orbital ordered state and the G-type spin/C-type orbital ordered state is observed for Eu1-xYxVO3 (x=0-0.52) without 4f moment. By comparing this phase diagram with the spin/orbital ordering in TbVO3 , it is evident that the critical competition between the C-type spin/G-type orbital ordered phase and the G-type spin/C-type orbital ordered one depends not only on the GdFeO3 -type lattice distortion but also on the presence of the 4f moment of the R ion. The magnetic field induced phase transition of the spin/orbital ordering is achieved concomitantly with polarizing R4f moments for DyVO3 and HoVO3 . For DyVO3 , the G-type spin/C-type orbital ordered phase is switched to the C-type spin/G-type orbital ordered one by applying a moderate magnetic field around 3 T. By contrast, the G-type spin/C-type orbital ordering is rather favored under the magnetic field in HoVO3 . The results cannot be uniquely explained in terms of the exchange interaction between the V3d spin and the R -ion 4f moment. The coupling of the R4f moment polarization with the lattice distortion tied with the orbital ordering of the V3d sublattice may also be relevant to this field induced phase transition.
Spin-controlled orbital motion in tightly focused high-order Laguerre-Gaussian beams.
Cao, Yongyin; Zhu, Tongtong; Lv, Haiyi; Ding, Weiqiang
2016-02-22
Spin angular momentum can contribute to both optical force and torque exerted on spheres. Orbit rate of spheres located in tightly focused LG beams with the same azimuthal mode index l is spin-controlled due to spin-orbit coupling. Laguerre-Gaussian beams with high-order azimuthal mode are used here to study the orbit rate of dielectric spheres. Orbit rates of spheres with varying sizes and refravtive indices are investigated as well as optical forces acting on spheres in LG beams with different azimuthal modes. These results would be much helpful to investigation on optical rotation and transfer of spin and orbital angular momentum. PMID:26906996
Photoinduced phase transition in charge order systems. Charge frustration and interplay with lattice
International Nuclear Information System (INIS)
Lattice effects on photoexcited states in an interacting charge-frustrated system are examined. Real-time dynamics in the interacting spinless fermion model on a triangular lattice coupled to lattice vibration are analyzed by applying the exact diagonalization method combined with the classical equation of motion. A photoinduced phase transition from the horizontal stripe-type charge order (CO) to the 3-fold CO occurs through a characteristic intermediate time domain. By analyzing the time evolution in detail, we find that these characteristic dynamics are seen when the electron and lattice sectors are not complementary to each other but show cooperative time evolutions. The dynamics are distinct from those from the vertical stripe-type CO, in which a monotonic CO melting occurs. A scenario of the photoinduced CO phase transition with lattice degree of freedom is presented from the viewpoint of charge frustration. (author)
Orbital angular momentum of the laser beam and the second order intensity moments
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre_Gaussian beam,but in any beam with an angular_dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.
Orbital angular momentum of the laser beam and the second order intensity moments
Institute of Scientific and Technical Information of China (English)
高春清[1; 魏光辉[2; HorstWeber[3
2000-01-01
From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre-Gaussian beam, but in any beam with an angular-dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.
Charge ordering phenomena and superconductivity in underdoped cuprates
Energy Technology Data Exchange (ETDEWEB)
Tassini, Leonardo [Bayerische Akademie der Wissenschaften, Muenchen (Germany). Lehrstuhl E23 fuer Technische Physik
2008-01-16
In this thesis electronic properties of two prototypical copper-oxygen superconductors were studied with Raman scattering. The underdoped regime including the onset point of superconductivity p{sub sc1} was investigated. Evidence of quasi one-dimensional (1D) dynamical stripes was found. The 1D structures have a universal preferential orientation along the diagonals of the CuO{sub 2} planes below p{sub sc1}. At p{sub sc1}, lattice and electron dynamics change discontinuously. The results show that charge ordering drives the transition at p{sub sc1} and that the maximal transition temperature to superconductivity at optimal doping T{sub c}{sup MAX} depends on the type of ordering at p{sub sc1}. (orig.)
Influence of orbital nematic order on spin responses in Fe-based superconductors
Su, Yuehua; Zhang, Chao; Li, Tao
2016-05-01
Electronic nematicity is ubiquitous in Fe-based superconductors, but what the primary nematic order is and how the various nematic phenomena correlate with each other are still elusive. In this manuscript we study the physical consequence of the orbital nematic order on the spin correlations. We find that the orbital nematic order can drive a significant spin nematicity and can enhance the integrated intensity of the spin fluctuations. Our study shows that the orbital nematic order has strong effect on the spin correlations and it can not be taken as an unimportant secondary effect of the nematic state in Fe-based superconductors.
Persistent Spin and Charge Currents in Open Conducting Ring Subjected to Rashba Spin-Orbit Coupling
Institute of Scientific and Technical Information of China (English)
ZHANG Xi-Sua; XIONG Shi-Jie
2008-01-01
We investigate persistent charge and spin currents of a one-dimensional ring with Rashba spin-orbit coupling and connected asymmetrically to two external leads spanned with angle (φ)0.Because of the asymmetry of the structure and the spin-reflection,the persistent charge and spin currents can be induced.The magnification of persistent currents can be obtained when tuning the energy of incident electron to the sharp zero and sharp resonance of transmission depending on the Aharonov-Casher (AC) phase due to the spin-orbit coupling and the angle spanned by two leads (φ)0.The general dependence of the charge and spin persistent currents on these parameters is obtained.This suggests a possible method of controlling the magnitude and direction of persistent currents by tuning the AC phase and (φ)0,without the electromagnetic flux though the ring.
Persistent Spin and Charge Currents in Open Conducting Ring Subjected to Rashba Spin—Orbit Coupling
International Nuclear Information System (INIS)
We investigate persistent charge and spin currents of a one-dimensional ring with Rashba spin—orbit coupling and connected asymmetrically to two external leads spanned with angle φ0. Because of the asymmetry of the structure and the spin-reflection, the persistent charge and spin currents can be induced. The magnification of persistent currents can be obtained when tuning the energy of incident electron to the sharp zero and sharp resonance of transmission depending on the Aharonov–Casher (AC) phase due to the spin—orbit coupling and the angle spanned by two leads φ0. The general dependence of the charge and spin persistent currents on these parameters is obtained. This suggests a possible method of controlling the magnitude and direction of persistent currents by tuning the AC phase and φ0, without the electromagnetic flux though the ring. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Charge ordering in low dimensional organic conductors: Structural aspects
Energy Technology Data Exchange (ETDEWEB)
Pouget, Jean-Paul; Foury-Leylekian, Pascale [Laboratoire de Physique des Solides, Universite Paris-sud, CNRS UMR 8502, Batiment 510, 91405 Orsay Cedex (France); Alemany, Pere [Departament de Quimica Fisica and Institut de Quimica Teorica i Computacional (IQTCUB), Universitat de Barcelona, Diagonal 627, 08028 Barcelona (Spain); Canadell, Enric [Institut de Ciencia de Materials de Barcelona, CSIC, Campus UAB, 08193 Bellaterra (Spain)
2012-05-15
The paper points out the importance of the coupling between anions and donors in order to achieve the 4k{sub F} charge localization observed in (TMTTF){sub 2}PF{sub 6}, {delta}-(EDT-TTF-CONMe{sub 2}){sub 2}Br and (o-DMTTF){sub 2}Cl/Br salts, the 2k{sub F} charge density wave (CDW) ground state of {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} and the metal to insulator transition of {alpha}-(BEDT-TTF){sub 2}I{sub 3}. This coupling leads to a cooperative displacement wave of the anions accompanied by a modulation of the density of {pi} holes on the donors. We distinguish two principal anion-donor coupling mechanisms: a direct mechanism via the Hartree anion potential on donor sites and an indirect mechanism via the polarization of {sigma} bonds activated by the modification of the H bonds network. Both kinds of interaction are tuned by the relative displacement of the anions with respect to the donors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Image-charge-induced localization of molecular orbitals at metal-molecule interfaces
DEFF Research Database (Denmark)
Strange, M.; Thygesen, K. S.
2012-01-01
Quasiparticle (QP) wave functions, also known as Dyson orbitals, extend the concept of single-particle states to interacting electron systems. Here we employ many-body perturbation theory in the GW approximation to calculate the QP wave functions for a semiempirical model describing a pi-conjugat......Quasiparticle (QP) wave functions, also known as Dyson orbitals, extend the concept of single-particle states to interacting electron systems. Here we employ many-body perturbation theory in the GW approximation to calculate the QP wave functions for a semiempirical model describing a pi......-conjugated molecular wire in contact with a metal surface. We find that image charge effects pull the frontier molecular orbitals toward the metal surface, while orbitals with higher or lower energy are pushed away. This affects both the size of the energetic image charge shifts and the coupling of the individual...... orbitals to the metal substrate. Full diagonalization of the QP equation and, to some extent, self-consistency in the GW self-energy, is important to describe the effect, which is not captured by standard density functional theory or Hartree-Fock. These results should be important for the understanding and...
Higher order branching of periodic orbits from polynomial isochrones
Directory of Open Access Journals (Sweden)
B. Toni
1999-09-01
Full Text Available We discuss the higher order local bifurcations of limit cycles from polynomial isochrones (linearizable centers when the linearizing transformation is explicitly known and yields a polynomial perturbation one-form. Using a method based on the relative cohomology decomposition of polynomial one-forms complemented with a step reduction process, we give an explicit formula for the overall upper bound of branch points of limit cycles in an arbitrary $n$ degree polynomial perturbation of the linear isochrone, and provide an algorithmic procedure to compute the upper bound at successive orders. We derive a complete analysis of the nonlinear cubic Hamiltonian isochrone and show that at most nine branch points of limit cycles can bifurcate in a cubic polynomial perturbation. Moreover, perturbations with exactly two, three, four, six, and nine local families of limit cycles may be constructed.
Homoclinic orbits at infinity for second-order Hamiltonian systems with fixed energy
Directory of Open Access Journals (Sweden)
Dong-Lun Wu
2015-06-01
Full Text Available We obtain the existence of homoclinic orbits at infinity for a class of second-order Hamiltonian systems with fixed energy. We use the limit for a sequence of approximate solutions which are obtained by variational methods.
Directory of Open Access Journals (Sweden)
Ying Lv
2013-01-01
Full Text Available We investigate the existence and multiplicity of homoclinic orbits for second-order Hamiltonian systems with local superquadratic potential by using the Mountain Pass Theorem and the Fountain Theorem, respectively.
Connection between charge-density-wave order and charge transport in the cuprate superconductors
Tabis, W.; Li, Y; Tacon, M. Le; Braicovich, L.; Kreyssig, A.; Minola, M.; Dellea, G.; Weschke, E.; Veit, M. J.; Ramazanoglu, M.; Goldman, A. I.; T. Schmitt; Ghiringhelli, G.; Barišić, N.; Chan, M. K.
2014-01-01
Charge-density-wave (CDW) correlations within the quintessential CuO$_2$ planes have been argued to either cause [1] or compete with [2] the superconductivity in the cuprates, and they might furthermore drive the Fermi-surface reconstruction in high magnetic fields implied by quantum oscillation (QO) experiments for YBa$_2$Cu$_3$O$_{6+{\\delta}}$ (YBCO) [3] and HgBa$_2$CuO$_{4+{\\delta}}$ (Hg1201) [4]. Consequently, the observation of bulk CDW order in YBCO was a significant development [5,6,7]...
High-order moments of spin-orbit energy in a multielectron configuration.
Na, Xieyu; Poirier, M
2016-07-01
In order to analyze the energy-level distribution in complex ions such as those found in warm dense plasmas, this paper provides values for high-order moments of the spin-orbit energy in a multielectron configuration. Using second-quantization results and standard angular algebra or fully analytical expressions, explicit values are given for moments up to 10th order for the spin-orbit energy. Two analytical methods are proposed, using the uncoupled or coupled orbital and spin angular momenta. The case of multiple open subshells is considered with the help of cumulants. The proposed expressions for spin-orbit energy moments are compared to numerical computations from Cowan's code and agree with them. The convergence of the Gram-Charlier expansion involving these spin-orbit moments is analyzed. While a spectrum with infinitely thin components cannot be adequately represented by such an expansion, a suitable convolution procedure ensures the convergence of the Gram-Charlier series provided high-order terms are accounted for. A corrected analytical formula for the third-order moment involving both spin-orbit and electron-electron interactions turns out to be in fair agreement with Cowan's numerical computations. PMID:27575229
Complex charge ordering in CeRuSn
Energy Technology Data Exchange (ETDEWEB)
Feyerherm, Ralf; Dudzik, Esther; Valencia, Sergio [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, 12489 Berlin (Germany); Mydosh, John A. [MPI-CPFS, 01187 Dresden (Germany); Kamerlingh Onnes Laboratory, Leiden University, 2300RA Leiden (Netherlands); Hermes, Wilfried; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, 48149 Muenster (Germany)
2012-07-01
At room temperature (RT), CeRuSn exhibits coexistence of trivalent Ce{sup 3+} and intermediate valent Ce{sup (4-{delta})+} in a metallic environment. Charge ordering produces a doubling of the unit cell along the c-axis with respect to the basic CeCoAl type structure. Below RT, a phase transition with broad hysteresis has been observed in various bulk properties. The present X-ray diffraction results show that at low temperatures the doubling of the CeCoAl type structure is replaced by an ill-defined modulated ground state in which at least three modulation periods compete. The dominant mode is close to a tripling of the basic cell. XANES data suggest that the average Ce valence remains constant. We propose a qualitative structure model with modified stacking sequences of Ce{sup 3+} and Ce{sup (4-{delta})+} layers in the various modulated phases. Surprisingly, far below 100 K the modulated state is sensitive to synchrotron X-ray irradiation. With a photon flux {approx} 10{sup 12} s{sup -1}, the modulated ground state is destroyed on a timescale of minutes and the doubling of the CeCoAl cell observed at room temperature is recovered. The final state is metastable at 10 K. Heating the sample above 60 K again leads to a recovery of the modulated state.
Tursunov, Arman; Kološ, Martin
2016-01-01
We study motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasi-circular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyse the circular orbits using the so called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum and specific energy of the circular orbits in dependence on the black hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with outward oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged parti...
Molenkamp, Laurens; Nitta, Junsaku
2009-05-01
As the information and communications technology industries continue to demand smaller and more powerful electronic devices, it is becoming clear that the technologies which we currently rely upon to store, process and encode data are no longer sufficient. Over the past two decades, the field of spintronics has emerged as a promising source of the new technologies that will help to meet these needs. Following the discovery of giant magnetoresistance in the late 1980s research originally focused on achieving larger and larger magnetoresistance effects in metal-based systems. The resulting devices have already found widespread applications (as read heads in hard drives, for example) and more recent developments (spin torque, domain wall effects) demonstrate a similarly large potential. The development of semiconductor spintronic devices, which promise an even more enhanced functionality, has proved a tougher challenge to researchers. While the physics of spin injection in semiconductors is well understood by now, we presently still do not have a reliable and robust means for spin detection. Moreover, while ferromagnetic semiconductors have shown a wealth of novel device physics, the applicability of these concepts is limited because the community still has not found a material that demonstrates robust ferromagnetism at and above room temperature. Because of this, a growing number of researchers has turned to the utilization of spin--orbit interaction as a tool to manipulate spin behaviour within semiconductors. This cluster of articles reflects this trend in spintronics research and the blend of reviews and novel research provides a good overview of the current status of investigation into spin--orbit interaction and its effect on charge transport. The collection includes review papers on the theory of the impact of spin-orbit effects on weak localization in semiconductor heterostructures (Glazov and Golub) and of shot noise in 2DEG devices (Nikolic and Dragomirova
Third-order energy derivative corrections to the Kohn-Sham orbital hardness tensor
Indian Academy of Sciences (India)
Tzonka Mineva
2005-09-01
The third term in the Taylor expansion of the total energy functional around the number of electrons is evaluated as the second-order derivative of orbital Kohn-Sham energies with respect to orbital occupancy. Present approach is an extension of an efficient algorithm to compute densityfunctional based orbital reactivity indices. Various energy derivatives used to approximate orbital reactivity indices are defined within the space spanned by the orbital occupation numbers and the Kohn-Sham one-electron energies. The third-order energy functional derivative has to be considered for singular hardness tensor ([]). On the contrary, this term has negligible influence on the reactivity index values for atomic or molecular systems with positively defined hardness tensors. In this context, stability of a system in equilibrium state estimated through the eigenvalues of [h] is discussed. Numerical illustration of the Kohn-Sham energy functional derivatives in orbital resolution up to the third order is shown for benchmark molecules such as H2O, H2S, and OH-.
EuBaFe2O5+w: Valence mixing and charge ordering are two separate cooperative phenomena
International Nuclear Information System (INIS)
Mixed-valence EuBaFe2O5+w exhibits a robust Verwey-type transition. The trend in the volume change suggests a first-order transition up to the nonstoichiometry level of about w=0.25. 57Fe Mossbauer spectroscopy, differential scanning calorimetry and synchrotron X-ray powder diffraction are used to study the valence mixing and charge ordering in EuBaFe2O5+w as a function of the nonstoichiometry parameter w. 151Eu Mossbauer spectroscopy is used as a selective probe into the ferromagnetic valence-mixing coupling along c above the Verwey transition, and reveals that increasing w destroys this coupling in favor of a G-type magnetic order in parallel with the progressive removal of the valence-mixed iron states accounted for by 57Fe Mossbauer spectroscopy. This removal proceeds according to a probability scheme of mixing between ferromagnetically coupled divalent and trivalent neighbor iron atoms along c across the R layer. In contrast, the concentration decrease of the orbital- and charge-ordered states in EuBaFe2O5+w is found to be a linear function of w. Valence mixing and charge ordering are therefore two separate cooperative phenomena. The enthalpy of the Verwey-type transition between these two cooperative systems is a linear function of w, which suggests that it originates from the latent heat of freezing into the long-range ordered orbital- and charge-ordered state. The enthalpy becomes zero at the nonstoichiometry level of about w=0.25
Abstracts of the workshop on orbital ordering and fluctuations in d- and f-electron systems
Energy Technology Data Exchange (ETDEWEB)
Ueda, Kazuo; Hotta, Takashi (eds.) [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment
2002-12-01
Strongly correlated f- and d-electron systems including heavy Fermion systems and transition metal oxides are important source of exciting new phenomena in condensed matter physics. Recently it has been recognized in more profound way that the orbital degeneracy of the f- and d-electrons plays very important role underlying those exotic phenomena. The idea of the present workshop is to bring active researchers in the field together and to exchange ideas in informal atmosphere. In the workshop, twenty seven papers were presented and the following subjects were discussed: orbital ordering in transition metal oxides, role of orbital degeneracy in heavy Fermion systems and effect of geometrical frustration on orbital fluctuations. (author)
Abstracts of the workshop on orbital ordering and fluctuations in d- and f-electron systems
International Nuclear Information System (INIS)
Strongly correlated f- and d-electron systems including heavy Fermion systems and transition metal oxides are important source of exciting new phenomena in condensed matter physics. Recently it has been recognized in more profound way that the orbital degeneracy of the f- and d-electrons plays very important role underlying those exotic phenomena. The idea of the present workshop is to bring active researchers in the field together and to exchange ideas in informal atmosphere. In the workshop, twenty seven papers were presented and the following subjects were discussed: orbital ordering in transition metal oxides, role of orbital degeneracy in heavy Fermion systems and effect of geometrical frustration on orbital fluctuations. (author)
On the relation between Jahn-Teller ordering and charge ordering
International Nuclear Information System (INIS)
This thesis compares the structures of KCusup(II)F3 and Cs2Ausup(I)Ausup(III)Cl6. Both compounds have a structure that can be thought to result from a deformation of the cubic perovskite structure. The deformation of KCusup(II)F3 is a result of a cooperative Jahn-Teller effect and the deformation of Cs2Ausup(I)Ausup(III)Cl6 results in two sublattices. The structures of both compounds result from a continuous phase transition from the cubic pervskite structure due to a deformation of symmetry. Using local coordinates and a calculation of the electron-lattice interaction in a static approximation, four structure types were derived. One is the structure of Cs2AuAuCl6 at ambient temperature and pressure and the second contains a group of structures corresponding to the structures found for KCuF3. The third structure type was recently suggested for Cs2AuAuCl6 under pressure and the fourth has not been found experimentally. Two types show a Jahn-Teller ordering and the other two charge ordering (Auth./C.F.)
Villanueva, J R
2015-01-01
Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is presented in this paper. Radial and angular motion are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analysed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys. Rev. D 85: 024033, 2012), Olivares & Villanueva (Eur. Phys. J. C 73: 2659, 2013) and Blaga (Automat. Comp. Appl. Math. 22, 41 (2013); Serb. Astron. J. 190, 41 (2015)) for time-like geodesics.
Energy Technology Data Exchange (ETDEWEB)
Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile); Centro de Astrofisica de Valparaiso, Valparaiso (Chile); Olivares, Marco [Universidad Diego Portales, Avenida Ejercito Libertador 441, Facultad de Ingenieria, Santiago (Chile)
2015-11-15
Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)
Characterization of topological charge and orbital angular momentum of shaped optical vortices.
Amaral, Anderson M; Falcão-Filho, Edilson L; de Araújo, Cid B
2014-12-01
Optical vortices (OV) are usually associated to cylindrically symmetric light beams. However, they can have more general geometries that extends their applicability. Since the typical experimental characterization methods are not appropriate for OV with arbitrary shapes, we discuss in this work how the definitions of the classical orbital angular momentum and the topological charge can be used to retrieve these informations in the general case. The concepts discussed are experimentally demonstrated and may be specially useful in areas such as optical tweezers and plasmonics. PMID:25606960
Villanueva, J. R.; Olivares, Marco
2015-11-01
Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.
International Nuclear Information System (INIS)
Properties of the motion of electrically charged particles in the background of the Gibbons-Maeda-Garfinkle-Horowitz-Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41-48, 2013; Serb Astron 190:41, 2015) for time-like geodesics. (orig.)
International Nuclear Information System (INIS)
Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics
Energy Technology Data Exchange (ETDEWEB)
Villanueva, J. R., E-mail: jose.villanuevalob@uv.cl [Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso (Chile); Centro de Astrofísica de Valparaíso, Gran Bretaña 1111, Playa Ancha, Valparaíso (Chile); Olivares, Marco, E-mail: marco.olivaresr@mail.udp.cl [Facultad de Ingeniería, Universidad Diego Portales, Avenida Ejército Libertador 441, Casilla 298–V, Santiago (Chile)
2015-11-27
Properties of the motion of electrically charged particles in the background of the Gibbons–Maeda–Garfinkle–Horowitz–Strominger black hole is presented in this paper. Radial and angular motions are studied analytically for different values of the fundamental parameter. Therefore, gravitational Rutherford scattering and Keplerian orbits are analyzed in detail. Finally, this paper complements previous work by Fernando for null geodesics (Phys Rev D 85:024033, 2012), Olivares and Villanueva (Eur Phys J C 73:2659, 2013) and Blaga (Automat Comp Appl Math 22:41–48, 2013; Serb Astron 190:41, 2015) for time-like geodesics.
Spin and charge transport in the presence of spin-orbit interaction
Indian Academy of Sciences (India)
T P Pareek; P Bruno
2002-02-01
We present the study of spin and charge transport in nanostructures in the presence of spin-orbit (SO) interaction. Single band tight binding Hamiltonians for Elliot–Yafet and Rashba SO interaction are derived. Using these tight binding Hamiltonians and spin resolved Landauer–Büttiker formula, spin and charge transport is studied. Speciﬁcally numerical results are presented for a new method to perform magnetic scanning tunneling microscopy with non-magnetic tip but in the presence of Elliot–Yafet SO interaction. The spin relaxation phenomena in two-dimensional electron gas in the presence of Rashba SO interaction are studied and contrary to naive expectation, it is shown that disorder helps to reduce spin relaxation.
Metal-insulator and charge ordering transitions in oxide nanostructures
Singh, Sujay Kumar
. First principles calculations show that the destabilization of the insulating phase during the gating arises due to the formation of oxygen vacancies in VO2; the rutile phase is far more amenable to electrochemical reduction as compared to the monoclinic phase, likely due to its higher electrical conductivity. The generation of oxygen vacancies appears thermodynamically favorable if the removed oxygen atoms from VO2 oxidize the anions in the ionic liquid. Finally, electronic properties of single crystalline, individual nanowires of vanadium oxide bronzes (MxVO 2O5) are presented. The intercalation effects of metal cation and the stoichiometry (x) are explored and discussed. These nanowires exhibit thermally and electrically driven charge ordering and metal to insulator transitions. The electrolyte gating measurements show resistance modulations across the phase transition but the effect is not as dramatic as in VO2.
d-Density Wave Scenario Description of the New Hidden Charge Order in Cuprates
Makhfudz, Imam
2016-06-01
In this paper, we show that the theory of high Tc superconductivity based on a microscopic model with d-density wave (DDW) scenario in the pseudogap phase is able to reproduce some of the most important features of the recent experimentally discovered hidden charge order in several families of Cuprates. In particular, by computing and comparing energies of charge orders of different modulation directions derived from a full microscopic theory with d-density wave scenario, the axial charge order ϕX(Y) with wavevector {Q} = (Q0,0)((0,Q0)) is shown to be unambiguously energetically more favorable over the diagonal charge order ϕX±Y with wavevector {Q} = (Q0, ± Q0) at least in commensurate limit, to be expected also to hold even to more general incommensurate case, in agreement with experiment. The two types of axial charge order ϕX and ϕY are degenerate by symmetry. We find that within the superconducting background, biaxial (checkerboard) charge order is energetically more favorable than uniaxial (stripe) charge order, and therefore checkerboard axial charge order should be the one observed in experiments, assuming a single domain of charge ordered state on each CuO2 plane.
Arbitrary Order Charge Approximation Event Driven Phase Lock Loop Model
Daniels, Brian; Farrell, Ronan; Baldwin, Gerard
2004-01-01
An alternative technique for the derivation of an event driven phase lock loop (PLL) model is presented enabling the modelling of higher order PLLs. Event driven models have previously been developed for 2nd, and 3rd order PLLs [1,2,3], however for higher order systems (5th, 6th etc.) the derivation of the loop filter difference equations are not amenable. This paper introduces a technique to model PLLs with arbitrary order filters that removes the restriction on the loop...
Spin-orbit precession for eccentric black hole binaries at first order in the mass ratio
Akcay, Sarp; Dolan, Sam
2016-01-01
We consider spin-orbit ("geodetic") precession for a compact binary in strong-field gravity. Specifically, we compute $\\psi$, the ratio of the accumulated spin-precession and orbital angles over one radial period, for a spinning compact body orbiting a non-rotating black hole. We show that $\\psi$ can be computed for eccentric orbits in both the gravitational self-force and post-Newtonian frameworks, and that the results appear to be consistent. We present a post-Newtonian expansion for $\\psi$ at next-to-next-to-leading order, and a Lorenz-gauge gravitational self-force calculation for $\\psi$ at first order in the mass ratio. The latter provides new numerical data in the strong-field regime to inform the Effective One-Body model of the gravitational two-body problem. We conclude that $\\psi$ complements the Detweiler redshift $z$ as a key invariant quantity characterizing eccentric orbits in the gravitational two-body problem.
Orbital angular momentum of a high-order Bessel light beam
Energy Technology Data Exchange (ETDEWEB)
Volke-Sepulveda, K [Instituto Nacional de Astrofisica, Optica y Electronica, Apdo. Postal 51/216, Puebla, Pue., Mexico 72000 (Mexico); Garces-Chavez, V [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, Scotland (United Kingdom); Chavez-Cerda, S [Instituto Nacional de Astrofisica, Optica y Electronica, Apdo. Postal 51/216, Puebla, Pue., Mexico 72000 (Mexico); Arlt, J [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, Scotland (United Kingdom); Dholakia, K [School of Physics and Astronomy, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)
2002-04-01
The orbital angular momentum density of Bessel beams is calculated explicitly within a rigorous vectorial treatment. This allows us to investigate some aspects that have not been analysed previously, such as the angular momentum content of azimuthally and radially polarized beams. Furthermore, we demonstrate experimentally the mechanical transfer of orbital angular momentum to trapped particles in optical tweezers using a high-order Bessel beam. We set transparent particles of known dimensions into rotation, where the sense of rotation can be reversed by changing the sign of the singularity. Quantitative results are obtained for rotation rates. This paper's animations are available from the Multimedia Enhancements page.
Slussarenko S.; Karimi E.; Piccirillo B.; Marrucci L.; Santamato E.
2011-01-01
We present a novel optical device to encode and decode two bits of information into different Orbital Angular Momentum (OAM) states of a paraxial optical beam. Our device generates the four angular momentum states of order $\\pm 2$ and $\\pm4$ by Spin-To-Orbital angular momentum Conversion (STOC) in a triangular optical loop arrangement. The switching among the four OAM states is obtained by changing the polarization state of the circulating beam by two quarter wave plates and the two-bit infor...
Theoretical study of orbital ordering induced structural phase transition in iron pnictides
Jena, Sushree Sangita; Panda, S. K.; Rout, G. C.
2016-05-01
We attribute the structural phase transition (SPT) in the parent compounds of the iron pnictides to orbital ordering. Due to anisotropy of the dxz and dyz orbitals in the xy plane, orbital ordering makes the orthorhombic structure more favorable and thus inducing the SPT. We consider a one band model Hamiltonian consisting of first and second-nearest-neighbor hopping of the electrons. We introduce Jahn-Tellar (JT) distortion in the system arising due to the orbital ordering present in this system. We calculate the electron Green's function by using Zuvareb's Green's function technique and hence calculate an expression for the temperature dependent lattice strain which is computed numerically and self-consistently. The temperature dependent electron specific heat is calculated by minimizing the free energy of the system. The lattice strain is studied by varying the JT coupling and elastic constant of the system. The structural anomaly is studied through the electron occupation number and the specific heat by varying the physical parameters like JT coupling, lattice constant, chemical potential and hopping integrals of the system.
The Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle Astronomy
Mitchell, John; Krizmanic, J. F.; Stecker, F. W.; Streitmatter, R. E.
2009-01-01
The space-based OWL mission is designed to perform high-statistics measurements of ultra-high-energy cosmic rays (UHECR) using the Earth's atmosphere as a vast particle calorimeter, furthering the field of charged-particle astronomy. OWL has been developed in formal NASA instrument and mission studies and is comprised of two large telescopes separated by approx.600 km in 1000 km, near-equatorial orbits to stereoscopically image the near-UV air fluorescence emitted by UHECR-induced particle cascades. The High Resolution Fly's Eye (HiRes) Collaboration, and subsequently the Pierre Auger Observatory, recently reported confirmation of the expected Greisen-Zatsepin-Kuzmin (GZK) suppression of the UHECR flux above a few times 10(exp 19) eV. This observation is consistent with the majority of UHECR originating in astrophysical objects and reduces the need to invoke exotic physical processes. Particles observed above the GZK threshold energy must have come from sources within about 100 Mpc from the Earth. The small particle deflection angles expected at UHECR energies, with standard assumptions of extragalactic magnetic fields, are on the order of 1 degree. Thus by observing particles above the GZK threshold with sufficient exposure, there is the potential of identifying and characterizing individual UHECR sources. Auger has reported significant anisotropy in the arrival directions of UHECR at energies above about 6 10(exp 19) eV observed in the South, and a correlation to AGN in the 12th VCV catalog, suggesting that the sources of UHECR are traced by the distribution of luminous matter in the Universe. However, with similar statistics and the same event selection criteria, HiRes observations in the North are consistent with isotropy. Extended observations by Auger-South, by Telescope Array in the North, and possibly by the proposed Auger-North, will further these investigations. However, much greater exposures will be required to fully identify individual sources and
International Nuclear Information System (INIS)
An energy decomposition analysis (EDA) of intermolecular interactions is proposed for second-order Møller–Plesset perturbation theory (MP2) based on absolutely localized molecular orbitals (ALMOs), as an extension to a previous ALMO-based EDA for self-consistent field methods. It decomposes the canonical MP2 binding energy by dividing the double excitations that contribute to the MP2 wave function into classes based on how the excitations involve different molecules. The MP2 contribution to the binding energy is decomposed into four components: frozen interaction, polarization, charge transfer, and dispersion. Charge transfer is defined by excitations that change the number of electrons on a molecule, dispersion by intermolecular excitations that do not transfer charge, and polarization and frozen interactions by intra-molecular excitations. The final two are separated by evaluations of the frozen, isolated wave functions in the presence of the other molecules, with adjustments for orbital response. Unlike previous EDAs for electron correlation methods, this one includes components for the electrostatics, which is vital as adjustment to the electrostatic behavior of the system is in some cases the dominant effect of the treatment of electron correlation. The proposed EDA is then applied to a variety of different systems to demonstrate that all proposed components behave correctly. This includes systems with one molecule and an external electric perturbation to test the separation between polarization and frozen interactions and various bimolecular systems in the equilibrium range and beyond to test the rest of the EDA. We find that it performs well on these tests. We then apply the EDA to a halogen bonded system to investigate the nature of the halogen bond
Energy Technology Data Exchange (ETDEWEB)
Thirman, Jonathan, E-mail: thirman@berkeley.edu; Head-Gordon, Martin, E-mail: mhg@cchem.berkeley.edu [Department of Chemistry, Kenneth S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, Berkeley, California 94720 (United States)
2015-08-28
An energy decomposition analysis (EDA) of intermolecular interactions is proposed for second-order Møller–Plesset perturbation theory (MP2) based on absolutely localized molecular orbitals (ALMOs), as an extension to a previous ALMO-based EDA for self-consistent field methods. It decomposes the canonical MP2 binding energy by dividing the double excitations that contribute to the MP2 wave function into classes based on how the excitations involve different molecules. The MP2 contribution to the binding energy is decomposed into four components: frozen interaction, polarization, charge transfer, and dispersion. Charge transfer is defined by excitations that change the number of electrons on a molecule, dispersion by intermolecular excitations that do not transfer charge, and polarization and frozen interactions by intra-molecular excitations. The final two are separated by evaluations of the frozen, isolated wave functions in the presence of the other molecules, with adjustments for orbital response. Unlike previous EDAs for electron correlation methods, this one includes components for the electrostatics, which is vital as adjustment to the electrostatic behavior of the system is in some cases the dominant effect of the treatment of electron correlation. The proposed EDA is then applied to a variety of different systems to demonstrate that all proposed components behave correctly. This includes systems with one molecule and an external electric perturbation to test the separation between polarization and frozen interactions and various bimolecular systems in the equilibrium range and beyond to test the rest of the EDA. We find that it performs well on these tests. We then apply the EDA to a halogen bonded system to investigate the nature of the halogen bond.
Surface Ordering of Orbitals at a Higher Temperature in LaCoO3 Thin Film
Yamasaki, Yuichi; Fujioka, Jun; Nakao, Hironori; Okamoto, Jun; Sudayama, Takaaki; Murakami, Youichi; Nakamura, Masao; Kawasaki, Masashi; Arima, Takahisa; Tokura, Yoshinori
2016-02-01
We report on the distinct surface state of electronic orders, including spin, orbital, and spin-state degrees of freedom of Co3+ ion, in an epitaxially strained thin film of LaCoO3 grown on (LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7 (LSAT) substrate. The surface ordered state was detected by the grazing-incidence resonant soft x-ray scattering at Co L-edge, where the probing depth is less than the topmost 4 nm of surface. Comparing with the result of bulk sensitive x-ray diffraction, we revealed that the transition temperature of the orbital order (spin order) at the surface region is about 30 K (20 K) higher (lower) than that of the bulk. A novel phenomenon of the surface order and bulk disorder of the orbital degree of freedom can be attributed to its collective and lattice-coupled nature which is strongly affected by the translational/inversion symmetry breaking at the surface.
PITCH ANGLE RESTRICTIONS IN LATE-TYPE SPIRAL GALAXIES BASED ON CHAOTIC AND ORDERED ORBITAL BEHAVIOR
International Nuclear Information System (INIS)
We built models for low bulge mass spiral galaxies (late type as defined by the Hubble classification) using a three-dimensional self-gravitating model for spiral arms, and analyzed the orbital dynamics as a function of pitch angle, ranging from 10° to 60°. Indirectly testing orbital self-consistency, we search for the main periodic orbits and studied the density response. For pitch angles up to approximately ∼20°, the response closely supports the potential readily permitting the presence of long-lasting spiral structures. The density response tends to 'avoid' larger pitch angles in the potential by keeping smaller pitch angles in the corresponding response. Spiral arms with pitch angles larger than ∼20° would not be long-lasting structures but would rather be transient. On the other hand, from an extensive orbital study in phase space, we also find that for late-type galaxies with pitch angles larger than ∼50°, chaos becomes pervasive, destroying the ordered phase space surrounding the main stable periodic orbits and even destroying them. This result is in good agreement with observations of late-type galaxies, where the maximum observed pitch angle is ∼50°.
PITCH ANGLE RESTRICTIONS IN LATE-TYPE SPIRAL GALAXIES BASED ON CHAOTIC AND ORDERED ORBITAL BEHAVIOR
Energy Technology Data Exchange (ETDEWEB)
Perez-Villegas, A.; Pichardo, B.; Moreno, E.; Peimbert, A. [Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F. (Mexico); Velazquez, H. M., E-mail: barbara@astroscu.unam.mx [Observatorio Astronomico Nacional, Universidad Nacional Autonoma de Mexico, Apdo. Postal 877, 22800 Ensenada (Mexico)
2012-01-20
We built models for low bulge mass spiral galaxies (late type as defined by the Hubble classification) using a three-dimensional self-gravitating model for spiral arms, and analyzed the orbital dynamics as a function of pitch angle, ranging from 10 Degree-Sign to 60 Degree-Sign . Indirectly testing orbital self-consistency, we search for the main periodic orbits and studied the density response. For pitch angles up to approximately {approx}20 Degree-Sign , the response closely supports the potential readily permitting the presence of long-lasting spiral structures. The density response tends to 'avoid' larger pitch angles in the potential by keeping smaller pitch angles in the corresponding response. Spiral arms with pitch angles larger than {approx}20 Degree-Sign would not be long-lasting structures but would rather be transient. On the other hand, from an extensive orbital study in phase space, we also find that for late-type galaxies with pitch angles larger than {approx}50 Degree-Sign , chaos becomes pervasive, destroying the ordered phase space surrounding the main stable periodic orbits and even destroying them. This result is in good agreement with observations of late-type galaxies, where the maximum observed pitch angle is {approx}50 Degree-Sign .
Bouchard, Frédéric; Schulz, Sebastian A; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W
2014-01-01
Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded \\qo{space} for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of OAM $\\ell$. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge $q$. When a circularly polarised light beam traverse...
Strong orbital fluctuations in multipolar ordered states of PrV2Al20
Matsumoto, Yosuke; Tsujimoto, Masaki; Tomita, Takahiro; Sakai, Akito; Nakatsuji, Satoru
2016-02-01
PrT2Al20 (T=Ti, V) are ideal systems to study the quadrupole Kondo effect and quantum criticality arising from orbital degrees of freedom. The both systems have the nonmagnetic cubic Γ3 crystal electric field ground doublet with the well separated excited state. In particular, PrV2Al20 exhibits anomalous metallic behavior above and below the multipolar ordering temperatures, reflecting the even stronger hybridization between f and conduction electrons possibly due to a proximity to an orbital quantum critical point. Here we report the anomalous metallic behaviors found in a pure single crystal of PrV2Al20. Our detailed analyses revealed that the resistivity indicates power law temperature dependence proportional to T3. Furthermore, we pointed out that the 4f electron contribution to the specific heat also exhibits power law behavior proportional to T4. Both observations are in a sharp contrast to the gapped behavior found in PrTi2Al20 and indicate the strong c-f hybridization and strong orbital fluctuations in PrV2Al20. In addition, the 4f electron contribution to the entropy in PrV2Al20 reaches only 50% of R ln 2 at an orbital ordering at T=0.75 K, suggesting another 50% of R ln 2 expected for Γ3 doublet is already released at higher temperature possibly due to quadrupole Kondo effect.
Samantaray, B.; Khan, N.; Midya, A.; Ravi, S.; Mandal, P.
2016-01-01
We present results on resistivity (ρ), magnetization (M), thermal conductivity (κ), magnetostriction (\\frac{Δ L}{L(0)}) and specific heat (C p ) of the charge-orbital ordered antiferromagnetic Nd0.8Na0.2MnO3 compound. Magnetic-field-induced antiferromagnetic/charge-orbital ordered insulating to ferromagnetic metallic transition leads to giant magnetothermal conductivity and magnetostriction effect. The low-temperature irreversibility behavior in ρ, M, κ and \\frac{Δ L}{L(0)} due to field cycling together with a striking similarity among the field and temperature dependence of these parameters manifest the presence of a strong and complex spin-charge-lattice coupling in this compound. The giant magnetothermal conductivity is attributed mainly to the suppression of phonon scattering due to the destabilization of spin fluctuations and static/dynamic Jahn-Teller distortion by the application of magnetic field.
Eccentric orbit E/IMRI gravitational wave fluxes to 7PN order
Forseth, Erik; Evans, Charles R.; Hopper, Seth
2016-03-01
Knowledge of gravitational wave fluxes (energy and angular momentum, at both infinity and the horizon) from eccentric-orbit inspirals is extended from 3PN to 7PN order at lowest order in small mass ratio. Previous post-Newtonian eccentric-orbit results up to 3PN relative order are confirmed by our new black hole perturbation calculations. The calculations are based on Mano, Suzuki, and Takasugi (MST) analytic function expansions, and results are computed to 200 decimal places of accuracy using Mathematica. Over 1,700 distinct orbits were computed, each with as many as 7,000 Fourier-harmonic modes. A large number of PN coefficients between 3.5PN and 7PN orders were determined, either in exact analytic form or with accurate numerical values, in expansions in powers of a PN compactness parameter and its logarithm, and powers of eccentricity. We show a parametrization that removes singularities in the fluxes as the eccentricity approaches unity, thus making the expansions more convergent at high eccentricity. We also found (nearly) arbitrarily accurate expansions for the previously discussed 1.5PN, 2.5PN, and 3PN hereditary terms.
Distinguishing Patterns of Charge Order: Stripes or Checkerboards
Energy Technology Data Exchange (ETDEWEB)
Robertson, J.A.
2010-04-06
In two dimensions, quenched disorder always rounds transitions involving the breaking of spatial symmetries so, in practice, it can often be difficult to infer what form the symmetry breaking would take in the 'ideal,' zero disorder limit. We discuss methods of data analysis which can be useful for making such inferences, and apply them to the problem of determining whether the preferred order in the cuprates is 'stripes' or 'checkerboards.' In many cases we show that the experiments clearly indicate stripe order, while in others (where the observed correlation length is short), the answer is presently uncertain.
Charge-order driven multiferroic and magneto-dielectric properties of rare earth manganates
Indian Academy of Sciences (India)
Claudy Rayan Serrao; Jyoti Ranjan Sahu; Anirban Ghosh
2010-04-01
Charge-order driven magnetic ferroelectricity is shown to occur in several rare earth manganates of the general formula, Ln1–AMnO3 (Ln = rare earth, A = alkaline earth). Charge-ordered manganates exhibit dielectric constant anomalies around the charge-ordering or the antiferromagnetic transition temperature. Magnetic fields have a marked effect on the dielectric properties of these compounds, indicating the presence of coupling between the magnetic and electrical order parameters. Magneto-dielectric properties are retained in small particles of the manganates. The observation of magneto-ferroelectricity in these manganates is in accordance with theoretical predictions.
Orbital Ordering and Spin-Ladder Formation in La2RuO5
Eyert, V.; Ebbinghaus, S. G.; Kopp, T.
2006-06-01
The semiconductor-semiconductor transition of La2RuO5 is studied by means of augmented spherical wave electronic structure calculations as based on density-functional theory and the local density approximation. This transition has lately been reported to lead to orbital ordering and a quenching of the local spin magnetic moment. Our results hint towards an orbital ordering scenario which, markedly different from the previously proposed scheme, preserves the local S=1 moment at the Ru sites in the low-temperature phase. The unusual magnetic behavior is interpreted by the formation of spin ladders, which result from the structural changes occurring at the transition and are characterized by antiferromagnetic coupling along the rungs.
Higher-order adaptive finite-element methods for orbital-free density functional theory
Motamarri, Phani; Iyer, Mrinal; Knap, Jaroslaw; Gavini, Vikram
2011-01-01
In the present work, we investigate the computational efficiency afforded by higher-order finite-element discretization of the saddle-point formulation of orbital-free density functional theory. We first investigate the robustness of viable solution schemes by analyzing the solvability conditions of the discrete problem. We find that a staggered solution procedure where the potential fields are computed consistently for every trial electron-density is a robust solution procedure for higher-or...
Orbital ordering in {sup 154}SmNiO{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Medarde, M.; Rosenkranz, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Rodrigeuez-Carvajal, J. [Laboratoire Leon Brillouin (LLB) - Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France); Lacorre, P. [Lab. Fluorures, LeMans (France); Trounov, V. [PNPI, Gatchina (Russian Federation); Fernandez-Diaz, M.T. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)
1997-09-01
We have investigated the existence of a structural distortion associated to the k = (1/2 0 1/2) orbital ordering recently proposed to explain the magnetic structure of RNiO{sub 3} perovskites (R = rare earth). Our results on a {sup 154}SmNiO{sub 3} powder sample indicate that, if existing, the associated superstructure reflections are as a maximum 10{sup 4} times smaller than the largest nuclear reflection. (author) 2 figs., 3 refs.
Homoclinic Orbits for Second-Order Hamiltonian Systems with Some Twist Condition
Directory of Open Access Journals (Sweden)
Qi Wang
2012-01-01
Full Text Available We study the existence and multiplicity of homoclinic orbits for second-order Hamiltonian systems q¨−L(tq+∇qW(t,q=0, where L(t is unnecessarily positive definite for all t∈ℝ, and ∇qW(t,q is of at most linear growth and satisfies some twist condition between the origin and the infinity.
Photoinduced melting of charge order in quasi-two-dimensional organic conductors
Energy Technology Data Exchange (ETDEWEB)
Tanaka, Yasuhiro; Yonemitsu, Kenji, E-mail: yasuhiro@ims.ac.j [Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)
2009-02-01
Photoinduced melting of charge order in quasi-two-dimensional organic conductors alpha-(ET){sub 2}I{sub 3} (ET=BEDT-TTF) and theta-(ET){sub 2}RbZn(SCN){sub 4} is investigated theoretically. By solving the time-dependent Schroedinger equation numerically within the Hartree-Fock approximation for an extended Peierls-Hubbard model, we study the photoinduced dynamics in each compound. The obtained charge, spin and lattice dynamics are considered to reflect the different natures of charge ordered states in these systems. In particular, the melting of charge order needs more energy for theta-(ET){sub 2}RbZn(SCN){sub 4} than for alpha-(ET){sub 2}I{sub 3}, which is a consequence of large lattice distortion and the essential role of electron-phonon coupling in stabilizing the charge order in theta-(ET){sub 2}RbZn(SCN){sub 4}.
Effect of Lattice Distortion on Charge Order in Manganites at Doping x = 0.5
Institute of Scientific and Technical Information of China (English)
WANG Hai-Long; TIAN Guang-Shan; LIN Hai-Qing
2005-01-01
In the present paper, we continue our investigation on the antiferromagnetic origin of the charge order observed in the half-doped manganese. By introducing a Su-Schrieffer-Heeger (SSH) type of perturbation interaction to the double-exchange Hamiltonian, we calculate again its ground-state phase diagram at filling x = 0.5 by the unrestricted real-space Hartree-Fock approximation method. We find that, as the SSH electron-phonon interaction increases, the charge order parameter decreases to zero rapidly but the CE-type antiferromagnetic order becomes more stable. In other words, the charge order is much more fragile than the CE-type or the Neel-type antiferromagnetic orders under the electron-phonon perturbation. These results support the proposed theory in the recent publications that the charge order in these systems is induced by the antiferromagnetic correlations.
Cage connectivity and frontier π orbitals govern the relative stability of charged fullerene isomers
Wang, Yang; Díaz-Tendero, Sergio; Alcamí, Manuel; Martín, Fernando
2015-11-01
Fullerene anions and cations have unique structural, electronic, magnetic and chemical properties that make them substantially different from neutral fullerenes. Although much theoretical effort has been devoted to characterizing and predicting their properties, this has been limited to a fraction of isomeric forms, mostly for fullerene anions, and has practically ignored fullerene cations. Here we show that the concepts of cage connectivity and frontier π orbitals allow one to understand the relative stability of charged fullerene isomers without performing elaborate quantum chemistry calculations. The latter is not a trivial matter, as the number of possible isomers for a medium-sized fullerene is many more than 100,000. The model correctly predicts the structures observed experimentally and explains why the isolated pentagon rule is often violated for fullerene anions, but the opposite is found for fullerene cations. These predictions are relevant in fields as diverse as astrophysics, electrochemistry and supramolecular chemistry.
The second-order post-newtonian orbit equation of light
Xiao, Y.; Fei, B. J.; Sun, W. J.; Ji, C. X.
2008-04-01
The photon's orbital equation is often used to discuss the movement of man-made satellite, small planet and photon in the solar system. It is also applied to the studies of astronomical measure such as VLBI, GPS and XNAV etc. In this paper, based on the second-order post-Newtonian approximation under the DSX scheme of GTR, it is educed that the second-order post-Newtonian orbit equation of light in axis-symmetrical stationary space-time using Lagrange equation. From here, the orbit equation and deflection angle of light propagating in equatorial plane are got. The conclusions are consistent with that of Schwarzchild and Kerr metric in the precision of measure. Because the oblateness of star is considered, it is more accurate than that of Kerr metric. The great advantage of the second-order post-Newtonian approximation under the DSX scheme of GTR is satisfy linear superposition. So, the conclusions in the paper can be applied to deal with the motion of light in multiple systems, but in this situation Kerr metric is of no effect.
Non-Gaussian properties of second-order wave orbital velocity
Alberello, Alberto; Gramstad, Odin; Babanin, Alexander V; Toffoli, Alessandro
2015-01-01
A stochastic second-order wave model is applied to assess the statistical properties of wave orbital velocity in random sea states below the water surface. Directional spreading effects as well as the dependency of the water depth are investigated by means of a Monte-Carlo approach. Unlike for the surface elevation, sub-harmonics dominate the second-order contribution to orbital velocity. We show that a notable set-down occurs for the most energetic and steepest groups. This engenders a negative skewness in the temporal evolution of the orbital velocity. A substantial deviation of the upper and lower tails of the probability density function from the Gaussian distribution is noticed, velocities are faster below the wave trough and slower below the wave crest when compared with linear theory predictions. Second-order nonlinearity effects strengthen with reducing the water depth, while weaken with the broadening of the wave spectrum. The results are confirmed by laboratory data. Corresponding experiments have b...
Institute of Scientific and Technical Information of China (English)
张红; 张继彦; 杨向东; 杨国洪; 郑志坚
2003-01-01
A collisional radiative model based on the spin-orbit-split-arrays is used to determine the charge state distribution of gold plasmas. The ab initio atomic structure code of Cowan and the spin-orbit-split-array model were used to calculate all the emission spectra of the different gold species, and a non-local thermodynamic-equilibrium model was coupled to calculate the ion populations at a given plasma density and electron temperature. The charge state distribution and other plasma parameters were determined by comparing the experimental spectra with the theoretical simulated spectra of gold plasmas.
Pitch Angle Restrictions in Late Type Spiral Galaxies Based on Chaotic and Ordered Orbital Behavior
Perez-Villegas, Angeles; Moreno, Edmundo; Peimbert, Antonio; Velazquez, Hector M
2011-01-01
We built models for low bulge mass spiral galaxies (late type as defined by the Hubble classification) using a 3-D self-gravitating model for spiral arms, and analyzed the orbital dynamics as a function of pitch angle, going from 10$\\deg$ to 60$\\deg$. Testing undirectly orbital self-consistency, we search for the main periodic orbits and studied the density response. For pitch angles up to approximately $\\sim 20\\deg$, the response supports closely the potential permitting readily the presence of long lasting spiral structures. The density response tends to "avoid" larger pitch angles in the potential, by keeping smaller pitch angles in the corresponding response. Spiral arms with pitch angles larger than $\\sim 20\\deg$, would not be long-lasting structures but rather transient. On the other hand, from an extensive orbital study in phase space, we also find that for late type galaxies with pitch angles larger than $\\sim 50\\deg$, chaos becomes pervasive destroying the ordered phase space surrounding the main sta...
International Nuclear Information System (INIS)
Spin correlations in metallic and insulating phases of V2O3 and its derivatives are investigated using magnetic neutron scattering.Metallic samples have incommensurate spin correlations varying little with hole doping. Paramagnetic insulating samples have spin correlations only among near neighbors. The transition from either of these phases into the low temperature insulating antiferromagnetic phase is accompanied by an abrupt change of dynamic magnetic short range order. Our results support the idea that the transition into the antiferromagnetic insulator is also an orbital ordering transition. copyright 1997 The American Physical Society
Photo-induced changes in charge-ordered state of Ti4O7
International Nuclear Information System (INIS)
We have investigated photo-induced effects on the charge-ordered state of Ti4O7 with pump-probe spectroscopy. Reflectivity of the probe light changes after the pulsed pump excitation, and then recovers. The photo-induced effects are observed only when the pump power exceeds a threshold value, indicative of cooperative nature of the formation process, and the recovery rate shows thermally activated behaviour. We propose that the photo-induced state is a metastable charge localized state where charge disorder is induced by a photon-assisted charge transfer process from Ti26+ dimers to the neighbouring Ti4+ions. Moreover, it is found that subsequent cw laser irradiation converts the photo-induced state into the charge-ordered state. We interpret this result in terms of formation of Ti26+ dimers via an inverse charge transfer process assisted by the cw optical excitation.
Comparison of dust charging between orbital-motion-limited theory and particle-in-cell simulations
International Nuclear Information System (INIS)
The Orbital-Motion-Limited (OML) theory has been modified to predict the dust charge and the results were contrasted with the Whipple approximation [X. Z. Tang and G. L. Delzanno, Phys. Plasmas 21, 123708 (2014)]. To further establish its regime of applicability, in this paper, the OML predictions (for a non-electron-emitting, spherical dust grain at rest in a collisionless, unmagnetized plasma) are compared with particle-in-cell simulations that retain the absorption radius effect. It is found that for large dust grain radius rd relative to the plasma Debye length λD, the revised OML theory remains a very good approximation as, for the parameters considered (rd/λD ≤ 10, equal electron and ion temperatures), it yields the dust charge to within 20% accuracy. This is a substantial improvement over the Whipple approximation. The dust collected currents and energy fluxes, which remain the same in the revised and standard OML theories, are accurate to within 15%–30%
Comparison of dust charging between orbital-motion-limited theory and particle-in-cell simulations
Energy Technology Data Exchange (ETDEWEB)
Delzanno, Gian Luca, E-mail: delzanno@lanl.gov; Tang, Xian-Zhu, E-mail: xtang@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2015-11-15
The Orbital-Motion-Limited (OML) theory has been modified to predict the dust charge and the results were contrasted with the Whipple approximation [X. Z. Tang and G. L. Delzanno, Phys. Plasmas 21, 123708 (2014)]. To further establish its regime of applicability, in this paper, the OML predictions (for a non-electron-emitting, spherical dust grain at rest in a collisionless, unmagnetized plasma) are compared with particle-in-cell simulations that retain the absorption radius effect. It is found that for large dust grain radius r{sub d} relative to the plasma Debye length λ{sub D}, the revised OML theory remains a very good approximation as, for the parameters considered (r{sub d}/λ{sub D} ≤ 10, equal electron and ion temperatures), it yields the dust charge to within 20% accuracy. This is a substantial improvement over the Whipple approximation. The dust collected currents and energy fluxes, which remain the same in the revised and standard OML theories, are accurate to within 15%–30%.
Abeykoon, A. M. Milinda; Bozin, Emil S.; Yin, Wei-Guo; Gu, Genda; Hill, John P.; Tranquada, John M.; Billinge, Simon J. L.
2015-03-01
The temperature evolution of structural modulation associated with charge and spin order in La1.67Sr0.33NiO4 has been investigated using neutron powder diffraction. For the first time we report an anomalous shrinking of the c/a lattice parameter ratio that correlates with TCO at the temperature where long-range stacking order of charge stripes disappears. The sign of this change can be explained by the change in interlayer Coulomb energy between the static-stripe-ordered state and the fluctuating-stripe-ordered state or the charge-disordered state. In addition, we identify a contribution to the mean-square displacements of Ni and in-plane O atoms whose width correlates quite well with the size of the pseudogap extracted from the reported optical conductivity, with a non-Debye-like component that persists below and well above TCO. Local structural parameters in the atomic pair distribution function (PDF) well-agree with this result. We infer that dynamic charge-stripe correlations survive to T ~ 2TCO. This work was supported by the DOE Grant, DE- AC02-98CH10886.
Even and Odd Charge Coherent States: Higher-Order Nonclassical Properties and Generation Scheme
Duc, Truong Minh; Dinh, Dang Huu; Dat, Tran Quang
2016-06-01
We examine the higher-order nonclassical properties of the even and odd charge coherent states as well as proposing a scheme to generate these states whose modes can freely travel in open space. We show that the even and odd charge coherent states exhibit both higher-order antibunching and higher-order squeezing. While the two-mode higher-order antibunching occurs in any order and essentially depends on the charge number, the two-mode higher-order squeezing appears only in the even orders. We also prove that these states are genuinely entangled, and they can be generated by means of cross-Kerr media, beam splitters, phase shifts and threshold detectors. We find that the fidelity and the corresponding success probability to generate these states are dependent on the correlative parameters.
International Nuclear Information System (INIS)
We present a time-dependent density functional theory (TDDFT) approach with proper asymptotic long-range potential for nonperturbative treatment of high-order harmonic generation (HHG) of diatomic molecules with their molecular axis parallel to the laser field polarization. A time-dependent two-center generalized pseudospectral method in prolate spheroidal coordinate system is used for accurate and efficient treatment of the TDDFT equations in space and time. The theory is applied to a detailed all-electron nonperturbative investigation of HHG processes of homonuclear (N2 and F2) and heteronuclear (CO, BF, and HF) molecules in intense ultrashort laser pulses with the emphasis on the role of multiple molecular orbitals (MOs). The results reveal intriguing and substantially different nonlinear optical response behaviors for homonuclear and heteronuclear molecules. In particular, we found that the HHG spectrum for homonuclear molecules features a destructive interference of MO contributions while heteronuclear molecules show mostly constructive interference of orbital contributions.
Charge-order domain walls with enhanced conductivity in a layered manganite
Ma, Eric Yue; Bryant, Benjamin; Tokunaga, Yusuke; Aeppli, Gabriel; Tokura, Yoshinori; Shen, Zhi-Xun
2015-07-01
Interfaces and boundaries in condensed-matter systems often have electronic properties distinct from the bulk material and thus have become a topic of both fundamental scientific interest and technological importance. Here we identify, using microwave impedance microscopy, enhanced conductivity of charge-order domain walls in the layered manganite Pr(Sr0.1Ca0.9)2Mn2O7. We obtain a complete mesoscopic map of surface topography, crystalline orientation and electronic phase, and visualize the thermal phase transition between two charge-ordered phases. In both phases, charge-order domains occur with domain walls showing enhanced conductivity likely due to local lifting of the charge order. Finite element analysis shows that the resolved domain walls can be as narrow as few nanometres. The domain walls are stabilized by structural twins and have a strong history dependence, suggesting that they may be manipulated to create novel devices.
International Nuclear Information System (INIS)
Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.
Energy Technology Data Exchange (ETDEWEB)
Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim, E-mail: ekarimi@uottawa.ca [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Boyd, Robert W. [Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5 Canada (Canada); Institute of Optics, University of Rochester, Rochester, New York 14627 (United States)
2014-09-08
Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded “space” for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulating conventional orbital angular momentum generators. In this work, we design and fabricate an ultra-thin spin-to-orbital angular momentum converter, based on plasmonic nano-antennas and operating in the visible wavelength range that is capable of converting spin to an arbitrary value of orbital angular momentum ℓ. The nano-antennas are arranged in an array with a well-defined geometry in the transverse plane of the beam, possessing a specific integer or half-integer topological charge q. When a circularly polarised light beam traverses this metasurface, the output beam polarisation switches handedness and the orbital angular momentum changes in value by ℓ=±2qℏ per photon. We experimentally demonstrate ℓ values ranging from ±1 to ±25 with conversion efficiencies of 8.6% ± 0.4%. Our ultra-thin devices are integratable and thus suitable for applications in quantum communications, quantum computations, and nano-scale sensing.
Energy Technology Data Exchange (ETDEWEB)
Tessmer, M; Hartung, J; Schaefer, G, E-mail: m.tessmer@uni-jena.d [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany)
2010-08-21
A quasi-Keplerian parameterization for the solutions of second post-Newtonian (PN) accurate equations of motion for spinning compact binaries is obtained including leading order spin-spin and next-to-leading order spin-orbit interactions. Rotational deformation of the compact objects is incorporated. For arbitrary mass ratios the spin orientations are taken to be parallel or anti-parallel to the orbital angular momentum vector. The emitted gravitational wave forms are given in analytic form up to 2PN point particle, 1.5PN spin-orbit and 1PN spin-spin contributions, whereby the spins are assumed to be of 0PN order.
International Nuclear Information System (INIS)
A quasi-Keplerian parameterization for the solutions of second post-Newtonian (PN) accurate equations of motion for spinning compact binaries is obtained including leading order spin-spin and next-to-leading order spin-orbit interactions. Rotational deformation of the compact objects is incorporated. For arbitrary mass ratios the spin orientations are taken to be parallel or anti-parallel to the orbital angular momentum vector. The emitted gravitational wave forms are given in analytic form up to 2PN point particle, 1.5PN spin-orbit and 1PN spin-spin contributions, whereby the spins are assumed to be of 0PN order.
Bauer, Johannes; Sachdev, Subir(Department of Physics, Harvard University, Cambridge, MA, 02138, USA)
2015-01-01
We study charge ordered solutions for fermions on a square lattice interacting with dynamic antiferromagnetic fluctuations. Our approach is based on real space Eliashberg equations which are solved self-consistently. We first show that the antiferromagnetic fluctuations can induce arc features in the spectral functions, as spectral weight is suppressed at the hot spots; however, no real pseudogap is generated. At low temperature spontaneous charge order with a $d$-form factor can be stabilize...
Eremin, Ilya; Nogueira, Flavio S.; Tarento, Rene-Jean
2005-01-01
We consider the spin and charge Josephson current between two non-uniform Fulde-Ferrel-Larkin-Ovchinnikov superconductors with helimagnetic order. We demonstrate that the presence of the helimagnetic phase generates a spin Josephson effect and leads to additional contributions to both single-particle and Josephson charge current. It is shown that for such systems the AC effect differs more radically from the DC effect than in the case of a BCS superconductor with helimagnetic order considered...
Orbital ordering in the two-dimensional ferromagnetic semiconductor Rb2CrCl4
Schwingenschlögl, U.; Eyert, V.
2007-05-01
We present the results of electronic structure calculations for the two-dimensional ferromagnet Rb2CrCl4. They are obtained by the augmented spherical wave (ASW) method as based on density functional theory and the local density approximation. In agreement with experimental data, Rb2CrCl4 is found to be semiconducting and displays long-range ferromagnetic order of the localized Cr 3d moments. The magnetic properties are almost independent of the structural modifications arising from the Jahn-Teller instability, which leads from the parent body-centered tetragonal K2NiF4 structure to a side-centered orthorhombic lattice. In contrast, the insulating gap is observed only for the latter structure due to the reduced symmetry. Our results thus suggest to interpret the orbital ordering as a necessary prerequisite for the opening of the gap rather than for the ferromagnetic order.
Self-Deflection of Dark Screening Spatial Solitons Based on Higher-Order Space Charge Field
Institute of Scientific and Technical Information of China (English)
ZHANG Guang-Yong; LIU Jin-Song; LIU Shi-Xiong; WANG Cheng; ZHANG Hui-Lan
2007-01-01
The effects of higher-order space charge field on the self-deflection of dark screening spatial solitons in biased photorefractive crystals are numerically investigated under steady-state conditions. The expression for an induced space-charge electric field including higher-order space-charge field terms is obtained. Numerical results indicate that dark solitons possess a self-deflection process during propagation, and the solitons always bend in the direction of the c axis of the crystal The self-deflection of dark solitons can experience considerable increase especially in the regime of high bias field strengths.
Higher-order adaptive finite-element methods for orbital-free density functional theory
International Nuclear Information System (INIS)
In the present work, we study various numerical aspects of higher-order finite-element discretizations of the non-linear saddle-point formulation of orbital-free density-functional theory. We first investigate the robustness of viable solution schemes by analyzing the solvability conditions of the discrete problem. We find that a staggered solution procedure where the potential fields are computed consistently for every trial electron-density is a robust solution procedure for higher-order finite-element discretizations. We next study the convergence properties of higher-order finite-element discretizations of orbital-free density functional theory by considering benchmark problems that include calculations involving both pseudopotential as well as Coulomb singular potential fields. Our numerical studies suggest close to optimal rates of convergence on all benchmark problems for various orders of finite-element approximations considered in the present study. We finally investigate the computational efficiency afforded by various higher-order finite-element discretizations, which constitutes the main aspect of the present work, by measuring the CPU time for the solution of discrete equations on benchmark problems that include large Aluminum clusters. In these studies, we use mesh coarse-graining rates that are derived from error estimates and an a priori knowledge of the asymptotic solution of the far-field electronic fields. Our studies reveal a significant 100–1000 fold computational savings afforded by the use of higher-order finite-element discretization, alongside providing the desired chemical accuracy. We consider this study as a step towards developing a robust and computationally efficient discretization of electronic structure calculations using the finite-element basis.
Unraveling Orbital Ordering in La0.5Sr1.5MnO4
International Nuclear Information System (INIS)
Orbital ordering (OO) in the layered perovskite La0.5Sr1.5MnO4 has been investigated using the enhanced sensitivity of soft x-ray resonant diffraction at the Mn L edges. The energy dependence of an OO diffraction peak over the L2,3 edges is compared to ligand-field calculations allowing a distinction between the influences of Jahn-Teller distortions and spin correlations. The energy dependence of the diffraction peak at the Mn L1 edge is remarkably different from that observed at the Mn K edge
Halford, Sarah Juliette
2013-01-01
I always knew I was from another planet. Earth was my home, yes, I liked hamburgers and roller coasters, but there was still an orbit in me that seemed out of place. My imaginative orbit felt like it didn't to spin the "normal" way. As a performer I spent more time alienating myself and judging how different I felt, rather than owning the creative space I lived in and applying it to my craft. My past three years at UC San Diego have been the perfect atmosphere for my artist self. I have been ...
Gate-Tunable Spin-Charge Conversion and the Role of Spin-Orbit Interaction in Graphene
Dushenko, S.; Ago, H.; Kawahara, K.; Tsuda, T.; Kuwabata, S.; Takenobu, T.; Shinjo, T.; Ando, Y.; Shiraishi, M.
2016-04-01
The small spin-orbit interaction of carbon atoms in graphene promises a long spin diffusion length and the potential to create a spin field-effect transistor. However, for this reason, graphene was largely overlooked as a possible spin-charge conversion material. We report electric gate tuning of the spin-charge conversion voltage signal in single-layer graphene. Using spin pumping from an yttrium iron garnet ferrimagnetic insulator and ionic liquid top gate, we determined that the inverse spin Hall effect is the dominant spin-charge conversion mechanism in single-layer graphene. From the gate dependence of the electromotive force we showed the dominance of the intrinsic over Rashba spin-orbit interaction, a long-standing question in graphene research.
Tessmer, Manuel; Schaefer, Gerhard
2010-01-01
A quasi-Keplerian parameterisation for the solutions of second post-Newtonian (PN) accurate equations of motion for spinning compact binaries is obtained including leading order spin-spin and next-to-leading order spin-orbit interactions. Rotational deformation of the compact objects is incorporated. For arbitrary mass ratios the spin orientations are taken to be parallel or anti-parallel to the orbital angular momentum vector. The emitted gravitational wave forms are given in analytic form up to 2PN point particle, 1.5PN spin orbit and 1PN spin-spin contributions, where the spins are counted of 0PN order.
International Nuclear Information System (INIS)
We compute the next-to-next-to-leading order spin–orbit contributions in the total energy flux emitted in gravitational waves by compact binary systems. Such contributions correspond to the post-Newtonian order 3.5PN for maximally spinning compact objects. Continuing our recent work on the next-to-next-to-leading spin–orbit terms at the 3.5PN order in the equations of motion, we obtain the spin–orbit terms in the multipole moments of the compact binary system up to the same order within the multipolar post-Newtonian wave generation formalism. Our calculation of the multipole moments is valid for general orbits and in an arbitrary frame, the moments are then reduced to the center-of-mass frame and the resulting energy flux is specialized to quasi-circular orbits. The test-mass limit of our final result for the flux agrees with the already known Kerr black hole perturbation limit. Furthermore, the various multipole moments of the compact binary reduce in the one-body case to those of a single-boosted Kerr black hole. We briefly discuss the implications of our result for the gravitational wave flux in terms of the binary’s phase evolution, and address its importance for the future detection and parameter estimation of signals in gravitational wave detectors. (paper)
International Nuclear Information System (INIS)
Atomic-orbital close-coupling calculations of neon and argon ions colliding with H(1s) will be presented. The high principal quantum numbers n that need to be included in the expansion of the wavefunction of the active electron in the ion center make very large basis sets necessary. The resulting state resolved charge exchange and ionisation cross sections are of special interest for nuclear fusion research.
Krah, Tim; Ben Amor, Nadia; Maynau, Daniel; Berger, J A; Robert, Vincent
2014-07-01
Based on localized molecular orbitals, the proposed method reduces large configuration interaction (CI) spaces while maintaining agreement with reference values. Our strategy concentrates the numerical effort on physically pertinent CI-contributions and is to be considered as a tool to tackle large systems including numerous open-shells. To show the efficiency of our method we consider two 4-electron parent systems. First, we illustrate our approach by describing the van der Waals interactions in the (H2)2 system. By systematically including local correlation, dispersion and charge transfer mechanisms, we show that 90% of the reference full CI dissociation energy of the H2 dimer is reproduced using only 3% of the full CI space. Second, the conformational cis/trans rotation barrier of the butadiene molecule is remarkably reproduced (97% of the reference value) with less than 1% of the reference space. This work paves the way to numerical strategies which afford the electronic structure determination of large open-shell systems avoiding the exponential limitation. At the same time, a physical analysis of the contents of the wave function is offered. PMID:24935105
Sheikh-Jabbari, M M
2016-01-01
Expanding upon [arXiv:1404.4472, 1511.06079], we provide further detailed analysis of Banados geometries, the most general solutions to the AdS3 Einstein gravity with Brown-Henneaux boundary conditions. We analyze in some detail the causal, horizon and boundary structure, and geodesic motion on these geometries, as well as the two class of symplectic charges one can associate with these geometries: charges associated with the exact symmetries and the Virasoro charges. We elaborate further the one-to-one relation between representations of two copies of Virasoro group (Virasoro coadjoint orbits) and Banados geometries. We discuss that the information about the Banados goemetries fall into two categories: "orbit invariant" information and "Virasoro hairs". The former are geometric quantities while the latter are specified by the non-local surface integrals. We elaborate on multi-BTZ geometries which have some number of disconnected pieces at the horizon bifurcation curve. We study multi-BTZ black hole thermodyn...
Q. Zhang; Singh, K.; Simon, C; Tung, L. D.; Balakrishnan, G.; Hardy, V.
2012-01-01
The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin and orbital ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic ...
$d$-wave bond-order charge excitations in electron-doped cuprates
Yamase, Hiroyuki; Bejas, Matías; Greco, Andrés
2015-01-01
We study charge excitation spectra in the two-dimensional $t$-$J$ model on a square lattice to explore a charge-order tendency recently found in electron-doped cuprates around the carrier density 0.15. The static susceptibility of $d$-wave charge density, which corresponds to the nematic susceptibility at the momentum transfer ${\\bf q}=(0,0)$, shows two characteristic peaks at momenta of the form ${\\bf q}_{1}=(q',q')$ and ${\\bf q}_{2}=(q,0)$. These two peaks originate from the so-called $2k_{...
Effect of charge order on the plasmon dispersion in transition-metal dichalcogenides
Van Wezel, Jasper; Schuster, Roman; König, Andreas; Knupfer, Martin; Brink, Jeroen van den; Berger, Helmuth; Büchner, Bernd
2012-01-01
We investigate the dispersion of the charge carrier plasmon in the three prototypical charge-density wave bearing transition-metal dichalcogenides 2H-TaSe₂, 2H-TaS₂, and 2H-NbSe₂ employing electron energy-loss spectroscopy. For all three compounds the plasmon dispersion is found to be negative for small momentum transfers. This is in contrast with the generic behavior observed in simple metals as well as the related system 2H-NbS₂, which does not exhibit charge order. We present a semiclassic...
The Effect of Charge Order on the Plasmon Dispersion in Transition-Metal Dichalcogenides
Van Wezel, Jasper; Schuster, Roman; König, Andreas; Knupfer, Martin; Brink, Jeroen van den; Berger, Helmuth; Büchner, Bernd
2011-01-01
We investigate the dispersion of the charge carrier plasmon in the three prototypical charge-density wave bearing transition-metal dichalcogenides 2H-TaSe2, 2H-TaS2 and 2H-NbSe2 employing electron energy-loss spectroscopy. For all three compounds the plasmon dispersion is found to be negative for small momentum transfers. This is in contrast to the generic behavior observed in simple metals as well as the related system 2H-NbS2, which does not exhibit charge order. We present a semiclassical ...
The Bond Order of C2 from a Strictly N-Representable Natural Orbital Energy Functional Perspective.
Piris, Mario; Lopez, Xabier; Ugalde, Jesus M
2016-03-14
The bond order of the ground electronic state of the carbon dimer has been analyzed in the light of natural orbital functional theory calculations carried out with an approximate, albeit strictly N-representable, energy functional. Three distinct solutions have been found from the Euler equations of the minimization of the energy functional with respect to the natural orbitals and their occupation numbers, which expand upon increasing values of the internuclear coordinate. In the close vicinity of the minimum energy region, two of the solutions compete around a discontinuity point. The former, corresponding to the absolute minimum energy, features two valence natural orbitals of each of the following symmetries, σ, σ*, π and π*, and has three bonding interactions and one antibonding interaction, which is very suggestive of a bond order large than two but smaller than three. The latter, features one σ-σ* linked pair of natural orbitals and three degenerate pseudo-bonding like orbitals, paired each with one triply degenerate pseudo-antibonding orbital, which points to a bond order larger than three. When correlation effects, other than Hartree-Fock for example, between the paired natural orbitals are accounted for, this second solution vanishes yielding a smooth continuous dissociation curve. Comparison of the vibrational energies and electron ionization energies, calculated on this curve, with their corresponding experimental marks, lend further support to a bond order for C2 intermediate between acetylene and ethylene. PMID:26822104
Explicitly correlated atomic orbital basis second order Møller-Plesset theory
Hollman, David S.; Wilke, Jeremiah J.; Schaefer, Henry F.
2013-02-01
The scope of problems treatable by ab initio wavefunction methods has expanded greatly through the application of local approximations. In particular, atomic orbital (AO) based wavefunction methods have emerged as powerful techniques for exploiting sparsity and have been applied to biomolecules as large as 1707 atoms [S. A. Maurer, D. S. Lambrecht, D. Flaig, and C. Ochsenfeld, J. Chem. Phys. 136, 144107 (2012)], 10.1063/1.3693908. Correlated wavefunction methods, however, converge notoriously slowly to the basis set limit and, excepting the use of large basis sets, will suffer from a severe basis set incompleteness error (BSIE). The use of larger basis sets is prohibitively expensive for AO basis methods since, for example, second-order Møller-Plesset perturbation theory (MP2) scales linearly with the number of atoms, but still scales as O(N^5) in the number of functions per atom. Explicitly correlated F12 methods have been shown to drastically reduce BSIE for even modestly sized basis sets. In this work, we therefore explore an atomic orbital based formulation of explicitly correlated MP2-F12 theory. We present working equations for the new method, which produce results identical to the widely used molecular orbital (MO) version of MP2-F12 without resorting to a delocalized MO basis. We conclude with a discussion of several possible approaches to a priori screening of contraction terms in our method and the prospects for a linear scaling implementation of AO-MP2-F12. The discussion includes concrete examples involving noble gas dimers and linear alkane chains.
Strong coupling critique of spin fluctuation driven charge order in underdoped cuprates
Mishra, Vivek; Norman, M. R.
2015-08-01
Charge order has emerged as a generic feature of doped cuprates, leading to important questions about its origin and its relation to superconductivity. Recent experiments on two classes of hole doped cuprates indicate a novel d -wave symmetry for the order. These were motivated by earlier spin fluctuation theoretical studies based on an expansion about hot spots in the Brillouin zone that indicated such an order would be competitive with d -wave superconductivity. Here, we reexamine this problem by solving strong coupling equations in the full Brillouin zone for experimentally relevant parameters. We find that bond-oriented order, as seen experimentally, is strongly suppressed. We also include coupling to B1 g phonons and do not see any qualitative change. Our results argue against an itinerant model for the charge order, implying instead that such order is likely due to Coulombic phase separation of the doped holes.
Superconductivity, spin and charge order, and quantum criticality in correlated electron materials
Chu J.-H.; Fisher I. R.; White B. D.; Baumbach R. E.; Janoschek M.; Zocco D. A.; Hamlin J. J.; Maple M. B.
2012-01-01
We describe recent experiments performed in our laboratory that address spin or charge ordered phases in novel rare earth and actinide based materials and phenomena that emerge when these ordered phases are suppressed toward 0 K by varying an external control parameter such as chemical composition, pressure, or magnetic field. Specific examples discussed include magnetic order, heavy fermion behavior, and unconventional quantum criticality in noncentrosymmetric M2T12P7 compounds (M = rare ear...
International Nuclear Information System (INIS)
Subperoxidic O23- charge ordering presents a satisfying basis for a quantitative, conceptually realistic, and unifying understanding of cuprate superconductors. The activity of O- manifests itself in a variety of ways including a universal Tc scaling with O- per total O, or more generally, in the subperoxide radical concentration. Also, a characteristic crystal chemistry of O- placement is indicated. As an example, trends to preferential O- occupation of the apical sites are correlated with c axis and Tc decreases providing a new crystallographic interpretation of the overdoping question. Generally, subperoxides can be created on overoxidation or through various modes of self doping through lattice pressure-related factors. Accordingly, the role of peranion formation is seen as a most general chemical principle for ameliorating stacking mismatch through electronic liquefaction under internal stress . Cases are discussed (e.g., YBa2Cu3O6.5) where the tension on cooling can result in stratified self-doping steps. A variety of experiments indicating charge order properties, such as stripes and slow charge propagation, are interpreted on the anionic model. Subperoxidic pair formation and charge ordering energetics are discussed. Concepts are further generalized for other cases (e.g., carbides or nitrides) of anionic metallicity and superconductivity. Common aspects are mobile, paired charge orders of radicals coupled through bond polarizations
High-resolution x-ray scattering studies of charge ordering in highly correlated electron systems
Ghazi, M E
2002-01-01
addition, another very weak satellites with wavevector (1/2, 1, 1/2) were observed possibly due to spin ordering. two-dimensional in nature both by measurements of their correlation lengths and by measurement of the critical exponents of the charge stripe melting transition with an anomaly at x = 0.25. The results show by decreasing the hole concentration from the x = 0.33 to 0.2, the well-correlated charge stripes change to a glassy state at x = 0.25. The electronic transition into the charge stripe phase is second-order without any corresponding structural transition. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. In a single-crystal of Nd sub 1 sub / sub 2 Sr sub 1 sub / sub 2 MnO sub 3 a series of phase transitions were observed using high-resolution synchrotron X-ray scattering. Above the charge ordering transition temperature, T sub C sub O , by measuring the peak profiles of Bragg reflections as a function of temperature, it was foun...
Li, Lin-Sen
The influence of the electronic induction drag on the variation of the orbital elements of a charged satellite moving in a magnetic-field-free ionosphere are studied. The theoretical result show that the induction drag results in both the secular and periodic variations of the semi-major axis, however the eccentricity, the argument of perigee and the mean longitude of epoch exhibits no secular variation, but only periodic variation. The inclination and the ascending node remain no variation. As example, the secular effect of the induction drag on the orbital semi-major axis at a supposed satellite is calculated. It can be shown that the semi-major axis is contracted due to the induction drag, if this satellite carries many charges in an ionosphere.
Orbital geometry determined by orthogonal high-order harmonic polarization components
International Nuclear Information System (INIS)
We study the polarization state of high-order harmonics produced by linearly polarized light interacting with two-center molecules. By generating high-harmonic 'polarization maps' from Radon transformations of excited electronic wave functions, we show that the polarization of the harmonic radiation can be linked to the geometry of the molecular orbital. While in the Radon transformation the plane-wave approximation for the rescattered electron is implicitly assumed, numerical solutions of the two-dimensional time-dependent Schro··dinger equation, in which this approximation is not made, confirm the validity of this topological connection. We also find that measuring two orthogonal amplitude components of the harmonics provides a method for quantum tomography that substantially improves the quality of reconstructed molecular states.
Lohr, M E; Payne, S G; West, R G; Wheatley, P J
2015-01-01
Orbital period changes of binary stars may be caused by the presence of a third massive body in the system. Here we have searched the archive of the Wide Angle Search for Planets (SuperWASP) project for evidence of period variations in 13927 eclipsing binary candidates. Sinusoidal period changes, strongly suggestive of third bodies, were detected in 2% of cases; however, linear period changes were observed in a further 22% of systems. We argue on distributional grounds that the majority of these apparently linear changes are likely to reflect longer-term sinusoidal period variations caused by third bodies, and thus estimate a higher-order multiplicity fraction of 24% for SuperWASP binaries, in good agreement with other recent figures for the fraction of triple systems amongst binary stars in general.
Ayuel, K.; de Châtel, P. F.; Amani, Salah
2002-04-01
Charge, current and spin densities are calculated for a two-electron system, maintaining the explicit form of the wave functions, in terms of Slater determinants. The two-electron Russell-Saunders spin-orbit coupled eigenstates | L, S, J, MJ> are expressed as four-component spinors, and the operators of the above densities as 4×4 matrices. The contributions of various one-electron states to these densities are identified.
Burnus, Tobias
2008-01-01
Transition-metal compounds show a wealth of intriguing properties such as superconductivity, piezoelectricity, giant magnetoresistance, spin and metal-insulator transitions, which are governed by the interplay of charge, spin, and orbital degrees of freedom. The knowledge of their electronic structure is crucial for understanding and predicting the fascinating properties of these often strongly correlated materials. In this thesis x-ray absorption spectroscopy including x-ray magnetic circula...
Phase Fluctuations and the Absence of Topological Defects in Photo-excited Charge Ordered Nickelate
Energy Technology Data Exchange (ETDEWEB)
Lee, W.S.; Chuang, Y.D.; Moore, R.G.; Zhu, Y.; Patthey, L.; Trigo, M.; Lu, D.H.; Kirchmann, P.S.; Krupin, O.; Yi, M.; Langner, M.; Huse, N.; Robinson, J.S.; Chen, Y.; Zhou, S.Y.; Coslovich, G.; Huber, B.; Reis, D.A.; Kaindl, R.A.; Schoenlein, R.W.; Doering, D.
2012-05-15
The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La{sub 1.75}Sr{sub 0.25}NiO{sub 4} to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.
Phase fluctuations and the absence of topological defects in photo-excited charge ordered nickelate
Energy Technology Data Exchange (ETDEWEB)
Lee, W.S.; Chuang, Y.D.; Moore, R.G.; Zhu, Y.; Patthey, L.; Trigo, M.; Lu, D.H.; Kirchmann, P.S.; Krupin, O.; Yi, M.; Langner, M.; Huse, N.; Robinson, J.S.; Chen, Y.; Zhou, S.Y.; Coslovich, G.; Huber, B.; Reis, D.A.; Kaindl, R.A.; Schoenlein, R.W.; Doering, D.; Denes, P.; Schlotter, W.F.; Turner, J.J.; Johnson, S.L.; F& #246; rst, M.; Sasagawa, T.; Kung, Y.F.; Sorini, A.P.; Kemper, A.F.; Moritz, B.; Devereaux, T.P.; Lee, D.-H.; Shen, Z.X.; Hussain, Z.
2012-01-01
The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerging in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of measuring material properties at atomic and electronic time scales out of equilibrium, can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here we combine time-resolved femotosecond optical and resonant X-ray diffraction measurements on charge ordered La1.75Sr0.25NiO4 to reveal unforeseen photoinduced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, distinct from thermal phase fluctuations near the critical temperature in equilibrium. Importantly, relaxation of the phase fluctuations is found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limits charge order recovery. This new aspect of phase fluctuations provides a more holistic view of the phase's importance in ordering phenomena of quantum matter.
Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor
Campi, G.; Bianconi, A.; Poccia, N.; Bianconi, G.; Barba, L.; Arrighetti, G.; Innocenti, D.; Karpinski, J.; Zhigadlo, N. D.; Kazakov, S. M.; Burghammer, M.; Zimmermann, M. V.; Sprung, M.; Ricci, A.
2015-09-01
It has recently been established that the high-transition-temperature (high-Tc) superconducting state coexists with short-range charge-density-wave order and quenched disorder arising from dopants and strain. This complex, multiscale phase separation invites the development of theories of high-temperature superconductivity that include complexity. The nature of the spatial interplay between charge and dopant order that provides a basis for nanoscale phase separation remains a key open question, because experiments have yet to probe the unknown spatial distribution at both the nanoscale and mesoscale (between atomic and macroscopic scale). Here we report micro X-ray diffraction imaging of the spatial distribution of both short-range charge-density-wave `puddles' (domains with only a few wavelengths) and quenched disorder in HgBa2CuO4 + y, the single-layer cuprate with the highest Tc, 95 kelvin (refs 26, 27, 28). We found that the charge-density-wave puddles, like the steam bubbles in boiling water, have a fat-tailed size distribution that is typical of self-organization near a critical point. However, the quenched disorder, which arises from oxygen interstitials, has a distribution that is contrary to the usually assumed random, uncorrelated distribution. The interstitial-oxygen-rich domains are spatially anticorrelated with the charge-density-wave domains, because higher doping does not favour the stripy charge-density-wave puddles, leading to a complex emergent geometry of the spatial landscape for superconductivity.
Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor.
Campi, G; Bianconi, A; Poccia, N; Bianconi, G; Barba, L; Arrighetti, G; Innocenti, D; Karpinski, J; Zhigadlo, N D; Kazakov, S M; Burghammer, M; Zimmermann, M v; Sprung, M; Ricci, A
2015-09-17
It has recently been established that the high-transition-temperature (high-Tc) superconducting state coexists with short-range charge-density-wave order and quenched disorder arising from dopants and strain. This complex, multiscale phase separation invites the development of theories of high-temperature superconductivity that include complexity. The nature of the spatial interplay between charge and dopant order that provides a basis for nanoscale phase separation remains a key open question, because experiments have yet to probe the unknown spatial distribution at both the nanoscale and mesoscale (between atomic and macroscopic scale). Here we report micro X-ray diffraction imaging of the spatial distribution of both short-range charge-density-wave 'puddles' (domains with only a few wavelengths) and quenched disorder in HgBa2CuO4 + y, the single-layer cuprate with the highest Tc, 95 kelvin (refs 26-28). We found that the charge-density-wave puddles, like the steam bubbles in boiling water, have a fat-tailed size distribution that is typical of self-organization near a critical point. However, the quenched disorder, which arises from oxygen interstitials, has a distribution that is contrary to the usually assumed random, uncorrelated distribution. The interstitial-oxygen-rich domains are spatially anticorrelated with the charge-density-wave domains, because higher doping does not favour the stripy charge-density-wave puddles, leading to a complex emergent geometry of the spatial landscape for superconductivity. PMID:26381983
Charge-correlation effects in calculations of atomic short-range order in metallic alloys
Energy Technology Data Exchange (ETDEWEB)
Pinski, F.J. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Staunton, J.B. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Johnson, D.D. [Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois 61801 (United States)
1998-06-01
The {open_quotes}local{close_quotes} chemical environment that surrounds an atom directly influences its electronic charge density. These atomic charge correlations play an important role in describing the Coulomb and total energies for random substitutional alloys. Although the electronic structure may be well represented by a single-site theory, such as the coherent potential approximation, the electrostatic energy is not as well represented when these charge correlations are ignored. For metals, including the average effect from the charge correlation coming from only the nearest-neighbor shell has been shown to be sufficient to determine accurately the energy of formation. In this paper, we incorporate such charge correlations into the concentration-wave approach for calculating the atomic short-range order in random (substitutional) alloys. We present changes within the formalism, and apply the resulting equations to equiatomic nickel platinum. By including these effects, we obtain significantly better agreement with experimental data. In fact, particular to NiPt, a consequence of the charge correlation is a screening which cancels much of the electrostatic contribution to the energy and thus to the atomic short-range order, resulting in agreement with a picture originally outlined using only {open_quotes}band-energy{close_quotes} contributions. {copyright} {ital 1998} {ital The American Physical Society}
Bond orbital description of the strain-induced second-order optical susceptibility in silicon
Damas, Pedro; Marris-Morini, Delphine; Cassan, Eric; Vivien, Laurent
2016-04-01
We develop a theoretical model, relying on the well established sp3 bond-orbital theory, to describe the strain-induced χ(2 ) in tetrahedrally coordinated centrosymmetric covalent crystals, like silicon. With this approach we are able to describe every component of the χ(2 ) tensor in terms of a linear combination of strain gradients and only two parameters α and β which can be theoretically estimated. The resulting formula can be applied to the simulation of the strain distribution of a practical strained silicon device, providing an extraordinary tool for optimization of its optical nonlinear effects. The application of the first order theory to the photoelastic effect in C, Si, and Ge showed very good phenomenological and numerical agreement, up to 3% in Si. The model was then used to the second-order nonlinear susceptibility, and we were able not only to confirm the main valid claims known about χ(2 ) in strained silicon, but also estimate the order of magnitude of the χ(2 ) generated in that device.
Topological charge order and binding in a frustrated XY model and related systems
International Nuclear Information System (INIS)
We prove the existence of a finite temperature Z2 phase transition for the topological charge ordering within the fully frustrated XY model. Our method enables a proof of the topological charge confinement within the conventional XY models from a rather general vista. One of the complications that we face is the non-exact equivalence of the continuous (angular) XY model and its discrete topological charge dual. In reality, the energy spectra of the various topological sectors are highly nested, much unlike that suggested by the discrete dual models. We surmount these difficulties by exploiting the reflection positivity symmetry that this periodic flux phase model possesses. The techniques introduced here may prove binding of topological charges in numerous models and might be applied to examine transitions associated with various topological defects, e.g., the confinement of disclinations in the isotropic to nematic transition. (paper)
Energy Technology Data Exchange (ETDEWEB)
Feier, Hilary M.; Reid, Obadiah G.; Pace, Natalie A.; Park, Jaehong; Bergkamp, Jesse J.; Sellinger, Alan; Gust, Devens; Rumbles, Garry
2016-03-23
How free charge is generated at organic donor-acceptor interfaces is an important question, as the binding energy of the lowest energy (localized) charge transfer states should be too high for the electron and hole to escape each other. Recently, it has been proposed that delocalization of the electronic states participating in charge transfer is crucial, and aggregated or otherwise locally ordered structures of the donor or the acceptor are the precondition for this electronic characteristic. The effect of intermolecular aggregation of both the polymer donor and fullerene acceptor on charge separation is studied. In the first case, the dilute electron acceptor triethylsilylhydroxy-1,4,8,11,15,18,22,25-octabutoxyphthalocyaninatosilicon(IV) (SiPc) is used to eliminate the influence of acceptor aggregation, and control polymer order through side-chain regioregularity, comparing charge generation in 96% regioregular (RR-) poly(3-hexylthiophene) (P3HT) with its regiorandom (RRa-) counterpart. In the second case, ordered phases in the polymer are eliminated by using RRa-P3HT, and phenyl-C61-butyric acid methyl ester (PC61BM) is used as the acceptor, varying its concentration to control aggregation. Time-resolved microwave conductivity, time-resolved photoluminescence, and transient absorption spectroscopy measurements show that while ultrafast charge transfer occurs in all samples, long-lived charge carriers are only produced in films with intermolecular aggregates of either RR-P3HT or PC61BM, and that polymer aggregates are just as effective in this regard as those of fullerenes.
Ultrafast melting of charge ordering in LuFe2O4 probed by terahertz spectroscopy
International Nuclear Information System (INIS)
Ultrafast terahertz response of charge ordering (CO) in LuFe2O4 was investigated by near-infrared-pump (1.55 eV) and terahertz-probe (2–9 meV) spectroscopy. Photoinduced absorption observed immediately (1 ps) after the photoexcitation was attributed to photoinduced melting of the CO. The charge dynamics thereafter can be characterized by subsequent development of the photoinduced conductivity in the low-energy region (2–3 meV), implying the formation of a metallic state. - Highlights: ► We investigated ultrafast optical response of charge ordering (CO) in LuFe2O4. ► Instantaneous photoinduced absorption was ascribed to photoinduced melting of CO. ► Subsequent change in the optical conductivity implies the metallic state formation.
Dielectric anomaly in NaV2O5 : evidence for charge ordering
Smirnov, A.I.; Popova, M.N.; Sushkov, A.B.; Golubchik, S.A.; Khomskii, D.I.; Mostovoy, M.V.; Vasil'ev, A.N.; Isobe, M.; Ueda, Y.
2000-01-01
We found a high-frequency dielectric and magnetic anomaly in NaV2O5 at the phase transition into the spin-gap state. The dielectric constant anomaly is of the antiferroelectric type, which is in agreement with the models assuming the zigzag charge ordering in the ab-plane.
Lara, Martin; Palacian, Jesus F.
2007-01-01
Frozen orbits of the Hill problem are determined in the double averaged problem, where short and long period terms are removed by means of Lie transforms. The computation of initial conditions of corresponding quasi periodic solutions in the non-averaged problem is straightforward for the perturbation method used provides the explicit equations of the transformation that connects the averaged and non-averaged models. A fourth order analytical theory reveals necessary for the accurate computation of quasi periodic, frozen orbits.
International Nuclear Information System (INIS)
The charge ordering in Nd0.5Sr0.5MnO3 (A> = 1.24 A, which occurs on cooling the ferromagnetic metallic ground state, is readily destroyed on application of a magnetic field of 6 T. For Y0.5Ca0.5MnO3 (A> = 1.13 A), for which the ground state is charge ordered, on the other hand, magnetic fields have no effect on the charge ordering. In order to understand such a marked difference in charge-ordering behaviour of the manganates, we have investigated the structure as well as the electrical and magnetic properties of Ln0.5Ca0.5MnO3 compositions (Ln=Nd, Sm, Gd and Dy) wherein A> varies over the range 1.17-1.13 A. The lattice distortion index, D, and charge-ordering transition temperature, TCO, for the manganates increase with the decreasing A>. The charge-ordered state is transformed to a metallic state on applying a magnetic field of 6 T in the case of Nd0.5Ca0.5MnO3 (A>=1.17 A), but this is not the case with the analogous Sm, Gd and Dy manganates with A> less than 1.17 A. In order to explain this behaviour, we have examined the A>-dependence of the Mn-O-Mn bond angle, the average Mn-O distance and the apparent one-electron bandwidth, obtained from these structural parameters. It is suggested that the extraordinary sensitivity of the charge ordering to A> arises from factors other than those based on the Mn-O-Mn bond angle and average Mn-O distances alone. It is possible that the competition between the covalent mixing of the oxygen O: 2pσ orbital with the A-site and B-site cation orbitals plays a crucial role. Strain effects due to size mismatch between A-site cations could also cause considerable changes in TCO. (author)
Matveev, Oleg; Shvaika, Andrij; Devereaux, Thomas; Freericks, James
The charge-density-wave phase of the Falicov-Kimball model displays a number of anomalous behavior including the appearance of subgap density of states as the temperature increases. These subgap states should have a significant impact on transport properties, particularly the nonlinear response of the system to a large dc electric field. Using the Kadanoff-Baym-Keldysh formalism, we employ nonequilibrium dynamical mean-field theory to exactly solve for this nonlinear response. We examine both the current and the order parameter of the conduction electrons as the ordered system is driven by a dc electric field. Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, Lviv, Ukraine.
Spin excitations in a model of FeSe with orbital ordering
Kreisel, A.; Mukherjee, Shantanu; Hirschfeld, P. J.; Andersen, Brian M.
2015-12-01
We present a theoretical study of the dynamical spin susceptibility for the intriguing Fe-based superconductor FeSe, based on a tight-binding model developed to account for the temperature-dependent band structure in this system. The model allows for orbital ordering in the dx z/dy z channel below the structural transition and presents a strongly C4-symmetry-broken Fermi surface at low temperatures which accounts for the nematic properties of this material. The calculated spin excitations are peaked at wave vector (π ,0 ) in the 1-Fe Brillouin zone, with a broad maximum at energies of order a few meV. In this range, the occurrence of superconductivity sharpens this peak in energy, creating a (π ,0 ) "neutron resonance" as seen in recent experiments. With the exception of the quite low energy scale of these fluctuations, these results are roughly similar to standard behavior in Fe pnictide systems. At higher energies, however, intensity increases and shifts to wave vectors along the (π ,0 )-(π ,π ) line. We compare with existing inelastic neutron experiments and NMR data, and give predictions for further studies.
Higher-order finite-difference formulation of periodic Orbital-free Density Functional Theory
Ghosh, Swarnava; Suryanarayana, Phanish
2016-02-01
We present a real-space formulation and higher-order finite-difference implementation of periodic Orbital-free Density Functional Theory (OF-DFT). Specifically, utilizing a local reformulation of the electrostatic and kernel terms, we develop a generalized framework for performing OF-DFT simulations with different variants of the electronic kinetic energy. In particular, we propose a self-consistent field (SCF) type fixed-point method for calculations involving linear-response kinetic energy functionals. In this framework, evaluation of both the electronic ground-state and forces on the nuclei are amenable to computations that scale linearly with the number of atoms. We develop a parallel implementation of this formulation using the finite-difference discretization. We demonstrate that higher-order finite-differences can achieve relatively large convergence rates with respect to mesh-size in both the energies and forces. Additionally, we establish that the fixed-point iteration converges rapidly, and that it can be further accelerated using extrapolation techniques like Anderson's mixing. We validate the accuracy of the results by comparing the energies and forces with plane-wave methods for selected examples, including the vacancy formation energy in Aluminum. Overall, the suitability of the proposed formulation for scalable high performance computing makes it an attractive choice for large-scale OF-DFT calculations consisting of thousands of atoms.
Higher-order finite-difference formulation of periodic Orbital-free Density Functional Theory
Ghosh, Swarnava
2014-01-01
We present a real-space formulation and higher-order finite-difference implementation of periodic Orbital-free Density Functional Theory (OF-DFT). Specifically, utilizing a local reformulation of the electrostatic and kernel terms, we develop a generalized framework suitable for performing OF-DFT simulations with different variants of the electronic kinetic energy. In particular, we develop a self-consistent field (SCF) type fixed-point method for calculations involving linear-response kinetic energy functionals. In doing so, we make the calculation of the electronic ground-state and forces on the nuclei amenable to computations that altogether scale linearly with the number of atoms. We develop a parallel implementation of this formulation using the finite-difference discretization, using which we demonstrate that higher-order finite-differences can achieve relatively large convergence rates with respect to mesh-size in both the energies and forces. Additionally, we establish that the fixed-point iteration c...
Spencer, J.; Gajdos, F.; Blumberger, J.
2016-08-01
We introduce a fragment orbital-based fewest switches surface hopping method, FOB-SH, designed to efficiently simulate charge carrier transport in strongly fluctuating condensed phase systems such as organic semiconductors and biomolecules. The charge carrier wavefunction is expanded and the electronic Hamiltonian constructed in a set of singly occupied molecular orbitals of the molecular sites that mediate the charge transfer. Diagonal elements of the electronic Hamiltonian (site energies) are obtained from a force field, whereas the off-diagonal or electronic coupling matrix elements are obtained using our recently developed analytic overlap method. We derive a general expression for the exact forces on the adiabatic ground and excited electronic state surfaces from the nuclear gradients of the charge localized electronic states. Applications to electron hole transfer in a model ethylene dimer and through a chain of ten model ethylenes validate our implementation and demonstrate its computational efficiency. On the larger system, we calculate the qualitative behaviour of charge mobility with change in temperature T for different regimes of the intermolecular electronic coupling. For small couplings, FOB-SH predicts a crossover from a thermally activated regime at low temperatures to a band-like transport regime at higher temperatures. For higher electronic couplings, the thermally activated regime disappears and the mobility decreases according to a power law. This is interpreted by a gradual loss in probability for resonance between the sites as the temperature increases. The polaron hopping model solved for the same system gives a qualitatively different result and underestimates the mobility decay at higher temperatures. Taken together, the FOB-SH methodology introduced here shows promise for a realistic investigation of charge carrier transport in complex organic, aqueous, and biological systems.
Tessmer, Manuel; Schäfer, Gerhard
2013-01-01
This publication will deal with an explicit determination of the time evolution of the spin orientation axes and the evolution of the orbital phase in the case of circular orbits under next-to-leading order spin-orbit interactions. We modify the method of Schneider and Cui proposed in ["Theoreme \\"uber Bewegungsintegrale und ihre Anwendungen in Bahntheorien", Verlag der Bayerischen Akademie der Wissenschaften, volume 212, 2005.] to iteratively remove oscillatory terms in the equations of motion for different masses that were not present in the case of equal masses. Our smallness parameter is chosen to be the difference of the symmetric mass ratio to the value 1/4. Before the first Lie transformation, the set of conserved quantities consists of the total angular momentum, the amplitudes of the orbital angular momentum and of the spins, $L, S_1,$ and $S_2$. In contrary, the magnitude of the total spin $S=|S_1+S_2|$ is not conserved and we wish to shift its non-conservation to higher orders of the smallness para...
X-ray absorption measurements of charge-ordered La{sub 0.5}Sr{sub 1.5}MnO{sub 4}
Energy Technology Data Exchange (ETDEWEB)
Saitoh, T.; Villella, P.M.; Dessau, D.S. [Univ. of Colorado, Boulder, CO (United States)] [and others
1997-04-01
Perovskite and {open_quotes}layered perovskite{close_quotes}-type manganese oxides show a variety of electronic and magnetic properties such as the colossal magnetoresistance (CMR) or the charge ordering. Among them, La{sub 0.5}Sr{sub 1.5}MnO{sub 4} (K{sub 2}NiF{sub 4} structure) which has 0.5 holes per Mn site (d{sup 3.5}) shows the charge-order transition at {approximately}220 K below which Mn{sup 3+} and Mn{sup 4+} sites are believed to order in the CE-type. Although the charge ordering phenomenon has also been observed in the perovskite manganites Pr{sub 0.5}Sr{sub 1.5}MnO{sub 3} or Pr{sub 0.5}Ca{sub 1.5}MnO{sub 3}, the present system has another advantage that it has a layered structure. This enables the authors to address the issue of the orbital symmetry which should be directly related to the charge ordering. In this report, they present the results of x-ray absorption spectroscopy (XAS) on La{sub 0.5}Sr{sub 1.5}MnO{sub 4}, for two polarization angles and two (above and below the transition temperature T{sub CO}) temperatures.
Positron-impact ionization of highly charged ions in lowest-order QED theory
International Nuclear Information System (INIS)
Lowest-order QED theory using distorted-wave states is applied to the calculation of positron-impact ionization cross sections for highly charged atomic ions. Electron and positron ionization cross sections for atomic ions are predicted to differ by substantial amounts in the threshold region. For highly charged ions like U90+, the smaller positron ionization cross section is more strongly affected by transverse photon interactions than the corresponding electron ionization cross section. At twice the threshold for U90+ ionization, the annihilation terms are found to reduce the positron cross section by about 12%
Soto, C A Téllez; Costa, A C; Versiane, O; Lemma, T; Machado, N C F; Mondragón, M A; Martin, A A
2015-07-01
Theoretical and experimental bands have been assigned to the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethyldithiocarbamate)Cd(II) complex, abbreviated as ([Cd(DDTC)2]). The calculations and spectral interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis to assist in the assignment of observed fundamentals. This study validated the unusual pseudo tetrahedral molecular structure formed around the Cd(II) cation. Surface-enhanced Raman scattering (SERS) was used to determine the interactions of the normal-modes of the diethyldithiocarbamate cadmium (II) complex on nano-structured silver surfaces. Natural bond orbital (NBO) analysis was also carried out to study the Cd(II) hybridization causing the pseudo tetrahedral geometry of the framework of the [Cd(DDTC)2] complex, and to confirm the charge transfer mechanisms through second order perturbation theory analysis of the Fox Matrix. In order to find out the electronic dispersion of the Mulliken atomic charges (MAC) in the normal modes, we calculated the MAC for each normal mode and correlated these values with the SERS effect. Experimental UV-Vis spectra were obtained and charge transfer bands were assigned. Good agreement between the calculated and experimental values for the vibrational and UV-Vis spectra was obtained. PMID:25813176
Téllez Soto, C. A.; Costa, A. C.; Versiane, O.; Lemma, T.; Machado, N. C. F.; Mondragón, M. A.; Martin, A. A.
2015-07-01
Theoretical and experimental bands have been assigned to the Fourier Transform Infrared (FT-IR) and FT-Raman spectra of the bis(diethyldithiocarbamate)Cd(II) complex, abbreviated as ([Cd(DDTC)2]). The calculations and spectral interpretation have been based on the DFT/B3LYP method, infrared and Raman second derivative spectra, and band deconvolution analysis to assist in the assignment of observed fundamentals. This study validated the unusual pseudo tetrahedral molecular structure formed around the Cd(II) cation. Surface-enhanced Raman scattering (SERS) was used to determine the interactions of the normal-modes of the diethyldithiocarbamate cadmium (II) complex on nano-structured silver surfaces. Natural bond orbital (NBO) analysis was also carried out to study the Cd(II) hybridization causing the pseudo tetrahedral geometry of the framework of the [Cd(DDTC)2] complex, and to confirm the charge transfer mechanisms through second order perturbation theory analysis of the Fox Matrix. In order to find out the electronic dispersion of the Mulliken atomic charges (MAC) in the normal modes, we calculated the MAC for each normal mode and correlated these values with the SERS effect. Experimental UV-Vis spectra were obtained and charge transfer bands were assigned. Good agreement between the calculated and experimental values for the vibrational and UV-Vis spectra was obtained.
Ordered charge asphericity around dysprosium and structural deformation in DyB2C2
International Nuclear Information System (INIS)
The oribitally ordered phase of DyB2C2 has been studied by nonresonant x-ray diffraction with high-brilliance synchrotron radiation. From the condition of diffraction, the symmetry property of the charge distribution around dysprosium has been concluded at the quadrupolar level. The quantitative inspection, furthermore, indicates that the observed signals cannot be interpreted as arising only from the 4f electrons of dysprosium responsible for the ordering; instead, the experiment can be described rather well by considering a distortion of the metaloid network concomitant with the ordering
Non-thermal separation of electronic and structural orders in a persisting charge density wave
Porer, M; Ménard, J -M; Dachraoui, H; Mouchliadis, L; Perakis, I E; Heinzmann, U; Demsar, J; Rossnagel, K; Huber, R
2016-01-01
The simultaneous ordering of different degrees of freedom in complex materials undergoing spontaneous symmetry-breaking transitions often involves intricate couplings that have remained elusive in phenomena as wide ranging as stripe formation, unconventional superconductivity or colossal magnetoresistance. Ultrafast optical, x-ray and electron pulses can elucidate the microscopic interplay between these orders by probing the electronic and lattice dynamics separately, but a simultaneous direct observation of multiple orders on the femtosecond scale has been challenging. Here we show that ultrabroadband terahertz pulses can simultaneously trace the ultrafast evolution of coexisting lattice and electronic orders. For the example of a charge-density-wave (CDW) in 1T-TiSe2, we demonstrate that two components of the CDW order parameter - excitonic correlations and a periodic lattice distortion (PLD) - respond very differently to 12-fs optical excitation. Even when the excitonic order of the CDW is quenched, the PL...
Directory of Open Access Journals (Sweden)
ZHANG Jingtao
2015-08-01
Full Text Available High-order harmonics generated from aligned molecules are studied by a nonperturbative QED theory and the effect of the multiple molecular orbits is included.The harmonic spectra generated from single molecular orbit exhibit an interference minimum which is induced by the molecular structure.The location of the spectral minimum shifts with the laser intensity in long laser pulses,but is fixed in ultrashort laser pulses.This difference is owed to the quiver motion of the electron in the laser pulses.The maximal shift of the spectral minimum equals to the increment of the ponderomotive energy and depends linearly on the laser intensity.The interference between the harmonics generated from multiple molecular orbits has two principal effects:one is obscuring the deep minima in the overall harmonic spectrum,the other is manifesting the phase jump in the harmonics generated from single molecular orbit.
Photon Orbital Angular Momentum and Proca effects in rotating and charged spacetimes
Tamburini, F; Thidé, B.
2011-01-01
We analyze the effect of Proca mass and orbital angular momentum of photons imposed by a structured plasma in Kerr-Newman and Reissner-Nordstrom-de Sitter spacetimes. The presence of characteristic lengths in a turbulent plasma converts the virtual Proca photon mass on orbital angular momentum, with the result of decreasing the virtual photon mass. The combination of this plasma effect and that of the gravitational field leads to a new astrophysical phenomenon that imprints a specific distrib...
Q-plates as higher order polarization controllers for orbital angular momentum modes of fiber.
Gregg, P; Mirhosseini, M; Rubano, A; Marrucci, L; Karimi, E; Boyd, R W; Ramachandran, S
2015-04-15
We demonstrate that a |q|=1/2 plate, in conjunction with appropriate polarization optics, can selectively and switchably excite all linear combinations of the first radial mode order |l|=1 orbital angular momentum (OAM) fiber modes. This enables full mapping of free-space polarization states onto fiber vector modes, including the radially (TM) and azimuthally polarized (TE) modes. The setup requires few optical components and can yield mode purities as high as ∼30 dB. Additionally, just as a conventional fiber polarization controller creates arbitrary elliptical polarization states to counteract fiber birefringence and yield desired polarizations at the output of a single-mode fiber, q-plates disentangle degenerate state mixing effects between fiber OAM states to yield pure states, even after long-length fiber propagation. We thus demonstrate the ability to switch dynamically, potentially at ∼GHz rates, between OAM modes, or create desired linear combinations of them. We envision applications in fiber-based lasers employing vector or OAM mode outputs, as well as communications networking schemes exploiting spatial modes for higher dimensional encoding. PMID:25872059
Development of multi-mode diabatic spin-orbit models at arbitrary order
Weike, Thomas; Eisfeld, Wolfgang
2016-03-01
The derivation of diabatic spin-orbit (SO) Hamiltonians is presented, which are expanded in terms of nuclear coordinates to arbitrary order including the treatment of multi-mode systems, having more than one mode of the same symmetry. The derivation is based on the microscopic Breit-Pauli SO operator and the consequent utilization of time reversal and spatial symmetry transformation properties of basis functions and coordinates. The method is demonstrated for a set of 2E and 2A1 states in C3 v ∗ (double group) symmetry, once for a 3D case of one a1 and one e mode and once for a 9D case of three a1 and three e coordinates. It is shown that the general structure of the diabatic SO Hamiltonian only depends on the basis states and is strictly imposed by time reversal symmetry. The resulting matrix can be expressed easily by a power series using six parametrized structure matrices as expansion coefficients multiplied by the associated monomials in terms of symmetrized coordinates. The explicit example presented here provides a full-dimensional diabatic SO model for methyl halide cations, which will be studied in the future.
International Nuclear Information System (INIS)
Understanding the charge transport properties in general of different molecular components in a self-assembled monolayer (SAM) is of importance for the rational design of SAM molecular structures for molecular electronics. In this study, we study an important aspect of the charge transport properties, i.e. the charge transfer (CT) dynamics between the active molecular component (in this case, the ferrocenyl moieties of a ferrocenyl-n-alkanethiol SAM) and the electrode using synchrotron-based core-hole clock (CHC) spectroscopy. The characteristic CT times are found to depend strongly on the character of the ferrocenyl-derived molecular orbitals (MOs) which mediate the CT process. Furthermore, by systemically shifting the position of the ferrocenyl moiety in the SAM, it is found that the CT characteristics of the ferrocenyl MOs display distinct dependence on its distance to the electrode. These results demonstrate experimentally that the efficiency and rate of charge transport through the molecular backbone can be modulated by resonant injection of charge carriers into specific MOs. (paper)
2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion
Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning
2016-08-01
Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility.
International Nuclear Information System (INIS)
The single particle orbit code, TIBRO, has been modified extensively to improve the interpolation methods used and to allow use of vector potential fields in the simulation of charged particle orbits on a 3D domain. A 3D cubic B-spline algorithm is used to generate spline coefficients used in the interpolation. Smooth and accurate field representations are obtained. When vector potential fields are used, the 3D cubic spline interpolation formula analytically generates the magnetic field used to push the particles. This field has del.BETA = 0 to computer roundoff. When magnetic induction is used the interpolation allows del.BETA does not equal 0, which can lead to significant nonphysical results. Presently the code assumes quadrupole symmetry, but this is not an essential feature of the code and could be easily removed for other applications. Many details pertaining to this code are given on microfiche accompanying this report
Long-range charge order on the Fe3 O4 (001) surface
Shvets, I. V.; Mariotto, G.; Jordan, K.; Berdunov, N.; Kantor, R.; Murphy, S.
2004-10-01
The Verwey transition in magnetite is of fundamental importance for the understanding of metal-insulator transitions but, in spite of being the subject of many studies over the last century, its nature is not fully understood. This is even more true in the case of the magnetite surface, where the low dimensionality plays an additional role in the determination of the Verwey transition temperature. We have atomically resolved the (2×2)R45° reconstructed surface by scanning tunneling microscopy and we have modeled our experimental results by density functional theory calculations. We attribute the observed pattern to the charge ordering of Fe2+-Fe2+ and Fe3+-Fe3+ dimers. We propose a mechanism for the formation of this charge ordered surface and provide an explanation for the increase of the Verwey transition temperature at the (001) surface of magnetite.
Measurement of the azimuthal ordering of charged hadrons with the ATLAS detector
Aad, G.; Abbott, B.; Abdallah, J.; Abdelalim, A. A.; Abdesselam, A.; Abdinov, O.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Acerbi, E.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Aderholz, M.; Adomeit, S.; Adragna, P.; Adye, T.; Aefsky, S.; Aguilar-Saavedra, J. A.; Aharrouche, M.; Ahlen, S. P.; Ahles, F.; Ahmad, A.; Ahsan, M.; Aielli, G.; Akdogan, T.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Akiyama, A.; Alam, M. S.; Alam, M. A.; Albert, J.; Albrand, S.; Aleksa, M.; Aleksandrov, I. N.; Alessandria, F.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Aliev, M.; Alimonti, G.; Alison, J.; Aliyev, M.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amaral, P.; Amelung, C.; Ammosov, V. V.; Amorim, A.; Amorós, G.; Amram, N.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Andrieux, M.-L.; Anduaga, X. S.; Angerami, A.; Anghinolfi, F.; Anisenkov, A.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoun, S.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Archambault, J. P.; Arfaoui, S.; Arguin, J.-F.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnault, C.; Artamonov, A.; Artoni, G.; Arutinov, D.; Asai, S.; Asfandiyarov, R.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astbury, A.; Astvatsatourov, A.; Aubert, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Avramidou, R.; Axen, D.; Ay, C.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Baccaglioni, G.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Bachy, G.; Backes, M.; Backhaus, M.; Badescu, E.; Bagnaia, P.; Bahinipati, S.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, M. D.; Baker, S.; Banas, E.; Banerjee, P.; Banerjee, Sw.; Banfi, D.; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barashkou, A.; Barbaro Galtieri, A.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Bardin, D. Y.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Barrillon, P.; Bartoldus, R.; Barton, A. E.; Bartsch, V.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battaglia, A.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beale, S.; Beare, B.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, S.; Beckingham, M.; Becks, K. H.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Begel, M.; Behar Harpaz, S.; Behera, P. K.; Beimforde, M.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellina, F.; Bellomo, M.; Belloni, A.; Beloborodova, O.; Belotskiy, K.; Beltramello, O.; Ben Ami, S.; Benary, O.; Benchekroun, D.; Benchouk, C.; Bendel, M.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Benoit, M.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernat, P.; Bernhard, R.; Bernius, C.; Berry, T.; Bertella, C.; Bertin, A.; Bertinelli, F.; Bertolucci, F.; Besana, M. I.; Besson, N.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Biscarat, C.; Bitenc, U.; Black, K. M.; Blair, R. E.; Blanchard, J.-B.; Blanchot, G.; Blazek, T.; Blocker, C.; Blocki, J.; Blondel, A.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. B.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boelaert, N.; Böser, S.; Bogaerts, J. A.; Bogdanchikov, A.; Bogouch, A.; Bohm, C.; Boisvert, V.; Bold, T.; Boldea, V.; Bolnet, N. M.; Bona, M.; Bondarenko, V. G.; Bondioli, M.; Boonekamp, M.; Boorman, G.; Booth, C. N.; Bordoni, S.; Borer, C.; Borisov, A.; Borissov, G.; Borjanovic, I.; Borroni, S.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Botterill, D.; Bouchami, J.; Boudreau, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozhko, N. I.; Bozovic-Jelisavcic, I.; Bracinik, J.; Braem, A.; Branchini, P.; Brandenburg, G. W.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brelier, B.; Bremer, J.; Brenner, R.; Bressler, S.; Breton, D.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Brodbeck, T. J.; Brodet, E.; Broggi, F.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, W. K.; Brown, G.; Brown, H.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.
2012-09-01
This paper presents a study of the possible ordering of charged hadrons in the azimuthal angle relative to the beam axis in high-energy proton-proton collisions at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons, driven by the search for phenomena related to the structure of the QCD field, is performed. Data were recorded with the ATLAS detector at center-of-mass energies of s=900GeV and s=7TeV. The correlations measured in a kinematic region dominated by low-pT particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helixlike ordered gluon chain.
Spin Polarized Photons from Axially Charged Plasma at Weak Coupling: Complete Leading Order
Mamo, Kiminad A
2015-01-01
In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin-aligned, which is a unique P- and CP-odd signature of axial charge in the photon emission observables. We compute this "P-odd photon emission rate" in weak coupling regime at high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P-even total emission rate in the literature, the computation of P-odd emission rate at leading order consists of three parts: 1) Compton and Pair Annihilation processes with hard momentum exchange, 2) soft t- and u-channel contributions with Hard Thermal Loop re-summation, 3) Landau-Pomeranchuk-Migdal (LPM) re-summation of collinear Bremstrahlung and Pair Annihilation. We present analytical and numerical evaluations of these contributions to our P-odd photon emission rate observable.
Spin polarized photons from an axially charged plasma at weak coupling: Complete leading order
Mamo, Kiminad A.; Yee, Ho-Ung
2016-03-01
In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin aligned, which is a unique P - and C P -odd signature of axial charge in the photon emission observables. We compute this "P -odd photon emission rate" in a weak coupling regime at a high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P -even total emission rate in the literature, the computation of the P -odd emission rate at leading order consists of three parts: (1) Compton and pair annihilation processes with hard momentum exchange, (2) soft t - and u -channel contributions with hard thermal loop resummation, (3) Landau-Pomeranchuk-Migdal resummation of collinear bremsstrahlung and pair annihilation. We present analytical and numerical evaluations of these contributions to our P -odd photon emission rate observable.
Charge ordering in the electron-doped superconductor Nd(2-x)Ce(x)CuO₄.
da Silva Neto, Eduardo H; Comin, Riccardo; He, Feizhou; Sutarto, Ronny; Jiang, Yeping; Greene, Richard L; Sawatzky, George A; Damascelli, Andrea
2015-01-16
In cuprate high-temperature superconductors, an antiferromagnetic Mott insulating state can be destabilized toward unconventional superconductivity by either hole or electron doping. In hole-doped (p-type) cuprates, a charge ordering (CO) instability competes with superconductivity inside the pseudogap state. We report resonant x-ray scattering measurements that demonstrate the presence of charge ordering in the n-type cuprate Nd(2-x)Ce(x)CuO4 near optimal doping. We find that the CO in Nd(2-x)Ce(x)CuO4 occurs with similar periodicity, and along the same direction, as in p-type cuprates. However, in contrast to the latter, the CO onset in Nd(2-x)Ce(x)CuO4 is higher than the pseudogap temperature, and is in the temperature range where antiferromagnetic fluctuations are first detected. Our discovery opens a parallel path to the study of CO and its relationship to antiferromagnetism and superconductivity. PMID:25593186
Measurement of the azimuthal ordering of charged hadrons with the ATLAS detector
Aad, Georges; Abdallah, Jalal; Abdelalim, Ahmed Ali; Abdesselam, Abdelouahab; Abdinov, Ovsat; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Acerbi, Emilio; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Aderholz, Michael; Adomeit, Stefanie; Adragna, Paolo; Adye, Tim; Aefsky, Scott; Aguilar-Saavedra, Juan Antonio; Aharrouche, Mohamed; Ahlen, Steven; Ahles, Florian; Ahmad, Ashfaq; Ahsan, Mahsana; Aielli, Giulio; Akdogan, Taylan; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Akiyama, Kunihiro; Alam, Mohammad; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alison, John; Aliyev, Magsud; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral, Pedro; Amelung, Christoph; Ammosov, Vladimir; Amorim, Antonio; Amorós, Gabriel; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Andrieux, Marie-Laure; Anduaga, Xabier; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoun, Sahar; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Archambault, John-Paul; Arfaoui, Samir; Arguin, Jean-Francois; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnault, Christian; Artamonov, Andrei; Artoni, Giacomo; Arutinov, David; Asai, Shoji; Asfandiyarov, Ruslan; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astbury, Alan; Astvatsatourov, Anatoli; Aubert, Bernard; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Avramidou, Rachel Maria; Axen, David; Ay, Cano; Azuelos, Georges; Azuma, Yuya; Baak, Max; Baccaglioni, Giuseppe; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Bachy, Gerard; Backes, Moritz; Backhaus, Malte; Badescu, Elisabeta; Bagnaia, Paolo; Bahinipati, Seema; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Mark; Baker, Sarah; Banas, Elzbieta; Banerjee, Piyali; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barashkou, Andrei; Barbaro Galtieri, Angela; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Barrillon, Pierre; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bates, Richard; Batkova, Lucia; Batley, Richard; Battaglia, Andreas; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beare, Brian; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Sebastian; Beckingham, Matthew; Becks, Karl-Heinz; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Begel, Michael; Behar Harpaz, Silvia; Behera, Prafulla; Beimforde, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellina, Francesco; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Ben Ami, Sagi; Benary, Odette; Benchekroun, Driss; Benchouk, Chafik; Bendel, Markus; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Benoit, Mathieu; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Berry, Tracey; Bertella, Claudia; Bertin, Antonio; Bertinelli, Francesco; Bertolucci, Federico; Besana, Maria Ilaria; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare; Biscarat, Catherine; Bitenc, Urban; Black, Kevin
2012-01-01
This paper presents a measurement of the ordering of charged hadrons in the azimuthal angle relative to the beam axis in high-energy proton-proton collisions at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons, driven by the search for phenomena related to the structure of the QCD field, is performed. Data were recorded with the ATLAS detector at centre-of-mass energies of $\\sqrt{s}$ = 900 GeV and $\\sqrt{s}$ = 7 TeV. The correlations measured in a phase space region dominated by low-pT particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helix-like ordered gluon chain.
Experimental evidence of orbital order in α-B12 and γ-B28 polymorphs of elemental boron
Mondal, Swastik; van Smaalen, Sander; Parakhonskiy, Gleb; Prathapa, Siriyara Jagannatha; Noohinejad, Leila; Bykova, Elena; Dubrovinskaia, Natalia; Chernyshov, Dmitry; Dubrovinsky, Leonid
2013-07-01
The electron density of the α form of boron has been obtained by multipole refinement against high-resolution, single-crystal x-ray diffraction data measured on a high-quality single crystal at a temperature of 100 K. Topological properties of this density have been used to show that all chemical bonds between B12 clusters in α-B12 are formed due to one orbital on each boron atom that is oriented perpendicular to the surface of the cluster. It is shown that the same orbital order on B12 clusters persists in both α-B12 and γ-B28 polymorphs and in several dodecaboranes, despite the fact that in every case the B12 clusters participate in entirely different kinds of exocluster bonds. It is likely that the same orbital order of B12 clusters can explain bonding in other boron polymorphs and boron-rich solids.
Energy Technology Data Exchange (ETDEWEB)
Cheng Bitao, E-mail: chengbitao2006@126.com [College of Mathematics and Information Science, Qujing Normal University, Qujing, Yunnan 655011 (China)
2011-10-15
Highlights: > We study a class of second order Hamiltonian systems with superlinear and sublinear nonlinearity. > Some new solvable conditions of periodic orbits for the system are established. > Some new multiplicity results of periodic orbits for the system are obtained via some critical point theorems. > The methods and results are different from the past references. - Abstract: This paper is concerned with a class of second order Hamiltonian systems with superlinear and sublinear nonlinearity (P){l_brace} (table) ) where b(t) is a real function defined on [0, T], {mu} > 2 and H : [0, T] x R{sup N} {yields} R is a Caratheodory function. Some new multiplicity results of periodic orbits for the problem (P) are obtained via some critical point theorems.
Mendoza, J. H.; Díaz, C. F.; Acevedo, C. H.; Torres, Y.
2016-02-01
The orbital angular momentum of light has a big contribution in many engineering applications like optical communications, because this physical property allows eigenstates characteristic of the wavefront rotation when the beam is propagated. The nature of these eigenstates allows that information can be encoded and gives immunity to electromagnetic interference, allowing an increase of bandwidth, cadence and capacity of the communication channel. This work shown the methodology using nanometric thin films like Titanium based (TiO2) grown over strontium titanate (SrTiO3) support, to distinguish and discriminate a well- defined integer value of the topological charge of an OAM beam.
Local Lattice Distortion Caused by Short Range Charge Ordering in LiMn2O4
Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shin-ichi; Ikeda, Kazutaka; Oshita, Hidetoshi; Kaneko, Naokatsu; Otomo, Toshiya; Suzuya, Kentaro
2013-09-01
We have performed powder neutron diffraction on 7Li-enriched sample of LiMn2O4 at 300 K. The crystal structure determined by Rietveld analysis is a cubic spinel with space group of Fd\\bar{3}m in which all Mn atoms are crystallograghically equivalent, consistent with many preceding studies. However, the atomic pair distribution function (PDF) of this compound can not be fitted by the cubic structure with space group of Fd\\bar{3}m satisfactorily, and it can be reproduced by the orthorhombic structure with Fddd. It corresponds with the structure of charge ordered phase below about 260 K, indicating a short range charge ordering. In the local structure determined by PDF analysis, two types of MnO6 octahedra with long and short atomic distances between Mn and O atoms exist and their Mn--O distances are almost consistent with the distances in the charge ordered phase. From these results, valence electrons are localized at Mn sites like a glass even in the cubic phase, resulting in the non-metallic electrical conductivity.
Local lattice distortion caused by short range charge ordering in LiMn2O4
International Nuclear Information System (INIS)
We have performed powder neutron diffraction on 7Li-enriched sample of LiMn2O4 at 300 K. The crystal structure determined by Rietveld analysis is a cubic spinel with space group of Fd3-bar m in which all Mn atoms are crystallograghically equivalent, consistent with many preceding studies. However, the atomic pair distribution function (PDF) of this compound can not be fitted by the cubic structure with space group of Fd3-bar m satisfactorily, and it can be reproduced by the orthorhombic structure with Fddd. It corresponds with the structure of charge ordered phase below about 260 K, indicating a short range charge ordering. In the local structure determined by PDF analysis, two types of MnO6 octahedra with long and short atomic distances between Mn and O atoms exist and their Mn-O distances are almost consistent with the distances in the charge ordered phase. From these results, valence electrons are localized at Mn sites like a glass even in the cubic phase, resulting in the non-metallic electrical conductivity. (author)
Charge and anion ordering phase transitions in (TMTTF){sub 2}X salt conductors
Energy Technology Data Exchange (ETDEWEB)
Nad, F. [Centre de Recherches sur les Tres Basses Temperatures, laboratoire associe a l' Universite Joseph Fourier, CNRS, BP 166, Grenoble (France); Institute of Radioengineering and Electronics, Russian Academy of Sciences, Moscow (Russian Federation); Monceau, P. [Centre de Recherches sur les Tres Basses Temperatures, laboratoire associe a l' Universite Joseph Fourier, CNRS, BP 166, Grenoble (France); Carcel, C.; Fabre, J.M. [Heterochimie et Materiaux Organiques, ENSCM/ESA, Montpellier (France)
2001-07-23
We report measurements of the low frequency conductivity and dielectric permittivity of quasi-one-dimensional organic (TMTTF){sub 2}X salts with non-centrosymmetrical anions X=ReO{sub 4} and SCN. We show that the 'structureless transition' at 227.5 K in (TMTTF){sub 2}ReO{sub 4} is due to charge ordering and has a ferroelectric character. The anion ordering transition strongly affects the dielectric response: it suppresses the polarizability in (TMTTF){sub 2}ReO{sub 4} and induces probably an antiferroelectric state in (TMTTF){sub 2}SCN. (author). Letter-to-the-editor.
International Nuclear Information System (INIS)
The correlations between long-wavelength fluctuations of concentration in a liquid binary alloy are determined by a balance between an elastic strain free energy and an Ornstein-Zernike effective interaction. The latter is extracted from thermodynamic data in the case of the Li-Pb system, which is well known to chemically order with stoichiometric composition corresponding to Li4Pb. Strong attractive interactions between concentration fluctuations near the composition of chemical ordering originate from electronic charge transfer, which is estimated from the electron-ion partial structure factors as functions of composition in the liquid alloy. (author). 20 refs, 2 figs
International Nuclear Information System (INIS)
Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian spin-orbit Hamiltonian for spinning binaries [J. Hartung and J. Steinhoff, arXiv:1104.3079.] we improve the effective-one-body description of the dynamics of two spinning black holes by including NNLO effects in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order spin-orbit Hamiltonian computed in [T. Damour, P. Jaranowski, and G. Schaefer, Phys. Rev. D 78, 024009 (2008).]. The present effective-one-body Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the next-to-leading order spin-orbit coupling.
Matsuyama, A.; Yagi, M.; Kagei, Y.; Nakajima, N.
2014-12-01
During major disruptions, an induced loop voltage accelerates runaway electrons (REs) towards high energy, being in the order of 1-100 MeV in present tokamaks and ITER. The stochastization mechanisms of such high-energy RE drift orbits are investigated by three-dimensional (3D) orbit following in tokamak plasmas. Drift resonance is shown to play an important role in determining the onset of stochastic drift orbits for different electron energies, particularly in cases with low-order perturbations that have radially global eigenfunctions of the scale of the plasma minor radius. The drift resonance due to the coupling between the cross-field drift motion with radially global modes yields a secondary island structure in the RE drift orbit, where the width of the secondary drift islands shows a square-root dependence on the relativistic gamma factor γ. Only for highly relativistic REs (γ ≫ 1), the widths of secondary drift islands are comparable with those of magnetic islands due to the primary resonance, thus the stochastic threshold becoming sensitive to the RE energy. Because of poloidal asymmetry due to toroidicity, the threshold becomes sensitive not only to the relative amplitude but also to the phase difference between the modes. In this paper, some examples of 3D orbit-following calculations are presented for analytic models of magnetic perturbations with multiple toroidal mode numbers, for both possibilities that the drift resonance enhances and suppresses the stochastization being illustrated.
International Nuclear Information System (INIS)
During major disruptions, an induced loop voltage accelerates runaway electrons (REs) towards high energy, being in the order of 1–100 MeV in present tokamaks and ITER. The stochastization mechanisms of such high-energy RE drift orbits are investigated by three-dimensional (3D) orbit following in tokamak plasmas. Drift resonance is shown to play an important role in determining the onset of stochastic drift orbits for different electron energies, particularly in cases with low-order perturbations that have radially global eigenfunctions of the scale of the plasma minor radius. The drift resonance due to the coupling between the cross-field drift motion with radially global modes yields a secondary island structure in the RE drift orbit, where the width of the secondary drift islands shows a square-root dependence on the relativistic gamma factor γ. Only for highly relativistic REs (γ ≫ 1), the widths of secondary drift islands are comparable with those of magnetic islands due to the primary resonance, thus the stochastic threshold becoming sensitive to the RE energy. Because of poloidal asymmetry due to toroidicity, the threshold becomes sensitive not only to the relative amplitude but also to the phase difference between the modes. In this paper, some examples of 3D orbit-following calculations are presented for analytic models of magnetic perturbations with multiple toroidal mode numbers, for both possibilities that the drift resonance enhances and suppresses the stochastization being illustrated. (paper)
The stability of steady motion of magnetic domain wall: Role of higher-order spin-orbit torques
Energy Technology Data Exchange (ETDEWEB)
He, Peng-Bin, E-mail: hepengbin@hnu.edu.cn; Yan, Han; Cai, Meng-Qiu [School of Physics and Electronics, Hunan University, Changsha 410082 (China); Li, Zai-Dong [Department of Applied Physics, Hebei University of Technology, Tianjin 300401 (China)
2015-12-14
The steady motion of magnetic domain wall driven by spin-orbit torques is investigated analytically in the heavy/ferromagnetic metal nanowires for three cases with a current transverse to the in-plane and perpendicular easy axis, and along the in-plane easy axis. By the stability analysis of Walker wall profile, we find that if including the higher-order spin-orbit torques, the Walker breakdown can be avoided in some parameter regions of spin-orbit torques with a current transverse to or along the in-plane easy axis. However, in the case of perpendicular anisotropy, even considering the higher-order spin-orbit torques, the velocity of domain wall cannot be efficiently enhanced by the current. Furthermore, the direction of wall motion is dependent on the configuration and chirality of domain wall with a current along the in-plane easy axis or transverse to the perpendicular one. Especially, the direction of motion can be controlled by the initial chirality of domain wall. So, if only involving the spin-orbit mechanism, it is preferable to adopt the scheme of a current along the in-plane easy axis for enhancing the velocity and controlling the direction of domain wall.
Directory of Open Access Journals (Sweden)
Martin Lara
2009-01-01
Full Text Available Frozen orbits of the Hill problem are determined in the double-averaged problem, where short and long-period terms are removed by means of Lie transforms. Due to the perturbation method we use, the initial conditions of corresponding quasi-periodic solutions in the nonaveraged problem are computed straightforwardly. Moreover, the method provides the explicit equations of the transformation that connects the averaged and nonaveraged models. A fourth-order analytical theory is necessary for the accurate computation of quasi-periodic frozen orbits.
Li, Xiao-Hong; Mei, Zheng; Zhang, Xian-Zhou
2014-01-01
The vibrational frequencies of acetophenone thiosemicarbazone in the ground state have been calculated using density functional method (B3LYP) with 6-31G(d), 6-31G(d,p) and 6-311++G(d,p) basis sets. The analysis of natural bond orbital was also performed. The IR spectra were obtained and interpreted by means of potential energies distributions (PEDs) using MOLVIB program. In addition, the results show that there exist Nsbnd H…N and Nsbnd H…S hydrogen bonds in the title compound, which play a major role in stabilizing the molecule and are confirmed by the natural bond orbital analysis. The predicted NLO properties show that the title compound is a good candidate as second-order NLO material. In addition, the frontier molecular orbitals were analyzed and the crystal structure obtained by molecular mechanics belongs to the Pbca space group, with lattice parameters Z = 8, a = 16.0735 Å, b = 7.1719 Å, c = 7.8725 Å, ρ = 0.808 g/cm3.
Magnetic compton profile study of orbital ordering state of 3d electrons in YTiO3
International Nuclear Information System (INIS)
Orbital ordering state of 3d electrons in YTiO3 has been studied by magnetic Compton profile (MCP) measurement for crystallographic directions of [100] (a-axis) and [001] (c-axis). The magnetic effect of the observed MCP leads to the spin moment that is equal to the saturated magnetic moment within the estimated errors, which strongly suggests quenching of the orbital moment. Shape of the observed MCPs shows directional anisotropy between the two axes. The MCPs are calculated by using an atomic model wave function of a linear combination of two 3d-t2g orbitals, udyz ± vdzx (u2 + v2=1) for the Ti sites. The observed MCP is best reproduced by the calculated MCP with u=0.84±0.04 and v=0.54±0.04. This value of u is slightly larger than those obtained in the previous studies. (author)
Alieva, Tatiana; Bastiaans, Martin J
2004-07-15
We analyze the evolution of the vortex and the asymmetrical parts of orbital angular momentum during its propagation through separable first-order optical systems. We find that the evolution of the vortex part depends on only parameters a(x), a(y), b(x), and b(y) of the ray transformation matrix and that isotropic systems with the same ratio b/a produce the same change of the vortex part of the orbital angular momentum. Finally, it is shown that, when light propagates through an optical fiber with a quadratic refractive-index profile, the vortex part of the orbital angular momentum cannot change its sign more than four times per period. PMID:15309827
Pound, Adam
2014-01-01
A compact object moving on a quasicircular orbit about a Schwarzschild black hole gradually spirals inward due to the dissipative action of its gravitational self-force. But in addition to driving the inspiral, the self-force has a conservative piece. Within a second-order self-force formalism, I derive a second-order generalization of Detweiler's redshift variable, which provides a gauge-invariant measure of conservative effects on quasicircular orbits. I sketch a frequency-domain numerical scheme for calculating this quantity. Once this scheme has been implemented, its results may be used to determine high-order terms in post-Newtonian theory and parameters in effective-one-body theory.
Nagar, Alessandro
2011-01-01
Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian (PN) spin-orbit Hamiltonian for spinning binaries \\cite{Hartung:2011te} we extend the effective-one-body (EOB) description of the dynamics of two spinning black-holes to NNLO in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order (NLO) spin-orbit Hamiltonian computed in Ref. \\cite{Damour:2008qf}. The present EOB Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the NLO spin-orbit coupling.
Ritter, C.; Ivanov, S. A.; Bazuev, G. V.; Fauth, F.
2016-02-01
The thermal evolution of structural and magnetic details of the orthovanadate TmV O3 , studied in detail by neutron and synchrotron powder diffraction, is reported. Crystallizing in space group Pnma at room temperature, TmV O3 undergoes a first structural phase transition to P 21/a at TOO=180 K , where a G -type orbital ordered state develops. At TS=75 K , a change back to Pnma occurs, and the establishment of C -type orbital order takes place. The V3 + ions order antiferromagnetically with a magnetic propagation vector k =0 below TN 1=105 K , while the T m3 + sublattice orders at TN 2=20 K following the same propagation vector. Between TN 1 and TS, a coexistence of G -type (P 21/a ) and C -type (Pnma) orbital ordered states exists. The P 21/a phase is magnetically separated into two fractions, which adopt a CxCy0 and Gx00 coupling, respectively, while the Pnma volume fraction follows a 0 Gy0 magnetic structure. At TN 2, the appearance of the Tm sublattice magnetization (0 Cy0 ) leads to a spin flop transition of the V sublattice from 0 Gy0 to Gx00 . The results are presented and analyzed in the general context of the series of R V O3 compounds, and they are used to discuss recent magnetization results.
Charge-Insensitive Single-Atom Spin-Orbit Qubit in Silicon
Salfi, Joe; Mol, Jan A.; Culcer, Dimitrie; Rogge, Sven
2016-06-01
High fidelity entanglement of an on-chip array of spin qubits poses many challenges. Spin-orbit coupling (SOC) can ease some of these challenges by enabling long-ranged entanglement via electric dipole-dipole interactions, microwave photons, or phonons. However, SOC exposes conventional spin qubits to decoherence from electrical noise. Here, we propose an acceptor-based spin-orbit qubit in silicon offering long-range entanglement at a sweet spot where the qubit is protected from electrical noise. The qubit relies on quadrupolar SOC with the interface and gate potentials. As required for surface codes, 105 electrically mediated single-qubit and 104 dipole-dipole mediated two-qubit gates are possible in the predicted spin lifetime. Moreover, circuit quantum electrodynamics with single spins is feasible, including dispersive readout, cavity-mediated entanglement, and spin-photon entanglement. An industrially relevant silicon-based platform is employed.
He, Yang; Zhang, Ruili; Wang, Yulei; Liu, Jian; Qin, Hong
2016-01-01
We construct high order symmetric volume-preserving methods for the relativistic dynamics of a charged particle by the splitting technique with processing. Via expanding the phase space to include time $t$, we give a more general construction of volume-preserving methods that can be applied to systems with time-dependent electromagnetic fields. The newly derived methods provide numerical solutions with good accuracy and conservative properties over long time of simulation. Furthermore, because of the use of processing technique the high order methods are explicit, and cost less than the methods derived from standard compositions, thus are more efficient. The results are verified by the numerical experiments. Linear stability analysis of the methods show that the high order processed method allows larger time step size during integration.
Lüdicke, F.; Hussmann, H.; Oberst, J.
2008-09-01
Introduction We developed an orbit simulation tool for BepiColombo scheduled for arrival at Mercury in 2019. The mission will consist of two spacecraft, the MPO (Mercury Planetary Orbiter, ESA) and the MMO (Mercury Magnetospheric Orbiter, JAXA). We simulate the orbit evolutions of the two considering perturbing forces for a time of 2 years from arrival. This study was undertaken for mission planning purposes and estimates of surface coverage for the onboard mapping instruments. Orbit Perturbations Perturbing forces acting on the Keplerian MPO and MMO orbits include Mercury's non-spherical mass distribution parameters, the gravitational force of the sun, and solar radiation pressure (faintest). Because of the perturbing accelerations, semi-major axis, eccentricity, inclination, ascending node, argument of pericenter, show complex variations. The program simulates the evolution of all these elements over a period of 2 years. The software was programmed in FORTRAN, using SPICE subroutines. Numerical Integration Several of the Runge-Kutta methods are implemented in the software for a numerical integration of the equations of motion. Starting from initial values for the state vector (i.e., position and velocity) at time t0 given in [2], we obtain the spacecraft trajectory with an accuracy of the order of 1 m by choosing a stepsize of 50 s [1]. The results of the numerical calculation were checked with the results of a similar Bepi Colombo orbit simulation by ESOC [2] and showed very good agreement. Gravity Field Coefficients The MARINER 10 spacecraft executed 3 flybys of Mercury (1974/75). From spacecraft tracking, a first estimate of the gravity parameter GM and crude limits for J2 could be obtained. Higher-order gravitational coefficients, e.g., C30 and C22 are practically unknown. Results (Examples) Fig. 1 shows the evolution of the pericenter height for the MPO during the 2 mission years using the typical error bounds (6.0 ± 2.0)E-5 [4] for J2 = -C20. In addition
Molecular orbital (SCF-Xα-SW) theory of metal-metal charge transfer processes in minerals
Sherman, David M.
1987-01-01
A number of mixed valence iron oxides and silicates (e.g., magnetite, ilvaite) exhibit thermally induced electron delocalization between adjacent Fe2+ and Fe3+ ions and optically induced electronic transitions which are assigned to Fe2+→Fe3+ intervalence charge transfer.
Energy Technology Data Exchange (ETDEWEB)
Oshima, Y.; Kimata, M.; Kishigi, K.; Ohta, H.; Koyama, K.; Motokawa, M.; Nishikawa, H.; Kikuchi, K.; Ikemoto, I
2004-04-30
Magneto-optical measurements of a quasi-one-dimensional (q1D) organic superconductor (DMET){sub 2}I{sub 3} has been performed by using a cavity perturbation technique. Several resonant absorption lines, which can be attributed to the q1D periodic orbit resonance (q1D POR), as well as the quite unusual high-order q1D POR coming from the corrugated Fermi surface (FS) in the interlayer direction were observed. Moreover, other harmonic resonances are also observed when the AC electric field is applied along the c*-axis. We will also show its estimated q1D FS from the data analysis where the estimated FS clearly shows why there is no spin-density-wave or charge-density-wave transition in (DMET){sub 2}I{sub 3} despite having a q1D FS.
Explicit high-order symplectic integrators for charged particles in general electromagnetic fields
Tao, Molei
2016-01-01
This article considers non-relativistic charged particle dynamics in both static and non-static electromagnetic fields, which are governed by nonseparable, possibly time-dependent Hamiltonians. For the first time, explicit symplectic integrators of arbitrary high-orders are constructed for accurate and efficient simulations of such mechanical systems. Performances superior to the standard non-symplectic method of Runge-Kutta are demonstrated on two examples: the first is on the confined motion of a particle in a static toroidal magnetic field used in tokamak; the second is on how time-periodic perturbations to a magnetic field inject energy into a particle via parametric resonance at a specific frequency.
Energy Technology Data Exchange (ETDEWEB)
Yonemitsu, Kenji; Tanaka, Yasuhiro; Miyashita, Satoshi [Institute for Molecular Science, Okazaki 444-8585 (Japan); Maeshima, Nobuya, E-mail: kxy@ims.ac.j [Institute of Materials Science, University of Tsukuba, Tsukuba 305-8573 (Japan)
2009-02-01
Photoinduced charge dynamics in one- and two-dimensional organic conductors are studied theoretically in extended Peierls-Hubbard models. For quasi-one-dimensional (EDO-TTF){sub 2}PF{sub 6}, photoinduced change in the charge order pattern from (0110) to (1010) is accompanied by probe-energy-dependent oscillations of conductivity. This is caused by coexistence of charge order and delocalized electrons. For quasi-two-dimensional alpha-(BEDT-TTF){sub 2}I{sub 3} and theta-(BEDT-TTF){sub 2}RbZn(SCN){sub 4}, photoinduced melting of the horizontal-stripe charge order proceeds easier in the alpha-type salt than in the theta-type salt. This is because the charge order in the theta-type salt is more strongly stabilized by electron-phonon interactions.
Zhang, Q.; Singh, K.; Simon, C.; Tung, L. D.; Balakrishnan, G.; Hardy, V.
2014-07-01
The orthovanadate DyVO3 crystal, known to exhibit multiple structural, spin-, and orbital-ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric, and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high TC of 108 K over a wide temperature range including different spin-orbital-ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic C-type spin-ordering transition taking place at 108 K, which indicates that DyVO3 belongs to type-II multiferroics exhibiting a coupling between magnetism and ferroelectricity. Some anomalies detected on the temperature dependence of electric polarization are discussed with respect to the nature of the spin-orbital-ordered states of the V sublattice and the degree of spin alignment in the Dy sublattice. The orthovanadates RVO3 (R= rare earth or Y) form an important new category for searching for high-TC multiferroics.
Orbital molecules in electronic materials
Energy Technology Data Exchange (ETDEWEB)
Attfield, J. Paul, E-mail: j.p.attfield@ed.ac.uk [Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JZ (United Kingdom)
2015-04-01
Orbital molecules are made up of coupled orbital states on several metal ions within an orbitally ordered (and sometimes also charge-ordered) solid such as a transition metal oxide. Spin-singlet dimers are known in many materials, but recent discoveries of more exotic species such as 18-electron heptamers in AlV{sub 2}O{sub 4} and magnetic 3-atom trimerons in magnetite (Fe{sub 3}O{sub 4}) have shown that orbital molecules constitute a general new class of quantum electronic states in solids.
Energy Technology Data Exchange (ETDEWEB)
Popushoi, M.N.
1985-12-01
This paper obtains expressions for recovering the central interaction potential of charged particles in the case when the interaction leads to multiplication of the S matrix defined in the complex plane of the Coulomb coupling constant by a rational S function. A study is made of the influence of the sign of the potential on the position of the poles of the S function and of the behavior of the phase shift.
Energy Technology Data Exchange (ETDEWEB)
Itoh, Hirotake, E-mail: hiroitoh@m.tohoku.ac.jp; Iwai, Shinichiro, E-mail: s-iwai@m.tohoku.ac.jp [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); JST, CREST, Sendai 980-8578 (Japan); Itoh, Keisuke; Goto, Kazuki [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Yamamoto, Kaoru [Department of Applied Physics, Okayama University of Science, Okayama 700-0005 (Japan); Yakushi, Kyuya [Toyota Physical and Chemical Research Institute, Nagakute 480-1192 (Japan)
2014-04-28
Efficient terahertz (THz) wave generation in strongly correlated organic compounds α-(ET){sub 2}I{sub 3} and α′-(ET){sub 2}IBr{sub 2} (ET:bis(ethylenedithio)-tetrathiafulvalene) was demonstrated. The spontaneous polarization induced by charge ordering or electronic ferroelectricity was revealed to trigger the THz-wave generation via optical rectification; the estimated 2nd-order nonlinear optical susceptibility for α-(ET){sub 2}I{sub 3} is over 70 times larger than that for prototypical THz-source ZnTe. Ultrafast (<1 ps) and sensitive (∼40%) photoresponse of the THz wave was observed for α-(ET){sub 2}I{sub 3}, which is attributable to photoinduced quenching of the polarization accompanied by insulator(ferroelectric)-to-metal transition. Modulation of the THz wave was observed for α′-(ET){sub 2}IBr{sub 2} upon the poling procedure, indicating the alignment of polar domains.
Fractional-order modeling and State-of-Charge estimation for ultracapacitors
Zhang, Lei; Hu, Xiaosong; Wang, Zhenpo; Sun, Fengchun; Dorrell, David G.
2016-05-01
Ultracapacitors (UCs) have been widely recognized as an enabling energy storage technology in various industrial applications. They hold several advantages including high power density and exceptionally long lifespan over the well-adopted battery technology. Accurate modeling and State-of-Charge (SOC) estimation of UCs are essential for reliability, resilience, and safety in UC-powered system operations. In this paper, a novel fractional-order model composed of a series resistor, a constant-phase-element (CPE), and a Walburg-like element, is proposed to emulate the UC dynamics. The Grünald-Letnikov derivative (GLD) is then employed to discretize the continuous-time fractional-order model. The model parameters are optimally extracted using genetic algorithm (GA), based on the time-domain data acquired through the Federal Urban Driving Schedule (FUDS) test. By means of this fractional-order model, a fractional Kalman filter is synthesized to recursively estimate the UC SOC. Validation results prove that the proposed fractional-order modeling and state estimation scheme is accurate and outperforms current practice based on integer-order techniques.
Sandro da Silva Fernandes; Francisco das Chagas Carvalho
2008-01-01
A complete first-order analytical solution, which includes the short periodic terms, for the problem of optimal low-thrust limited-power transfers between arbitrary elliptic coplanar orbits in a Newtonian central gravity field is obtained through canonical transformation theory. The optimization problem is formulated as a Mayer problem of optimal control theory with Cartesian elements—position and velocity vectors—as state variables. After applying the Pontryagin maximum principle and determi...
Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering
Shi, Dong
2016-04-15
We report the crystal structure and hole-transport mechanism in spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells. Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure calculations enabled us to map spiro-OMeTAD’s intermolecular charge-hopping pathways. Promisingly, single-crystal mobilities were found to exceed their thin-film counterparts by three orders of magnitude. Our findings underscore mesoscale ordering as a key strategy to achieving breakthroughs in hole-transport material engineering of solar cells.
Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering
Shi, Dong; Qin, Xiang; Li, Yuan; He, Yao; Zhong, Cheng; Pan, Jun; Dong, Huanli; Xu, Wei; Li, Tao; Hu, Wenping; Brédas, Jean-Luc; Bakr, Osman M.
2016-01-01
We report the crystal structure and hole-transport mechanism in spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells. Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure calculations enabled us to map spiro-OMeTAD’s intermolecular charge-hopping pathways. Promisingly, single-crystal mobilities were found to exceed their thin-film counterparts by three orders of magnitude. Our findings underscore mesoscale ordering as a key strategy to achieving breakthroughs in hole-transport material engineering of solar cells. PMID:27152342
Long-range orders and spin/orbital freezing in the two-band Hubbard model
Steiner, Karim; Hoshino, Shintaro; Nomura, Yusuke; Werner, Philipp
2016-08-01
We solve the orbitally degenerate two-band Hubbard model within dynamical mean field theory and map out the instabilities to various symmetry-broken phases based on an analysis of the corresponding lattice susceptibilities. Phase diagrams as a function of the Hund coupling parameter J are obtained both for the model with rotationally invariant interaction and for the model with Ising-type anisotropy. For negative J , an intraorbital spin-singlet superconducting phase appears at low temperatures, while the normal state properties are characterized by an orbital-freezing phenomenon. This is the negative-J analog of the recently discovered fluctuating-moment induced s -wave spin-triplet superconductivity in the spin-freezing regime of multiorbital models with J >0 .
Mialitsin, Aleksej
Subject of this dissertation is the investigation with experimental means of how the Raman response of three structurally similar materials -- MgB2, NbSe2, and CaC6 -- is affected by superconductivity (all three), charge ordering (NbSe2), or crystalline order-to-disorder phase transitions (CaC6). Universal characteristics of spectral renormalization pertaining to the superconducting phase transition are observed in all three compounds. Yet, the crystalline and electronic structures are sufficiently distinct, such that specific for each compound characteristics are imposed on this superconductivity-induced renormalization. Consequently, the method of polarized Raman scattering has been used to establish a variety of physical concepts: (1) Multi-band superconductivity in the layered superconductor MgB2 and its primary mediation by the strongly coupled 640 cm--1 E2g phonon. Additionally, it is shown how a Josephson-like coupling of two SC condensates in the reciprocal space is responsible for an exotic collective mode, the Leggett's resonance. (2) Interplay between the superconducting and the incommensurate charge-density-wave order parameters in NbSe2, which has been found to be consistent with an isotropic multi-band superconductivity scenario. This scenario is proposed in the frame of a picture that involves a combined 'superconductivity plus charge-density-wave' order parameter. (3) The Fano-Breit-Wigner line-shape formalism to account for an anti-resonance interference in the low temperature Raman response from NbSe2, in the polarization geometry corresponding to the non-symmetric E 2g symmetry channel. (4) Validity of the double resonant Raman scattering picture in the presence of disorder in the graphite intercalation compound CaC6. Simultaneously, it is explored how disorder suppresses superconductivity. To that end, the CaC6 superconducting coherence peak, too, is presented. All these phenomena are manifestations of electron-phonon coupling in solids. It is
Krizmanic, John F.; Mitchell, John W.; Streitmatter, Robert E.
2013-01-01
OWL [1] uses the Earth's atmosphere as a vast calorimeter to fully enable the emerging field of charged-particle astronomy with high-statistics measurements of ultra-high-energy cosmic rays (UHECR) and a search for sources of UHE neutrinos and photons. Confirmation of the Greisen-Zatsepin-Kuzmin (GZK) suppression above approx. 4 x 10(exp 19) eV suggests that most UHECR originate in astrophysical objects. Higher energy particles must come from sources within about 100 Mpc and are deflected by approx. 1 degree by predicted intergalactic/galactic magnetic fields. The Pierre Auger Array, Telescope Array and the future JEM-EUSO ISS mission will open charged-particle astronomy, but much greater exposure will be required to fully identify and measure the spectra of individual sources. OWL uses two large telescopes with 3 m optical apertures and 45 degree FOV in near-equatorial orbits. Simulations of a five-year OWL mission indicate approx. 10(exp 6) sq km/ sr/ yr of exposure with full aperture at approx. 6 x 10(exp 19) eV. Observations at different altitudes and spacecraft separations optimize sensitivity to UHECRs and neutrinos. OWL's stereo event reconstruction is nearly independent of track inclination and very tolerant of atmospheric conditions. An optional monocular mode gives increased reliability and can increase the instantaneous aperture. OWL can fully reconstruct horizontal and upward-moving showers and so has high sensitivity to UHE neutrinos. New capabilities in inflatable structures optics and silicon photomultipliers can greatly increase photon sensitivity, reducing the energy threshold for n detection or increasing viewed area using a higher orbit. Design trades between the original and optimized OWL missions and the enhanced science capabilities are described.
Charge Transfer and Orbital Reconstruction in Strain-Engineered (La,Sr)MnO3/LaNiO3 Heterostructures.
Peng, Jingjing; Song, Cheng; Li, Fan; Cui, Bin; Mao, Haijun; Wang, Yuyan; Wang, Guangyue; Pan, Feng
2015-08-19
We investigate charge transfer, orbital reconstruction, and the emergence of exchange bias in (La,Sr)MnO3/LaNiO3 heterostructures. We demonstrate that charge transfer from Mn(3+) ions to Ni(3+) ions is accompanied by the formation of hybridized Mn/Ni 3z(2) - r(2) orbits at the interface, instead of strain-stabilized Mn and Ni x(2) - y(2) orbits in the bulk films. In the heterostructures with ultrathin LaNiO3, orbital reconstruction induced by charge transfer results in magnetization frustration of (La,Sr)MnO3 at the interface. But the strain effect exerted by the growth of the LaNiO3 top layer plays a dominant role on orbital reconstruction in the heterostructures with thick LaNiO3, stabilizing 3z(2) - r(2) orbits. In this case, robust spin glass, associated with larger magnetization frustration, accounts for the exchange bias effect. Our work builds a bridge between the microscopic electronic structure and the macroscopic magnetic property, providing the possibility of manipulating the exotic states with the aid of strain engineering in oxide-based electronics. PMID:26214290
Mazumdar, S.; Clay, R. T.
2008-01-01
We demonstrate a robust frustration-driven charge-order to superconductivity transition in the half-filled negative-U extended Hubbard model. Superconductivity extends over a broad region of the parameter space. We argue that the model provides the correct insight to understanding unconventional superconductivity in the organic charge-transfer solids and other quarter-filled systems.
Third-order QCD corrections to the charged-current structure function F3
International Nuclear Information System (INIS)
We compute the coefficient function for the charge-averaged W±-exchange structure function F3 in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling αs and of 1/Q2 power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F3 in powers of αs is stable at all values of x relevant to measurements at high scales Q2. At small x the third-order coefficient function is dominated by diagrams with the colour structure dabcdabc not present at lower orders. At large x the coefficient function for F3 is identical to that of F1 up to terms vanishing for x→1. (orig.)
Third-order QCD corrections to the charged-current structure function F{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Vermaseren, J.A.M. [NIKHEF, Amsterdam (Netherlands); Vogt, A. [Liverpool Univ. (United Kingdom). Dept. of Mathematical Sciences
2008-12-15
We compute the coefficient function for the charge-averaged W{sup {+-}}-exchange structure function F{sub 3} in deep-inelastic scattering (DIS) to the third order in massless perturbative QCD. Our new three-loop contribution to this quantity forms, at not too small values of the Bjorken variable x, the dominant part of the next-to-next-to-next-to-leading order corrections. It thus facilitates improved determinations of the strong coupling {alpha}{sub s} and of 1/Q{sup 2} power corrections from scaling violations measured in neutrino-nucleon DIS. The expansion of F{sub 3} in powers of {alpha}{sub s} is stable at all values of x relevant to measurements at high scales Q{sup 2}. At small x the third-order coefficient function is dominated by diagrams with the colour structure d{sup abc}d{sub abc} not present at lower orders. At large x the coefficient function for F{sub 3} is identical to that of F{sub 1} up to terms vanishing for x{yields}1. (orig.)
Localized charged states and phase separation near second order phase transition
Kabanov, V. V.; Mamin, R. F.; Shaposhnikova, T. S.
2008-01-01
Localized charged states and phase segregation are described in the framework of the phenomenological Ginzburg-Landau theory of phase transitions. The Coulomb interactions determines the charge distribution and the characteristic length of the phase separated states. The phase separation with charge segregation becomes possible because of the large dielectric constant and the small density of extra charge in the range of charge localization. The phase diagram is calculated and the energy gain...
Non-collinear magnetic order and spin–orbit coupling effect in 4d transition metal monatomic chains
International Nuclear Information System (INIS)
Using density functional theory, the structures, stabilities and magnetic properties of 4d transition metals monatomic chains are systematically investigated. We found that the ground states of Y and Pd zigzag chains possess non-collinear magnetisms. Further investigation shows that such novel non-collinear magnetic phases arise from enhanced metallic bond. In addition, for Ru zigzag chain, the ground state of the chain changes from ferromagnetic to antiferromagnetic after dimerization, indicating that Peierls distortion could also cause magnetic transition in actual one-dimensional system. Finally, we found that the orbital magnetic moments are very significant in some 4d systems. Specially, strong spin–orbit coupling was observed in two non-collinear magnetic zigzag chains. - Highlights: • The magnetic orders of ground states of Y and Pd zigzag chains are non-collinear states. • The enhanced metallic bond is the physical origin of the non-collinear magnetic chains. • The magnetic order of ground state of Ru chain is antiferromagnetic state. • The magnetic phase transition is caused by dimerization in the Ru zigzag chain. • There exists a strong spin–orbit coupling interaction in non-collinear magnetic systems
Yuan, Zhe; Kelly, Paul J.
2016-06-01
To study the effect of spin-orbit coupling (SOC) on spin-transfer torque in magnetic materials, we have implemented two theoretical formalisms that can accommodate SOC. Using the "charge-pumping" formalism, we find two contributions to the out-of-plane spin-transfer torque parameter β in ballistic Ni domain walls (DWs). For short DWs, the nonadiabatic reflection of conduction electrons caused by the rapid spatial variation of the exchange potential results in an out-of-plane torque that increases rapidly with decreasing DW length. For long DWs, the Fermi level conduction channel anisotropy that gives rise to an intrinsic DW resistance in the presence of SOC leads to a linear dependence of β on the DW length. To understand this counterintuitive divergence of β in the long DW limit, we use the "nonequilibrium magnetization" formalism to examine the spatially resolved spin-transfer torque. The SOC-induced out-of-plane torque in ballistic DWs is found to be quantitatively consistent with the values obtained using the charge-pumping calculations, indicating the equivalence of the two theoretical methods.
Krizmanic, John F; Streitmatter, Robert E
2013-01-01
OWL uses the Earth's atmosphere as a vast calorimeter to fully enable the emerging field of charged-particle astronomy with high-statistics measurements of ultra-high-energy cosmic rays (UHECR) and a search for sources of UHE neutrinos and photons. Confirmation of the Greisen-Zatsepin-Kuzmin (GZK) suppression above ~4 x 10^19 eV suggests that most UHECR originate in astrophysical objects. Higher energy particles must come from sources within about 100 Mpc and are deflected by ~1 degree by predicted intergalactic/galactic magnetic fields. The Pierre Auger Array, Telescope Array and the future JEM-EUSO ISS mission will open charged-particle astronomy, but much greater exposure will be required to fully identify and measure the spectra of individual sources. OWL uses two large telescopes with 3 m optical apertures and 45 degree FOV in near-equatorial orbits. Simulations of a five-year OWL mission indicate ~10^6 km^2 sr yr of exposure with full aperture at ~6 x 10^19 eV. Observations at different altitudes and sp...
Spin-charge order and excitonic effects in sawtooth-like graphene nanoribbons
Wu, Sha; Lu, Wengang; Qi, Jingshan
2016-09-01
In this paper we systematically study electronic structures and excitonic effects in one type of the sawtooth-like graphene nanoribbons. A main feature is that the local magnetism is developed for the certain width and changes with the increase of width. A variety of magnetic orders root in the competition of the short range interaction between the same spin-electrons and long range exchange interaction between opposite spin-electrons. For excitonic effects, the binding energy of degenerate spin-triplets T1 and T-1 is higher than that of T0 for all studied nanoribbons and is size dependent. We reveal the underlying physical mechanism from the charge distributions of excitons and its correlation with the spin-resolved charge density distributions in the ground state. We find that the electrons and holes in degenerate spin-triplets T1 and T-1 are closer together and thus the interaction between them is more strong, while the distribution of electrons and holes is relatively more disperse for T0, indicating the weaker interaction. We hope that these interesting results are able to be detected in the experiment and these multi-performance samples are better utilized in future device applications.
Exploring the charge-ordering transition in (TMTTF){sub 2}X via thermal expansion measurements
Energy Technology Data Exchange (ETDEWEB)
Souza, Mariano de, E-mail: mariano@physik.uni-frankfurt.d [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany); Hofmann, Daniel [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany); Foury-Leylekian, Pascale; Moradpour, Alec; Pouget, Jean-Paul [Laboratoire de Physique des Solides, Universite Paris Sud, CNRS UMR 8502, 91405 Orsay (France); Lang, Michael [Physikalisches Institut, Goethe-Universitaet Frankfurt, SFB/TRR 49, D-60438 Frankfurt am Main (Germany)
2010-06-01
We report results of high-resolution measurements of the c{sup *}-axis expansivity ({alpha}{sub c}{sup *}) at the charge-ordering (CO) transition for the quasi-1D (TMTTF){sub 2}X compounds with X=SbF{sub 6} and Br and make a comparison with previous results for the X=PF{sub 6} and AsF{sub 6} salts. For X=SbF{sub 6}, due to the screening of the long-range Coulomb forces, a sharp {lambda}-type anomaly is observed at T{sub CO}, which contrasts with the step-like mean-field anomaly at T{sub CO} for PF{sub 6} and AsF{sub 6}, where CO occurs in the Mott-Hubbard charge-localized regime. For the latter two salts, a negative contribution to {alpha}{sub c}{sup *} is observed above T{sub CO}. This feature is assigned to the anions' rigid-unit modes, which become inactive for T
Sherman, David M.
1987-01-01
A molecular orbital description, based on Xα-Scattered wave calculations on a (FeTiO10)14− cluster, is given for Fe2+ → Ti4+ charge transfer transitions in minerals. The calculated energy for the lowest Fe2+ → Ti4+ metal-metal charge transfer transition is 18040 cm−1 in reasonable agreement with energies observed in the optical spectra of Fe-Ti oxides and silicates. As in the case of Fe2+ → Fe3+ charge transfer in mixed-valence iron oxides and silicates, Fe2+ → Ti4+ charge transfer is associated with Fe-Ti bonding across shared polyhedral edges. Such bonding results from the overlap of the Fe(t 2g ) and Ti(t 2g ) 3d orbitals.
Anisotropic pressure effects on the charge order transition of (TMTTF){sub 2}X
Energy Technology Data Exchange (ETDEWEB)
Nagasawa, M., E-mail: nagasawa@chiba.dendai.ac.j [Department of Physics, Tokyo Denki University (Japan); Department of Green and Sustainable Chemistry, Tokyo Denki University (Japan); Nagasawa, T. [Department of Green and Sustainable Chemistry, Tokyo Denki University (Japan); Ichimura, K. [Division of Applied Physics, Hokkaido University (Japan); Nomura, K. [Division of Physics, Hokkaido University (Japan)
2010-06-01
We measured the conductivity along the a-direction {sigma}{sub a}(T) of the quasi one-dimensional organic conductor (TMTTF){sub 2}SbF{sub 6} under several anisotropic pressures of uniaxial strains which are parallel and perpendicular to the a-direction. The uniaxial strains were generated by so-called 'Frozen oil method'. It was found that the tendencies of the uniaxial strain dependence of the conductivity and the charge order (CO) transition temperature T{sub CO} are different. According to T{sub CO}, it decreases strongly with increasing uniaxial strain parallel to the a-direction; however, it is almost constant for that perpendicular to the a-direction. We discuss the effects of compressive uniaxial strains on the conductivity and the CO transition of (TMTTF){sub 2}SbF{sub 6}.
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.
Charge ordered ferromagnetic phase in La0.5Ca0.5MnO3
Loudon, James C.; Mathur, Neil D; Midgley, Paul A.
2002-01-01
Mixed valent manganites are noted for their unusual magnetic,electronic and structural phase transitions. The La1-xCaxMnO3 phase diagram shows that below transition temperatures in the range 100-260 K, compounds with 0.2 < x < 0.5 are ferromagnetic and metallic whereas those with 0.5 < x < 0.9 are antiferromagnetic and charge ordered. In a narrow region around x = 0.5, these totally dissimilar states are thought to coexist. Uehara et al. have shown that charge order and charge disorder can co...
Eccentric-orbit EMRI gravitational wave energy fluxes to 7PN order
Forseth, Erik; Hopper, Seth
2015-01-01
We present new results through 7PN order on the energy flux from eccentric extreme-mass-ratio binaries. The black hole perturbation calculations are made at very high accuracy (200 decimal places) using a Mathematica code based on the Mano-Suzuki-Takasugi (MST) analytic function expansion formalism. All published coefficients in the expansion through 3PN order are confirmed and new analytic and numeric terms are found to high order in $e^2$ at orders between 3.5PN and 7PN. We also show original work in finding (nearly) arbitrarily accurate expansions for hereditary terms at 1.5PN, 2.5PN, and 3PN orders. We fit to a model where at each PN order an eccentricity singular function is factored out, improving substantially the fit even as $e \\to 1$.
Electric-field breakdown of the insulating charge-ordered state in LuFe2O4 thin films
International Nuclear Information System (INIS)
We have studied the dielectric breakdown of the insulating charge-ordered state and the associated current switching phenomenon in layered ferrite LuFe2O4. To elucidate the correlation between the ordering pattern and current switching behaviour, we synthesized highly c-axis oriented thin films by pulsed-laser deposition. An enhanced switching effect was achieved in the three-dimensional charge-ordered phase below ∼310 K, but not in the high-temperature two-dimensional phase. High-field transport measurements revealed that collective depinning of localized charge carriers is essential to induce switching. The lack of collective charge motion is proposed as the origin of the switching suppression in the two-dimensional phase. (paper)
Cleghorn, T. F.; Saganti, P. B.; Zeitlin, C.; Cucinotta, F. A.
2004-01-01
Knowledge of the space radiation environment is crucial both for human space exploration, and robotic space missions. It is likely that human explorers will return to the moon, and then go to Mars within the next thirty years. The radiation environment that they will encounter is a significant obstacle to future exploration, and must be dealt with successfully before longterm human missions outside of the magnetosphere can take place. Shielding technologies and materials must be developed to lower the dose and dose equivalent that human beings will receive on such missions. To begin this development, a fairly complete and accurate understanding of the space environment must be obtained. The major components of the space particle radiation environment that are most hazardous to humans are: galactic cosmic rays (GCR), the particles contained in solar particle events, (SPE), and secondary particles generated in material in the spacecraft itself. The intensity of the GCR varies by roughly a factor of two over the eleven-year solar cycle, inversely with the level of solar activity. These GCR particles are fully stripped nuclei, predominantly protons and helium, but also significant numbers of heavier ions, including carbon, oxygen, and iron. Since the ionization caused by nuclei passing through matter is proportional to the square of its charge (Z=10). The MARIE instrument has been described elsewhere.
Energy Technology Data Exchange (ETDEWEB)
Wakabayashi,Y.; Bizen, D.; Kubo, Y.; Nakao, H.; Murakami, Y.; Nakamura, M.; Ogimoto, Y.; Miyano, K.; Sawa, H.
2008-01-01
Structural study of orbital-ordered manganite thin films has been conducted using synchrotron radiation, and a ground state electronic phase diagram is made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3 (NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or [(LaAlO3)0.3(SrAl0.5Ta0.5O3)0.7] (LSAT), were measured as a function of temperature. The result shows, as expected based on previous knowledge of bulk materials, that the films' resistivity is closely related to their structures. Observed superlattice reflections indicate that NSMO thin films have an antiferro-orbital-ordered phase as their low-temperature phase while PSMO film on LSAT has a ferro-orbital-ordered phase, and that on STO has no orbital-ordered phase. A metallic ground state was observed only in films having a narrow region of A-site ion radius, while larger ions favor ferro-orbital-ordered structure and smaller ions stabilize antiferro-orbital-ordered structure. The key to the orbital-ordering transition in (011) film is found to be the in-plane displacement along [011] direction.
Directory of Open Access Journals (Sweden)
Francisco das Chagas Carvalho
2008-10-01
Full Text Available A complete first-order analytical solution, which includes the short periodic terms, for the problem of optimal low-thrust limited-power transfers between arbitrary elliptic coplanar orbits in a Newtonian central gravity field is obtained through canonical transformation theory. The optimization problem is formulated as a Mayer problem of optimal control theory with Cartesian elementsÃ¢Â€Â”position and velocity vectorsÃ¢Â€Â”as state variables. After applying the Pontryagin maximum principle and determining the maximum Hamiltonian, classical orbital elements are introduced through a Mathieu transformation. The short periodic terms are then eliminated from the maximum Hamiltonian through an infinitesimal canonical transformation built through Hori method. Closed-form analytical solutions are obtained for the average canonical system by solving the Hamilton-Jacobi equation through separation of variables technique. For transfers between close orbits a simplified solution is straightforwardly derived by linearizing the new Hamiltonian and the generating function obtained through Hori method.
Three-dimensional charge density wave order in YBCO at high magnetic field
Lee, Wei-Sheng
Charge density wave (CDW) correlations have been shown to universally exist in cuprate superconductors. However, their nature at high magnetic fields, e . g . inferred from nuclear magnetic resonance, Hall coefficient, and sound velocity measurements, is distinct from that measured by x-ray scattering at zero and low fields. In this talk, I will discuss our recent experiment which combines a pulsed magnet with an x-ray free electron laser to characterize the CDW in YBa2Cu3O6.67 via x-ray scattering in fields up to 28 Tesla. While the zero-field CDW order, which develops below ~150 K, is essentially two dimensional, a three-dimensionally ordered CDW emerges at magnetic fields beyond 15 Tesla and at temperatures below the zero-field superconducting transition temperature. While the two CDW arrange differently along the c-axis, they share the same incommensurate periodicity in the CuO2plane. Our observations imply that the two forms of CDW and high-temperature superconductivity are intimately linked.
Bini, Donato; Damour, Thibault
2016-05-01
We consider Detweiler's redshift variable z for a nonspinning mass m1 in circular motion (with orbital frequency Ω ) around a nonspinning mass m2. We show how the combination of effective-one-body (EOB) theory with the first law of binary dynamics allows one to derive a simple, exact expression for the functional dependence of z on the (gauge-invariant) EOB gravitational potential u =(m1+m2)/R . We then use the recently obtained high-post-Newtonian(PN)-order knowledge of the main EOB radial potential A (u ;ν ) [where ν =m1m2/(m1+m2)2] to decompose the second-self-force-order contribution to the function z (m2Ω ,m1/m2) into a known part (which goes beyond the 4PN level in including the 5PN logarithmic term and the 5.5PN contribution) and an unknown one [depending on the yet unknown, 5PN, 6 PN ,… , contributions to the O (ν2) contribution to the EOB radial potential A (u ;ν )]. We apply our results to the second-self-force-order contribution to the frequency shift of the last stable orbit. We indicate the expected singular behaviors, near the lightring, of the second-self-force-order contributions to both the redshift and the EOB A potential. Our results should help both in extracting information of direct dynamical significance from ongoing second-self-force-order computations and in parametrizing their global strong-field behaviors. We also advocate computing second-self-force-order conservative quantities by iterating the time-symmetric Green-function in the background spacetime.
Directory of Open Access Journals (Sweden)
Sergienko Alexander V.
2014-01-01
The potential for efficient identification of objects carrying elements of high-order symmetry using correlated orbital angular momentum (OAM states is demonstrated. The enhanced information capacity of this approach allows the recognition of specific spatial symmetry signatures present in objects with the use of fewer resources than in a conventional pixel-by-pixel imaging, representing the first demonstration of compressive sensing using OAM states. This approach demonstrates the capability to quickly evaluate multiple Fourier coefficients directly linked with the symmetry features of the object. The results suggest further application in small-scale biological contexts where symmetry and small numbers of noninvasive measurements are important.
Bini, Donato
2016-01-01
We consider Detweiler's redshift variable $z$ for a nonspinning mass $m_1$ in circular motion (with orbital frequency $\\Omega$) around a nonspinning mass $m_2$. We show how the combination of effective-one-body (EOB) theory with the first law of binary dynamics allows one to derive a simple, exact expression for the functional dependence of $z$ on the (gauge-invariant) EOB gravitational potential $u=(m_1+m_2)/R$. We then use the recently obtained high-post-Newtonian(PN)-order knowledge of the main EOB radial potential $A(u ; \
Nakaoka, Hironori; Yamakawa, Youichi; Kontani, Hiroshi
2016-06-01
The electronic nematic state without magnetization emerges in various strongly correlated metals such as Fe-based and cuprate superconductors. To understand this universal phenomenon, we focus on the nematic state in Ti oxypnictide BaTi2(As,Sb ) 2O , which is expressed as the three-dimensional ten-orbital Hubbard model. The antiferromagnetic fluctuations are caused by the Fermi surface nesting. Interestingly, we find the spin-fluctuation-driven orbital order due to the strong orbital-spin interference, which is described by the Aslamazov-Larkin vertex correction (AL-VC). The predicted intra-unit-cell nematic orbital order is consistent with the recent experimental reports on BaTi2(As,Sb ) 2O . Thus, the spin-fluctuation-driven orbital order due to the AL-VC mechanism is expected to be universal in various two- and three-dimensional multiorbital metals.
Maruyama, T.; Murakami, Y.; Shindo, D.; Abe, N.; Arima, T.
2012-08-01
Both charge-ordered and magnetic domains produced in LuFe2O4, which have attracted significant attention due to the interplay of electronic and magnetic degrees of freedom, have been studied using transmission electron microscopy techniques. Dark-field images, obtained using a weak satellite reflection, revealed the nanometer-scale charge-ordered domains, which were observed over a wide temperature range below TCO (critical temperature of charge ordering; ˜310 K). Electron holography demonstrated an aspect of the long-range magnetic order wherein the magnetic flux lines were completely parallel to the c axis of LuFe2O4, in a specimen cooled to 17 K under an applied magnetic field. In contrast, there was no appreciable magnetic signal observed in a specimen cooled in a negligible magnetic field. These observations provide useful information for further understanding of the complex magnetic phase transitions in this compound.
Kerr, Justin H.; Grosch, Donald
2001-01-01
Engineers at the NASA Johnson Space Center have conducted hypervelocity impact (HVI) performance evaluations of spacecraft meteoroid and orbital debris (M/OD) shields at velocities in excess of 7 km/s. The inhibited shaped charge launcher (ISCL), developed by the Southwest Research Institute, launches hollow, circular, cylindrical jet tips to approximately 11 km/s. Since traditional M/OD shield ballistic limit performance is defined as the diameter of sphere required to just perforate or spall a spacecraft pressure wall, engineers must decide how to compare ISCL derived data with those of the spherical impactor data set. Knowing the mass of the ISCL impactor, an equivalent sphere diameter may be calculated. This approach is conservative since ISCL jet tips are more damaging than equal mass spheres. A total of 12 tests were recently conducted at the Southwest Research Institute (SWRI) on International Space Station M/OD shields. Results of these tests are presented and compared to existing ballistic limit equations. Modification of these equations is suggested based on the results.
Jahn-Teller induced nematic orbital order in tetragonal Sr2VO4
Teyssier, J.; Giannini, E.; Stucky, A.; Černý, R.; Eremin, M. V.; van der Marel, D.
2016-03-01
Using high resolution x-ray diffraction (XRD) on high purity powders, we resolved the structure and a b symmetry of the intriguing compound Sr2VO4 from room temperature down to 20 K to an unprecedented level of accuracy. Upon cooling, this set of data unambiguously reveals a second-order phase transition lowering the symmetry from tetragonal to orthorhombic at a temperature Tc 2=136 K. The observation of an orthorhombic distortion of the a b plane is attributed to nematic phase formation supported by local Jahn-Teller (JT) dynamical instability. At TN=105 K, spins order and at Tc 1=100 K the tetragonal structure is recovered with an elongated c axis.
On the nature of the low temperature insulating state of ferromagnetic and charge ordered manganites
International Nuclear Information System (INIS)
Based on electroresistance (ER) measurements founded on a current induced resistivity switching (CIRS) phenomena, we establish the presence of a 'colossal' ER in the low temperature ferromagnetic insulating (FMI) phase exhibited by certain hole doped manganites. Notably, concomitant with the build-up of ER, is a sharp drop in the magnetoresistance (MR). This intelligibly demonstrates an effective decoupling of the mechanisms underlying ER and MR in the FMI phase. ER (CIRS) and MR were measured on single crystals of two widely different FMI manganites: La0.82Ca0.18MnO3 and Nd0.7Pb0.3MnO3. The samples have Curie temperatures, TC∼165 and 150 K, and the FMI state is realized for temperatures, T≤100 and 130 K, respectively. The ER, arising from a strong nonlinear dependence of resistivity (ρ) on current density (j), attains a value ≅100% in the FMI state. The severity of the nonlinear behavior of resistivity at high current densities is progressively enhanced with decreasing temperature. The MR, however, collapses (<20%) even in magnetic field, H=14 T. Comparison with magnetotransport data on charge ordered insulating (COI) manganites reveal discernible differences in response to applied current and magnetic field. This is credible proof that the nature of the insulating state, in the FMI and COI phases, is different
Magnetic reversal of an artificial square ice: dipolar correlation and charge ordering
Morgan, Jason; Stein, Aaron; Langridge, Sean; Marrows, Christopher
2012-02-01
Artificial spin ices are lithographically patterned arrays of single domain nanomagnets [1-4]. The elongated elements form a 2D system of interlinked vertices at which Ising-like dipole moments meet with incompatible interactions. They are directly analogous to 3D bulk spin ice materials [5]. We report on the magnetic reversal of an athermal artificial square ice pattern subject to a sequence of magnetic fields applied slightly off the diagonal symmetry axis, investigated via magnetic force microscopy of the remanent states that result [1]. From an initial diagonally polarised state, sublattice independent reversal is observed via bulk-nucleated incrementally-pinned flipped moment chains along parallel channels of magnetic elements, as evident from analysis of vertex populations and dipolar correlation functions. Weak dipolar interactions between adjacent chains favour antialignment and give rise to weak charge ordering of ``monopole'' vertices during reversal. [4pt] [1] J. P. Morgan, A. Stein, S. Langridge & C.H. Marrows, New Journal of Physics (2011), 13, 105002.[0pt] [2] R. F. Wang et al., Nature (2006), 439, 303-306.[0pt] [3] E. Mengotti et al., Nature Physics (2011), 7, 68-74.[0pt] [4] J. P. Morgan et al., Nature Physics (2011), 7, 75-79.[0pt] [5] M. J. Harris et al., PRL (1997), 79, 2554-255
Institute of Scientific and Technical Information of China (English)
DONG Shuai; ZHU Han; LIU Jun-ming
2006-01-01
Earlier theoretical approaches to manganites mainly stern from magnetic framework in which the electronic transports are thought to be spin-dependent and the double exchange plays a vital role.However,quite a number of experimental observations cannot be explained in the magnetic framework,yet.For example,multiplicate insulator-metal transitions and resistivity reduction induced by perturbations other than magnetic field,such as electric current,are not well understood in this framework.Here we present a comprehensive analysis on the magnetic framework and give a Monte Carlo study on the resistivity of a charge ordered/disordered model without accounting for the spin degree of freedom.The result shows a colossal resistivity change as a resultant of the transition between two types of insulated states.This transition has intrinsic difference from the popular insulated-to-metallic transition in the magnetic framework.The present scenario can be used to explain some experimental facts for electronic transports in manganites,which are not accessible in the magnetic framework.
Linzner, Dominik; Koster, Malte; Grusdt, Fabian; Fleischhauer, Michael
2016-05-01
Since the discovery of the quantum Hall effect, topological states of matter have attracted the attention of scientists in many fields of physics. By now there is a rather good understanding of topological order in closed, non-interacting systems. In contrast the extension to open systems in particular with interactions is entirely in its infancy. Recently there have been advances in characterizing topology in reservoir driven systems without interactions, but the topological invariants introduced lack a clear physical interpretation and are restricted to non-interacting systems. We consider a one-dimensional interacting topological system whose dynamics is entirely driven by reservoir couplings. By slowly tuning these couplings periodically in time we realize an open-system analogue of the Thouless charge pump that proves to be robust against unitary and non-unitary perturbations. Making use of this Thouless pump we introduce a topological invariant, which is applicable to interacting systems. Finally we propose a conceptual detection scheme that translates the open-system topological invariant into the context of a well understood closed system.
Li, Lin-Sen
2016-01-01
The secular effects of the electric induction drag on the orbit of a charged satellite moving in the ionosphere are examined by the method of average values. The first solutions are obtained under the assumption of non-rotation of the Earth; the second solutions are obtained assuming rotation of the Earth. In the first case the semi-major axis exhibits secular variation, but the other orbital elements exhibit no secular variation. In the second case both semi-major axis and eccentricity exhibit secular variation, but the other orbital elements exhibit no secular variation. It can be shown that the semi-major axis is contracted due to the action of the electric induction drag if the satellite has enough charge in the ionosphere. The eccentricity is decreased gradually with time, but its variation is very small for the case of a rotating Earth. An example is presented in which the secular effects of the electric induction drag on the orbits of a charged satellite are calculated. The numerical results are given in Table 1 and a discussion of them is presented in Table 2.
Nagar, Alessandro
2011-10-01
Building on the recently computed next-to-next-to-leading order (NNLO) post-Newtonian spin-orbit Hamiltonian for spinning binaries [J. Hartung and J. Steinhoff, arXiv:1104.3079.] we improve the effective-one-body description of the dynamics of two spinning black holes by including NNLO effects in the spin-orbit interaction. The calculation that is presented extends to NNLO the next-to-leading order spin-orbit Hamiltonian computed in [T. Damour, P. Jaranowski, and G. Schaefer, Phys. Rev. DPRVDAQ1550-7998 78, 024009 (2008).10.1103/PhysRevD.78.024009]. The present effective-one-body Hamiltonian reproduces the spin-orbit coupling through NNLO in the test-particle limit case. In addition, in the case of spins parallel or antiparallel to the orbital angular momentum, when circular orbits exist, we find that the inclusion of NNLO spin-orbit terms moderates the effect of the next-to-leading order spin-orbit coupling.
Lei, Yanlian; Deng, Ping; Lin, Ming; Zheng, Xuelin; Zhu, Furong; Ong, Beng S
2016-08-01
A facile polymer-matrix-mediated molecular self-assembly of polymer semiconductors into highly crystalline orders for efficient charge transport in organic thin-film transistors is demonstrated. Phenomenal enhancements in field-effect mobility of about one order of magnitude and current on/off ratio of two to three orders of magnitude are realized with polyacrylonitrile-incorporated polymer semiconductor compositions via solution deposition. PMID:27168128
Bouchard, Frédéric; De Leon, Israel; Schulz, Sebastian A.; Upham, Jeremy; Karimi, Ebrahim; Boyd, Robert W.
2014-01-01
Orbital angular momentum associated with the helical phase-front of optical beams provides an unbounded \\qo{space} for both classical and quantum communications. Among the different approaches to generate and manipulate orbital angular momentum states of light, coupling between spin and orbital angular momentum allows a faster manipulation of orbital angular momentum states because it depends on manipulating the polarisation state of light, which is simpler and generally faster than manipulat...
Directory of Open Access Journals (Sweden)
Renxin Xiao
2016-03-01
Full Text Available In order to properly manage lithium-ion batteries of electric vehicles (EVs, it is essential to build the battery model and estimate the state of charge (SOC. In this paper, the fractional order forms of Thevenin and partnership for a new generation of vehicles (PNGV models are built, of which the model parameters including the fractional orders and the corresponding resistance and capacitance values are simultaneously identified based on genetic algorithm (GA. The relationships between different model parameters and SOC are established and analyzed. The calculation precisions of the fractional order model (FOM and integral order model (IOM are validated and compared under hybrid test cycles. Finally, extended Kalman filter (EKF is employed to estimate the SOC based on different models. The results prove that the FOMs can simulate the output voltage more accurately and the fractional order EKF (FOEKF can estimate the SOC more precisely under dynamic conditions.
Charge ordering in reactive sputtered (1 0 0) and (1 1 1) oriented epitaxial Fe3O4 films
Mi, Wenbo
2013-06-01
Epitaxial Fe3O4 films with (1 0 0) and (1 1 1) orientations fabricated by reactive sputtering present simultaneous magnetic and electrical transitions at 120 and 124 K, respectively. The symmetry decreases from face-centered cubic to monoclinic structure across the Verwey transition. Extra spots with different brightness at different positions appear in selected-area diffraction patterns at 95 K. The extra spots come from the charge ordering of outer-layer electrons of Fe atoms, and should be related to the charge ordering of octahedral B-site Fe atoms. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Shape invariant higher-order Bessel-like beams carrying orbital angular momentum
International Nuclear Information System (INIS)
We present a method for generating higher-order Bessel beams with z-dependent cone angles. Such fields, if engineered correctly, are shape invariant during propagation and thus do not suffer from a transition from a Bessel-shaped intensity profile in the near field to an annular ring in the far field. We demonstrate the production of such fields in the laboratory with an optical system comprising a combination of two axicons and a lens, allowing for control of the cone angle of the resulting field. While the resulting shape invariant fields are not perfectly non-diffracting, they do maintain many of the same properties as Bessel beams, including self-reconstruction. (paper)
Photo-induced changes in charge-ordered state of Ti{sub 4}O{sub 7}
Energy Technology Data Exchange (ETDEWEB)
Watanabe, M [Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501 (Japan); Miyahara, M; Tanaka, K, E-mail: j51061@sakura.kudpc.kyoto-u.ac.j [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan)
2009-02-01
We have investigated photo-induced effects on the charge-ordered state of Ti{sub 4}O{sub 7} with pump-probe spectroscopy. Reflectivity of the probe light changes after the pulsed pump excitation, and then recovers. The photo-induced effects are observed only when the pump power exceeds a threshold value, indicative of cooperative nature of the formation process, and the recovery rate shows thermally activated behaviour. We propose that the photo-induced state is a metastable charge localized state where charge disorder is induced by a photon-assisted charge transfer process from Ti{sub 2}{sup 6+} dimers to the neighbouring Ti{sup 4+}ions. Moreover, it is found that subsequent cw laser irradiation converts the photo-induced state into the charge-ordered state. We interpret this result in terms of formation of Ti{sub 2}{sup 6+} dimers via an inverse charge transfer process assisted by the cw optical excitation.
Zhao, Song-Feng; Zhou, Xiao-Xin; Lin, C. D.
It is shown that measurement of alignment-dependent ionization probability and high-order harmonic generation (HHG) of molecules in an intense laser field can be used to probe the orbital symmetry of molecules. In this review, recent progress of molecular tunneling ionization (MO-ADK) model of Tong et al. [Phys. Rev. A 66, 033402 (2002)] is first reviewed. In particular, an efficient method to obtain wavefunctions of linear molecules in the asymptotic region was developed by solving the time-independent Schrödinger equation with B-spline functions, and molecular potential energy surfaces were constructed based on the density functional theory. The accurate wavefunctions are used to extract improved structure parameters in the MO-ADK model. The loss of accuracy of the MO-ADK model in the low intensity multiphoton ionization regime is also addressed by comparing with the molecular Perelomov-Popov-Terent'ev (MO-PPT) model, the single-active-electron time-dependent Schrödinger equation (SAE-TDSE) method, and the experimental data. Finally, how the orbital symmetry affects the HHG of molecules within the strong-field approximation (SFA) was reviewed.
Magnetic ordering in spin-orbit Mott insulator Ba2IrO4 probed by μSR
International Nuclear Information System (INIS)
Magnetic properties in the novel spin-orbit Mott insulator Ba2IrO4 were studied using muon spin rotation (μSR) technique. Zero-field μSR experiments revealed that Ba2IrO4 shows an antiferromagnetic transition at TN ∼ 240 K without any spontaneous magnetization. The most stable μ+ site was determined by the electrostatic (Madelung) potential calculation. The effective magnetic moment of the iridium ions (|μ|) in the antiferromagnetic ordered state was calculated using a dipolar-field model, with an internal field obtained by μSR experiments. The magnetic moment is significantly reduced (|μ| ∼ 0.34 μB) due to a low-dimensional quantum spin fluctuation with a large intra-plane correlation. The magnetic ground state of the spin-orbit Mott insulator Ba2IrO4 is quite similar to those in parent materials of high-TC cuprate superconductors such as La2CuO4.
Energy Technology Data Exchange (ETDEWEB)
Wang, Haiou, E-mail: wanghaiou@hdu.edu.cn [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China); Yang, Weifeng; Su, Kunpeng [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Huo, Dexuan, E-mail: dxhuo@hdu.edu.cn [Institute of Materials Physics, Hangzhou Dianzi University, Hangzhou, 310018 (China); Tan, Weishi [Key Laboratory of Soft Chemistry and Functional Materials, Ministry of Education, Department of Applied Physics, Nanjing University of Science and Technology, Nanjing, 210094 (China)
2015-11-05
Epitaxial bilayer structure consisting of ferromagnetic metallic Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3} (PSMO) and charge-ordered insulator La{sub 0.5}Ca{sub 0.5}MnO{sub 3} (LCMO) was fabricated on (001) SrTiO{sub 3} substrate by pulsed laser deposition. High-resolution synchrotron X-ray diffraction showed high quality of epitaxial layer. However, besides diffraction peaks from PSMO layer, LCMO layer and SrTiO{sub 3} substrate, we observed an additional shoulder peak, which might stem from the inhomogeneities of composition in PSMO/LCMO. Further the atomic force microscopy measurement showed the presence of non-stoichiometric large particulates at surface, imparting an overall inhomogeneous composition to the film. This implied that the variation of crystalline structure of PSMO/LCMO occurred due to inhomogeneous composition. Moreover, studies on magnetic properties showed that surface inhomogeneities and ferromagnetic clusters at the PSMO/LCMO interface probably influenced the ferromagnetism of the bilayer film together, tuning exchange bias effect. - Highlights: • We report the epitaxial growth of Pr{sub 0.7}Sr{sub 0.3}MnO{sub 3}/La{sub 0.5}Ca{sub 0.5}MnO{sub 3} bilayer on SrTiO{sub 3}. • The non-stoichiometric particulates at surface impart inhomogeneous composition. • Inhomogeneities in the film lead to the variation of crystalline structure. • Surface inhomogeneities reduce ferromagnetism and enhance exchange bias effect.
Next-to-next-to-leading order post-Newtonian spin-orbit Hamiltonian for self-gravitating binaries
Hartung, Johannes
2011-01-01
We present the next-to-next-to-leading order post-Newtonian (PN) spin-orbit Hamiltonian for two self-gravitating spinning compact objects. If at least one of the objects is rapidly rotating, then the corresponding interaction is comparable in strength to a 3.5PN effect. The result in the present paper in fact completes the knowledge of the post-Newtonian Hamiltonian for binary spinning black holes up to and including 3.5PN. The Hamiltonian is checked via known results for the test-spin case and via the global Poincar\\'e algebra with the center-of-mass vector uniquely determined by an ansatz.
Davies, J; Moch, S; Vermaseren, J A M
2016-01-01
We have calculated the coefficient functions for the structure functions F_2, F_L and F_3 in nu-nubar charged-current deep-inelastic scattering (DIS) at the third order in the strong coupling alpha_s, thus completing the description of unpolarized inclusive W^(+-) exchange DIS to this order of massless perturbative QCD. In this brief note, our new results are presented in terms of compact approximate expressions that are sufficiently accurate for phenomenological analyses. For the benefit of such analyses we also collect, in a unified notation, the corresponding lower-order contributions and the flavour non-singlet coefficient functions for nu+nubar charged-current DIS. The behaviour of all six third-order coefficient functions at small Bjorken-x is briefly discussed.
International Nuclear Information System (INIS)
A table of charged particle energies versus magnetic field strength x orbit radius (Bρ) is presented. Particles p, d, t, 3He++, 4He+, 4He++, 6Li+, 6Li++, 6Li+++, 7Li+, 7Li++, 7Li+++. Values of Bρ: 100 to 1200 kG.cm by steps of 0.5 kG.cm. Values of energies are given in keV. (author)
Charge ordered ferromagnetic phase in La_0.5Ca_0.5MnO_3
Mathur, Neil
2003-03-01
Charge order and ferromagnetism should be mutually exclusive in the manganites, because ferromagnetism in these materials is normally promoted by delocalised electrons. Surprisingly, a phase that is both strongly charge ordered and fully ferromagnetic is observed [1] at 90 K in La_0.5Ca_0.5MnO_3, using Fresnel imaging, dark-field TEM and electron holography. This new phase coexists with the two low temperature phases that were already known to coexist in La_0.5Ca_0.5MnO_3. (One of these expected phases is ferromagnetic but not charge-ordered, the other is charge-ordered but not ferromagnetic.) Strain fields could be responsible for the novel microscopic texture presented here - perhaps creating conditions in which nearest neighbour hopping is sufficient to promote ferromagnetism. Similarly, strain fields are believed to cause sub-micron phase separation in the manganites. It therefore seems that the manganites can adapt to their environments over a wide range of length scales [2]. [1] http://xxx.lanl.gov/abs/cond-mat/0209436 [2] Neil Mathur and Peter Littlewood, Physics Today, early 2003.
The effect of deuteration on the transition into a charge ordered state of (TMTTF)2X salts
International Nuclear Information System (INIS)
From dielectric permittivity measurements, we show that deuteration yields a large increase of the transition temperature for the charge ordered state of (TMTTF)2X (X = AsF6, SbF6, ReO4) salts. We propose an explanation of this phenomenon, suggesting that deuteration induces a modification of the (TMTTF)2X crystal unit cell. (letter to the editor)
International Nuclear Information System (INIS)
The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I2, At2, IO+, and AtO+ species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakens the covalent character of the bond in At2 even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems
Soroka, Pavlo V.; Vakhnin, Alexander Yu; Skryshevskiy, Yuriy A; Boiko, Oleksandr P.; Anisimov, Maksim I; Slominskiy, Yuriy L; Nazarenko, Vassili G.; Genoe, Jan; Kadashchuk, Andrey
2014-01-01
Charge carrier trapping in thin films of lyotropic chromonic liquid crystals (LCLCs) based on ionic perylene diimide derivative and in chemically-similar neutral N,N′-dipentyl-3,4,9,10-perylene-dicarboximide (PTCDI-C5) films is investigated by thermally-stimulated luminescence (TSL) technique. The LCLC films comprise elongated molecular aggregates featuring a long-range orientational order. The obtained results provide direct evidence for the improved energetic ordering (smaller effective ene...
Wang, ZD; F. Zhong
2000-01-01
The order parameters of the magnetic, charge, and structural orders at half-doped manganites are identified. A corresponding Landau theory of the phase transitions is formulated. Many structural and thermodynamical behaviors are accounted for and clarified within the framework. In particular, the theory provides a unified picture for the scenario of the phase transitions and their nature with respect to the variation of the tolerance factor of the manganites. It also accounts for the origin o...
Controlling the Orbital Sequence in Individual Cu-Phthalocyanine Molecules
Uhlmann, C.; Swart, I.; Repp, J.
2013-01-01
We report on the controlled change of the energetic ordering of molecular orbitals. Negatively charged copper(II)phthalocyanine on NaCl/Cu(100) undergoes a Jahn–Teller distortion that lifts the degeneracy of two frontier orbitals. The energetic order of the levels can be controlled by Au and Ag atom
Suppression of Three-Dimensional Charge Density Wave Ordering via Thickness Control
Kim, Gideok; Neumann, Michael; Kim, Minu; Le, Manh Duc; Kang, Tae Dong; Noh, Tae Won
2015-11-01
Barium bismuth oxide (BaBiO3 ) is the end member of two families of high-Tc superconductors, i.e., BaPb1 -xBix O3 and Ba1 -xKx BiO3 . The undoped parent compound is an insulator, exhibiting a charge density wave that is strongly linked to a static breathing distortion in the oxygen sublattice of the perovskite structure. We report a comprehensive spectroscopic and x-ray diffraction study of BaBiO3 thin films, showing that the minimum film thickness required to stabilize the breathing distortion and charge density wave is ≈11 unit cells, and that both phenomena are suppressed in thinner films. Our results constitute the first experimental observation of charge density wave suppression in bismuthate compounds without intentionally introducing dopants.
Santiesteban, Raul; Floquet, Thierry; Orlov, Yuri; Riachy, Samer; Richard, Jean-Pierre
2008-01-01
Orbital stabilization of an underactuated cart-pendulum system is under study. The quasihomogeneous control synthesis is utilized to design a second order sliding mode controller that drives the actuated cart to a periodic reference orbit in finite time, while the non-actuated pendulum produces bounded oscillations. A modified Van der Pol oscillator is introduced into the synthesis as an asymptotic generator of the periodic motion. The resulting closed-loop system is capable of moving from on...
Zhou, Jie; Zhang, Wuhong; Chen, Lixiang
2016-03-01
Based on our constructed robust π/2 mode converter, we report a concise yet high-efficient experiment to realize the detection of both high-order and fractional orbital angular momentum (OAM). The π/2 mode converter that consists of a pair of cylindrical lens is actually not new. However, our experiment shows clearly its excellent robustness, as we have detected the high-order OAM numbers up to ℓ = 100 carried by standard Laguerre-Gaussian (LG) modes. The observed patterns of two-dimensional optical lattices indicate that the radial index p of LG beams can be straightforwardly inferred as well. The versatility of the converter is also manifested by input modified LG beams carrying tunable fractional OAM, where we observe the output lattices exhibiting an interesting evolvement from Hermite-Gaussian mode HG m , 0 to its adjacent HG m + 1 , 0 . Numeric simulations based on OAM eigen-mode decomposition support the experimental results. Our demonstration has potential in both classical and quantum information applications where high OAM modes are needed.
Energy Technology Data Exchange (ETDEWEB)
Stringfield, R.M.; Fazio, M.V.; Rickel, D.G.; Kwan, T.J.T.; Peratt, A.L.; Kinross-Wright, J.; Van Haaften, F.W.; Hoeberling, R.F.; Faehl, R.; Carlsten, B.; Destler, W.W.; Warner, L.B.
1990-01-01
Los Alamos is investigating a number of high power microwave sources for their potential to power advanced accelerators. Included in this investigation are the large orbit gyrotron amplifier and oscillator (LOG) and the relativistic klystron amplifier (RKA). LOG amplifier development is newly underway. Electron beam power levels of 3 GW, 70 ns duration, are planned, with anticipated conversion efficiencies into RF on the order of 20 percent. Ongoing investigations on this device include experimental improvement of the electron beam optics, and computational studies of resonator design and RF extraction. Recent RKA studies have operated at electron beam powers into the device of 1.35 GW in microsecond duration pulses. The device has yielded modulated electron beam power approaching 300 MW using 3--5 kW of RF input drive. RF powers extracted into waveguide have been up to 70 MW, suggesting that more power is available from the device that we have converted to-date in the extractor. We have examined several aspects of operation, including beam bunching phenomena and RF power extraction techniques. In addition, investigations of the amplifier gain as a function of input drive, electron beam parameters and axial magnetic field strength also have been explored. The effect of ions formed during device operation also has been considered.
Negi, D. S.; Loukya, B.; Datta, R.
2015-12-01
We report on the observation of Co vacancy (VCo) induced charge ordering and ferromagnetism in CoO epitaxial thin film. The ordering is associated with the coexistence of commensurate, incommensurate, and discommensurate electronic phases. Density functional theory calculation indicates the origin of ordering in Co atoms undergoing high spin to low spin transition immediately surrounding the VCo(16.6 at. %). Electron magnetic chiral dichroism experiment confirms the ferromagnetic signal at uncompensated Co spins. Such a native defects induced coexistence of different electronic phases at room temperature in a simple compound CoO is unique and adds to the richness of the field with the possibility of practical device application.
Buza, M.; van Neerven, W. L.
1997-01-01
The most important part of the order $\\alpha_s^2$ corrections to the charm component of the charged-current structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ have been calculated. This calculation is based on the asymptotic form of the heavy-quark coefficient functions corresponding to the higher order corrections to the W-boson-gluon fusion process. These coefficient functions which are in principle only valid for $Q^2 \\gg m^2$ can be also used to estimate the order $\\alpha_s^2$ contribution...
Institute of Scientific and Technical Information of China (English)
Chen Bao-Xin
2006-01-01
An elliptical Gaussian wave formalism model of a charged-particle beam is proposed by analogy with an elliptical Gaussian light beam.In the paraxial approximation.the charged-particle beam can be described as a whole by a complex radius of curvature in the real space domains.Therefore,the propagation and transform of charged-particle beam passing through a first-order optical system is represented by the ABCD-like law.As an example of the application of this model,the relation between the beam waist and the minimum beam spot at a fixed target is discussed.The result.well matches that from conventional phase space model,and proves that the Gaussian wave formalism model is highly effective and reasonable.
Separation of charge-order and magnetic QCPs in heavy fermions and high Tc cuprates
Harrison, Neil
2010-03-01
The Fermi surface topology of high temperature superconductors inferred from magnetic quantum oscillation measurements provides clues for the origin of unconventional pairing thus previously not accessed by other spectroscopy techniques. While the overdoped regime of the high Tc phase diagram has a large Fermi surface consistent with bandstructure calculations, the underdoped regime of YBa2Cu2O6+x is found to be composed of small pockets. There is considerable debate as to whether the small observed ``pocket'' is hole-like or electron-like- whether the Fermi surface is best described by a t-J model or a conventional band folding picture- whether or not a Fermi liquid description applies- or- whether bilayer coupling splits the degeneracy of the observed pockets. We (myself and collaborators) have now collected an extensive body of experimental data that brings this debate to rest, but raises new questions about the nature of itinerant magnetism in underdoped high Tc cuprates. Quantum oscillation measurements are performed on multiple samples in magnetic fields extending to 85 T, temperatures between 30 mK (dilution fridge in dc fields to 45 T) and 18 K, over a range of hole dopings and with samples rotated in-situ about multiple axes with respect to the magnetic field. We perform a topographical map of the Fermi surface, enabling the in-plane shape of one of the pockets to be determined- imposing stringent constraints on the origin of the Fermi surface. While quantum oscillations measurements are consistent with a topological Fermi surface change associated with magnetism near optimal doping, they also point to a secondary instability deep within the underdoped regime beneath a high Tc superconducting sub-dome. An steep upturn in the quasiparticle effective mass is observed on underdoping, suggestive of a quantum critical point near x= 0.46 separating the metallic regime (composed of small pockets) from a more underdoped insulating charge-ordered regime (earlier
International Nuclear Information System (INIS)
short-range charge and orbital order present above TC. In an neutron powder diffraction measurement at the Hahn-Meitner Institut in Berlin, we investigated the temperature dependence of the anisotropic Debye-Waller factors of the oxygen atoms in La0.7Sr0.3MnO3. According to the present point of view, the sudden increase of the Debye-Waller factors at TC should be proportional to the strength of the colossal magnetoresistance effect. However, we found experimental values for La0.7Sr0.3MnO3, which are in close vicinity or even bigger than values of compounds with a much stronger magnetoresistance effect. (orig.)
2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion.
Kang, Keehoon; Watanabe, Shun; Broch, Katharina; Sepe, Alessandro; Brown, Adam; Nasrallah, Iyad; Nikolka, Mark; Fei, Zhuping; Heeney, Martin; Matsumoto, Daisuke; Marumoto, Kazuhiro; Tanaka, Hisaaki; Kuroda, Shin-Ichi; Sirringhaus, Henning
2016-08-01
Doping is one of the most important methods to control charge carrier concentration in semiconductors. Ideally, the introduction of dopants should not perturb the ordered microstructure of the semiconducting host. In some systems, such as modulation-doped inorganic semiconductors or molecular charge transfer crystals, this can be achieved by spatially separating the dopants from the charge transport pathways. However, in conducting polymers, dopants tend to be randomly distributed within the conjugated polymer, and as a result the transport properties are strongly affected by the resulting structural and electronic disorder. Here, we show that in the highly ordered lamellar microstructure of a regioregular thiophene-based conjugated polymer, a small-molecule p-type dopant can be incorporated by solid state diffusion into the layers of solubilizing side chains without disrupting the conjugated layers. In contrast to more disordered systems, this allows us to observe coherent, free-electron-like charge transport properties, including a nearly ideal Hall effect in a wide temperature range, a positive magnetoconductance due to weak localization and the Pauli paramagnetic spin susceptibility. PMID:27159015
Energy Technology Data Exchange (ETDEWEB)
Miyashita, Satoshi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Yonemitsu, Kenji, E-mail: satoshi@ims.ac.j [Institute for Molecular Science, Okazaki 444-8585 (Japan)
2009-02-01
Effects of spin fluctuations, charge fluctuations and lattice distortions on charge orders in theta-(BEDT-TTF){sub 2}RbZn(SCN){sub 4} and alpha-(BEDT-TTF){sub 2}I{sub 3} are investigated theoretically in a two-dimensional extended Peierls-Hubbard model. By using exact diagonalization, we have calculated hole-density distributions and transfer modulations with transfer integrals based on the corresponding high-temperature structures as a function of electron-phonon couplings. The results clearly show the origin of their lattice-effect differences, namely, the lattice effect on theta-(BEDT-TTF){sub 2}RbZn(SCN){sub 4} is much larger than that on alpha-(BEDT-TTF){sub 2}I{sub 3}. This finding is systematically explained by the strong-coupling perturbation theory. It is found that spin fluctuations induce lattice distortions in theta-(BEDT-TTF){sub 2}RbZn(SCN){sub 4}, but their effects are partially cancelled by charge fluctuations in alpha-(BEDT-TTF){sub 2}I{sub 3}.
Phase diagram of the restricted primitive model: charge-ordering instability
Directory of Open Access Journals (Sweden)
O.V.Patsahan
2004-01-01
Full Text Available We study the phase behaviour of the restricted primitive model (RPM using a microscopic approach based on the method of collective variables with a reference system. Starting from the Hamiltonian of the RPM we derive the functional of the grand partition function given in terms of the two collective variables: the collective variables ρk and ck describing fluctuations of the total number density and charge density, respectively. Within the framework of the Gaussian approximation we found the boundary of stability with respect to fluctuations of the charge density. It is shown that due to the approximated character of the theory the boundary of stability is very sensitive to the particular choice of the long-range part of potential inside the hard core. This point is discussed in more detail.
Hartung, Johannes
2010-01-01
We derive the post-Newtonian next-to-leading order conservative spin-orbit and spin(a)-spin(b) gravitational interaction Hamiltonians for arbitrary many compact objects. The spin-orbit Hamiltonian completes the knowledge of Hamiltonians up to and including 2.5PN for the general relativistic three-body problem. The new Hamiltonians include highly nontrivial three-body interactions, in contrast to the leading order consisting of two-body interactions only. This may be important for the study of effects like Kozai resonances in mergers of black holes with binary black holes.
Institute of Scientific and Technical Information of China (English)
Humei Wang; Wei Yang; Junfeng Li
2005-01-01
Using the reference orbital element approach, the precise governing equations for the relative motion of formation flight are formulated. A number of ideal formations with respect to an elliptic orbit can be designed based on the relative motion analysis from the equations. The features of the oscillating reference orbital elements are studied by using the perturbation theory. The changes in the relative orbit under perturbation are divided into three categories, termed scale enlargement, drift and distortion respectively. By properly choosing the initial mean orbital elements for the leader and follower satellites, the deviations from originally regular formation orbit caused by the perturbation can be suppressed. Thereby the natural formation is set up. It behaves either like non-disturbed or need little control to maintain.The presented reference orbital element approach highlights the kinematics properties of the relative motion and is convenient to incorporate the results of perturbation analysis on orbital elements. This method of formation design has advantages over other methods in seeking natural formation and in initializing formation.
International Nuclear Information System (INIS)
We extend our previous work devoted to the computation of the next-to-next-to-leading order spin–orbit correction (corresponding to 3.5PN order) in the equations of motion of spinning compact binaries by (i) deriving the corresponding spin–orbit terms in the evolution equations for the spins, the conserved integrals of the motion and the metric regularized at the location of the particles (obtaining also the metric all over the near zone but with some lower precision); (ii) performing the orbital reduction of the precession equations, near-zone metric and conserved integrals to the center-of-mass frame and then further assuming quasi-circular orbits (neglecting gravitational radiation reaction). The results are systematically expressed in terms of the spin variables with a conserved Euclidean norm instead of the original antisymmetric spin tensors of the pole–dipole formalism. This work paves the way to the future computation of the next-to-next-to-leading order spin–orbit terms in the gravitational-wave phasing of spinning compact binaries. (paper)
Energy Technology Data Exchange (ETDEWEB)
Alekhin, S. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation); Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)
2008-11-15
We study the perturbative QCD corrections to structure functions of charged-lepton deep-inelastic scattering and their impact on global fits of parton distributions. We include the logarithmically enhanced terms near threshold due to soft gluon resummation in the QCD corrections at next-to-next-to-leading order. We demonstrate that this approximation is sufficient to describe the available HERA data in most parts of the kinematic region. The threshold-enhanced next-to-next-to-leading order corrections improve the agreement between predictions based on global fits of the parton distribution functions and the HERA collider data even in the small-x region. (orig.)
Directory of Open Access Journals (Sweden)
Eduardo A. Castro
2004-12-01
Full Text Available We report the results of a calculation of the normal boiling points of a representative set of 200 organic molecules through the application of QSPR theory. For this purpose we have used a particular set of flexible molecular descriptors, the so called Correlation Weighting of Atomic Orbitals with Extended Connectivity of Zero- and First-Order Graphs of Atomic Orbitals. Although in general the results show suitable behavior to predict this physical chemistry property, the existence of some deviant behaviors points to a need to complement this index with some other sort of molecular descriptors. Some possible extensions of this study are discussed.
A Secondary Operator Ordering Problem for a Charged Rigid Planar Rotator in Uniform Magnetic Field
Institute of Scientific and Technical Information of China (English)
XIAO Yan-Ping; LAI Mei-Mei; HOU Ji-Xuan; CHEN Xu-Wen; LIU Quan-Hui
2005-01-01
When the motion of a particle is constrained, an excess term exists using hermitian form of Cartesian momentum pi (i = 1, 2, 3) in usual kinetic energy (1/2μ)∑p2i, and the correct kinetic energy turns out to be (1/2μ) ∑(1/ fi)pifipi, where the fi are dummy factors in classical mechanics and nontrivial in quantum mechanics. In this paper the explicit form of the dummy functions fi is given for a charged rigid planar rotator in the uniform magnetic field.
Charge transfer and orbital reconstruction in the (La2/3Sr1/3MnO3)m/(SrRuO3)n superlattices
International Nuclear Information System (INIS)
The structural, electronic, and magnetic properties of (La2/3Sr1/3MnO3)m/(SrRuO3)n superlattices have been investigated based on the first principles calculations. An obvious Jahn-Teller distortion, which depends on m, n, appears in MnO6 octahedron in the superlattices. The stretch along c-axis of MnO6 octahedron at the interface lifts the Mn eg orbital degeneracy, with electrons preferring the lower energy 3z2−r2 to the higher energy x2−y2. Benefitting from the charge transfer at the interface, the still occupied x2−y2 orbital can mediate a robust in-plane double exchange interaction. La2/3Sr1/3MnO3 block is ferromagnetic and metallic, even for the superlattice with m = n = 1
Competing charge, spin, and superconducting orders in underdoped YBa2Cu3Oy
DEFF Research Database (Denmark)
Hücker, M.; Christensen, Niels Bech; Holmes, A. T.;
2014-01-01
, and appears independent of the type and correlation length of the oxygen-chain order. The onset temperature of the CDW order is remarkably close to a temperature T† that marks the maximum of 1/(T1T) in planar 63Cu NQR/NMR experiments, potentially indicating a response of the spin dynamics to the formation...
Entropy of a rotating and charged black string to all orders in the Planck length
International Nuclear Information System (INIS)
By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein–Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein–Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates
Entropy of a rotating and charged black string to all orders in the Planck length
Institute of Scientific and Technical Information of China (English)
Zhao Ren; Wu Yue-Qin; Zhang Li-Chun
2009-01-01
By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein-Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein-Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates.
van der Maarel, Johan R. C.
Amphiphilic diblock copolymers with a polyelectrolyte block comprise two linearly attached moieties: a charged and a hydrophobic chain part. Owing to their specific properties and the increased need of water supported poly- mer materials, these copolymers have found widespread applications from the stabilization of colloidal suspensions, through encapsulation and delivery of bioactive agents, to the control of gelation, lubrication, and flow behavior [1,2]. Besides these technological applications, progress in this area also has implica- tions for biophysics. Polyelectrolyte brushes are a model system for the exter- nal envelope of certain microorganisms (glycocalix) and are thought to play a role in, e.g., cell recognition and cushioning properties of synovial fluid [3, 4]. The hydrophobic attachment provides a mechanism for self-assembling of the copolymers into units of mesoscopic size, which are large compared to the molecular dimensions. Major factors controlling the self-assembled structures are solvent composition, charge, ionic strength, and chemical nature and the respective sizes of the blocks. For ionic diblocks of poly(styrene-block-acrylate) (PS-b-PA) with a polyelectrolyte (PA) block length smaller than the length of the polystyrene (PS) block, a multitude of different "crew-cut" structures has been observed by Eisenberg and coworkers [5-7].
Inoue, Yasuhide; Sato, Hiroki; Koyama, Yasumasa
2016-02-01
The formation of the C-type orbital-ordered (COO) state from the disordered cubic (DC) state in Sr1-xNdxMnO3 (SNMO) with the simple perovskite structure has been examined mainly by transmission electron microscopy. As the COO state has tetragonal I4/mcm symmetry, its formation is associated with the cubic-to-tetragonal structural transition. It was found that, when SNMO samples were cooled down from the DC state, the R25-type rotational displacement of MnO6 octahedra was first induced, together with the symmetry change into the tetragonal I4/mcm structure. The C-type orbital ordering then appeared due to the induction of the Jahn-Teller distortion as a response of a lattice system to this orbital ordering. Because no symmetry change occurred in the latter case, the Jahn-Teller distortion can be regarded as a dilatational distortion. One interesting feature is that the appearance of the dilatational Jahn-Teller distortion led to a nanometer-scale banded structure, characterized by an alternating array of two tetragonal variants with different c/a values. In addition, the formation of the COO state from the DC state exhibited a time-relaxation phenomenon. The origin of this relaxation phenomenon is also discussed here in terms of the competition between the tetragonal spontaneous strain for the rotational displacement and the dilatational Jahn-Teller distortion for orbital ordering.
International Nuclear Information System (INIS)
We study hole, electron, and exciton transports in a charge transfer system in the presence of underdamped vibrational motion. We analyze the signature of these processes in the linear and third-, and fifth-order nonlinear electronic spectra. Calculations are performed with a numerically exact hierarchical equations of motion method for an underdamped Brownian oscillator spectral density. We find that combining electron, hole, and exciton transfers can lead to non-trivial spectra with more structure than with excitonic coupling alone. Traces taken during the waiting time of a two-dimensional (2D) spectrum are dominated by vibrational motion and do not reflect the electron, hole, and exciton dynamics directly. We find that the fifth-order nonlinear response is particularly sensitive to the charge transfer process. While third-order 2D spectroscopy detects the correlation between two coherences, fifth-order 2D spectroscopy (2D population spectroscopy) is here designed to detect correlations between the excited states during two different time periods
Charge-ordering transition in iron oxide Fe4O5 involving competing dimer and trimer formation
Ovsyannikov, Sergey V.; Bykov, Maxim; Bykova, Elena; Kozlenko, Denis P.; Tsirlin, Alexander A.; Karkin, Alexander E.; Shchennikov, Vladimir V.; Kichanov, Sergey E.; Gou, Huiyang; Abakumov, Artem M.; Egoavil, Ricardo; Verbeeck, Johan; McCammon, Catherine; Dyadkin, Vadim; Chernyshov, Dmitry; van Smaalen, Sander; Dubrovinsky, Leonid S.
2016-05-01
Phase transitions that occur in materials, driven, for instance, by changes in temperature or pressure, can dramatically change the materials’ properties. Discovering new types of transitions and understanding their mechanisms is important not only from a fundamental perspective, but also for practical applications. Here we investigate a recently discovered Fe4O5 that adopts an orthorhombic CaFe3O5-type crystal structure that features linear chains of Fe ions. On cooling below ∼150 K, Fe4O5 undergoes an unusual charge-ordering transition that involves competing dimeric and trimeric ordering within the chains of Fe ions. This transition is concurrent with a significant increase in electrical resistivity. Magnetic-susceptibility measurements and neutron diffraction establish the formation of a collinear antiferromagnetic order above room temperature and a spin canting at 85 K that gives rise to spontaneous magnetization. We discuss possible mechanisms of this transition and compare it with the trimeronic charge ordering observed in magnetite below the Verwey transition temperature.
Coexistence of charge order and antiferromagnetism in (TMTTF){sub 2}SbF{sub 6}: NMR study
Energy Technology Data Exchange (ETDEWEB)
Nomura, K., E-mail: knmr@phys.sci.hokudai.ac.jp; Yamamoto, M.; Matsunaga, N.; Hirose, S.; Shimohara, N.; Satoh, T.; Isome, T.; Liu, Y.; Kawamoto, A.
2015-03-01
The electronic state of (TMTTF){sub 2}SbF{sub 6} was investigated by the {sup 1}H and {sup 13}C NMR measurements. The temperature dependence of T{sub 1}{sup −1} in {sup 1}H NMR shows a sharp peak associated with the antiferromagnetic transition at T{sub AF}=6 K. The temperature dependence of T{sub 1}{sup −1} is described by the power law T{sup 2.4} below T{sub AF}. This suggests the nodal gapless spin wave excitation in antiferromagnetic phase. In {sup 13}C NMR, two sharp peaks at high temperature region, associated with the inner and the outer carbon sites in TMTTF dimer, split into four peaks below 150 K. It indicates that the charge disproportionation occurs. The degree of charge disproportionation Δρ is estimated as (0.25±0.09)e from the chemical shift difference. This value of Δρ is consistent with that obtained from the infrared spectroscopy. In the antiferromagnetic state (AFI), the observed line shape is well fitted by eight Lorentzian peaks. This suggests that the charge order with the same degree still remains in the AF state. From the line assignment, the AF staggered spin amplitude is obtained as 0.70 μ{sub B} and 0.24 μ{sub B} at the charge rich and the poor sites, respectively. These values corresponding to almost 1 μ{sub B} per dimer are quite different from 0.11 μ{sub B} of another AF (AFII) state in (TMTTF){sub 2}Br with effective higher pressure. As a result, it is understood that the antiferromagnetic staggered spin order is stabilized on the CO state in the AFI phase of (TMTTF){sub 2}SbF{sub 6}.
Three-Dimensional Charge Density Wave Order in YBa2Cu3O6.67 at High Magnetic Fields
Energy Technology Data Exchange (ETDEWEB)
Gerber, S.; Jang, H.; Nojiri, H.; Matsuzawa, S.; Yasumura, H.; Bonn, D. A.; Liang, R.; Hardy, W.; Islam, Z.; Lee, W. -S.; Zhu, D.; Lee, J. -S.
2015-11-20
Charge density wave (CDW) correlations have been shown to universally exist in cuprate superconductors. However, their nature at high fields inferred from nuclear magnetic resonance is distinct from that measured by x-ray scattering at zero and low fields. Here we combine a pulsed magnet with an x-ray free electron laser to characterize the CDW in YBa2Cu3O6.67 via x-ray scattering in fields up to 28 Tesla. While the zero-field CDW order, which develops below T ~ 150 K, is essentially two-dimensional, at lower temperature and beyond 15 Tesla, another three-dimensionally ordered CDW emerges. The field-induced CDW onsets around the zero-field superconducting transition temperature, yet the incommensurate inplane ordering vector is field-independent. This implies that the two forms of CDW and hightemperature superconductivity are intimately linked.
Energy Technology Data Exchange (ETDEWEB)
Negi, D. S., E-mail: devendranegi@jncasr.ac.in, E-mail: ranjan@jncasr.ac.in; Loukya, B.; Datta, R., E-mail: devendranegi@jncasr.ac.in, E-mail: ranjan@jncasr.ac.in [International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India); Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064 (India)
2015-12-07
We report on the observation of Co vacancy (V{sub Co}) induced charge ordering and ferromagnetism in CoO epitaxial thin film. The ordering is associated with the coexistence of commensurate, incommensurate, and discommensurate electronic phases. Density functional theory calculation indicates the origin of ordering in Co atoms undergoing high spin to low spin transition immediately surrounding the V{sub Co(16.6 at. %)}. Electron magnetic chiral dichroism experiment confirms the ferromagnetic signal at uncompensated Co spins. Such a native defects induced coexistence of different electronic phases at room temperature in a simple compound CoO is unique and adds to the richness of the field with the possibility of practical device application.
Partial dissociation of water on Fe$_{3}$O$_{4}$(001): adsorbate induced charge and orbital order
Mulakaluri, N.; Pentcheva, R.; Wieland, M.; Moritz, W.; Scheffler, M.
2009-01-01
The interaction of water with Fe$_3$O$_4$(001) is studied by density functional theory (DFT) calculations including an on-site Coulomb term. For isolated molecules dissociative adsorption is strongly promoted at surface defect sites, while at higher coverages a hydrogen-bonded network forms with alternating molecular and dissociated species. This mixed adsorption mode and a suppression of the $(\\sqrt{2}\\times \\sqrt{2})R45^{\\circ}$-reconstruction are confirmed by a quantitative low energy elec...
Sherman, David M.
1990-01-01
Metal-metal charge-transfer and magnetic exchange interactions have important effects on the optical spectra, crystal chemistry, and physics of minerals. Previous molecular orbital calculations have provided insight on the nature of Fe2+-Fe3+ and Fe2+-Ti4+ charge-transfer transitions in oxides and silicates. In this work, spin-unrestricted molecular orbital calculations on (FeMnO10) clusters are used to study the nature of magnetic exchange and electron delocalization (charge transfer) associated with Fe3+-Mn2+, Fe3+-Mn3+, and Fe2+-Mn3+ interactions in oxides and silicates.
Elovaara, T.; Ahlqvist, T.; Majumdar, S.; Huhtinen, H.; Paturi, P.
2015-05-01
We report melting of the charge-ordered state in low bandwidth manganite PCMO (x=0.3-0.5) thin films under substantially lower magnetic field. Two different in situ post-deposition annealing conditions were applied on the PCMO thin films grown by pulsed laser deposition at a deposition temperature of 500 °C, which is significantly lower compared to the traditional deposition temperature for complex oxides. Thorough structural and magnetic characterization of these two films show improved crystalline and magnetic properties in PCMO thin films annealed at a lower temperature that leads to stronger ferromagnetic interaction at the cost of charge- and orbital-ordered states. In these structurally improved film a larger irreversible metamagnetic transition can be observed and the onset magnetic field required to melt the charge-ordered state reduces to only around 2 T at 70 K temperature in the sample with x=0.4 and nearly around 2.5 T for x=0.5. Additionally, the in situ post-deposition annealing at 500 °C decreases the insulator-metal transition about 2.5 T when compared to the samples annealed at 700 °C. Therefore, a larger colossal magnetoresistance effect is observed under a moderate value of applied magnetic field in these PCMO films with better crystalline order. This result is of extreme importance for the future generation of oxide electronics using phase-change property of strongly correlated materials.
Naresh, P.; Hitesh, C.; Patel, A.; Kolge, T.; Sharma, Archana; Mittal, K. C.
2013-08-01
A fourth order (LCLC) resonant converter based capacitor charging power supply (CCPS) is designed and developed for pulse power applications. Resonant converters are preferred t utilize soft switching techniques such as zero current switching (ZCS) and zero voltage switching (ZVS). An attempt has been made to overcome the disadvantages in 2nd and 3rd resonant converter topologies; hence a fourth order resonant topology is used in this paper for CCPS application. In this paper a novel fourth order LCLC based resonant converter has been explored and mathematical analysis carried out to calculate load independent constant current. This topology provides load independent constant current at switching frequency (fs) equal to resonant frequency (fr). By changing switching condition (on time and dead time) this topology has both soft switching techniques such as ZCS and ZVS for better switching action to improve the converter efficiency. This novel technique has special features such as low peak current through switches, DC blocking for transformer, utilizing transformer leakage inductance as resonant component. A prototype has been developed and tested successfully to charge a 100 μF capacitor to 200 V.
Buza, M
1997-01-01
The most important part of the order $\\alpha_s^2$ corrections to the charm component of the charged-current structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ have been calculated. This calculation is based on the asymptotic form of the heavy-quark coefficient functions corresponding to the higher order corrections to the W-boson-gluon fusion process. These coefficient functions which are in principle only valid for $Q^2 \\gg m^2$ can be also used to estimate the order $\\alpha_s^2$ contributions at lower $Q^2$ values provided $x < 0.1$. It turns out that the above corrections are appreciable in the large $Q^2$-region and they explain the discrepancy found for the structure functions between the fixed-flavour scheme (FFS) and the variable-flavour-number scheme (VFNS). These corrections also hamper the extraction of the strange-quark density from the data obtained for the charged-current and the electromagnetic-current processes.
Khanna, V.; Mankowsky, R.; Petrich, M.; Bromberger, H.; Cavill, S. A.; Möhr-Vorobeva, E.; Nicoletti, D.; Laplace, Y.; Gu, G. D.; Hill, J. P.; Först, M.; Cavalleri, A.; Dhesi, S. S.
2016-06-01
We show that disruption of charge-density-wave (stripe) order by charge transfer excitation, enhances the superconducting phase rigidity in La1.885Ba0.115CuO4 . Time-resolved resonant soft x-ray diffraction demonstrates that charge order melting is prompt following near-infrared photoexcitation whereas the crystal structure remains intact for moderate fluences. THz time-domain spectroscopy reveals that, for the first 2 ps following photoexcitation, a new Josephson plasma resonance edge, at higher frequency with respect to the equilibrium edge, is induced indicating enhanced superconducting interlayer coupling. The fluence dependence of the charge-order melting and the enhanced superconducting interlayer coupling are correlated with a saturation limit of ˜0.5 mJ /cm2 . Using a combination of x-ray and optical spectroscopies we establish a hierarchy of timescales between enhanced superconductivity, melting of charge order, and rearrangement of the crystal structure.
Striped superconductors: how spin, charge and superconducting orders intertwine in the cuprates
International Nuclear Information System (INIS)
Recent transport experiments in the original cuprate high temperature superconductor, La2-xBaxCuO4, have revealed a remarkable sequence of transitions and crossovers that give rise to a form of dynamical dimensional reduction, in which a bulk crystal becomes essentially superconducting in two directions while it remains poorly metallic in the third. We identify these phenomena as arising from a distinct new superconducting state, the 'striped superconductor', in which the superconducting order is spatially modulated, so that its volume average value is zero. Here, in addition to outlining the salient experimental findings, we sketch the order parameter theory of the state, stressing some of the ways in which a striped superconductor differs fundamentally from an ordinary (uniform) superconductor, especially concerning its response to quenched randomness. We also present the results of density matrix renormalization group calculations on a model of interacting electrons in which sign oscillations of the superconducting order are established. Finally, we speculate concerning the relevance of this state to experiments in other cuprates, including recent optical studies of La2-xSrxCuO4 in a magnetic field, neutron scattering experiments in underdoped YBa2Cu3O6+x and a host of anomalies seen in STM and ARPES studies of Bi2Sr2CaCu2O8+δ.
Indian Academy of Sciences (India)
Navneet K Pandey; Prahallad Padhan; R C Budhani
2002-05-01
We report measurements of non-linear charge transport in epitaxial (La1-Pr)0.7Ca0.3MnO3 thin ﬁlms fabricated on (100) oriented SrTiO3 single crystals by pulsed laser deposition. The end members of this series, namely Pr0.7Ca0.3MnO3 and La0.7Ca0.3MnO3 are canonical charge-ordered (CO) and ferromagnetic manganites, respectively. The onset of the CO state in Pr0.7Ca0.3MnO3 is manifested by a pronounced insulating behavior below ∼ 200 K. The CO state remains stable even when a large (∼ 2 × 105 V/cm) electric ﬁeld is applied across the thin ﬁlm samples. However, on substitution of Pr with La, a crossover from the highly resistive CO state to a state of metallic character is observed at relatively low electric ﬁelds. The current–voltage characteristics of the samples at low temperatures show hysteretic and history dependent effects. The electric ﬁeld driven charge transport in the system is modelled on the basis of an inhomogeneous medium consisting of ferromagnetic metallic clusters dispersed in a CO background.
Directory of Open Access Journals (Sweden)
R. C. Domingos
2013-01-01
Full Text Available The equations for the variations of the Keplerian elements of the orbit of a spacecraft perturbed by a third body are developed using a single average over the motion of the spacecraft, considering an elliptic orbit for the disturbing body. A comparison is made between this approach and the more used double averaged technique, as well as with the full elliptic restricted three-body problem. The disturbing function is expanded in Legendre polynomials up to the second order in both cases. The equations of motion are obtained from the planetary equations, and several numerical simulations are made to show the evolution of the orbit of the spacecraft. Some characteristics known from the circular perturbing body are studied: circular, elliptic equatorial, and frozen orbits. Different initial eccentricities for the perturbed body are considered, since the effect of this variable is one of the goals of the present study. The results show the impact of this parameter as well as the differences between both models compared to the full elliptic restricted three-body problem. Regions below, near, and above the critical angle of the third-body perturbation are considered, as well as different altitudes for the orbit of the spacecraft.
Influence of molecular order on charge carrier photogeneration in perylene derivative layer
International Nuclear Information System (INIS)
X-ray diffraction investigations show, that in the vacuum evaporated layers of 2,9-di(pent-3yl)-anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8, 10-tetrone (PTCDI) the PTCDI molecules may have edge-on or face-on arrangement. For the samples with different molecular arrangement the dependences of the photogeneration quantum yield on electric field were determined by using the photoinduced surface potential decay technique. The obtained results were analysed using the Onsager's model of photogeneration. The clear influence of the molecular order on the photogeneration efficiency has been found
Third-order TRANSPORT: A computer program for designing charged particle beam transport systems
International Nuclear Information System (INIS)
TRANSPORT has been in existence in various evolutionary versions since 1963. The present version of TRANSPORT is a first-, second-, and third-order matrix multiplication computer program intended for the design of static-magnetic beam transport systems. This report discusses the following topics on TRANSPORT: Mathematical formulation of TRANSPORT; input format for TRANSPORT; summaries of TRANSPORT elements; preliminary specifications; description of the beam; physical elements; other transformations; assembling beam lines; operations; variation of parameters for fitting; and available constraints -- the FIT command
Soroka, Pavlo V.; Vakhnin, Alexander Yu.; Skryshevskiy, Yuriy A.; Boiko, Oleksandr P.; Anisimov, Maksim I.; Slominskiy, Yuriy L.; Nazarenko, Vassili G.; Genoe, Jan; Kadashchuk, Andrey
2014-12-01
Charge carrier trapping in thin films of lyotropic chromonic liquid crystals (LCLCs) based on ionic perylene diimide derivative and in chemically-similar neutral N,N'-dipentyl-3,4,9,10-perylene-dicarboximide (PTCDI-C5) films is investigated by thermally-stimulated luminescence (TSL) technique. The LCLC films comprise elongated molecular aggregates featuring a long-range orientational order. The obtained results provide direct evidence for the improved energetic ordering (smaller effective energetic disorder) in aggregated LCLC films as compared to conventional PTCDI-C5 films. The width of the density-of-state distribution of 0.09 eV and 0.13 eV was estimated for the LCLC and PTCDI-C5 films, respectively. Relatively small effective energetic disorder in LCLC films is ascribed to formation of macroscopically larger LCLC aggregates.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Q [Ames Laboratory; Singh, K [Laboratoire CRISMAT; Simon, C [Institut Laue Langevin; Tung, L D [University of Warwick; Balakrishnan, G [University of Warwick; Hardy, V [Laboratoire CRISMAT
2014-07-01
The orthovanadate DyVO_{3} crystal, known to exhibit multiple structural, spin-, and orbital-ordering transitions, is presently investigated on the basis of magnetization, heat capacity, resistivity, dielectric, and polarization measurements. Our main result is experimental evidence for the existence of multiferroicity below a high T_{C} of 108 K over a wide temperature range including different spin-orbital-ordered states. The onset of ferroelectricity is found to coincide with the antiferromagnetic C-type spin-ordering transition taking place at 108 K, which indicates that DyVO_{3} belongs to type-II multiferroics exhibiting a coupling between magnetism and ferroelectricity. Some anomalies detected on the temperature dependence of electric polarization are discussed with respect to the nature of the spin-orbital-ordered states of the V sublattice and the degree of spin alignment in the Dy sublattice. The orthovanadates RVO_{3} (R= rare earth or Y) form an important new category for searching for high-T_{C} multiferroics.
The gravitational Hamiltonian, first order action, Poincar\\'e charges and surface terms
Corichi, Alejandro
2015-01-01
We consider the issue of attaining a consistent Hamiltonian formulation, after a 3+1 splitting, of a well-defined action principle for asymptotically flat gravity. More precisely, our starting point is the gravitational first order Holst action with surface terms and fall-off conditions that make the variational principle and the covariant phase space formulation well-defined for asymptotically flat spacetimes. Keeping all surface terms and paying due attention to subtleties that arise from the different cut-offs at infinity, we give a derivation of the gravitational Hamiltonian starting from this action. The 3+1 decomposition and time gauge fixing results in a well-defined Hamiltonian action and a well-defined Hamiltonian formulation for the standard -and more general- asymptotic ADM conditions. Unlike the case of the Einstein-Hilbert action with Gibbons-Hawking-York or Hawking-Horowitz terms, here we {\\it {do}} recover the ADM energy-momentum from the covariant surface term also when more general variations...
International Nuclear Information System (INIS)
The crystal structure of the layered cobaltite HoBaCo2O5.5 (substituted with both 16O and 18O) was studied across an insulator to metal (MI) transition at TMI=305 K employing high-resolution neutron diffraction. We have found that the transition at TMI is of the first-order type, accompanied by an abrupt negative change of the unit cell volume (∼0.15%) and melting of the orbital order in the pyramids. The existence of an isotope effect on TMI suggests that the structure changes are caused by the electron delocalization above the transition
Charge Ordering on the (√ × √)R45° Reconstructed Fe3O4 (001) Surface
Mariotto, G.; Jordan, K.; Ceballos, S. F.; Murphy, S.; Berdunov, N.; Shvets, I. V.
2003-12-01
The (001) surface of magnetite has been studied using Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). A clean, octahedrally terminated surface was obtained by a combination of in-situ annealing in an O2 atmosphere, Ar+ ion etching and subsequent annealing in UHV. LEED exhibits a (√ × √)R45° mesh. STM was carried out with probes made from antiferromagnetic MnNi. Atomically resolved images of the octahedrally terminated surface show rows, running along the [110] direction, separated by 6 Å. Along these rows two different atomic scale features are imaged, with a periodicity of 6 Å, as opposed to the 3 Å periodicity of the Fe ions expected for bulk terminated magnetite (001). A model explaining the observed symmetry in terms of charge ordering of the Fe2+ and Fe3+ cations, on the surface octahedral sites, is proposed.
Doping dependence of the charge-density-wave order in HgBa2CuO4+δ
Yu, Biqiong
Following the original discovery of short-range charge-density-wave (CDW) order in the orthorhombic double-layer cuprate YBa2Cu3O6+δ (YBCO) below optimal doping, resonant X-ray scattering measurements have revealed that the simple tetragonal single-layer compound HgBa2CuO4+δ (Hg1201; Tc = 71 K) exhibits short-range CDW order as well. Here we report on the doping dependence of the CDW order in Hg1201 and contrast our results with the extensive data available for YBCO. Work done in collaboration with: W. Tabis, G. Yu, M.J. Veit, N. BarisŬić, M.K. Chan, C.J. Dorow, X. Zhao, M. Greven (University of Minnesota); M. Bluschke, E. Weschke (BESSY, Berlin); T. Kolodziej, I. Bialo, A. Kozlowski (AGH, Krakow); M. Hepting, H. Gretarsson, M. Le Tacon, M. Minola, B. Keimer (MPI, Stuttgart); Ronny Sutarto (CLS, Saskatoon); Y. Li (PKU, Beijing); L. Braicovich, G. Dellea, G. Ghiringhelli (CNR-SPIN, Milano); A. Kreyssig, M. Ramazanoglu, A.I. Goldman (Iowa State University and Ames Lab); T. Schmitt (PSI, Switzerland). We acknowledge the support from US Department of Energy, Office of Basic Energy Sciences.
Fujita, Ryuichi
2014-01-01
We compute the energy flux of the gravitational waves radiated by a particle of mass $\\m$ in circular orbits around a rotating black hole of mass $M$ up to the 11th post-Newtonian order (11PN), i.e. $v^{22}$ beyond the leading Newtonian approximation where $v$ is the orbital velocity of the particle. By comparing the PN results for the energy flux with high precision numerical results in black hole perturbation theory, we find the region of validity in the PN approximation becomes larger with increasing PN orders. If one requires the relative error of the energy flux in the PN approximation to be less than $10^{-5}$, the energy flux at 11PN (4PN) can be used for $v\\lessapprox 0.33$ ($v\\lessapprox 0.13$). The region of validity can be further extended to $v\\lessapprox 0.4$ if one applies a resummation method to the energy flux at 11PN. We then compare the orbital phase during two-year inspiral from the PN results with the high precision numerical results. We find that for late (early) inspirals when $q\\le 0.3$...
Modulation of electronic properties from stacking orders and spin-orbit coupling for 3R-type MoS2
Fan, Xiaofeng; Zheng, W. T.; Kuo, Jer-Lai; Singh, David J.; Sun, C. Q.; Zhu, W.
2016-04-01
Two-dimensional crystals stacked by van der Waals coupling, such as twisted graphene and coupled graphene-BN layers with unusual phenomena have been a focus of research recently. As a typical representative, with the modulation of structural symmetry, stacking orders and spin-orbit coupling, transitional metal dichalcogenides have shown a lot of fascinating properties. Here we reveal the effect of stacking orders with spin-orbit coupling on the electronic properties of few-layer 3R-type MoS2 by first principles methods. We analyze the splitting of states at the top of valence band and the bottom of conduction band, following the change of stacking order. We find that regardless of stacking orders and layers’ number, the spin-up and spin-down channels are evidently separated and can be as a basis for the valley dependent spin polarization. With a model Hamiltonian about the layer’s coupling, the band splitting can be effectively analyzed by the coupling parameters. It is found that the stacking sequences, such as abc and abca, have the stronger nearest-neighbor coupling which imply the popular of periodic abc stacking sequence in natural growth of MoS2.
International Nuclear Information System (INIS)
The interplay between electron-phonon and electron-electron interactions in quasi-one-dimensional systems can give rise to competition and possible coexistence of various symmetry broken ground states like bond-order-wave (BOW), charge-density-wave (CDW) and spin-density-wave (SDW). The halogen-bridged mixed-valence transition-metal linear chain complexes (HMMC or MX chains) is a typical example of such systems. In this and a companion paper, we study the ground states and localized excitations like polarons and excitons in these competing systems using a single band Peierls-Hubbard model and the Bogoliubov-de Gennes formalism. We first focus on configurations of these excitations and number of bound states within the gap in competing BOW and CDW systems as functions of the electron-phonon coupling strength. The lattice relaxation approach to quasi-one-dimensional systems, developed by Su and Yu earlier, has been applied to study the radiative and non-radiative transitions of these excitations. A non-monotonic dependence of the relaxation rate on the coupling strength is predicted from the theory and is mainly due to the emergence of new bound states inside the gap. The possible connection of this effect with photoluminescence experiments is discussed. Similar phenomena may occur in other quasi-one-dimensional systems as well. (author). 28 refs, 13 figs, 1 tab
Nan, Guangjun; Shi, Qiang; Shuai, Zhigang; Li, Zesheng
2011-05-28
The electronic coupling between adjacent molecules is an important parameter for the charge transport properties of organic semiconductors. In a previous paper, a semiclassical generalized nonadiabatic transition state theory was used to investigate the nonperturbative effect of the electronic coupling on the charge transport properties, but it is not applicable at low temperatures due to the presence of high-frequency modes from the intramolecular conjugated carbon-carbon stretching vibrations [G. J. Nan et al., J. Chem. Phys., 2009, 130, 024704]. In the present paper, we apply a quantum charge transfer rate formula based on the imaginary-time flux-flux correlation function without the weak electronic coupling approximation. The imaginary-time flux-flux correlation function is then expressed in terms of the vibrational-mode path average and is evaluated by the path integral approach. All parameters are computed by quantum chemical approaches, and the mobility is obtained by kinetic Monte-Carlo simulation. We evaluate the intra-layer mobility of sexithiophene crystal structures in high- and low-temperature phases for a wide range of temperatures. In the case of strong coupling, the quantum charge transfer rates were found to be significantly smaller than those calculated using the weak electronic coupling approximation, which leads to reduced mobility especially at low temperatures. As a consequence, the mobility becomes less dependent on temperature when the molecular packing leads to strong electronic coupling in some charge transport directions. The temperature-independent charge mobility in organic thin-film transistors from experimental measurements may be explained from the present model with the grain boundaries considered. In addition, we point out that the widely used Marcus equation is invalid in calculating charge carrier transfer rates in sexithiophene crystals. PMID:21503350
Ramkumaar, G. R.; Srinivasan, S.; Bhoopathy, T. J.; Gunasekaran, S.
2012-12-01
The solid phase FT-IR and FT-Raman spectra of zidovudine (AZT) were recorded in the regions 4000-400 and 3500-100 cm-1, respectively. The optimized geometry, frequency and intensity of the vibrational bands of zidovudine were obtained by the Restricted Hartree-Fock (RHF) density functional theory (DFT) with complete relaxation in the potential energy surface using 6-31G(d,p) basis set. The harmonic vibrational frequencies for zidovudine were calculated and the scaled values have been compared with experimental values of FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The harmonic vibrational wave numbers and intensities of vibrational bands of zidovudine with its cation and anion were calculated and compared with the neutral AZT. The DFT calculated HOMO and LUMO energies shows that charge transfer occurs within the molecule. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in AZT.
Energy Technology Data Exchange (ETDEWEB)
Hartung, Johannes; Steinhoff, Jan [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany)
2011-07-01
At the next-to-leading order spin-orbit and spin(a)-spin(b) interaction levels, counted within a post-Newtonian approximation scheme, the complexity of Einstein's general relativity becomes apparent. Due to the nonlinearity of the field equations there appear certain three-body interaction terms in the respective Hamiltonians. In this talk we discuss those gravitational three-body correlations. Afterwards an outline of the derivation of the Hamiltonians mentioned above for arbitrary many compact objects is given. A discussion of the relative strength of the next-to-leading order interaction terms in relation to the leading order ones - via a preliminary analysis of certain special configurations of the three-body system - is provided.
Charge-ordered ferromagnetic phase in La(0.5)Ca(0.5)MnO3.
Loudon, James C; Mathur, Neil D; Midgley, Paul A
Mixed-valent manganites are noted for their unusual magnetic, electronic and structural phase transitions. For example, the La(1-x)Ca(x)MnO(3) phase diagram shows that below transition temperatures in the range 100-260 K, compounds with 0.2 electron microscopy data for La(0.5)Ca(0.5)MnO(3) that shed light on the distribution of these coexisting phases, and uncover an additional, unexpected phase. Using electron holography and Fresnel imaging, we find micrometre-sized ferromagnetic regions spanning several grains coexisting with similar-sized regions with no local magnetization. Holography shows that the ferromagnetic regions have a local magnetization of 3.4 +/- 0.2 Bohr magnetons per Mn atom (the spin-aligned value is 3.5 micro (B) per Mn). We use electron diffraction and dark-field imaging to show that charge order exists in regions with no net magnetization and, surprisingly, can also occur in ferromagnetic regions. PMID:12490944
Charge-ordered ferromagnetic phase in La0.5Ca0.5MnO3
Loudon, James C.; Mathur, Neil D.; Midgley, Paul A.
2002-12-01
Mixed-valent manganites are noted for their unusual magnetic, electronic and structural phase transitions. For example, the La1-xCaxMnO3 phase diagram shows that below transition temperatures in the range 100-260K, compounds with 0.2 electron microscopy data for La0.5Ca0.5MnO3 that shed light on the distribution of these coexisting phases, and uncover an additional, unexpected phase. Using electron holography and Fresnel imaging, we find micrometre-sized ferromagnetic regions spanning several grains coexisting with similar-sized regions with no local magnetization. Holography shows that the ferromagnetic regions have a local magnetization of 3.4 +/- 0.2Bohr magnetons per Mn atom (the spin-aligned value is 3.5µB per Mn). We use electron diffraction and dark-field imaging to show that charge order exists in regions with no net magnetization and, surprisingly, can also occur in ferromagnetic regions.
Energy Technology Data Exchange (ETDEWEB)
Nagasawa, Mitsuharu [Department of Physics, Tokyo Denki University, Tokyo (Japan); Department of Green and Sustainable Chemistry, Tokyo Denki University, Tokyo (Japan); Nagasawa, Tokiko [Department of Green and Sustainable Chemistry, Tokyo Denki University, Tokyo (Japan); Ichimura, Koichi [Division of Applied Physics, Hokkaido University, Sapporo (Japan); Nomura, Kazushige [Division of Physics, Hokkaido University, Sapporo (Japan)
2012-05-15
We measured the electrical conductance along the a-direction {sigma}{sub a} of (TMTTF){sub 2}SbF{sub 6} under anisotropic external pressure P{sub Ec} which is parallel to the c{sup *}-direction. It is expected that P{sub Ec} achieves the uniaxial strain along the c*-direction to the sample. We found that {sigma} a is strongly influenced by applying P{sub Ec} and the charge order (CO) transition temperature T{sub CO} decreases with increasing P{sub Ec}. The tendencies of the P{sub Ec} dependence of {sigma} a and T{sub CO} is different from that of the anisotropic external pressures which are parallel to the a- and the b-directions. We discuss the P{sub Ec} effects on both {sigma}{sub a} and the CO transition. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
DEFF Research Database (Denmark)
Freeman, P.G.; Christensen, Niels Bech; Prabhakaran, D.;
2010-01-01
The temperature dependence of the magnetic order of stripe-ordered La1.725Sr0.275NiO4 is investigated by neutron diffraction. Upon cooling, the widths of the magnetic Bragg peaks are observed to broaden. The degree of broadening is found to be very different for l = odd-integer and l = even......-integer magnetic peaks. We argue that the observed behaviour is a result of competition between magnetic and charge order....
International Nuclear Information System (INIS)
The inspiral of a stellar compact object into a massive black hole, an extreme-mass-ratio inspiral, is one of the main sources of gravitational waves for the future space-based Laser Interferometer Space Antenna. We expect to be able to detect and analyze many cycles of these slowly inspiraling systems, which makes them truly high-precision tools for gravitational-wave astronomy. To that end, the use of very precise theoretical waveform templates in the data analysis is required. To build them, we need to have a deep understanding of the gravitational backreaction mechanism responsible for the inspiral. The self-force approach describes the inspiral as the action of a local force that can be obtained from the regularization of the perturbations created by the stellar compact object on the massive black hole geometry. In this paper we extend a new time-domain technique for the computation of the self-force from the circular case to the case of eccentric orbits around a nonrotating black hole. The main idea behind our scheme is to use a multidomain framework in which the small compact object, described as a particle, is located at the interface between two subdomains. Then, the equations at each subdomain are homogeneous wave-type equations, without distributional sources. In this particle-without-particle formulation, the solution of the equations is smooth enough to provide good convergence properties for the numerical computations. This formulation is implemented by using a pseudospectral collocation method for the spatial discretization, combined with a Runge-Kutta algorithm for the time evolution. We present results from several simulations of eccentric orbits in the case of a scalar charged particle around a Schwarzschild black hole, an excellent test bed model for testing the techniques for self-force computations. In particular, we show the convergence of the method and its ability to resolve the field and its derivatives across the particle location. Finally
Structural and morphological changes associated with charge ordering in La0.2Ca0.8MnO3
International Nuclear Information System (INIS)
Both structural and morphological changes associated with charge ordering in perovskite manganese oxide, La0.2Ca0.8MnO3, were studied by electron microscopic observations with imaging plates. Two types of long-period structures were observed at around 107 K, i.e., the structure with about 4-fold periodicity to the unit lattice distance of the room-temperature phase and the structure with much larger periodicity such as 23-fold. These long-period structures were suggested to be formed by a similar mechanism due to charge ordering of manganese ions, since they showed some crystallographic and morphological similarities. Superlattice reflections of a near 4-fold structure were observed as a function of temperature. They were found to become weak diffuse scattering just before the disappearance, and the peak positions moved slightly with heating. Considering those features, the kinetics of the charge ordering in this oxide was discussed
Antiferromagnetic resonance in charge ordering state of Pr0.5Ca0.5MnO3-δ single crystal
International Nuclear Information System (INIS)
An antiferromagnetic resonance (AFMR) is observed in the charge ordered antiferromagnetic phase of Pr0.5Ca0.5MnO3-δ single crystal for the first time. Above the Neel temperature, TN=173 K, a paramagnetic resonance with g=2.0 is observed. There is no significant change of the resonance spectra at the charge ordering transition temperature, TCO=242 K. Below TN, a branch of AFMR is found. Since the resonance field of this mode increases linearly as the frequency is decreased, this branch is assigned as the spin-flop mode. Below 60 K, the critical fields, BC, evaluated as the extrapolation of this mode to zero frequency agree well with the insulator-metal transition fields, BCO, at which the melting of the charge-ordering phase occurs. Present results indicate that the temperature dependence of BCO is affected by the temperature dependence of BC
Antiferromagnetic resonance in charge ordering state of Pr 0.5Ca 0.5MnO 3- δ single crystal
Kawamata, S.; Noguchi, S.; Okuda, K.; Nojiri, H.; Motokawa, M.
2001-05-01
An antiferromagnetic resonance (AFMR) is observed in the charge ordered antiferromagnetic phase of Pr 0.5Ca 0.5MnO 3- δ single crystal for the first time. Above the Néel temperature, TN=173 K, a paramagnetic resonance with g=2.0 is observed. There is no significant change of the resonance spectra at the charge ordering transition temperature, TCO=242 K. Below TN, a branch of AFMR is found. Since the resonance field of this mode increases linearly as the frequency is decreased, this branch is assigned as the spin-flop mode. Below 60 K, the critical fields, BC, evaluated as the extrapolation of this mode to zero frequency agree well with the insulator-metal transition fields, BCO, at which the melting of the charge-ordering phase occurs. Present results indicate that the temperature dependence of BCO is affected by the temperature dependence of BC.
Czech Academy of Sciences Publication Activity Database
Cooper, D.L.; Ponec, Robert; Kohout, M.
2015-01-01
Roč. 113, 13-14 (2015), s. 1682-1689. ISSN 0026-8976 Institutional support: RVO:67985858 Keywords : domain averaged fermi holes * shared electron-distribution indices * Cioslowski covalent bond orders Subject RIV: CC - Organic Chemistry Impact factor: 1.720, year: 2014
Institute of Scientific and Technical Information of China (English)
Zhonghua Hao(郝中华); Jinsong Liu(刘劲松)
2003-01-01
Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.
Saltzman, Barry
1992-01-01
The development of a theory of the evolution of the climate of the earth over millions of years can be subdivided into three fundamental, nested, problems: (1) to establish by equilibrium climate models (e.g., general circulation models) the diagnostic relations, valid at any time, between the fast-response climate variables (i.e., the 'weather statistics') and both the prescribed external radiative forcing and the prescribed distribution of the slow response variables (e.g., the ice sheets and shelves, the deep ocean state, and the atmospheric CO2 concentration); (2) to construct, by an essentially inductive process, a model of the time-dependent evolution of the slow-response climatic variables over time scales longer than the damping times of these variables but shorter than the time scale of tectonic changes in the boundary conditions (e.g., altered geography and elevation of the continents, slow outgassing, and weathering) and ultra-slow astronomical changes such as in the solar radiative output; and (3) to determine the nature of these ultra-slow processes and their effects on the evolution of the equilibrium state of the climatic system about which the above time-dependent variations occur. All three problems are discussed in the context of the theory of the Quaternary climate, which will be incomplete unless it is embedded in a more general theory for the fuller Cenozoic that can accommodate the onset of the ice-age fluctuations. We construct a simple mathematical model for the Late Cenozoic climatic changes based on the hypothesis that forced and free variations of the concentration of atmospheric greenhouse gases (notably CO2), coupled with changes in the deep ocean state and ice mass, under the additional 'pacemaking' influence of earth-orbital forcing, are primary determinants of the climate state over this period. Our goal is to illustrate how a single model governing both very long term variations and higher frequency oscillatory variations in the
Colossal thermoelectric power in charge ordered lanthanum calcium manganites (La0.5Ca0.5MnO3)
International Nuclear Information System (INIS)
Lanthanum calcium manganites (La0.5Ca0.5MnO3) with a composition close to charge ordering, synthesized by high energy ball milling, was found to exhibit colossal thermoelectric power. Thermoelectric power (TEP) data was systematically analyzed by dividing the entire temperature range (5 K–300 K) into three different regimes to explore different scattering mechanisms involved. Mandal's model has been applied to explain TEP data in the region below the Curie temperature (TC). It has been found that the variation of thermoelectric power with temperature is pronounced when the system enters the charge ordered region at T < 200 K. For temperatures lower than 120 K, due to the co-existence of charge ordered state with a spin-glass state, the variation of thermoelectric power is maximum and exhibited a peak value of −80 mV/K at 58 K. This has been explained by incorporating Kondo properties of the spin-glass along with magnon scattering. FC-ZFC magnetization measurements indicate the existence of a glassy state in the region corresponding to a maximum value of thermoelectric power. Phonon drag contribution instead of spin-glass contribution is taken into account to explain TEP in the region 120 K < T < TC. Mott's polaronic contribution of charge carriers are considered to interpret TEP in the high temperature region (T > TC). The optimal Mn4+-Mn3+ concentration in charge ordered La0.5Ca0.5MnO3 was examined by X-ray Photoelectron Spectroscopy analysis which confirms the charge ordered nature of this compound
Energy Technology Data Exchange (ETDEWEB)
Joy, Lija K.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India); Shanmukharao Samatham, S.; Ganesan, V. [Low temperature division, UGC-DAE Consortium for Scientific Research, Indore (India); Thomas, Senoy [Material Science and Technology Division, National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram–695019 (India); Al-Harthi, Salim [Department of Physics, Sultan Qaboos University, Muscat PC 123, Sultanate of Oman (Oman); Liebig, A.; Albrecht, M. [Institute of Physics, University of Augsburg, Augsburg 86135 (Germany)
2014-12-07
Lanthanum calcium manganites (La{sub 0.5}Ca{sub 0.5}MnO{sub 3}) with a composition close to charge ordering, synthesized by high energy ball milling, was found to exhibit colossal thermoelectric power. Thermoelectric power (TEP) data was systematically analyzed by dividing the entire temperature range (5 K–300 K) into three different regimes to explore different scattering mechanisms involved. Mandal's model has been applied to explain TEP data in the region below the Curie temperature (T{sub C}). It has been found that the variation of thermoelectric power with temperature is pronounced when the system enters the charge ordered region at T < 200 K. For temperatures lower than 120 K, due to the co-existence of charge ordered state with a spin-glass state, the variation of thermoelectric power is maximum and exhibited a peak value of −80 mV/K at 58 K. This has been explained by incorporating Kondo properties of the spin-glass along with magnon scattering. FC-ZFC magnetization measurements indicate the existence of a glassy state in the region corresponding to a maximum value of thermoelectric power. Phonon drag contribution instead of spin-glass contribution is taken into account to explain TEP in the region 120 K < T < T{sub C}. Mott's polaronic contribution of charge carriers are considered to interpret TEP in the high temperature region (T > T{sub C}). The optimal Mn{sup 4+}-Mn{sup 3+} concentration in charge ordered La{sub 0.5}Ca{sub 0.5}MnO{sub 3} was examined by X-ray Photoelectron Spectroscopy analysis which confirms the charge ordered nature of this compound.
Spin dynamics and charge order-disorder phase transition detected by EPR in α'-(BEDT-TTF)2IBr2
Dmitriev, A.; Chernenkaya, A.
2010-01-01
Stepwise changes in electron paramagnetic resonance (EPR) parameters (integral intensity, linewidth) accompanying localization of charge carriers have been found in the α'-(BEDT-TTF)2IBr2 crystals. In single crystal exchange narrowing of the EPR lines and sharp decrease in static and dynamic magnetic susceptibility caused by antiferromagnetic interaction of localized charge carriers is observed at Т Т > 50 K a difference between static and dynamic magnetic susceptibility is observed in the...
Mol’kov, S.; Savin, V.
2013-01-01
The Influence of surface processes of dust particles on the value of their charge is considered. The charge, defined by the parameters of nonperturbed plasma, significantly depends on the electron emission from the dust particle surface. Secondary electron emission, electron-ion emission, thermoand photoelectron emission were considered. It is shown that thermoemission is directly stipulated by the heat exchange between the surface of the particle and plasma components. Conditions in which th...
Papoulia, A.; Carlsson, B. G.; Ekman, J
2016-01-01
Background: Atomic spectral lines from different isotopes display a small shift in energy, commonly referred to as the line isotope shift. One of the components of the isotope shift is the field shift, which depends on the extent and the shape of the nuclear charge density distribution. Purpose: To investigate how sensitive field shifts are with respect to variations in the nuclear size and shape and what information of nuclear charge distributions that can be extracted from measured field sh...
Andrade-Ines, Eduardo; Michtchenko, Tatiana; Robutel, Philippe
2015-01-01
We analyse the secular dynamics of planets on S-type coplanar orbits in tight binary systems, based on first- and second-order analytical models, and compare their predictions with full N-body simulations. The perturbation parameter adopted for the development of these models depends on the masses of the stars and on the semimajor axis ratio between the planet and the binary. We show that each model has both advantages and limitations. While the first-order analytical model is algebraically simple and easy to implement, it is only applicable in regions of the parameter space where the perturbations are sufficiently small. The second-order model, although more complex, has a larger range of validity and must be taken into account for dynamical studies of some real exoplanetary systems such as $\\gamma$-Cephei and HD 41004A. However, in some extreme cases, neither of these analytical models yields quantitatively correct results, requiring either higher-order theories or direct numerical simulations. Finally, we ...
Ultrafast Mid-infrared Spectroscopy of the Charge- and Spin-Ordered Nickelate La1.75Sr0.25NiO4
Directory of Open Access Journals (Sweden)
Shen Z.-X.
2013-03-01
Full Text Available We present the first ultrafast mid-infrared study of charge and spin-ordered nickelates. A sub-picosecond modulation of the optical reflectivity is observed, indicating the filling and subsequent re-establishment of the pseudogap in the time-domain.
Energy Technology Data Exchange (ETDEWEB)
Grabowski, Ireneusz, E-mail: ig@fizyka.umk.pl; Śmiga, Szymon; Buksztel, Adam [Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun (Poland); Fabiano, Eduardo [National Nanotechnology Laboratory, Istituto Nanoscienze–CNR, Via per Arnesano, I-73100 Lecce (Italy); Teale, Andrew M. [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo (Norway); Sala, Fabio Della [National Nanotechnology Laboratory, Istituto Nanoscienze–CNR, Via per Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies @UNILE, Istituto Italiano di Tecnologia (IIT), Via Barsanti, 73010 Arnesano (LE) (Italy)
2014-07-14
The performance of correlated optimized effective potential (OEP) functionals based on the spin-resolved second-order correlation energy is analysed. The relative importance of singly- and doubly- excited contributions as well as the effect of scaling the same- and opposite- spin components is investigated in detail comparing OEP results with Kohn–Sham (KS) quantities determined via an inversion procedure using accurate ab initio electronic densities. Special attention is dedicated in particular to the recently proposed scaled-opposite–spin OEP functional [I. Grabowski, E. Fabiano, and F. Della Sala, Phys. Rev. B 87, 075103 (2013)] which is the most advantageous from a computational point of view. We find that for high accuracy, a careful, system dependent, selection of the scaling coefficient is required. We analyse several size-extensive approaches for this selection. Finally, we find that a composite approach, named OEP2-SOSh, based on a post-SCF rescaling of the correlation energy can yield high accuracy for many properties, being comparable with the most accurate OEP procedures previously reported in the literature but at substantially reduced computational effort.
Energy Technology Data Exchange (ETDEWEB)
MacLaren, Ian; Wang, LiQiu; McGrouther, Damien; Craven, Alan J.; McVitie, Stephen [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Schierholz, Roland [Institute of Energy and Climate Research: Fundamental Electrochemistry (IEK-9), Forschungszentrum Jülich, 52425 Jülich (Germany); Kovács, András [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen (Germany); Dunin-Borkowski, Rafal E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) and Peter Grünberg Institute (PGI), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany)
2015-07-15
Differential phase contrast (DPC) imaging in the scanning transmission electron microscope is applied to the study of a charged antiphase domain boundary in doped bismuth ferrite. A clear differential signal is seen, which matches the expected direction of the electric field at the boundary. However, further study by scanned diffraction reveals that there is no measurable deflection of the primary diffraction disc and hence no significant free E-field in the material. Instead, the DPC signal arises from a modulation of the intensity profile within the primary diffraction disc in the vicinity of the boundary. Simulations are used to show that this modulation arises purely from the local change in crystallographic structure at the boundary and not from an electric field. This study highlights the care that is required when interpreting signals recorded from ferroelectric materials using both DPC imaging and other phase contrast techniques. - Highlights: • We show clear differential phase contrast (DPC) at a charged boundary. • Scanning diffraction shows that the discs do not move. • Disc deflection by electric fields is not the source of the DPC signal. • Diffraction contrast within the disc is the source of the DPC signal. • DPC and holography of E fields is difficult due to diffraction contrast.
International Nuclear Information System (INIS)
Differential phase contrast (DPC) imaging in the scanning transmission electron microscope is applied to the study of a charged antiphase domain boundary in doped bismuth ferrite. A clear differential signal is seen, which matches the expected direction of the electric field at the boundary. However, further study by scanned diffraction reveals that there is no measurable deflection of the primary diffraction disc and hence no significant free E-field in the material. Instead, the DPC signal arises from a modulation of the intensity profile within the primary diffraction disc in the vicinity of the boundary. Simulations are used to show that this modulation arises purely from the local change in crystallographic structure at the boundary and not from an electric field. This study highlights the care that is required when interpreting signals recorded from ferroelectric materials using both DPC imaging and other phase contrast techniques. - Highlights: • We show clear differential phase contrast (DPC) at a charged boundary. • Scanning diffraction shows that the discs do not move. • Disc deflection by electric fields is not the source of the DPC signal. • Diffraction contrast within the disc is the source of the DPC signal. • DPC and holography of E fields is difficult due to diffraction contrast
Energy Technology Data Exchange (ETDEWEB)
Bergshoeff, Eric A., E-mail: E.A.Bergshoeff@rug.nl [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Marrani, Alessio, E-mail: Alessio.Marrani@cern.ch [Physics Department, Theory Unit, CERN, CH-1211, Geneva 23 (Switzerland); Riccioni, Fabio, E-mail: Fabio.Riccioni@roma1.infn.it [INFN Sezione di Roma, Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Piazzale Aldo Moro 2, 00185 Roma (Italy)
2012-08-01
We complete the classification of half-supersymmetric branes in toroidally compactified IIA/IIB string theory in terms of representations of the T-duality group. As a by-product we derive a last wrapping rule for the space-filling branes. We find examples of T-duality representations of branes in lower dimensions, suggested by supergravity, of which none of the component branes follow from the reduction of any brane in ten-dimensional IIA/IIB string theory. We discuss the constraints on the charges of half-supersymmetric branes, determining the corresponding T-duality and U-duality orbits.
Wakabayashi, Y.; Bizen, D.; Kubo, Y; Nakao, H; Murakami, Y.; Nakamura, M.; Ogimoto, Y.; Miyano, K.; Sawa, H.
2007-01-01
Structural study of orbital-ordered manganite thin films has been conducted using synchrotron radiation, and a ground state electronic phase diagram is made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3 (NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or [(LaAlO3){0.3}(SrAl0.5Ta0.5O3){0.7}] (LSAT), were measured as a function of temperature. The result shows, as expected based on previous knowledge of bulk materials, that the films' resistivity is close...
Jeon, Seokmin; Maksymovych, Petro
In contrast to the vast effort on bulk crystal phases of the prototypical organic charge-transfer complex, TTF-TCNQ, study of low-dimensional phases has been limited to monolayer phases on substrates. In this state, however, none of the physics of the bulk phase is observed owing to the overwhelming effect of the substrate. We investigate the molecular structure and electronic properties of a few layers of TTF-TCNQ grown on Au(111) and Ag(111) using STM/STS at 4.3 K. By decoupling the molecular electronic state from the metal surface, we have made the first observation of the effect of confinement on the electronic properties of TTF-TCNQ. STS reveals a plethora of sharp features due to molecular orbitals, each influenced by charge-transfer between the molecules. We hypothesize the existence of a Mott-insulator state in 3-layer islands, with a Coulomb gap of ~1 eV. In contrast, the corresponding bulk phase is a Peierls insulator with a gap of ~20 meV. The root cause of the nanoscale phase is traced to simultaneous electron confinement and structural frustration, which dramatically modify the energy balance of self-ionization allowing for integer charge transfer. These studies open broad opportunities to explore correlated electron physics in molecular systems. This research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.
Energy Technology Data Exchange (ETDEWEB)
Pompa, M.; Turtu, S.; Campanella, F.; Pettiti, I.; Udron, D. (INFM, Dipt. di Fisica, Rome-1 Univ. (Italy)); Bianconi, A. (INFM, Dipt. di Fisica, Rome-1 Univ. (Italy) Univ. of L' Aquila (Italy)); Flank, A.M.; Lagarde, P. (LURE, 91 - Orsay (France)); Li, C. (Inst. of Physics, Academia Sinica, Beijing (China))
1991-12-01
The change of the orbital angular momentum m{sub l} of the Cu 3d holes going from the insulating to the metallic phase has been studied in several families of high Tc superconductors. The symmetry of the 3d{sup 9}L states in the metallic phase has been studied by quantitative analysis of the variation of polarized Cu L{sub 3} X-ray absorption spectra. At a doping level n{sub h} {approx equal} 15% we have found 10% of Zhang-Rice singlets 3d{sub x}2{sub -y}2 L(b{sub 1}) and 5% of 3d{sub 3z}2{sub -r}2L(a{sub 1}) states. Therefore the percentage of the 3d{sub 3z}2{sub -r}2L states on the total number of the 3d{sup 9}L states is about 30% i.e. much larger than the probability of single hole states 3d{sub 3z}2{sub -r}2 in the insulating phase. The EXAFS and XANES studies of the Cu site structure and dynamics in Bi{sub 2}Sr{sub 2}Ca{sub 1-x}Y{sub x}Cu{sub 2}O{sub {proportional to}} {sub 8} system point toward the coupling of the charge carriers with distortions of the Cu sites driven by the m{sub l}=0 character of the Cu 3d holes that can be called a 3d{sub z}2{sub -r}2 polaron. (orig.).
Spin-induced symmetry breaking in orbitally ordered NiCr2O4 and CuCr2O4
Suchomel, Matthew R.; Shoemaker, Daniel P.; Ribaud, Lynn; Kemei, Moureen C.; Seshadri, Ram
2012-08-01
At room temperature, the normal oxide spinels NiCr2O4 and CuCr2O4 are tetragonally distorted and crystallize in the I41/amd space group due to cooperative Jahn-Teller ordering driven by the orbital degeneracy of tetrahedral Ni2+ (t24) and Cu2+ (t25). Upon cooling, these compounds undergo magnetic ordering transitions; interactions are somewhat frustrated for NiCr2O4 but not for CuCr2O4. We employ variable-temperature high-resolution synchrotron x-ray powder diffraction to establish that at the magnetic ordering temperatures there are further structural changes, which result in both compounds distorting to an orthorhombic structure consistent with the Fddd space group. NiCr2O4 exhibits additional distortion, likely within the same space group, at a yet-lower transition temperature of T=30 K. The tetragonal to orthorhombic structural transition in these compounds appears to primarily involve changes in NiO4 and CuO4 tetrahedra.
Xiang-Gruess, M
2015-01-01
In order to study the origin of the architectures of low mass planetary systems, we perform numerical surveys of the evolution of pairs of coplanar planets in the mass range $(1-4)\\ \\rmn{M}_{\\oplus}.$ These evolve for up to $2\\times10^7 \\rmn{yr}$ under a range of orbital migration torques and circularization rates assumed to arise through interaction with a protoplanetary disc. Near the inner disc boundary, significant variations of viscosity, interaction with density waves or with the stellar magnetic field could occur and halt migration, but allow ircularization to continue. This was modelled by modifying the migration and circularization rates. Runs terminated without an extended period of circularization in the absence of migration torques gave rise to either a collision, or a system close to a resonance. These were mostly first order with a few $\\%$ terminating in second order resonances. Both planetary eccentricities were small $< 0.1$ and all resonant angles liberated. This type of survey produced o...
Papoulia, A; Ekman, J
2016-01-01
Background: Atomic spectral lines from different isotopes display a small shift in energy, commonly referred to as the line isotope shift. One of the components of the isotope shift is the field shift, which depends on the extent and the shape of the nuclear charge density distribution. Purpose: To investigate how sensitive field shifts are with respect to variations in the nuclear size and shape and what information of nuclear charge distributions that can be extracted from measured field shifts. Methods: Nuclear properties are obtained from nuclear density functional theory calculations based on the Skyrme-Hartree-Fock-Bogoliubov approach. These results are combined with multiconfiguration Dirac-Hartree-Fock methods to obtain realistic field shifts. Results: Phenomena such as nuclear deformation and variations in the diffuseness of nuclear charge distributions give measurable contributions to the field shifts. Using a novel approach, we demonstrate the possibility to extract new information concerning the n...
Energy Technology Data Exchange (ETDEWEB)
Maurice, Rémi, E-mail: remi.maurice@subatech.in2p3.fr; Montavon, Gilles [SUBATECH, CNRS UMR 6457, IN2P3/EMN Nantes/Université de Nantes, 4 rue Alfred Kastler, BP 20722, 44307 Nantes Cedex 3 (France); Réal, Florent; Gomes, André Severo Pereira; Vallet, Valérie [Laboratoire PhLAM, CNRS UMR 8523, Université de Lille, 59655 Villeneuve d’Ascq Cedex (France); Galland, Nicolas [CEISAM, UMR CNRS 6230, Université de Nantes, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3 (France)
2015-03-07
The nature of chemical bonds in heavy main-group diatomics is discussed from the viewpoint of effective bond orders, which are computed from spin–orbit wave functions resulting from spin–orbit configuration interaction calculations. The reliability of the relativistic correlated wave functions obtained in such two-step spin–orbit coupling frameworks is assessed by benchmark studies of the spectroscopic constants with respect to either experimental data, or state-of-the-art fully relativistic correlated calculations. The I{sub 2}, At{sub 2}, IO{sup +}, and AtO{sup +} species are considered, and differences and similarities between the astatine and iodine elements are highlighted. In particular, we demonstrate that spin–orbit coupling weakens the covalent character of the bond in At{sub 2} even more than electron correlation, making the consideration of spin–orbit coupling compulsory for discussing chemical bonding in heavy (6p) main group element systems.
International Nuclear Information System (INIS)
The performance of π-conjugated polymer based electronic devices is directly governed by the molecular morphology of polymer aggregation, the extent to which a molecule is electronically coupled (self ordered and interacted) to neighboring molecules, and orientation. The well electronic coupled and crystalline/ordered polymer films have the potential to enhance the charge transport properties up to a benchmark. However, there is insufficient knowledge about the direct formation of large area, oriented, crystalline, and smooth films. In this study, we have presented Langmuir Schaefer technique to obtain the large area, oriented, crystalline, and smooth film of Poly (3,3‴-dialkylquarterthiophene) (PQT-12) polymer. The effect of self ordering and orientation of PQT-12 polymer on optical, morphological, and charge transport properties has been investigated. The prepared films have been characterized by UV-vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), selected area diffractions pattern (SAED), and atomic force microscopy (AFM) techniques. UV-vis spectra, TEM, SAED, and AFM images of monolayer films reveal the formation of well ordered and electronically coupled polymer domains. Layer by layer deposited films reveal the change in the orientation, which is confirmed by Raman spectra. Electronic properties and layer dependent charge transport properties are investigated using sandwiched structure Al/PQT-12/ITO Schottky configuration with perpendicular to the deposited films. It is observed that the charge transport properties and device electronic parameters (ideality factor and turn on voltage) are significantly changing with increasing the number of PQT-12 layers. Our study also demonstrates the charge transport between polymer crystallites and cause of deviation of ideal behavior of organic Schottky diodes. It may be further explored for improving the performance of other organic and optoelectronic devices
Energy Technology Data Exchange (ETDEWEB)
Pandey, Rajiv K.; Singh, Arun Kumar; Upadhyay, C.; Prakash, Rajiv, E-mail: rprakash.mst@itbhu.ac.in [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)
2014-09-07
The performance of π-conjugated polymer based electronic devices is directly governed by the molecular morphology of polymer aggregation, the extent to which a molecule is electronically coupled (self ordered and interacted) to neighboring molecules, and orientation. The well electronic coupled and crystalline/ordered polymer films have the potential to enhance the charge transport properties up to a benchmark. However, there is insufficient knowledge about the direct formation of large area, oriented, crystalline, and smooth films. In this study, we have presented Langmuir Schaefer technique to obtain the large area, oriented, crystalline, and smooth film of Poly (3,3‴-dialkylquarterthiophene) (PQT-12) polymer. The effect of self ordering and orientation of PQT-12 polymer on optical, morphological, and charge transport properties has been investigated. The prepared films have been characterized by UV-vis spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), selected area diffractions pattern (SAED), and atomic force microscopy (AFM) techniques. UV-vis spectra, TEM, SAED, and AFM images of monolayer films reveal the formation of well ordered and electronically coupled polymer domains. Layer by layer deposited films reveal the change in the orientation, which is confirmed by Raman spectra. Electronic properties and layer dependent charge transport properties are investigated using sandwiched structure Al/PQT-12/ITO Schottky configuration with perpendicular to the deposited films. It is observed that the charge transport properties and device electronic parameters (ideality factor and turn on voltage) are significantly changing with increasing the number of PQT-12 layers. Our study also demonstrates the charge transport between polymer crystallites and cause of deviation of ideal behavior of organic Schottky diodes. It may be further explored for improving the performance of other organic and optoelectronic devices.
International Nuclear Information System (INIS)
Molière’s series functions of higher orders describing angular distributions of charged particle under the multiple scattering process are solved by exactly evaluating Cauchy integral with poles within the contour of integration. The functions of Molière’s series giving higher-order terms are evaluated accurately by Poisson series expansion, both for spatial and projected angular distributions. Molière’s series for the integrated angular distributions are also derived. Accuracy of the Molière’s series expansion of higher orders is examined by comparing the reconstructed angular distributions with those derived exactly through the numerical Hankel transforms
Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Greg; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas
2014-09-01
Spatial Domain Multiplexing/Space Division Multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single mode pigtail laser sources of same wavelength into a carrier fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. In this endeavor we launch light from five different single mode pigtail laser sources at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation we get five distinct concentric donut shaped rings with negligible crosstalk at the output end of the fiber. These SDM channels also exhibit Orbital Angular Momentum (OAM), thereby adding an extra degree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.
Neutron scattering study of charge-ordering in R1/3Sr2/3FeO3 (R=La, Pr, Nd, Sm, and Y)
International Nuclear Information System (INIS)
The complicated physical phenomena in complex transition-metal oxides (TMO), such as high Tc superconductivity, colossal magnetoresistivity, metal-insulator transitions, etc., have long been the focus of intense inquiry and debate in condensed matter science, since they are related to strong electronic correlations and cannot be explained within the 'standard model' of solid state physics. These novel functionalities of the correlated electron systems have a wide range of potential for applications in industry, such as information storage, energy transportation, and so on. The charge-ordering (CO) transition is very common in TMO and there is a specific CO transition temperature, TCO. Above TCO, the charge is not ordered, which means that the electrons in a compound are itinerant and the positions of the electrons are not fixed. Below TCO, the charge is ordered, which means that the electrons are localized and the positions of the electrons are settled. Hence, the electrical conductivity of a material is changed at TCO and this transition is classified as metal-insulator transition. Usually the CO with commensurate hole doping in TMO is thought to play an important role in various cases, including the superconducting cuprates, where the spin/charge stripe formation competes with superconducting states, colossal magnetoresistive manganites, where CO competes with ferromagnetic metallic state stabilized by an external magnetic field, layered nickelates, where CO takes the form of the small polaron lattices, and layered manganites, where CO could be bothered by the correlated dynamics of spins and charges. Therefore understanding the causes and implications of CO phenomena is significantly important.
Neutron scattering study of charge-ordering in R1/3Sr2/3FeO3 (R=La, Pr, Nd, Sm, and Y)
Energy Technology Data Exchange (ETDEWEB)
Ma, Jie
2010-05-16
The complicated physical phenomena in complex transition-metal oxides (TMO), such as high Tc superconductivity, colossal magnetoresistivity, metal-insulator transitions, etc., have long been the focus of intense inquiry and debate in condensed matter science, since they are related to strong electronic correlations and cannot be explained within the 'standard model' of solid state physics. These novel functionalities of the correlated electron systems have a wide range of potential for applications in industry, such as information storage, energy transportation, and so on. The charge-ordering (CO) transition is very common in TMO and there is a specific CO transition temperature, TCO. Above TCO, the charge is not ordered, which means that the electrons in a compound are itinerant and the positions of the electrons are not fixed. Below TCO, the charge is ordered, which means that the electrons are localized and the positions of the electrons are settled. Hence, the electrical conductivity of a material is changed at TCO and this transition is classified as metal-insulator transition. Usually the CO with commensurate hole doping in TMO is thought to play an important role in various cases, including the superconducting cuprates, where the spin/charge stripe formation competes with superconducting states, colossal magnetoresistive manganites, where CO competes with ferromagnetic metallic state stabilized by an external magnetic field, layered nickelates, where CO takes the form of the small polaron lattices, and layered manganites, where CO could be bothered by the correlated dynamics of spins and charges. Therefore understanding the causes and implications of CO phenomena is significantly important.
Neutron scattering study of charge-ordering in R1/3Sr2/3FeO3 (R=La, Pr, Nd, Sm, and Y)
Energy Technology Data Exchange (ETDEWEB)
Ma, Jie [Iowa State Univ., Ames, IA (United States)
2010-01-01
The complicated physical phenomena in complex transition-metal oxides (TMO), such as high T_{c} superconductivity, colossal magnetoresistivity, metal-insulator transitions, etc., have long been the focus of intense inquiry and debate in condensed matter science, since they are related to strong electronic correlations and cannot be explained within the 'standard model' of solid state physics. These novel functionalities of the correlated electron systems have a wide range of potential for applications in industry, such as information storage, energy transportation, and so on. The charge-ordering (CO) transition is very common in TMO and there is a specific CO transition temperature, TCO. Above TCO, the charge is not ordered, which means that the electrons in a compound are itinerant and the positions of the electrons are not fixed. Below TCO, the charge is ordered, which means that the electrons are localized and the positions of the electrons are settled. Hence, the electrical conductivity of a material is changed at TCO and this transition is classified as metal-insulator transition. Usually the CO with commensurate hole doping in TMO is thought to play an important role in various cases, including the superconducting cuprates, where the spin/charge stripe formation competes with superconducting states, colossal magnetoresistive manganites, where CO competes with ferromagnetic metallic state stabilized by an external magnetic field, layered nickelates, where CO takes the form of the small polaron lattices, and layered manganites, where CO could be bothered by the correlated dynamics of spins and charges. Therefore understanding the causes and implications of CO phenomena is significantly important.
Nature of the magnetic order in the charge-ordered cuprate La1.48Nd0.4Sr0.12CuO4
DEFF Research Database (Denmark)
Christensen, Niels Bech; Rønnow, H.M.; Mesot, J.; Ewings, R.A.; Momono, N.; Oda, M.; Ido, M.; Enderle, M.; McMorrow, D.F.; Boothroyd, A.T.
2007-01-01
Using polarized neutron scattering we establish that the magnetic order in La1.48Nd0.4Sr0.12CuO4 is either (i) one dimensionally modulated and collinear, consistent with the stripe model or (ii) two dimensionally modulated with a novel noncollinear structure. The measurements rule out a number of...
International Nuclear Information System (INIS)
Structural, transport and optical properties of nano-crystalline Pr0.6Ca0.4MnO3 have been investigated to emphasize on the semiconducting properties of charge-ordered manganite. Rietveld refinement of X-ray diffraction pattern of Pr0.6Ca0.4MnO3 nanoparticles show that due to increase in sintering temperature, MnO6 octahedra elongated along z-direction and compressed in x-y plane. Both Mn–O–Mn angles are found to decrease with increasing sintering temperature. Fourier transform infrared (FTIR) spectroscopy measurements reveal that the stretching and bending vibration of Mn–O–Mn is responsible for the change in Mn–O–Mn bond length and bond angle respectively. With increasing sintering temperature, these vibrations tend to increase, which resulted in the further distortion of MnO6 octahedra. Magnetic measurements suggest that charge ordering is established and system becomes antiferromagnetic with increasing particle size. Resistivity behavior of Pr0.6Ca0.4MnO3 nanoparticles clearly exhibit semiconducting nature of these systems, which is due to the formation of charge-ordered state of Mn3+ and Mn4+. Estimated optical band-gap of ∼3.7 eV for Pr0.6Ca0.4MnO3 nanocrystals, makes it a potential candidate for wide band-gap magnetic semiconductors. - Highlights: • Pr0.6Ca0.4MnO3 nanoparticles have been synthesized via sol–gel route. • Optical properties of charge-ordered Pr0.6Ca0.4MnO3 have been investigated. • Pr0.6Ca0.4MnO3 nanoparticles exhibit wide band-gap (3.7 eV) semiconducting nature. • Potential candidate for wide band-gap magnetic semiconductor device applications
Magnetic and electrical studies on La0.4Sm0.1Ca0.5MnO3 charge ordered manganite
International Nuclear Information System (INIS)
We have reported in this work the effect of the partial substitution of lanthanum by samarium on the structural, electrical and magnetic properties of La0.5Ca0.5MnO3. The magnetic study indicated that substitution promotes charge ordering and weakens ferromagnetism. Below TC=123 K, the compound La0.4Sm0.1Ca0.5MnO3 is a mixture of ferromagnetic and charge ordered antiferromagnetic domains. Between TC and TCO=215 K, the structure is paramagnetic with the presence of antiferromagnetic domains. The fractions of the coexisting magnetic phases are highly dependent on the applied magnetic field value. Resistivity measurements reveal the presence of an insulating-metal transition at Tρ=123 K. The equality between TC and Tρ indicates the presence of a correlation between magnetization and resistivity. For only 1 T applied field, we have reported a colossal value of magnetoresistance reaching 73% around TC. The origin of this high value is attributed to phase separation phenomenon. - Highlights: • Sm doping enhances charge ordering and weakens ferromagnetism in La0.5Ca0.5MnO3. • Colossal magnetoresistance (73%) is recorded at 123 K for only 1 T applied field. • Phase separation is responsible for the magnetic and the magnetoresistive behavior
Energy Technology Data Exchange (ETDEWEB)
Yang, I. K.; Jeong, Y. H., E-mail: yhj@postech.ac.kr [Department of Physics, POSTECH, 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Kim, Jeehoon [Department of Physics, POSTECH, 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); CALDES, Institute of Basic Science, 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Lee, S. H. [YE Team, Samsung Electronics, 1 Samsungjeonja-Ro, Hwaseong 445-330 (Korea, Republic of); Cheong, S.-W. [Laboratory of Pohang Emergent Materials, POSTECH, 77 Cheongam-Ro, Pohang 790-784 (Korea, Republic of); Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)
2015-04-13
LuFe{sub 2}O{sub 4} is a multiferroic system which exhibits charge order, ferroelectricity, and ferrimagnetism simultaneously below ∼230 K. The ferroelectric/charge order domains of LuFe{sub 2}O{sub 4} are imaged with both piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM), while the magnetic domains are characterized by magnetic force microscopy (MFM). Comparison of PFM and EFM results suggests that the proposed ferroelectricity in LuFe{sub 2}O{sub 4} is not of usual displacive type but of electronic origin. Simultaneous characterization of ferroelectric/charge order and magnetic domains by EFM and MFM, respectively, on the same surface of LuFe{sub 2}O{sub 4} reveals that both domains have irregular patterns of similar shape, but the length scales are quite different. The domain size is approximately 100 nm for the ferroelectric domains, while the magnetic domain size is much larger and gets as large as 1 μm. We also demonstrate that the origin of the formation of irregular domains in LuFe{sub 2}O{sub 4} is not extrinsic but intrinsic.
Strategy Design of Orderly Charging and Discharging Management for Electric Vehicles%电动汽车有序充放电管理策略设计
Institute of Scientific and Technical Information of China (English)
杨文海; 王敬敏; 高亚静
2012-01-01
随着未来电动汽车的发展与普及，将会有大量电动汽车广泛随机接入电网，其无序充放电行为将对电力系统的运行产生非常不利的影响。因此，需要有相应的政策和手段对电动汽车充放电行为进行引导。将电动汽车有序充放电管理作为研究对象，从我国实际情况出发，结合需求侧响应，研究了4种电动汽车充电负荷的负荷特性，并分别提出了对其进行有序充放电管理的建议。%With the development and popularization of electric vehicles in the future, large numbers of the electric vehicles will connect to the power grid randomly. Such disorderly charging and discharging behavior will have serious negative impacts on the operation of the electric power system. Therefore, it is necessary and urgent to launch corresponding policies and take measures to guide the charging and discharging behavior. Taking orderly charging and discharging management of EV as the research object and considering the actual situation of China, this paper investigates the characteristics of the four kinds of EV＇s charging loads based on the demand-side response,, and presents recommendations for orderly charging and discharging management.
Spacecraft Charging Sensitivity to Material Properties
Minow, Joseph I.; Edwards, David L.
2015-01-01
Evaluating spacecraft charging behavior of a vehicle in the space environment requires knowledge of the material properties relevant to the charging process. Implementing surface and internal charging models requires a user to specify a number of material electrical properties including electrical resistivity parameters (dark and radiation induced), dielectric constant, secondary electron yields, photoemission yields, and breakdown strength in order to correctly evaluate the electric discharge threat posed by the increasing electric fields generated by the accumulating charge density. In addition, bulk material mass density and/or chemical composition must be known in order to analyze radiation shielding properties when evaluating internal charging. We will first describe the physics of spacecraft charging and show how uncertainties in material properties propagate through spacecraft charging algorithms to impact the results obtained from charging models. We then provide examples using spacecraft charging codes to demonstrate their sensitivity to material properties. The goal of this presentation is to emphasize the importance in having good information on relevant material properties in order to best characterize on orbit charging threats.
Zhu, W K; Tong, W; Ling, L; Starr, M; Wang, J M; Yang, W C; Losovyj, Y; Zhou, H D; Wang, Y Q; Lee, P -H; Wang, Y -K; Lu, Chi-Ken; Zhang, S X
2016-01-01
Double-perovskite oxides that contain both 3d and 5d transition metal elements have attracted growing interest as they provide a model system to study the interplay of strong electron interaction and large spin-orbit coupling (SOC). Here, we report on experimental and theoretical studies of the magnetic and electronic properties of double-perovskites (La$_{1-x}$Sr$_x$)$_2$CuIrO$_6$ ($x$ = 0.0, 0.1, 0.2, and 0.3). The undoped La$_2$CuIrO$_6$ undergoes a magnetic phase transition from paramagnetism to antiferromagnetism at T$_N$ $\\sim$ 74 K and exhibits a weak ferromagnetic behavior below $T_C$ $\\sim$ 52 K. Two-dimensional magnetism that was observed in many other Cu-based double-perovskites is absent in our samples, which may be due to the existence of weak Cu-Ir exchange interaction. First-principle density-functional theory (DFT) calculations show canted antiferromagnetic (AFM) order in both Cu$^{2+}$ and Ir$^{4+}$ sublattices, which gives rise to weak ferromagnetism. Electronic structure calculations sugges...
Vig, Sean; Kogar, Anshul; Mishra, Vivek; Rak, Melinda; Husain, Ali; Gu, Genda; Norman, Mike; Abbamonte, Peter
Classifying the collective electronic dynamics of materials is critical to addressing the high temperature superconductivity problem and understanding related collective phenomena. Most current probes are unable to measure the full energy and momentum dependence of the dynamic charge susceptibility in these strongly correlated materials at the meV energy scale relevant to superconductivity. We use our momentum-resolved electron energy loss spectroscopy (M-EELS) technique to perform this measurement, characterizing both the static charge density and the bosonic electronic excitations in the cuprate superconductor Bi2SrCaCu2O8+δ (Bi-2212). I present our measurement of a low temperature diffuse charge ordered state at optimal doping which modulates the observed dispersionless low energy collective excitations. Performing a one-loop correction to the bare electron dispersion, we show these modes reproduce the self-energy anomaly, or ``kink'', as measured by ARPES. I discuss the nature of the charge dynamics that we measured with our technique and its relation to the superconducting state. This work was supported as part of the Center for Emergent Superconductivity, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.
Charge density wave order in 1D mirror twin boundaries of single-layer MoSe2
Barja, Sara; Wickenburg, Sebastian; Liu, Zhen-Fei; Zhang, Yi; Ryu, Hyejin; Ugeda, Miguel M.; Hussain, Zahid; Shen, Zhi-Xun; Mo, Sung-Kwan; Wong, Ed; Salmeron, Miquel B.; Wang, Feng; Crommie, Michael F.; Ogletree, D. Frank; Neaton, Jeffrey B.; Weber-Bargioni, Alexander
2016-08-01
We provide direct evidence for the existence of isolated, one-dimensional charge density waves at mirror twin boundaries (MTBs) of single-layer semiconducting MoSe2. Such MTBs have been previously observed by transmission electron microscopy and have been predicted to be metallic in MoSe2 and MoS2. Our low-temperature scanning tunnelling microscopy/spectroscopy measurements revealed a substantial bandgap of 100 meV opening at the Fermi energy in the otherwise metallic one-dimensional structures. We found a periodic modulation in the density of states along the MTB, with a wavelength of approximately three lattice constants. In addition to mapping the energy-dependent density of states, we determined the atomic structure and bonding of the MTB through simultaneous high-resolution non-contact atomic force microscopy. Density functional theory calculations based on the observed structure reproduced both the gap opening and the spatially resolved density of states.
Dust charge measurement in a strongly coupled dusty plasma produced by an rf discharge
International Nuclear Information System (INIS)
The electric charge on silica microparticles (5 µm in diameter) levitating in the sheath of an rf discharge plasma is determined in a newly installed device for dusty plasma experiments at the IASST. The sheath potential profile is measured using an emissive probe and the electric field is obtained in order to determine the dust charge. The measured dust charge in the pressure range 0.50–5.0 Pa using the electric field value at the levitation height is found to be of the order of 104 elementary charges. Dust charge is also examined using the vertical resonance method which gives a similar order of charges. The experimentally measured charge is compared with the estimated values based on the orbital motion limited charging model. The coupling strength between the particles forming a 2D plasma crystal lattice is estimated using the measured dust charge. (paper)
Gao, Shuqin; Liao, Lifu; Xiao, Xilin; Zhao, Zhiyuan; Du, Nan; Du, Jiangfeng
2010-05-01
A new spectrophotometric method for the determination of nicotine in mixtures without pre-separation has been proposed. Nicotine could react with 2,4-dinitrophenol through a charge-transfer reaction to form a colored complex. The second-order data from the visible absorption spectra of the complex in a series of ethanol-water binary solvents with various water volume fractions could be expressed as the combination of two bilinear data matrices. With the bilinear model, the second-order spectra data of mixtures containing nicotine and other interferents could be analysed by using second-order calibration algorithms, and the determination of nicotine in the mixtures could be achieved. The algorithm used here was parallel factor analysis. The method has been successfully used to determine nicotine in tobacco samples with satisfactory results.
Energy Technology Data Exchange (ETDEWEB)
Popushoi, M.N.
1987-06-01
A generalized algebraic variant is proposed for solving the inverse problem of the potential scattering of charged particles for the case when the initial scattering data are taken in the presence of a linear relationship between the energy E, the square of the orbital angular momentum l, and the Coulomb coupling constant a. Expressions are obtained for constructing a central E-, l-, and a-independent potential corresponding to a Jost function characterized by rationality with respect to the parameters E, l, and a.
Teran, Natasha B; He, Guang S; Baev, Alexander; Shi, Yanrong; Swihart, Mark T; Prasad, Paras N; Marks, Tobin J; Reynolds, John R
2016-06-01
Exploiting synergistic cooperation between multiple sources of optical nonlinearity, we report the design, synthesis, and nonlinear optical properties of a series of electron-rich thiophene-containing donor-acceptor chromophores with condensed π-systems and sterically regulated inter-aryl twist angles. These structures couple two key mechanisms underlying optical nonlinearity, namely, (i) intramolecular charge transfer, greatly enhanced by increased electron density and reduced aromaticity at chromophore thiophene rings and (ii) a twisted chromophore geometry, producing a manifold of close-lying excited states and dipole moment changes between ground and excited states that are nearly twice that of untwisted systems. Spectroscopic, electrochemical, and nonlinear Z-scan measurements, combined with quantum chemical calculations, illuminate relationships between molecular structure and mechanisms of enhancement of the nonlinear refractive index. Experiment and calculations together reveal ground-state structures that are strongly responsive to the solvent polarity, leading to substantial negative solvatochromism (Δλ ≈ 10(2) nm) and prevailing zwitterionic/aromatic structures in the solid state and in polar solvents. Ground-to-excited-state energy gaps below 2.0 eV are obtained in condensed π-systems, with lower energy gaps for twisted versus untwisted systems. The real part of the second hyperpolarizability in the twisted structures is much greater than the imaginary part, with the highest twist angle chromophore giving |Re(γ)/Im(γ)| ≈ 100, making such chromophores very promising for all-optical-switching applications. PMID:27232098
Hu, Yueyun; Wouts, Marcel
2010-01-01
We study a quenched charged-polymer model, introduced by Garel and Orland in 1988, that reproduces the folding/unfolding transition of biopolymers. We prove that, below the critical inverse temperature, the polymer is delocalized in the sense that: (1) The rescaled trajectory of the polymer converges to the Brownian path; and (2) The partition function remains bounded. At the critical inverse temperature, we show that the maximum time spent at points jumps discontinuously from 0 to a positive fraction of the number of monomers, in the limit as the number of monomers tends to infinity. Finally, when the critical inverse temperature is large, we prove that the polymer collapses in the sense that a large fraction of its monomers live on four adjacent positions, and its diameter grows only logarithmically with the number of the monomers. Our methods also provide some insight into the annealed phase transition and at the transition due to a pulling force; both phase transitions are shown to be discontinuous.
Endoscopic treatment of orbital tumors
Signorelli, Francesco; Anile, Carmelo; Rigante, Mario; Paludetti, Gaetano; Pompucci, Angelo; Mangiola, Annunziato
2015-01-01
Different orbital and transcranial approaches are performed in order to manage orbital tumors, depending on the location and size of the lesion within the orbit. These approaches provide a satisfactory view of the superior and lateral aspects of the orbit and the optic canal but involve risks associated with their invasiveness because they require significant displacement of orbital structures. In addition, external approaches to intraconal lesions may also require deinsertion of extraocular ...
Kubota, M.; Oohara, Y.; Yoshizawa, H.; Fujioka, H.; Shimizu, K.; Hirota, K.; Moritomo, Y.; Endoh, Y.
2000-01-01
The charge ordering in the bilayer manganite system La$_{2-2x}$Sr$_{1+2x}$Mn$_{2}$O$_{7}$ with $0.30 \\le x \\le 0.50$ has been studied by neutron diffraction. The charge order is characterized by the propagation vector parallel to the [1 0 0] direction (MnO$_2$ direction), but the correlation length is short-ranged and extremely anisotropic, being $\\sim 0.02a^{*}$ and $\\sim 0.2a^{*}$ parallel and perpendicular to the modulation direction, respectively. The observed charge order can be viewed a...
International Nuclear Information System (INIS)
In this paper we introduce an alternative approach to studying the motion of a planar charged particle subject to a static uniform magnetic field. It is well known that an electric charge under a uniform magnetic field has a planar motion if its initial velocity is perpendicular to the magnetic field. Although some constants of motion (CsM), as the energy and the angular momentum, have been widely discussed for this system, others have been neglected. We find that the angular momentum, the generator of the magnetic translations and the magnetic Laplace–Runge–Lenz vector are CsM for this particular system. We show also that these three quantities form an orthogonal basis of vectors. The present work addresses many aspects of the motion of a charged particle in a magnetic field that should be useful for students and tutors of the classical mechanics courses at the senior undergraduate level. (paper)
Velasco-Martínez, D.; Ibarra-Sierra, V. G.; Sandoval-Santana, J. C.; Kunold, A.; Cardoso, J. L.
2014-09-01
In this paper we introduce an alternative approach to studying the motion of a planar charged particle subject to a static uniform magnetic field. It is well known that an electric charge under a uniform magnetic field has a planar motion if its initial velocity is perpendicular to the magnetic field. Although some constants of motion (CsM), as the energy and the angular momentum, have been widely discussed for this system, others have been neglected. We find that the angular momentum, the generator of the magnetic translations and the magnetic Laplace-Runge-Lenz vector are CsM for this particular system. We show also that these three quantities form an orthogonal basis of vectors. The present work addresses many aspects of the motion of a charged particle in a magnetic field that should be useful for students and tutors of the classical mechanics courses at the senior undergraduate level.
Freire, Hermann; de Carvalho, Vanuildo
2015-03-01
The two-loop renormalization group (RG) calculation is considerably extended here for a two-dimensional (2D) fermionic effective field theory model, which includes only the so-called ``hot spots'' that are connected by the spin-density-wave (SDW) ordering wavevector on a Fermi surface generated by the 2D t -t' Hubbard model at low hole doping. We compute the Callan-Symanzik RG equation up to two loops describing the flow of the single-particle Green's function, the corresponding spectral function, the Fermi velocity, and some of the most important order-parameter susceptibilities in the model at lower energies. As a result, we establish that - in addition to clearly dominant SDW correlations - an approximate (pseudospin) symmetry relating a short-range incommensurate d-wave charge order to the d-wave superconducting order indeed emerges at lower energy scales, which is in agreement with recent works available in the literature addressing the 2D spin-fermion model. We derive implications of this possible electronic phase in the ongoing attempt to describe the phenomenology of the pseudogap regime in underdoped cuprates. We acknowledge financial support from CNPq under Grant No. 245919/2012-0 and FAPEG under Grant No. 201200550050248 for this project.
Czech Academy of Sciences Publication Activity Database
Zakeri, Kh.; Hashemifar, S.J.; Lindner, J.; Barsukov, I.; Meckenstock, R.; Kratzer, P.; Frait, Zdeněk; Farle, M.
2008-01-01
Roč. 77, č. 10 (2008), 104430/1-104430/5. ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100520 Keywords : FeSi Heusler alloys * spin/orbital moments * ferromagnetic resonance * squid Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.322, year: 2008
Yamakawa, Youichi; Kontani, Hiroshi
2015-06-26
We present a microscopic derivation of the nematic charge-density wave (CDW) formation in cuprate superconductors based on the three-orbital d-p Hubbard model by introducing the vertex correction (VC) into the charge susceptibility. The CDW instability at q=(Δ(FS),0), (0,Δ(FS)) appears when the spin fluctuations are strong, due to the strong charge-spin interference represented by the VC. Here, Δ(FS) is the wave number between the neighboring hot spots. The obtained spin-fluctuation-driven CDW is expressed as the "intra-unit-cell orbital order" accompanied by the charge transfer between the neighboring atomic orbitals, which is actually observed by the scanning tunneling microscope measurements. We predict that the cuprate CDW and the nematic orbital order in Fe-based superconductors are closely related spin-fluctuation-driven phenomena. PMID:26197139
International Nuclear Information System (INIS)
The antiferromagnetic insulator La1.5Ca0.5CoO4 has been investigated by Co L2,3-edge and O K-edge X-ray absorption spectroscopy (XAS) measurements and Co L2,3-edge resonant soft X-ray magnetic scattering (RXMS) measurement to determine the Co electronic structures associated with magnetic ordering. Co L2,3-edge linear-dichroic XAS shows that Co2+ takes a high-spin (HS) state and Co3+ takes a low-spin (LS) state. Using Co L2,3-edge RXMS, we directly determined that an antiferromagnetic order is formed with a HS state of Co2+ ions. Moreover, the spin and orbital angular momenta of the Co2+ HS state are quantitatively estimated to be 1.1 ± 0.1 and 1.0 ± 0.1, respectively, and to align parallel in the ab plane by utilizing the cluster model calculation. The large orbital angular momentum of the Co2+ HS state originates from the small D4h-symmetry crystal field splitting of t2g levels, which is comparable with the spin-orbit coupling constant of the Co 3d orbital. (author)
The coupled electronic order of manganese and oxygen states in doped manganites
International Nuclear Information System (INIS)
Comparing resonant soft X-ray scattering (RSXS) experiments and realistic many-body calculations, the nature of the electronic crystal formed in the low-temperature phase of La7/8Sr1/8MnO3 is investigated. The analysis of the experimental data implies that the modulation of the Mn-valence must be very small and that the detected Mn-ordering is mainly of orbital nature. The emerging picture of manganese orbital order, which is coupled to charge and orbital order of the O 2p-states, seems to be a general feature of electronically ordered manganites.
Nuruzzaman, Md.; Yokogawa, Keiichi; Yoshino, Harukazu; Yoshimoto, Haruo; Kikuchi, Koichi; Kaihatsu, Takayuki; Yamada, Jun-ichi; Murata, Keizo
2012-12-01
We studied the electronic transport properties of the charge transfer salt β-(BDA-TTP)2I3 [BDA-TTP: 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] by applying uniaxial strains along the three crystallographic axes, and obtained three corresponding temperature-pressure phase diagrams. Three phase diagrams were quite dependent on the direction of compression. Following the preceding paper by Kikuchi et al., we speculate that the insulating states are of 1/2-filled Mott insulators for the a- and b-axes compressions, and of 1/4-filled charge ordered states for the c-axis compression as well as hydrostatic pressure. The superconducting phase under uniaxial strain was realized with Tc = 5 K at 1.9 GPa along the a-axis and with Tc = 5.6 K at 1.75 GPa along the b-axis. Superconductivity was also reproduced with a Tc of 9.5 K at 1.0 GPa for the c-axis compressions in the range of 0.85 to 1.53 GPa as previously reported. We studied tentative measurement on upper critical fields, Bc2's of these superconductivities and found that the extrapolated values, Bc2(0)'s, exceeded Pauli-limit by about 2--3 times. However, at least in terms of Bc2, the difference in superconductivity associated with two different insulating states was not clear.
Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Yin, Shizhuo; Hoffman, Robert C
2016-01-01
In this paper, we report a three orders-of-magnitude increase in the speed of a space-charge-controlled KTN beam deflector achieved by eliminating the electric field-induced phase transition (EFIPT) in a nanodisordered KTN crystal. Previously, to maximize the electro-optic effect, a KTN beam deflector was operated at a temperature slightly above the Curie temperature. The electric field could cause the KTN to undergo a phase transition from the paraelectric phase to the ferroelectric phase at this temperature, which causes the deflector to operate in the linear electro-optic regime. Since the deflection angle of the deflector is proportional to the space charge distribution but not the magnitude of the applied electric field, the scanning speed of the beam deflector is limited by the electron mobility within the KTN crystal. To overcome this speed limitation caused by the EFIPT, we propose to operate the deflector at a temperature above the critical end point. This results in a significant increase in the scanning speed from the microsecond to nanosecond regime, which represents a major technological advance in the field of fast speed beam scanners. This can be highly beneficial for many applications including high-speed imaging, broadband optical communications, and ultrafast laser display and printing. PMID:27610923
Energy Technology Data Exchange (ETDEWEB)
Nakaya, H; Takahashi, Y [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Yamamoto, K; Yakushi, K [Institute for Molecular Science, Okazaki, 444-8585 (Japan); Saito, S [Institute of Information and Communications Technology, Kobe, 651-2492 (Japan); Iwai, S, E-mail: s.iwai@sspp.phys.tohoku.ac.j
2009-02-01
Photo-induced insulator to metal transition in a two-dimensional charge-ordered (CO) organic salt alpha-(ET){sub 2}I{sub 3} (ET: [bis(ethylenedithio)]tetrathiafulvalene) was investigated using near-IR-pump and terahertz(THz)-probe spectroscopy. Electronic properties and electron-phonon (e-p) coupling of the photo-induced metallic state were discussed based on the excitation intensity and temperature dependences of transient absorption spectrum. Long-lived (ca. ns) induced absorption with large spectral weight at < 5 meV is detected for strong excitation at T{approx}T{sub CO} (T{sub CO}=135 K), which is attributable to the photo-induced macroscopic metallic state. On the other hand, short-lived transient absorption, reflecting generation of the microscopic metallic state, shows relatively small spectral weight for <5 meV at 20 K<
International Nuclear Information System (INIS)
Ca2-xPrxMnO4 (0 ≤ x ≤ 0.2) polycrystalline ceramic powders were synthesized by sol-gel method. The X-ray diffraction (XRD) profiles were indexed with a tetragonal and orthorhombic structure for Ca2MnO4 and Pr-doped compounds, respectively. Electrical properties were investigated by dc and ac electrical measurements. The dc measurements have revealed an insulating state for all compounds in 80-350 K temperature range. Both dc and ac measurements have highlighted a charge ordering (CO) transition at TCO = 233 and 245 K for x = 0.175 and 0.2, respectively. The CO state was found to be accompanied by a jump of the hopping activation energy and a rapid rise of both dielectric permittivity and imaginary part of ac electrical impedance.
International Nuclear Information System (INIS)
Neutron powder diffraction was used to study the crystallographic structure of a quenched tetragonal sample of YBa2Cu3O6.25 during room-temperature annealing. It is found that the lattice parameters decrease with anneal time. The time dependence of the two lattice parameters is characterized by a single relaxation time ∼760 min. Similar relaxation times were recently found for the electrical resistances Rab, Rc, in tetragonal single crystals of YBa2Cu3O6.25. These results are interpreted in terms of local ordering of the oxygen ions in the basal CuOx plane, leading to a charge transfer between the CuOx and CuO2 planes. It is the same effect that leads to the rise in Tc observed earlier in orthorhombic YBa2Cu3O6+x (x>0.35). The mechanism of the local ordering and the concept of oxygen ions ordering in a structure with tetragonal symmetry are discussed
A new pathway of Saturnian ring-ionosphere coupling via charged nanograins
Energy Technology Data Exchange (ETDEWEB)
Liu, Chin-Min; Ip, Wing-Huen, E-mail: wingip@astro.ncu.edu.tw [Institute of Space Science, National Central University, Jhongli City, Taoyuan County 32001, Taiwan (China)
2014-05-01
From a re-examination of the trajectories of small charged grains in the vicinity of the Saturnian rings, it is shown that the orbital motion of positively charged grains with a charge-to-mass ratio on the order of 10{sup –6} e amu{sup –1} could allow the injection of water material into the equatorial atmosphere. Thus, a mechanism of ionospheric depletion in the equatorial region is provided, as indicated by the Cassini radio occultation measurements.
International Nuclear Information System (INIS)
Charge density waves (CDW's) are now a frequently observed feature of highly anisotropic metals such as one-dimensional conductors and two-dimensional layered compounds. A close relation between charge-density wave formation and superconductivity is characteristic of the superconductors in the family typified by NbSe3. However, with the discovery of pnictide superconductors, the study of interplay between superconductivity (SC) and electron spectrum instabilities, namely charge density wave (CDW) and spin density wave (SDW), have gained considerable attention. SC and CDW are two very different cooperative phenomena both of which occur due to Fermi surface (FS) instabilities and results an opening up of a gap at the FS which leads to a reduction in the DOS at the FS below their respective transition temperatures. CDW effects have been known to happen only in quasi-low dimensional structures, However, recently CDW phenomena have been established in the series of polycrystalline compounds R2Ir3Si5 which essentially have a 3-dimensional structure. Among these compounds, Lu2Ir3Si5 adopts an orthorhombic U2Co3Si5 (Ibam) structure, and becomes superconducting below 3K. Also, it shows an unusual CDW like transition at high temperature (around 150-200 K) accompanied by a huge thermal hysteresis. Though, the polycrystalline compound studies contain no information on the anisotropy which is expected for a CDW compound. Hence, it is of interest to study the evolution of the superconductivity and the CDW transition when we substitute small quantities of Rh for Ir site in Lu2Ir3Si5. The Polycrystalline samples of Lu2(Ir1-xRhx)3Si5 (x=0, 0.01, 0.03, 0.1 and 0.2) were prepared by arc melting method. We have performed bulk measurements such as dc magnetic susceptibility, electrical resistivity and heat capacity on the pseudo-ternary alloys Lu2(Ir1-xRhx)3Si5 to study the interplay and competition between superconductivity and the charge-density-wave ordering transition. Our results
... Names Idiopathic orbital inflammatory syndrome (IOIS) Images Skull anatomy References Goodlick TA, Kay MD, Glaser JS, Tse DT, Chang WJ. Orbital disease and neuro-ophthalmology. In: Tasman W, Jaeger EA, eds. Duaneâ€™s ...
International Nuclear Information System (INIS)
Consideration is being given to a new way of approach of second and third order transformations for charged particle trajectories, performed by dipole, quadrupole magnets, widely used for acceleration and transport, separation and monochromatization of particles. The Way is based on the fact that for determination of transformation factors is necessary to conjugate two parts of particle trajectory, one of which is determined by initial particle coordinates, and another one - by terminal coordinates, presented in the form of series expansion according to initial coordinates and small parameters. Two trajectory parts are conjugated in that spot of transformation, where trajectories, typical for one out of four possible types of tra ectory brush transformation (''point to point'', ''point to parallels'', ''parallels to point'', ''parallels to parallels'') are parallel to the optical axis of transforming element or cross it. A new way of approach was used to obtain the system of unified, compact and symmetrical analytical expression for the first order coefficient with the obvious geometrical interpretation and simple algorithms for parameter search and calculation of characteristics of focusing and analyzing magnetic and electric elements (dipole magnets, electric deflectors, magnetic and electric quadrupole lenses)
Zhang, Shoubao; Saito, Takashi; Mizumaki, Masaichiro; Shimakawa, Yuichi
2014-07-28
Changes in the valence state of transition-metal ions in oxides drastically modify the chemical and physical properties of the compounds. Intersite charge transfer (ISCT), which involves simultaneous changes in the valence states of two valence-variable transition-metal cations at different crystallographic sites, further expands opportunities to show multifunctional properties. To explore new ISCT materials, we focus on A-site-ordered perovskite-structure oxides with the chemical formula AA'3 B4 O12 , which contain different transition-metal cations at the square-planar A' and octahedral B sites. We have obtained new A-site-ordered perovskites LaCu3 Cr4 O12 and YCu3 Cr4 O12 by synthesis under high-pressure and high-temperature conditions and found that they showed temperature-induced ISCT between A'-site Cu and B-site Cr ions. The compounds are the first examples of those, in which Cr ions are involved in temperature-induced ISCT. In contrast to the previously reported ISCT compounds, LaCu3 Cr4 O12 and YCu3 Cr4 O12 showed positive-thermal-expansion-like volume changes at the ISCT transition. PMID:24975031
Foerst, M.; Tobey, R. I.; Bromberger, H.; Wilkins, S. B.; Khanna, V.; Caviglia, A. D.; Chuang, Y. -D.; Lee, W. S.; Schlotter, W. F.; Turner, J. J.; Minitti, M. P.; Krupin, O.; Xu, Z. J.; Wen, J. S.; Gu, G. D.; Dhesi, S. S.; Cavalleri, A.; Hill, J. P.
2014-01-01
We report femtosecond resonant soft x-ray diffraction measurements of the dynamics of the charge order and of the crystal lattice in nonsuperconducting, stripe-ordered La1.875Ba0.125CuO4. Excitation of the in-plane Cu-O stretching phonon with a midinfrared pulse has been previously shown to induce a
Canizares, P; Jaramillo, J L
2010-01-01
[abridged] The inspiral of a stellar compact object into a massive black hole is one of the main sources of gravitational waves for the future space-based Laser Interferometer Space Antenna. We expect to be able to detect and analyze many cycles of these slowly inspiraling systems. To that end, the use of very precise theoretical waveform templates in the data analysis is required. To build them we need to have a deep understanding of the gravitational backreaction mechanism responsible for the inspiral. The self-force approach describes the inspiral as the action of a local force that can be obtained from the regularization of the perturbations created by the stellar compact object on the massive black hole geometry. In this paper we extend a new time-domain technique for the computation of the self-force from the circular case to the case of eccentric orbits around a non-rotating black hole. The main idea behind our scheme is to use a multidomain framework in which the small compact object, described as a p...
DMSP Auroral Charging at Solar Cycle 24 Maximum
Chandler, M.; Parker, L. Neergaard; Minow, J. I.
2013-01-01
It has been well established that polar orbiting satellites can experience mild to severe auroral charging levels (on the order of a few hundred volts to few kilovolts negative frame potentials) during solar minimum conditions. These same studies have shown a strong reduction in charging during the rising and declining phases of the past few solar cycles with a nearly complete suppression of auroral charging at solar maximum. Recently, we have observed examples of high level charging during the recent approach to Solar Cycle 24 solar maximum conditions not unlike those reported by Frooninckx and Sojka. These observations demonstrate that spacecraft operations during solar maximum cannot be considered safe from auroral charging when solar activity is low. We present a survey of auroral charging events experienced by the Defense Meteorological Satellite Program (DMSP) F16 satellite during Solar Cycle 24 maximum conditions. We summarize the auroral energetic particle environment and the conditions necessary for charging to occur in this environment, we describe how the lower than normal solar activity levels for Solar Cycle 24 maximum conditions are conducive to charging in polar orbits, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period.
Directory of Open Access Journals (Sweden)
Ian MacLaren
2013-08-01
Full Text Available Observation of an unusual, negatively-charged antiphase boundary in (Bi0.85Nd0.15(Ti0.1Fe0.9O3 is reported. Aberration corrected scanning transmission electron microscopy is used to establish the full three dimensional structure of this boundary including O-ion positions to ∼±10 pm. The charged antiphase boundary stabilises tetragonally distorted regions with a strong polar ordering to either side of the boundary, with a characteristic length scale determined by the excess charge trapped at the boundary. Far away from the boundary the crystal relaxes into the well-known Nd-stabilised antiferroelectric phase.
On the spacecraft attitude stabilization in the orbital frame
Antipov Kirill A.; Tikhonov Alexey A.
2012-01-01
The paper deals with spacecraft in the circular near-Earth orbit. The spacecraft interacts with geomagnetic field by the moments of Lorentz and magnetic forces. The octupole approximation of the Earth’s magnetic field is accepted. The spacecraft electromagnetic parameters, namely the electrostatic charge moment of the first order and the eigen magnetic moment are the controlled quasiperiodic functions. The control algorithms for the spacecraft electromagnetic parameters, which allows to...
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-03-31
The Ontario Energy Board examined an application by Consumers` Gas Company Ltd., for an order approving the rates to be charged for the sale, distribution, transmission and storage of gas for its 1999 fiscal year. This report addressed the approvals requested by Consumers` Gas for transactions between itself and an affiliate for specific regulatory treatment of certain programs. In its original application dated January 8, 1998, Consumers` Gas proposed to separate and remove the following from the existing operations of the regulated utility: (1) its merchandise sales program, (2) its heating parts replacement plan, and (3) about half of the service operations currently provided to customers. It was proposed that these services be transferred to Consumersfirst Ltd, a non-subsidiary affiliate of Consumers` Gas. Consumers` requested that an Unbundling Business Activities Deferral Account be established to record costs incurred in the 1998 and 1999 fiscal years in relation to the transfers proposed. It also requested approval for the ratemaking implications of its proposals relating to the rental program, including approval for the recovery from ratepayers of unrecorded deferred income taxes in relation to the program. This report presents the Board`s findings with respect to each of these requests.
Colossal thermoelectric power in charge-ordered Li-doped La0.75Li0.25MnO3 manganite system
Taran, Subhrangsu; Sun, C. P.; Yang, H. D.; Chatterjee, S.
2016-05-01
A detail study of transport and magnetic properties of La1-xLixMnO3+δ (0.05 ≤ x ≤ 0.3) system synthesized by wet-chemical mixing route has been done. The room temperature x-ray powder diffraction (XRD) data show single phase behavior of all samples except x = 0.3. Rietveld refinement of XRD data shows structural transition from rhombohedral (R3-C) to orthorhombic (Pnma) symmetry occurs at the Li-doping level x > 0.2 with both the lattice parameter and unit-cell volume decrease with increase of `x'. All the samples show ferromagnetic (FM) behavior while metallic behavior are shown by the samples up to Li-concentration x = 0.2. With further Li doping i.e. for x = 0.25, the sample shows insulating behavior accompanied by charge-order transition around T ~ 225K. Metallic part of the resistivity data of the samples is best fitted with an expression ρ(T) = ρ0 + ρ4.5T4.5 + C/ sinh2(hvs/2kBT) containing small-polaron contribution (last term). Most interesting finding in the present study is the observation of large anomalous decrease in thermoelectric power (S) below 100K shown by the sample with x = 0.25. Probable mechanisms responsible for the observed colossal thermoelectric power have been discussed.
Lovesey, S W; Khalyavin, D D
2015-12-16
A symmetry-based interpretation of published experimental results demonstrates that the pseudo-gap phase of underdoped HgBa2CuO(4+δ) (Hg1201) possesses an ordered state of magnetic charge epitomized by Cu magnetic monopoles. Magnetic properties of one-layer Hg1201 and two-layer YBa2Cu3O(6+x) (YBCO) cuprates have much in common, because their pseudo-gap phases possess the same magnetic space-group, e.g. both underdoped cuprates allow the magneto-electric (Kerr) effect. Differences in their properties stem from different Cu site symmetries, leaving Cu magnetic monopoles forbidden in YBCO. Resonant x-ray Bragg diffraction experiments can complement the wealth of information available from neutron diffraction experiments on five Hg1201 samples on which our findings are based. In the case of Hg1201 emergence of the pseudo-gap phase, with time-reversal violation, is accompanied by a reduction of Cu site symmetry that includes loss of a centre of inversion symmetry. In consequence, parity-odd x-ray absorption events herald the onset of the enigmatic phase, and we predict dependence of corresponding Bragg spots on magneto-electric multipoles, including the monopole, and the azimuthal angle (crystal rotation about the Bragg wavevector). PMID:26575373
Probing nuclear correlations with pion-nucleus double charge exchange
International Nuclear Information System (INIS)
In this paper we have calculated the lowest order pion double charge reaction mechanism using shell model wavefunctions of medium weight nuclei. We have the sequential reaction mechanism in which the pion undergoes two single-charge exchange scatterings on the valence neutrons. The distortion of the incoming, intermediate, and outgoing pion are included. The closure approximation is made for the intermediate states with an average excitation energy used in the pion propagator. The double-charge exchange is assumed to take place on the valence nucleons which are assumed to be in one spherical shell model orbital. 34 refs., 5 figs., 3 tabs
Economic analysis requirements in support of orbital debris regulatory policy
Greenberg, Joel S.
1996-10-01
As the number of Earth orbiting objects increases so does the potential for generating orbital debris with the consequent increase in the likelihood of impacting and damaging operating satellites. Various debris remediation approaches are being considered that encompass both in-orbit and return-to-Earth schema and have varying degrees of operations, cost, international competitiveness, and safety implications. Because of the diversity of issues, concerns and long-term impacts, there is a clear need for the setting of government policies that will lead to an orderly abatement of the potential orbital debris hazards. These policies may require the establishment of a supportive regulatory regime. The Department of Transportation is likely to have regulatory responsibilities relating to orbital debris stemming from its charge to protect the public health and safety, safety of property, and national security interests and foreign policy interests of the United States. This paper describes DOT's potential regulatory role relating to orbital debris remediation, the myriad of issues concerning the need for establishing government policies relating to orbital debris remediation and their regulatory implications, the proposed technological solutions and their economic and safety implications. Particular emphasis is placed upon addressing cost-effectiveness and economic analyses as they relate to economic impact analysis in support of regulatory impact analysis.
Partonic orbital angular momentum
Arash, Firooz; Taghavi-Shahri, Fatemeh; Shahveh, Abolfazl
2013-04-01
Ji's decomposition of nucleon spin is used and the orbital angular momentum of quarks and gluon are calculated. We have utilized the so called valon model description of the nucleon in the next to leading order. It is found that the average orbital angular momentum of quarks is positive, but small, whereas that of gluon is negative and large. Individual quark flavor contributions are also calculated. Some regularities on the total angular momentum of the quarks and gluon are observed.
Bodewits, E.; Hoekstra, R.; Dobes, K.; Aumayr, F.
2014-01-01
At keV energies, many electronic processes contribute to the emission of secondary electrons in the interaction of highly charged ions on surfaces. To unravel contributions resulting from isolated hollow atoms in front of the surface or embedded in the electron gas of the target, heavy highly charge
Modestino, Giuseppina
2016-01-01
The trajectory and the orbital velocity are determined for an object moving in a gravitational system, in terms of fundamental and independent variables. In particular, considering a path on equipotential line, the elliptical orbit is naturally traced, verifying evidently the keplerian laws. The case of the planets of the solar system is presented.
Directory of Open Access Journals (Sweden)
Dulal C. Ghosh
2004-09-01
Full Text Available The formation of the F3BÃ¢Â€Â“NH3 supermolecule by chemical interaction of its fragment parts, BF3 and NH3, and the dynamics of internal rotation about the Ã¢Â€Â˜BÃ¢Â€Â“NÃ¢Â€Â™ bond have been studied in terms of parameters provided by the molecular orbital and density functional theories. It is found that the pairs of frontier orbitals of the interacting fragments have matching symmetry and are involved in the charge transfer interaction. The donation process stems from the HOMO of the donor into the LUMO of the acceptor and simultaneously, back donation stems from the HOMO of acceptor into the LUMO of the donor. The density functional computation of chemical activation in the donor and acceptor fragments, associated with the physical process of structural reorganization just prior to the event of chemical reaction, indicates that BF3 becomes more acidic and NH3 becomes more basic, compared to their separate equilibrium states. Theoretically it is observed that the chemical reaction event of the formation of the supermolecule from its fragment parts is in accordance with the chemical potential equalization principle of the density functional theory and the electronegativity equalization principle of Sanderson. The energetics of the chemical reaction, the magnitude of the net charge transfer and the energy of the newly formed bond are quite consistent, both internally and with the principle of maximum hardness, PMH. The dynamics of the internal rotation of one part with respect to the other part of the supermolecule about the Ã¢Â€Â˜BÃ¢Â€Â“NÃ¢Â€Â™ bond mimics the pattern of the conformational isomerism of the isostructural ethane molecule. It is also observed that the dynamics and evolution of molecular conformations as a function of dihedral angles is also in accordance with the principle of maximum hardness, PMH. Quite consistent with spectroscopic predictions, the height of the molecule
Institute of Scientific and Technical Information of China (English)
刘劲松; 郝中华
2003-01-01
The self-deflection of a bright solitary beam can be controlled by a dark solitary beam via a parametric coupling effect between the bright and dark solitary beams in a separate bright-dark spatial soliton pair supported by an unbiased series photorefractive crystal circuit. The spatial shift of the bright solitary beam centre as a function of the input intensity of the dark solitary beam (p) is investigated by taking into account the higher-order space charge field in the dynamics of the bright solitary beam via both numerical and perturbation methods under steady-state conditions.The deflection amount (△s0), defined as the value of the spatial shift at the output surface of the crystal, is a monotonic and nonlinear function ofp. When p is weak or strong enough, △s0 is, in fact, unchanged with ρ, whereas △s0 increases or decreases monotonically withp in a middle range of p. The corresponding variation range (δs) depends strongly on the value of the input intensity of the bright solitary beam (r). There are some peak and valley values in the curve of δs versus r under some conditions. When p increases, the bright solitary beam can scan toward both the direction same as and opposite to the crystal's c-axis. Whether the direction is the same as or opposite to the c-axis depends on the parameter values and configuration of the crystal circuit, as well as the value of r. Some potential applications are discussed.
Gaseous charge transfer reactions of multiply charged ions
International Nuclear Information System (INIS)
Doubly charged ions produced in electron impact ionization have received relatively little study due to their low abundance and masking from singly charged ions which are detected at the same mass-to-charge ratio by a mass spectrometer. This interference problem was avoided by exploiting a technique in which doubly charged molecular and fragment ions are monitored using a collisional charge-exchange process where only fast singly charged product ions are allowed to reach the detector. Primary research efforts were to determine structures and energetics of multiply charged ions formed in high energy electron impact ionization processes and their reactivities in ion-molecule charge exchange interactions. Doubly charged ion mass distributions for various chemical classes (including acetylenes, alkenes, terpenes and organophosphorus compounds) were recorded and appearance energies of prominent doubly charged ions were measured. Computer molecular orbital calculations (at the MINDO/3 level) of ionic structures, energies and charge distributions were utilized to augment the analysis of experimental results
Molecular orbital excitations in cuprates
Kim, Young-June; Hill, J. P.; Gu, G. D.; Chou, F. C.; Wakimoto, S.; Birgeneau, R. J.; Komiya, Seiki; Ando, Yoichi; Motoyama, N.; Kojima, K. M.; Uchida, S; Casa, D.; Gog, T.
2004-01-01
We report resonant inelastic x-ray scattering studies of electronic excitations in a wide variety of cuprate compounds. Specifically, we focus on the charge-transfer type excitation of an electron from a bonding molecular orbital to an antibonding molecular orbital in a copper oxygen plaquette. Both the excitation energy and the amount of dispersion are found to increase significantly as the copper oxygen bond-length is reduced. We also find that the estimated bond-length dependence of the ho...
Orbits in a logarithmic potential
Energy Technology Data Exchange (ETDEWEB)
Hooverman, R. H.
2014-04-15
The characteristics of charged particle orbits in the logarithmic electrostatic potential field surrounding a straight conducting wire at a fixed potential are investigated. The equations of motion of an electron in a logarithmic potential are derived, the limiting cases are considered, and the results of numerical integration of the equations of motion are presented along with sketches of a few representative orbits. (C.E.S.)
DEFF Research Database (Denmark)
Chang, J.; Blackburn, E.; Holmes, A. T.;
2012-01-01
Superconductivity often emerges in the proximity of, or in competition with, symmetry-breaking ground states such as antiferromagnetism or charge density waves (CDW). A number of materials in the cuprate family, which includes the high transition-temperature (high-Tc) superconductors, show spin and...... charge density wave order. Thus a fundamental question is to what extent do these ordered states exist for compositions close to optimal for superconductivity. Here we use high-energy X-ray diffraction to show that a CDW develops at zero field in the normal state of superconducting YBa2Cu3O6.67 (Tc= 67 K......). This sample has a hole doping of 0.12 per copper and a well-ordered oxygen chain superstructure. Below Tc, the application of a magnetic field suppresses superconductivity and enhances the CDW. Hence, the CDW and superconductivity in this typical high-Tc material are competing orders with similar...
Institute of Scientific and Technical Information of China (English)
柯熙政; 郭新龙
2015-01-01
大气湍流引起大气折射率随机变化, 导致空间不均匀性.高阶贝塞尔光束在大气湍流中传输时, 空间不均匀性会使光子波函数改变,形成不同的光子态引起轨道角动量的弥散.在Rytov近似下,计算了高阶贝塞尔光束在大气斜程传输中各分量所占光束总能量的权重. 讨论并对比折射率结构常数,光束波长,天顶角,轨道角动量数,接收孔径和光斑大小等参数对螺旋谱的影响,并给予相应的物理解释. 结果表明:随着折射率结构常数,天顶角和传输距离的增加以及光束波长的减小,螺旋谐波主分量对应的谱减小,轨道角动量弥散越大,而且望远镜接收孔径和光斑大小对轨道角动量弥散的影响非常小.%Atmospheric turbulence can cause random variations of the refractive index, resulting in a spatial inhomogeneity. When a high order Bessel Gaussian beam is propagating through the atmospheric turbulence, spatial inhomogeneity can bring about the change of photon wave function that causes the disperse of the orbital angular momentum to form different photon states. Under the Rytov approximation, when the high order Bessel beam was propagating in a slant-path atmospheric turbulence, the weight of the spiral harmonic component of the beam energy was calculated. And then, the impact on the spiral spectrum of the beam propagating in the slant ways, caused by refractive index structure constant, the wavelength of the beam, the zenith, orbital angular momentum, the receiver aperture, spot size were discussed and compared and a series of concrete explanations were given. The research results show that with increasing refractive index structure constant and the zenith and with decreasing wavelength of the beam, the spectrum of the spiral harmonic main component reduces and the orbital angular momentum disperses more serious. The receiver aperture and spot size have little effect on the orbital angular momentum disperse .
See, Ronald F.
2009-01-01
Two systems were evaluated for drawing Lewis structures of period 2 and 3 non-metallic compounds: the octet rule and minimization of formal charge. The test set of molecules consisted of the oxides, halides, oxohalides, oxoanions, and oxoacids of B, N, O, F, Al, P, S, and Cl. Bond orders were quantified using experimental data, including bond…
DEFF Research Database (Denmark)
Yazdanfard, Younes; Heegard, Steffen; Fledelius, Hans C.;
2001-01-01
Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology......Ophthalmology, penetrating orbital injury, orbital foreign body, ultrasound, computed tomography (CT), histology...
International Nuclear Information System (INIS)
We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues
Kim, Inkoo; Lee, Yoon Sup
2014-10-01
We report the formulation and implementation of KRCASPT2, a two-component multi-configurational second-order perturbation theory based on Kramers restricted complete active space self-consistent field (KRCASSCF) reference function, in the framework of the spin-orbit relativistic effective core potential. The zeroth-order Hamiltonian is defined as the sum of nondiagonal one-electron operators with generalized two-component Fock matrix elements as scalar factors. The Kramers symmetry within the zeroth-order Hamiltonian is maintained via the use of a state-averaged density, allowing a consistent treatment of degenerate states. The explicit expressions are derived for the matrix elements of the zeroth-order Hamiltonian as well as for the perturbation vector. The use of a fully variational reference function and nondiagonal operators in relativistic multi-configurational perturbation theory is reported for the first time. A series of initial calculations are performed on the ionization potential and excitation energies of the atoms of the 6p-block; the results display a significant improvement over those from KRCASSCF, showing a closer agreement with experimental results. Accurate atomic properties of the superheavy elements of the 7p-block are also presented, and the electronic structures of the low-lying excited states are compared with those of their lighter homologues.
Orbital Fluctuations and Orbital Flipping in RVO3 Perovskites
Yan, J.-Q.; Zhou, J.-S.; Goodenough, J. B.; Ren, Y.; Cheng, J. G.; Chang, S.; Zarestky, J.; Garlea, O.; Liobet, A.; Zhou, H. D.; Sui, Y.; Su, W. H.; McQueeney, R. J.
2007-11-01
The effect of the average R-site ionic radius ⟨IR⟩ and variance on the orbital and magnetic order in R3+-doped YVO3 was studied in Y1-xLaxVO3 and Y1-x(La0.2337Lu0.7663)xVO3 with fixed ⟨IR⟩. The orbital flipping temperature TCG increases nonlinearly with increasing R-site variance, indicating that the V-O-V bond angle is not the primary driving force stabilizing the C-type orbitally ordered phase. The suppressed thermal conductivity in the G-type orbitally ordered phase signals some remaining orbital randomness that is enhanced by t2 and et hybridization in T1g3 site symmetry.
Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y; Al-Bataineh, H.; Alexander, J.; Aoki, K.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.
2014-01-01
Charged-pion-interferometry measurements were made with respect to the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event plane for Au$+$Au collisions at $\\sqrt{s_{_{NN}}}=200$ GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event planes. The results for the 2$^{\\rm nd}$-order dependence indicate that the initial eccentricity is reduced during the medium evolution, but not reversed in the final ...
Multistep Charge Method by Charge Arrays
Segami, Go; Kusawake, Hiroaki; Shimizu, Yasuhiro; Iwasa, Minoru; Kibe, Koichi
2008-09-01
We studied reduction of the size and weight of the Power Control Unit (PCU). In this study, we specifically examined the weight of the Battery Charge Regulator (BCR), which accounts for half of the PCU weight for a low earth orbit (LEO) satellite. We found a multistep charge method by charge arrays and adopted a similar method for GEO satellites, thereby enabling the BCR reduction. We found the possibility of reducing the size and weight of PCU through more detailed design than that for a conventional PCU.BCRC1R1batterySAPower Control UnitBCRC1R1batterySAPower UnitHowever, this method decreases the state of charge (SOC) of the battery. Battery tests, a battery simulator test, and numerical analysis were used to evaluate the SOC decrease. We also studied effects of this method on the battery lifetime. The multistep charge method by charge arrays enabled charging to the same level of SOC as the conventional constant current/ constant voltage (CC/CV) charge method for a LEO satellite.
International Nuclear Information System (INIS)
GOC (General Orbit Code) is a versatile program which will perform a variety of calculations relevant to isochronous cyclotron design studies. In addition to the usual calculations of interest (e.g., equilibrium and accelerated orbits, focusing frequencies, field isochronization, etc.), GOC has a number of options to calculate injections with a charge change. GOC provides both printed and plotted output, and will follow groups of particles to allow determination of finite-beam properties. An interactive PDP-10 program called GIP, which prepares input data for GOC, is available. GIP is a very easy and convenient way to prepare complicated input data for GOC. Enclosed with this report are several microfiche containing source listings of GOC and other related routines and the printed output from a multiple-option GOC run
Sausage mode of a pinched charged particle beam
International Nuclear Information System (INIS)
The axisymmetric oscillations of a self-pinched charged particle beam are analyzed using a dispersion relation derived from a 3/2 dimensional model. This calculation includes the effects of rounded profiles, finite conductivity, a steady return current, and phase mix damping among particle orbits. However, only the lowest order radial mode of distortion is treated, and this is done in an approximate fashion
Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E-J; Kim, S H; Kim, Y-J; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Niida, T; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L
2014-06-01
Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200 GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow. PMID:24949761
Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Jr., \\,; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Gunji, T; Gustafsson, H -Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E -J; Kim, S H; Kim, Y -J; Kinney, E; Kiriluk, K; Kiss, Á; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Levy, L A Linden; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Niida, T; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J -C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T -A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L
2014-01-01
Charged-pion-interferometry measurements were made with respect to the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event plane for Au$+$Au collisions at $\\sqrt{s_{_{NN}}}=200$ GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the 2$^{\\rm nd}$- and 3$^{\\rm rd}$-order event planes. The results for the 2$^{\\rm nd}$-order dependence indicate that the initial eccentricity is reduced during the medium evolution, but not reversed in the final state, which is consistent with previous results. In contrast, the results for the 3$^{\\rm rd}$-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the 3$^{\\rm rd}$-order oscillations are largely dominated by the dynamical effects from triangular flow.
Directory of Open Access Journals (Sweden)
Yutaka Nishio
2012-11-01
Full Text Available The metallic state of the molecular conductor β-(meso-DMBEDT-TTF2X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6 is transformed into the checkerboard-type charge-ordered state at around 75–80 K with accompanying metal-insulator (MI transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in β-(meso-DMBEDT-TTF2AsF6 as well as in the reported β-(meso-DMBEDT-TTF2PF6. The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS and the resonant valence bonded (RVB state in the quarter-filled band structure.
International Nuclear Information System (INIS)
The extended Peierls-Hubbard model is used to study the competition of the spin-density-wave (SDW) and charge-density-wave (CDW) states as well as the attendant localized excitations in quasi-one-dimensional systems like MX-chains. The ground state properties are first studied as a function of the Coulomb interaction U and the on-site electron-phonon coupling λ2. The SDW state dominates in the region of large U and small λ2, while the CDW state prevails in the opposite limit. In the intermediate region these two states compete with each other, one being stable, whereas the other being metastable. The localized excitations (polarons and excitons) are studied in detail in each region using the Bogoliubov-de Gennes formalism. The self-trapped excitons (STE) in the CDW dominating regime contain locally non-vanishing SDW distortions and vice versa. As λ2 increases, the number of bound states changes from two to four for the exciton case and from two to three for the polaron case. Upon its further increase, one type of STE with a certain pattern of SDW distortion and charge transfer is transforming into another type of STE with a different pattern. The possibilities of verifying the ground state properties in optical and transport experiments and identifying these local excitations in Raman and ENDOR measurements are discussed. (author). 25 refs, 11 figs
Geometric orbit datum and orbit covers
Institute of Scientific and Technical Information of China (English)
梁科; 侯自新
2001-01-01
Vogan conjectured that the parabolic induction of orbit data is independent of the choice of the parabolic subgroup. In this paper we first give the parabolic induction of orbit covers, whose relationship with geometric orbit datum is also induced. Hence we show a geometric interpretation of orbit data and finally prove the conjugation for geometric orbit datum using geometric method.
Orbital signatures of Fano-Kondo line shapes in STM adatom spectroscopy
Frank, Sebastian; Jacob, David
2015-12-01
We investigate the orbital origin of the Fano-Kondo line shapes measured in STM spectroscopy of magnetic adatoms on metal substrates. To this end we calculate the low-bias tunnel spectra of a Co adatom on the (001) and (111) Cu surfaces with our density functional theory-based ab initio transport scheme augmented by local correlations. In order to associate different d orbitals with different Fano line shapes we only correlate individual 3 d orbitals instead of the full Co 3 d shell. We find that Kondo peaks arising in different d levels indeed give rise to different Fano features in the conductance spectra. Hence, the shape of measured Fano features allows us to draw some conclusions about the orbital responsible for the Kondo resonance, although the actual shape is also influenced by temperature, effective interaction, and charge fluctuations. Comparison with a simplified model shows that line shapes are mostly the result of interference between tunneling paths through the correlated d orbital and the s p -type orbitals on the Co atom. Very importantly, the amplitudes of the Fano features vary strongly among orbitals, with the 3 z2 orbital featuring by far the largest amplitude due to its strong direct coupling to the s -type conduction electrons.
Spin Orbit Torque in Ferromagnetic Semiconductors
Li, Hang
2016-06-21
Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall
Spin- and orbital-Hall effect in cyclic group symmetric metasurface
Lee, Yeon Ui; Bedu, Frederic; Kim, Ji Su; Fages, Frederic; Wu, Jeong Weon
2016-01-01
Vortex beam carries orbital angular momentum (AM), important in increasing the signal channels for communications. Creation of vortex beams has been achieved by use of geometric phase in subwavelength diffraction grating and liquid crystal q-plates. Anisotropic planar structure, metasurface, is utilized to enhance spin-orbit interaction for spin-dependent shaping and control of the intensity and phase distributions. High-efficiency spin-to-orbital AM conversion (SOC) has been demonstrated to generate vortex beams with high topological charges in the visible based on dielectric metasurfaces. Here, we introduce a cyclic group symmetric metasurface (CGSM) to generate vortex beam exhibiting a spin- and orbital-AM dependent transverse shift in SOC. By designing CGSMs belonging to the cyclic group Cn, dynamical phase of cross-polarization scattered beam is altered according to the order n of cyclic group while keeping geometric phase constant. When n-fold rotational symmetry of azimuthal dynamical phase gradient is...
Echography - eye orbit; Ultrasound - eye orbit; Ocular ultrasonography; Orbital ultrasonography ... ophthalmology department of a hospital or clinic. Your eye is numbed with medicine (anesthetic drops). The ultrasound ...
Some Observations on Molecular Orbital Theory
Journal of Chemical Education, 2005
2005-01-01
A few flawed predictions in the context of homonuclear diatomic molecules are presented in order to introduce students to molecular orbital (MO) theory. A common misrepresentation of the relationship between the energy of an atomic orbital and the energy of the MO associated with the atomic orbital is illustrated.
Magneto-orbital coupling in iron pnictides
Ghosh, Sayandip; Raghuvanshi, Nimisha; Singh, Avinash
2016-05-01
A magneto-orbital coupling mechanism is proposed to account for the weak energy gap at the Fermi energy in the (π , 0) ordered SDW state of a realistic three-orbital model for iron pnictides involving dxz, dyz, and dxy Fe orbitals. The orbital mixing terms between the dxy and dxz /dyz orbitals, which are important in reproducing the orbital composition of the elliptical electron pockets at (± π , 0) and (0 , ± π), are shown to play a key role in the energy gap formation in the SDW state.
International Nuclear Information System (INIS)
We describe the preparation, crystal structure determination, magnetic and transport properties of two novel Mn-containing perovskites, with a different electronic configuration for Mn atoms located in B site. Ca3Mn3+2WO9 and Ca3Mn3+/4+2NbO9 were synthesized by standard ceramic procedures; the crystallographic structure was studied from X-ray powder diffraction (XRPD) and neutron powder diffraction (NPD). Both phases exhibit a monoclinic symmetry (S.G.: P21/n); Ca3Mn2WO9 presents a long-range ordering over the B sites, whereas Ca3Mn2NbO9 is strongly disordered. By “in-situ” NPD, the temperature evolution of the structure study presents an interesting evolution in the octahedral size (〈Mn–O〉) for Ca3Mn2NbO9, driven by a charge ordering effect between Mn3+ and Mn4+ atoms, related to the anomaly observed in the transport measurements at T≈160 K. Both materials present a magnetic order below TC=30 K and 40 K for W and Nb materials, respectively. The magneto-transport measurements display non-negligible magnetoresistance properties in the paramagnetic regime. - Graphical abstract: Comparison between the octahedron size and the magnetic behaviour for Ca3Mn2NbO9 in the temperature region where the charge and magnetic order occur. Display Omitted - Highlights: • Two novel Mn-containing double perovskites were obtained by solid-state reactions. • Both double perovskites are monoclinic (P21/n) determined by XRPD and NPD. • Ca3Mn2WO9 contains Mn3+ while Ca3Mn2NbO9 includes mixed-valence cations Mn3+/Mn4+. • Ca3Mn2NbO9 presents a charge-ordering effect between Mn3+ and Mn4+ evidenced by NPD. • The magnetic and transport studies evidenced the charge ordering in Ca3Mn2NbO9
Spin-Orbit Coupling and the Conservation of Angular Momentum
Hnizdo, V.
2012-01-01
In nonrelativistic quantum mechanics, the total (i.e. orbital plus spin) angular momentum of a charged particle with spin that moves in a Coulomb plus spin-orbit-coupling potential is conserved. In a classical nonrelativistic treatment of this problem, in which the Lagrange equations determine the orbital motion and the Thomas equation yields the…
... Diagnosis Treatment Medical Dictionary Additional Content Medical News Inflammation of the Orbit (Inflammatory Orbital Pseudotumor) By James ... Introduction to Eye Socket Disorders Cavernous Sinus Thrombosis Inflammation of the Orbit Orbital Cellulitis Preseptal Cellulitis Tumors ...
Control of the spin to charge conversion using the inverse Rashba-Edelstein effect
Energy Technology Data Exchange (ETDEWEB)
Sangiao, S. [Service de Physique de l' Etat Condensé, CEA Saclay, DSM/IRAMIS/SPEC, bat 772, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France); Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Fundación ARAID, 50018 Zaragoza (Spain); De Teresa, J. M. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Instituto de Ciencia de Materiales de Aragón (ICMA), Universidad de Zaragoza-CSIC, Facultad de Ciencias, 50009 Zaragoza (Spain); Morellon, L.; Martinez-Velarte, M. C. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Lucas, I. [Laboratorio de Microscopías Avanzadas (LMA), Instituto de Nanociencia de Aragón (INA) and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza (Spain); Fundación ARAID, 50018 Zaragoza (Spain); Viret, M., E-mail: michel.viret@cea.fr [Service de Physique de l' Etat Condensé, CEA Saclay, DSM/IRAMIS/SPEC, bat 772, CNRS UMR 3680, F-91191 Gif-sur-Yvette (France)
2015-04-27
We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the “Inverse Rashba Edelstein Effect” (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence.
International Nuclear Information System (INIS)
The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, L.
1995-01-01
The past fifteen years have witnessed a remarkable development of methods for analyzing single particle orbit dynamics in accelerators. Unlike their more classic counterparts, which act upon differential equations, these methods proceed by manipulating Poincare maps directly. This attribute makes them well matched for studying accelerators whose physics is most naturally modelled in terms of maps, an observation that has been championed most vigorously by Forest. In the following sections the author sketchs a little background, explains some of the physics underlying these techniques, and discusses the best computing strategy for implementing them in conjunction with modeling accelerators.
International Nuclear Information System (INIS)
The application by Union Gas Ltd. to the Ontario Energy Board for fixing just and reasonable rates and other charges for the sale, distribution, storage and transmission of natural gas was discussed. The proposed rates and other charges are based on projected results for the test year beginning January 1, 1999 and ending December 31, 1999. This document describes: (1) the application and the proceedings, (2) the revenue requirement and other matters, (3) cost allocation and rate design, (4) costs and completion of the proceedings. Based on the detailed examination of the Union Gas Application, comments by intervenors, and the Board's own observations the Board found a revenue sufficiency of $ 85.076 million, reduced to $ 71 million to reflect the E.B.R.O 499-01 Rate Order. The Board directs the Company to submit a Draft Rate Order accompanied by various additional documentation, and directs Union Gas to pay the Board's cost of the proceedings
Dudev, Todor; Bobadova-Parvanova, Petia; Pencheva, Daniela; Galabov, Boris
1997-12-01
The structural and vibrational spectroscopic parameters of a series of simple nitrile compounds were evaluated by HF/6-31+G(d,p) ab initio quantum mechanical calculations. The series includes HCN, FCN, CICN, CH 2FCN, CH 2CICN, CH 3CN, CF 3CN, CCl 3CN, HOCN, HSCN and NH 2CN. The theoretical infrared intensities were transformed into quantities associated with the charge distribution and dynamics in the molecules following the formalism of the effective bond charge method. Satisfactory linear relations were found between the effective bond charges and bond lengths, as well as between the bond charges and the molecular electrostatic potential at the nitrogen atom.
International Nuclear Information System (INIS)
Structure, magnetic and transport properties of polycrystalline Bi0.6-xPrxCa0.4MnO3 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) have been studied. Systematic substitution of Pr at Bi site induces an interesting interplay between the charge ordering and antiferromagnetism. The charge ordering temperature (TCO) decreases with increasing x. The antiferromagnetic (AFM) ordering temperature (TN) increases sharply at both the extremes but remains nearly constant from x=0.2 to 0.4. At temperatures lower than TN a transition to the glassy state is observed. The nature of this glass like state appears to be controlled by the Pr content, and at lower values of x this is akin to a spin glass, while at higher x it has a characteristic of cluster glass. The Pr doping also leads to enhancement in the magnetic moment. In the present work it has been proposed that the local lattice distortion induced due to size mismatch between the A-site cations and 6s2 character of Bi3+ lone pair electron is responsible for the observed magnetic and electrical properties.
Energy Technology Data Exchange (ETDEWEB)
Yadav, Kamlesh [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Singh, H.K. [National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 100012 (India); Varma, G.D., E-mail: gdvarfph@iitr.ernet.in [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India)
2012-04-15
Structure, magnetic and transport properties of polycrystalline Bi{sub 0.6-x}Pr{sub x}Ca{sub 0.4}MnO{sub 3} (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) have been studied. Systematic substitution of Pr at Bi site induces an interesting interplay between the charge ordering and antiferromagnetism. The charge ordering temperature (T{sub CO}) decreases with increasing x. The antiferromagnetic (AFM) ordering temperature (T{sub N}) increases sharply at both the extremes but remains nearly constant from x=0.2 to 0.4. At temperatures lower than T{sub N} a transition to the glassy state is observed. The nature of this glass like state appears to be controlled by the Pr content, and at lower values of x this is akin to a spin glass, while at higher x it has a characteristic of cluster glass. The Pr doping also leads to enhancement in the magnetic moment. In the present work it has been proposed that the local lattice distortion induced due to size mismatch between the A-site cations and 6s{sup 2} character of Bi{sup 3+} lone pair electron is responsible for the observed magnetic and electrical properties.
Chen, Shuang; Ma, Jing
2010-10-14
The lying-down and standing-up CuPc and F(16)CuPc films on HOPG (highly ordered pyrolytic graphite) and C8-SAM/Au(111) (octane-1-thiol terminated Au(111)) substrates are investigated by using a hybrid strategy combing the molecular dynamic (MD) simulations with density functional theory (DFT) calculations, in order to understand the influence of packing orientation on charge carrier mobilities. On the basis of the periodic slab model and consistent-valence force field, MD simulations show the populations of various packing configurations and radial distribution of intermolecular distance in the films at room temperature. It is also demonstrated that the external electric field (parallel or perpendicular to the substrate) perturbs the intermolecular distances in CuPc and F(16)CuPc films, especially for the slipped edge-to-face stackings. DFT calculations are then used to evaluate two key charge-transfer parameters, reorganization energy and transfer integral. An electrostatics embedding model is employed to approximately consider the external electrostatics contributions to reorganization energy. The thermal-averaged mobility is consequently estimated by taking account of both electronic structures of charge-hopping pairs and dynamic fluctuations in film morphologies under various experimental conditions. It is found that CuPc has smaller reorganization energy and larger hole (electron) mobilities than F(16)CuPc. Under the external electric field of 10(4)-10(7) V cm(-1), both hole and electron mobilities of CuPc and F(16)CuPc films would decrease to 1-3 orders of magnitude. CuPc (F(16)CuPc) films show substantial orientation dependence of mobilities on the ratio of standing-up versus lying-down orientations falling in the range of 10-1000. PMID:20714578
International Nuclear Information System (INIS)
Highlights: ► The structural, magnetic, and electrical properties of Ln0.5Sr0.5Mn0.9Cu0.1O3 (Ln = La, Pr, Nd, or Ho) have been studied. ► The influence of A-site cation radius (〈rA〉) and the A-site cation size-disorder (σ2) on magnetic properties are studied. ► The various interdependent phenomena such as ferromagnetism, phase separation, and charge ordering are investigated. - Abstract: The structural, magnetic, and electrical properties of Ln0.5Sr0.5Mn0.9Cu0.1O3 (Ln = La, Pr, Nd, or Ho) perovskite manganites have been investigated to explore the influence of A-site cation radius (〈rA〉) and the A-site cation size-disorder (σ2) on the various interdependent phenomena such as ferromagnetism (FM), phase separation (PS), and charge ordering (CO). The temperature dependence magnetization (M–T) curve of La-based sample shows four distinct points at ∼269 K, 255 K, 200 K, and 148 K corresponding to strong FM, cluster glass (CG), weak FM, and charged ordered antiferromagnetic (COAFM) transitions, respectively. Our investigation shows that Neel temperatures (TN) increases, whereas Curie (TC) and irreversibility temperatures (Tirr) decrease with decreasing 〈rA〉, i.e., with increasing σ2. Furthermore, the value of the magnetization decreases and resistivity increases with decreasing 〈rA〉. All samples exhibit insulating behavior in the temperature range 77–300 K and above 110 K the electronic conduction mechanism has been described within the framework of the variable range hopping (VRH) model.
Energy Technology Data Exchange (ETDEWEB)
Kumar, Satyam [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Dwivedi, G.D. [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Lourembam, J. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Kumar, Shiv; Saxena, U.; Ghosh, A.K. [Department of Physics, Banaras Hindu University, Varanaasi 221005 (India); Chou, H. [Department of Physics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (China); Chatterjee, Sandip, E-mail: schatterji.app@iitbhu.ac.in [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)
2015-11-15
Structural, transport and optical properties of nano-crystalline Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} have been investigated to emphasize on the semiconducting properties of charge-ordered manganite. Rietveld refinement of X-ray diffraction pattern of Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles show that due to increase in sintering temperature, MnO{sub 6} octahedra elongated along z-direction and compressed in x-y plane. Both Mn–O–Mn angles are found to decrease with increasing sintering temperature. Fourier transform infrared (FTIR) spectroscopy measurements reveal that the stretching and bending vibration of Mn–O–Mn is responsible for the change in Mn–O–Mn bond length and bond angle respectively. With increasing sintering temperature, these vibrations tend to increase, which resulted in the further distortion of MnO{sub 6} octahedra. Magnetic measurements suggest that charge ordering is established and system becomes antiferromagnetic with increasing particle size. Resistivity behavior of Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles clearly exhibit semiconducting nature of these systems, which is due to the formation of charge-ordered state of Mn{sup 3+} and Mn{sup 4+}. Estimated optical band-gap of ∼3.7 eV for Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanocrystals, makes it a potential candidate for wide band-gap magnetic semiconductors. - Highlights: • Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles have been synthesized via sol–gel route. • Optical properties of charge-ordered Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} have been investigated. • Pr{sub 0.6}Ca{sub 0.4}MnO{sub 3} nanoparticles exhibit wide band-gap (3.7 eV) semiconducting nature. • Potential candidate for wide band-gap magnetic semiconductor device applications.
Magnetic and charge ordering properties of Bi0.2Ca0.8Mn0.9X0.1O3 (where X = Ti, Cr, Fe, Co, Ni, Cu)
International Nuclear Information System (INIS)
Highlights: ► Structural, magnetic and transport properties of Bi0.2Ca0.8Mn0.9X0.1O3 (where X = Ti, Cr, Fe, Co, Ni, Cu) have been studied. ► TCO decreases by ∼10 K and ∼33 K, in Ni2+ and Cu2+ doped samples, while it increases by 42 K in Ti4+ doped sample. ► In case of Fe3+, Co3+ and Cr3+ doped samples charge-ordering (CO) completely disappears. ► Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. ► The magnetic exchange interactions between Mn and doped ions explain magnetic and electrical properties. - Abstract: Structural, magnetic and transport properties of Bi0.2Ca0.8Mn0.9X0.1O3 (where X = Ti, Cr, Fe, Co, Ni, Cu) have been investigated. The parent sample Bi0.2Ca0.8MnO3 (BCMO) exhibits robust charge-ordered antiferrromagnetic (COAFM) phase with charge ordering temperature (TCO) ∼155 K and AFM Neel temperature (TN) ∼105 K. TCO decreases by ∼10 K and ∼33 K, respectively, in Ni2+ and Cu2+ doped samples, while it increases by 42 K in Ti4+ doped sample. In case of Fe3+, Co3+ and Cr3+ doped samples charge-ordering (CO) completely melts. The paramagnetic (PM) to ferromagnetic (FM) transition temperatures (TC) of doped samples have lower values as compared to undoped one. In addition, a spin glass (SG) state is observed in all the samples and the magnetic state at T C is akin to a cluster glass (CG) for undoped and Ni, Cu, Ti doped samples formed due to the presence of FM clusters in COAFM matrix. Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Based on the present study it has been proposed that the disorder induced by doping on the Mn site and magnetic exchange interactions between Mn and doped ions play a key role in explaining magnetic and electrical properties.
Small Mercury Relativity Orbiter
Bender, Peter L.; Vincent, Mark A.
1989-01-01
The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.
Stable photon orbits in stationary axisymmetric electrovacuum spacetimes
Dolan, Sam R
2016-01-01
We investigate the existence and phenomenology of stable photon orbits (SPOs) in stationary axisymmetric electrovacuum spacetimes in four dimensions. First, we classify the equatorial circular photon orbits of Kerr-Newman spacetimes in the charge-spin plane. Second, using a Hamiltonian formulation, we show that Reissner-Nordstr\\"om di-holes (a family encompassing the Majumdar-Papapetrou and Weyl-Bach special cases) admit SPOs, in a certain parameter regime that we investigate. Third, we explore the transition from order to chaos for typical SPOs bounded within a torus around a di-hole, via a selection of Poincar\\'e sections. Finally, for general axisymmetric stationary spacetimes, we show that the Einstein-Maxwell field equations allow for the existence of SPOs in electrovacuum; but not in pure vacuum.
Gao, Jun; Li, Chong Sheng; Li, Zhao
2007-01-01
We present the calculations of the next-to-leading order (NLO) QCD corrections to the inclusive total cross sections for the associated production of the $W^{\\pm}H^{\\mp}$ through $b\\bar{b}$ annihilation in the Minimal Supersymmetric Standard Model at the CERN Large Hadron Collider. The NLO QCD corrections can either enhance or reduce the total cross sections, but they generally efficiently reduce the dependence of the total cross sections on the renormalization/factorization scale. The magnit...
Orbit propagation in Minkowskian geometry
Roa, Javier; Peláez, Jesús
2015-09-01
The geometry of hyperbolic orbits suggests that Minkowskian geometry, and not Euclidean, may provide the most adequate description of the motion. This idea is explored in order to derive a new regularized formulation for propagating arbitrarily perturbed hyperbolic orbits. The mathematical foundations underlying Minkowski space-time are exploited to describe hyperbolic orbits. Hypercomplex numbers are introduced to define the rotations, vectors, and metrics in the problem: the evolution of the eccentricity vector is described on the Minkowski plane in terms of hyperbolic numbers, and the orbital plane is described on the inertial reference using quaternions. A set of eight orbital elements is introduced, namely a time-element, the components of the eccentricity vector in , the semimajor axis, and the components of the quaternion defining the orbital plane. The resulting formulation provides a deep insight into the geometry of hyperbolic orbits. The performance of the formulation in long-term propagations is studied. The orbits of four hyperbolic comets are integrated and the accuracy of the solution is compared to other regularized formulations. The resulting formulation improves the stability of the integration process and it is not affected by the perihelion passage. It provides a level of accuracy that may not be reached by the compared formulations, at the cost of increasing the computational time.
Lageos orbit and solar eclipses
Rubincam, D. P.
1984-01-01
The objective was to assess the importance of solar eclipses on Lageos' orbit. Solar radiation pressure perturbs the orbit of the Lageos satellite. The GEODYN orbit determination computer program includes solar radiation pressure as one of the forces operating on the satellite as it integrates the orbit. GEODYN also takes into account the extinction of sunlight when Lageos moves into the Earth's shadow. The effect of solar eclipses on the semimajor axis of Lageos' orbit was computed analytically by assuming Lageos to be in a circular orbit, the Sun and the Moon to be in the plane of the orbit, and the Moon to be stationary in the sky in front of the Sun. Also, the magnitude of the radiation pressure is assumed to be linearly related to the angular separation of the Sun and Moon, and that Lageos is a perfect absorber of radiation. The computation indicates that an eclipse of the Sun by the Moon as seen by Lageos can affect the semimajor axis at the 1 centimeter (1 cm) level. Such a change is significant enough to include in GEODYN, in order to get an accurate orbit for Lageos.
Charge-transport simulations in organic semiconductors
Energy Technology Data Exchange (ETDEWEB)
May, Falk
2012-07-06
In this thesis we have extended the methods for microscopic charge-transport simulations for organic semiconductors, where weak intermolecular interactions lead to spatially localized charge carriers, and the charge transport occurs as an activated hopping process between diabatic states. In addition to weak electronic couplings between these states, different electrostatic environments in the organic material lead to a broadening of the density of states for the charge energies which limits carrier mobilities. The contributions to the method development include (i) the derivation of a bimolecular charge-transfer rate, (ii) the efficient evaluation of intermolecular (outer-sphere) reorganization energies, (iii) the investigation of effects of conformational disorder on intramolecular reorganization energies or internal site energies and (iv) the inclusion of self-consistent polarization interactions for calculation of charge energies. These methods were applied to study charge transport in amorphous phases of small molecules used in the emission layer of organic light emitting diodes (OLED). When bulky substituents are attached to an aromatic core in order to adjust energy levels or prevent crystallization, a small amount of delocalization of the frontier orbital to the substituents can increase electronic couplings between neighboring molecules. This leads to improved charge-transfer rates and, hence, larger charge-mobility. We therefore suggest using the mesomeric effect (as opposed to the inductive effect) when attaching substituents to aromatic cores, which is necessary for example in deep blue OLEDs, where the energy levels of a host molecule have to be adjusted to those of the emitter. Furthermore, the energy landscape for charges in an amorphous phase cannot be predicted by mesoscopic models because they approximate the realistic morphology by a lattice and represent molecular charge distributions in a multipole expansion. The microscopic approach shows that
Nonlinear optics of the electrostatic accelerator tubes-third order Lie map
International Nuclear Information System (INIS)
Lie algebraic method is used in the analysis of nonlinear transport for the relativistic charged particles in cylindrical symmetrical electrostatic fields, and particle orbits of third order approximation in the six dimensional phase space (x, x', y, y', τ, pτ) are obtained. In the analysis, the authors take the electrostatic accelerating tube as an example, and divide the electrostatic accelerating tube into three elements: entrance thin lens, uniform accelerating field and exit thin lens, on which Lie map is applied, and the solutions through third order of particle orbits are obtained finally. This method can also be used for the electrostatic lenses
PTCDA chemisorbed on Ag(110): Dispersion interactions and charge equilibration
Energy Technology Data Exchange (ETDEWEB)
Scholz, Reinhard [Walter Schottky Institut, TU Muenchen (Germany); Abbasi, Afshin [Institut fuer Physik, TU Chemnitz (Germany)
2009-07-01
The chemisorption of PTCDA on Ag(110) is analysed with 2{sup nd} order Moeller-Plesset perturbation theory (MP2), accounting therefore for the main part of the dispersion interactions at an ab initio level. Irrespective of the size of the rigid silver cluster used as a substrate model, the optimized geometry consists of a nearly flat perylene core, surrounded by carboxylic oxygens closer to the substrate, but with anhydride atoms at a larger height. The charge equilibration between adsorbate and substrate involves charge injection from the oxygen atoms into the substrate, and back transfer of two electrons into the former LUMO of the free molecule. Surprisingly, the resulting negative charge of the adsorbate has a very small contribution in the core region where the main part of the LUMO is localized, but instead accumulates on the end groups. It can be shown in detail that a rehybridization of molecular {sigma} and {pi} states results in a decoupling of several {pi} states on the oxygen atoms from the aromatic core, as opposed to the free molecule, where the {pi} states delocalize over the entire molecule. These decoupled {pi} states on the end groups are forming the binding Ag-O orbitals injecting electronic charge from the molecule into the substrate. Compared to the dominating mechanisms discussed above, the hybridization between orbitals in the core region and the underlying substrate plays only a minor role for the charge balance.
Electronic structure induced reconstruction and magnetic ordering at the LaAlO3/SrTiO3 interface
International Nuclear Information System (INIS)
The finding of a high mobility electron gas at the interface between two large band gap insulators LaAlO3 and SrTiO3 led to the observation of interface magnetic ordering and, more recently superconductivity. We study this interface using density functional theory (LDA and LDA+U), taking into account the possibility of interface structural relaxation, charge and spin ordering. We find that charge, orbital and magnetic ordering can occur in a quarter-filled band system. The lowest energy configuration is a charge-ordered antiferromagnetic insulator. At a slightly higher energy, we find a charge-ordered ferromagnetic insulator with a smaller band gap. We discuss various scenarios for explaining the experimental observations
International Nuclear Information System (INIS)
Emergent electromagnetic field which couples to electron's spin in ferromagnetic metals is theoretically studied. Rashba spin-orbit interaction induces spin electromagnetic field which is in the linear order in gradient of magnetization texture. The Rashba-induced effective electric and magnetic fields satisfy in the absence of spin relaxation the Maxwell's equations as in the charge-based electromagnetism. When spin relaxation is taken into account besides spin dynamics, a monopole current emerges generating spin motive force via the Faraday's induction law. The monopole is expected to play an important role in spin-charge conversion and in the integration of spintronics into electronics
Singular optical lattice generation using light beams with orbital angular momentum.
Soares, Willamys C; Moura, André L; Canabarro, Askery A; de Lima, Emerson; Hickmann, Jandir M
2015-11-15
In this Letter we numerically and experimentally demonstrated that a lattice with an optical vortex distributed over the entire lattice can be generated in the Fourier space using three higher-order Laguerre-Gauss beams placed at the vertices of an equilateral triangle in real space. In this scheme the optical vortice's lattice presents a topological defect in its central region. Probing the net topological charge of the whole lattice, we found that it corresponds to the topological charge associated with the orbital angular momentum of each beam in real space. PMID:26565816
Spin-orbit coupling and the conservation of angular momentum
Hnizdo, V.
2011-01-01
In nonrelativistic quantum mechanics, the total (i.e. orbital plus spin) angular momentum of a charged particle with spin that moves in a Coulomb plus spin-orbit-coupling potential is conserved. In a classical nonrelativistic treatment of this problem, in which the Lagrange equations determine the orbital motion and the Thomas equation yields the rate of change of the spin, the particle's total angular momentum in which the orbital angular momentum is defined in terms of the kinetic momentum ...
Johnston, A. S., (Nick); Ryder, Mel; Tyler, Tony R.
1998-01-01
An automated fluid and power interface system needs to be developed for future space missions which require on orbit consumable replenishment. Current method of fluid transfer require manned vehicles and extravehicular activity. Currently the US does not have an automated capability for consumable transfer on-orbit. This technology would benefit both Space Station and long duration satellites. In order to provide this technology the Automated Fluid Interface System (AFIS) was developed. The AFIS project was an advanced development program aimed at developing a prototype satellite servicer for future space operations. This mechanism could transfer propellants, cryogens, fluids, gasses, electrical power, and communications from a tanker unit to the orbiting satellite. The development of this unit was a cooperative effort between Marshall Space Flight Center in Huntsville, Alabama, and Moog, Inc. in East Aurora, New York. An engineering model was built and underwent substantial development testing at Marshall Space Flight Center (MSFC). While the AFIS is not suitable for spaceflight, testing and evaluation of the AFIS provided significant experience which would be beneficial in building a flight unit. The lessons learned from testing the AFIS provided the foundation for the next generation fluid transfer mechanism, the Orbital Fluid Transfer System (OFTS). The OFTS project was a study contract with MSFC and Moog, Inc. The OFTS was designed for the International Space Station (ISS), but its flexible design could used for long duration satellite missions and other applications. The OFTS was designed to be used after docking. The primary function was to transfer bipropellants and high pressure gases. The other items addressed by this task included propellant storage, hardware integration, safety and control system issues. A new concept for high pressure couplings was also developed. The results of the AFIS testing provided an excellent basis for the OFTS design. The OFTS
International Nuclear Information System (INIS)
Sm0.5-xPrxSr0.5MnO3 exhibits a variety of ground states as x is varied from 0 to 0.5. At an intermediate doping of x = 0.3 a charge-ordered CE-type antiferromagnetic insulating (AFI) ground state is seen. The transition to this ground state is from a paramagnetic-insulating (PMI) phase through a ferromagnetic-metallic phase (FMM). Local structures in PMI and AFI phases of the x = 0.3 sample have been investigated using Pr K-edge and Sm K-edge extended x-ray absorption fine structure (EXAFS). It can be seen that the tilting and rotation of the MnO6 octahedra about the b-axis are responsible for the charge-ordered CE-type antiferromagnetic ground state at low temperatures. In addition a shift in the position of the rare-earth ion along the c-axis has to be considered to account for observed distribution of bond distances around the rare-earth ion
Magnetic and charge ordering properties of Bi0.6−xEuxCa0.4MnO3 (0.0≤x≤0.6)
International Nuclear Information System (INIS)
We have studied structure, magnetic and transport properties of polycrystalline Bi0.6−xEuxCa0.4MnO3 (x=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) perovskite manganites. Magnetic measurements show that the charge-ordering temperature (TCO) decreases with increasing x up to x=0.4 and then slightly increases with further increasing x up to x=0.6. Further, the antiferromagnetic (AFM) ordering temperature (TN) decreases with increasing x. At TN a transition to metamagnetic glass like state is also seen. Eu doping also leads to enhancement in the magnetic moment and a concomitant decrease in resistivity up to x=0.2 and then an increase in resistivity up to x=0.5. We propose that the local lattice distortion induced by the size mismatch between the A-site cations and 6s2 character of Bi3+ lone pair electron are responsible for the observed variation in physical properties. - Highlights: ► We have studied structure, magnetic and transport properties of Bi0.6−xEuxCa0.4MnO3 (0.0≤x≤0.6). ► Substitution of Eu at Bi-site induces a strong interplay between the magnetic and charge-ordering properties. ► TCO decreases with increasing x up to x=0.4 and then slightly increases with further increasing x up to x=0.6. ► The antiferromagnetic ordering temperature (TN) decreases with increasing x. ► The A-site cations size mismatch and 6s2 character of Bi3+ lone pair electron explain variation in physical properties.
Orbital angular momentum microlaser
Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M.; Feng, Liang
2016-07-01
Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes.
Orbital angular momentum microlaser.
Miao, Pei; Zhang, Zhifeng; Sun, Jingbo; Walasik, Wiktor; Longhi, Stefano; Litchinitser, Natalia M; Feng, Liang
2016-07-29
Structured light provides an additional degree of freedom for modern optics and practical applications. The effective generation of orbital angular momentum (OAM) lasing, especially at a micro- and nanoscale, could address the growing demand for information capacity. By exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser producing a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. The polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Our OAM microlaser could find applications in the next generation of integrated optoelectronic devices for optical communications in both quantum and classical regimes. PMID:27471299
Full particle orbit effects in regular and stochastic magnetic fields
Ogawa, Shun; Cambon, Benjamin; Leoncini, Xavier; Vittot, Michel; del Castillo-Negrete, Diego; Dif-Pradalier, Guilhem; Garbet, Xavier
2016-07-01
We present a numerical study of charged particle motion in a time-independent magnetic field in cylindrical geometry. The magnetic field model consists of an unperturbed reversed-shear (non-monotonic q-profile) helical part and a perturbation consisting of a superposition of modes. Contrary to most of the previous studies, the particle trajectories are computed by directly solving the full Lorentz force equations of motion in a six-dimensional phase space using a sixth-order, implicit, symplectic Gauss-Legendre method. The level of stochasticity in the particle orbits is diagnosed using averaged, effective Poincare sections. It is shown that when only one mode is present, the particle orbits can be stochastic even though the magnetic field line orbits are not stochastic (i.e., fully integrable). The lack of integrability of the particle orbits in this case is related to separatrix crossing and the breakdown of the global conservation of the magnetic moment. Some perturbation consisting of two modes creates resonance overlapping, leading to Hamiltonian chaos in magnetic field lines. Then, the particle orbits exhibit a nontrivial dynamics depending on their energy and pitch angle. It is shown that the regions where the particle motion is stochastic decrease as the energy increases. The non-monotonicity of the q-profile implies the existence of magnetic ITBs (internal transport barriers) which correspond to shearless flux surfaces located in the vicinity of the q-profile minimum. It is shown that depending on the energy, these magnetic ITBs might or might not confine particles. That is, magnetic ITBs act as an energy-dependent particle confinement filter. Magnetic field lines in reversed-shear configurations exhibit topological bifurcations (from homoclinic to heteroclinic) due to separatrix reconnection. We show that a similar but more complex scenario appears in the case of particle orbits that depend in a non-trivial way on the energy and pitch angle of the
Institute of Scientific and Technical Information of China (English)
Nila; F.Moeloek
1993-01-01
Orbital anatomy, the clinical features of orbital tumors, the recent development of the diagnosis and management of orbital tumors were described. The incidence of orbital tumors in Dr. Cipto Mangunkusumo Hospital in the past years were introduced. The principle of management of orbital tumors and their prognosis were discussed.
Kalman Filter Implementation to Determine Orbit and Attitude of a Satellite in a Molniya Orbit
Keil, Elizabeth Marie
2014-01-01
This thesis details the development and implementation of an attitude and orbit determining Kalman filter algorithm for a satellite in a Molniya orbit. To apply the Kalman Filter for orbit determination, the equations of motion of the two body problem were propagated using Cowell's formulation. Four types of perturbing forces were added to the propagated model in order to increase the accuracy of the orbit prediction. These four perturbing forces are Earth oblateness, atmospheric drag, lunar ...