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Sample records for high quality ferromagnetic

  1. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    International Nuclear Information System (INIS)

    Tu, Nguyen Thanh; Hai, Pham Nam; Anh, Le Duc; Tanaka, Masaaki

    2016-01-01

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga_1_−_x,Fe_x)Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  2. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physics, Ho Chi Minh City University of Pedagogy, 280, An Duong Vuong Street, District 5, Ho Chi Minh City 748242 (Viet Nam); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Anh, Le Duc [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-05-09

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  3. High energy excitations in itinerant ferromagnets

    International Nuclear Information System (INIS)

    Prange, R.E.

    1984-01-01

    Itinerant magnets, those whose electrons move throughout the crystal, are described by band theory. Single particle excitations offer confirmation of band theory, but their description requires important corrections. The energetics of magnetism in iron and nickel is also described in band theory but requires complex bands. Magnetism above the critical temperature and the location of the critical temperature offer discriminants between the two major models of magnetism at high temperature and can be addressed by high energy excitations

  4. High-field susceptibility in ferromagnetic NpOs2

    International Nuclear Information System (INIS)

    Dunlap, B.D.; Aldred, A.T.; Lam, D.J.; Davidson, G.R.

    1975-01-01

    NpOs 2 is known to be a ferromagnet with a Curie temperature of 7.5 0 K. Previous bulk magnetization measurements indicated a field-induced magnetization even well below the transition temperature. By a measurement of the local high-field susceptibility, using the Moessbauer effect in 237 Np, a susceptibility of (1.2 +- 0.2) x 10 -2 emu/mole at 1.6 0 K is obtained, in general agreement with the bulk measurement. Such a large susceptibility is best understood by a model f itinerant magnetism, although other properties of the material indicate localized behavior

  5. Passive high-frequency devices based on superlattice ferromagnetic nanowires

    International Nuclear Information System (INIS)

    Ye, B.; Li, F.; Cimpoesu, D.; Wiley, J.B.; Jung, J.-S.; Stancu, A.; Spinu, L.

    2007-01-01

    In this paper we propose to tailor the bandwidth of a microwave filter by exploitation of shape anisotropy of nanowires. In order to achieve this control of shape anisotropy, we considered superlattice wires containing varying-sized ferromagnetic regions separated by nonferromagnetic regions. Superlattice wires of Ni and Au with a nominal diameter of 200 nm were grown using standard electrodeposition techniques. The microwave properties were probed using X-band (9.8 GHz) ferromagnetic resonance (FMR) experiments performed at room temperature. In order to investigate the effectiveness of the shape anisotropy on the superlattice nanowire based filter the FMR spectrum of superlattice structure is compared to the FMR spectra of nanowires samples with constant length

  6. Absence of field anisotropy in the intrinsic ferromagnetic signals of highly oriented pyrolytic graphite

    International Nuclear Information System (INIS)

    Ballestar, A.; Setzer, A.; Esquinazi, P.; Garcia, N.

    2011-01-01

    We have measured the magnetization of bulk samples of highly oriented pyrolytic graphite (HOPG) at magnetic fields applied parallel and perpendicular to the graphene layers. Within experimental error the intrinsic ferromagnetic signals of the samples show similar magnetic moments at saturation for the two magnetic field directions, in contrast to recently published data (J. Cervenka et al., Nat. Phys. 5 (2009) 840). To check that the SQUID device provides correctly the small ferromagnetic signals obtained after subtracting the 100 times larger diamagnetic background, we have prepared a sample with a superconducting Pb-film deposited on one of the HOPG surfaces. We show that the field dependence of the measured magnetic moment and after the background subtraction is highly reliable even in the sub-μ emu range providing the real magnetic properties of the embedded small ferromagnetic and superconducting signals. - Research Highlights: → We have measured the magnetization of bulk samples of highly oriented pyrolytic graphite (HOPG) at magnetic fields applied parallel and perpendicular to the graphene layers.→ Within experimental error the intrinsic ferromagnetic signals of the samples show similar magnetic moments at saturation for the two magnetic field directions.→ The absence of magnetic anisotropy of the intrinsic ferromagnetic order found in HOPG samples contrasts recently published data by Cervenka et al., Nat Phys 5, 840 (2009).

  7. Critical currents and superconductivity ferromagnetism coexistence in high-Tc oxides

    CERN Document Server

    Khene, Samir

    2016-01-01

    The book comprises six chapters which deal with the critical currents and the ferromagnetism-superconductivity coexistence in high-Tc oxides. It begins by gathering key data for superconducting state and the fundamental properties of the conventional superconductors, followed by a recap of the basic theories of superconductivity. It then discusses the differences introduced by the structural anisotropy on the Ginzburg-Landau approach and the Lawrence-Doniach model before addressing the dynamics of vortices and the ferromagnetism-superconductivity coexistence in high-Tc oxides, and provides an outline of the pinning phenomena of vortices in these materials, in particular the pinning of vortices by the spins. It elucidates the methods to improve the properties of superconducting materials for industrial applications. This optimization aims at obtaining critical temperatures and densities of critical currents at the maximum level possible. Whereas the primary objective is the basic mechanisms pushing the superco...

  8. High Power Laser Beam Welding of Thick-walled Ferromagnetic Steels with Electromagnetic Weld Pool Support

    Science.gov (United States)

    Fritzsche, André; Avilov, Vjaceslav; Gumenyuk, Andrey; Hilgenberg, Kai; Rethmeier, Michael

    The development of modern high power laser systems allows single pass welding of thick-walled components with minimal distortion. Besides the high demands on the joint preparation, the hydrostatic pressure in the melt pool increases with higher plate thicknesses. Reaching or exceeding the Laplace pressure, drop-out or melt sagging are caused. A contactless electromagnetic weld support system was used for laser beam welding of thick ferromagnetic steel plates compensating these effects. An oscillating magnetic field induces eddy currents in the weld pool which generate Lorentz forces counteracting the gravity forces. Hysteresis effects of ferromagnetic steels are considered as well as the loss of magnetization in zones exceeding the Curie temperature. These phenomena reduce the effective Lorentz forces within the weld pool. The successful compensation of the hydrostatic pressure was demonstrated on up to 20 mm thick plates of duplex and mild steel by a variation of the electromagnetic power level and the oscillation frequency.

  9. Defect mediated magnetic interaction and high Tc ferromagnetism in Co doped ZnO nanoparticles.

    Science.gov (United States)

    Pal, Bappaditya; Giri, P K

    2011-10-01

    Structural, optical and magnetic studies have been carried out for the Co-doped ZnO nanoparticles (NPs). ZnO NPs are doped with 3% and 5% Co using ball milling and ferromagnetism (FM) is studied at room temperature and above. A high Curie temperature (Tc) has been observed from the Co doped ZnO NPs. X-ray diffraction and high resolution transmission electron microscopy analysis confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. UV-visible absorption and photoluminescence studies on the doped samples show change in band structure and oxygen vacancy defects, respectively. Micro-Raman studies of doped samples shows defect related additional strong bands at 547 and 574 cm(-1) confirming the presence of oxygen vacancy defects in ZnO lattice. The field dependence of magnetization (M-H curve) measured at room temperature exhibits the clear M-H loop with saturation magnetization and coercive field of the order of 4-6 emu/g and 260 G, respectively. Temperature dependence of magnetization measurement shows sharp ferromagnetic to paramagnetic transition with a high Tc = 791 K for 3% Co doped ZnO NPs. Ferromagnetic ordering is interpreted in terms of overlapping of polarons mediated through oxygen vacancy defects based on the bound magnetic polaron (BMP) model. We show that the observed FM data fits well with the BMP model involving localised carriers and magnetic cations.

  10. Feasibility of introducing ferromagnetic materials to onboard bulk high-Tc superconductors to enhance the performance of present maglev systems

    International Nuclear Information System (INIS)

    Deng, Zigang; Wang, Jiasu; Zheng, Jun; Zhang, Ya; Wang, Suyu

    2013-01-01

    Highlights: ► Ferromagnetic materials guide the flux distribution of the PMG to bulk positions. ► With ferromagnetic materials, guidance performance can be enhanced greatly. ► A new HTS Maglev system with onboard ferromagnetic materials is designed. ► The design can meet large guidance force requirements for practical applications. -- Abstract: Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves

  11. Ferromagnetism carried by highly delocalized hybrid states in Sc-doped ZnO thin films

    KAUST Repository

    Benali Kanoun, Mohammed

    2012-05-29

    We present first-principles results for Sc-doped ZnOthin films. Neighboring Sc atoms in the surface and/or subsurface layers are found to be coupled ferromagnetically, where only two of the possible configurations induce spin polarization. In the first configuration, the polarization is carried by the Sc d states as expected for transition metaldoping. However, there is a second configuration which is energetically favorable. It is governed by polarized hybrid states of the Zns, O p, and Sc d orbitals. Such highly delocalized states can be an important ingredient for understanding the magnetism of dopedZnOthin films.

  12. Excitonic Wigner crystal and high T sub c ferromagnetism in RB sub 6

    CERN Document Server

    Kasuya, T

    2000-01-01

    The mechanisms for the high T sub c ferromagnetism in La-doped divalent hexaborides DB sub 6 are studied in detail comparing with similar family materials, in particular with YbB sub 6 , EuB sub 6 and Ce monopnictides. It is shown that in DB sub 6 the light-electron-heavy-hole paired excitonic states form the Wigner crystal, or Wigner glass in actual materials, in which the conventional intersite electron exchange interactions similar to that in Ni dominate the pair singlet formation due to the intra pair mixing causing a ferromagnetic spin glass-like ordering of electron spins. In the La-doped system La sub x D sub 1 sub - sub x B sub 6 , the population of molecular La impurity states with giant moments increases as x approaches the optimal value x sub 0 approx 0.005 for high T sub c providing vacant states for the roton-like fluctuations, which cause the high T sub c at the boundary of the delocalization of electron carriers. Therefore, the critical La concentration for delocalization coincides with the opt...

  13. Josephson junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    Wild, Georg Hermann

    2012-01-01

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  14. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  15. Feasibility of introducing ferromagnetic materials to onboard bulk high-Tc superconductors to enhance the performance of present maglev systems

    Science.gov (United States)

    Deng, Zigang; Wang, Jiasu; Zheng, Jun; Zhang, Ya; Wang, Suyu

    2013-02-01

    Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves.

  16. Computational nano-materials design for high-TC ferromagnetism in wide-gap magnetic semiconductors

    International Nuclear Information System (INIS)

    Katayama-Yoshida, H.; Sato, K.; Fukushima, T.; Toyoda, M.; Kizaki, H.; Dinh, V.A.; Dederichs, P.H.

    2007-01-01

    We propose materials design of high-T C wide band-gap dilute magnetic semiconductors (DMSs) based on first-principles calculations by using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method. First, we discuss a unified physical picture of ferromagnetism in II-VI and III-V DMSs and show that DMS family is categorized into two groups depending on the electronic structure. One is the system where Zener's double exchange mechanism dominates in the ferromagnetic interaction, and in the other systems Zener's p-d exchange mechanism dominates. Next, we develop an accurate method for T C calculation for the DMSs and show that the mean field approximation completely fails to predict Curie temperature of DMS in particular for wide-gap DMS where the exchange interaction is short-ranged. The calculated T C of homogeneous DMSs by using the present method agrees very well with available experimental values. For more realistic material design, we simulate spinodal nano-decomposition by applying the Monte Carlo method to the Ising model with ab initio chemical pair interactions between magnetic impurities in DMS. It is found that by controlling the dimensionality of the decomposition various characteristic phases occur in DMS such as 3D Dairiseki-phase and 1D Konbu-phase, and it is suggested that super-paramagnetic blocking phenomena should be important to understand the magnetism of wide-gap DMS. Based on the present simulations for spinodal nano-decomposition, we propose a new crystal growth method of positioning by seeding and shape controlling method in 100 Tera-bit density of nano-magnets in the semiconductor matrix with high-T C (or high-T B )

  17. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng

    2016-06-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin-up and spin-down electrons, which has shown great promise for use in different ferromagnetic materials. However, the low spin-filtering efficiency in some materials can be ascribed partially to the difficulty in fabricating high-quality thin film with high Curie temperature and/or partially to the improper model used to extract the spin-filtering efficiency. In this work, a new technique is successfully developed to fabricate high quality, ferrimagnetic insulating γ-Fe2O3 films as spin filter. To extract the spin-filtering effect of γ-Fe2O3 films more accurately, a new model is proposed based on Fowler–Nordheim tunneling and Zeeman effect to obtain the spin polarization of the tunneling currents. Spin polarization of the tunneled current can be as high as −94.3% at 2 K in γ-Fe2O3 layer with 6.5 nm thick, and the spin polarization decays monotonically with temperature. Although the spin-filter effect is not very high at room temperature, this work demonstrates that spinel ferrites are very promising materials for spin injection into semiconductors at low temperature, which is important for development of novel spintronics devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  18. Molecular ferromagnetism

    International Nuclear Information System (INIS)

    Epstein, A.J.

    1990-01-01

    This past year has been one of substantial advancement in both the physics and chemistry of molecular and polymeric ferromagnets. The specific heat studies of (DMeFc)(TCNE) have revealed a cusp at the three-dimensional ferromagnetic transition temperature with a crossover to primarily 1-D behavior at higher temperatures. This paper discusses these studies

  19. Dynamic temperature field in the ferromagnetic plate induced by moving high frequency inductor

    Directory of Open Access Journals (Sweden)

    Milošević-Mitić Vesna

    2014-01-01

    Full Text Available The subject of the paper is the temperature distribution in the thin metallic ferromagnetic plate influenced by moving linear high frequency induction heater. As a result of high frequency electromagnetic field, conducting currents appear in the part of the plate. Distribution of the eddy-current power across the plate thickness is obtained by use of complex analysis. The influences of the heater frequency, magnetic field intensity and plate thickness on the heat power density were discussed. By treating this power as a moving heat source, differential equations governing distribution of the temperature field are formulated. Temperature across the plate thickness is assumed to be in linear form. Differential equations are analytically solved by using integral-transform technique, Fourier finite-sine and finite-cosine transform and Laplace transform. The influence of the heater velocity to the plate temperature is presented on numerical examples based on theoretically obtained results. [Projekat Ministarstva nauke Republike Srbije, br. TR 35040 i br. TR 35011

  20. High-pressure catalytic chemical vapor deposition of ferromagnetic ruthenium-containing carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Khavrus, Vyacheslav O., E-mail: V.Khavrus@ifw-dresden.de; Ibrahim, E. M. M.; Bachmatiuk, Alicja; Ruemmeli, Mark H.; Wolter, A. U. B.; Hampel, Silke; Leonhardt, Albrecht [IFW Dresden (Germany)

    2012-06-15

    We report on the high-pressure catalytic chemical vapor deposition (CCVD) of ruthenium nanoparticles (NPs) and single-walled carbon nanotubes (SWCNTs) by means of gas-phase decomposition of acetonitrile and ruthenocene in a tubular quartz flow reactor at 950 Degree-Sign C and at elevated pressures (between 2 and 8 bar). The deposited material consists of Ru metal cores with sizes ranging between 1 and 3 nm surrounded by a carbon matrix. The high-pressure CCVD seems to be an effective route to obtain composite materials containing metallic NPs, Ru in this work, inside a nanostructured carbon matrix protecting them from oxidation in ambient air. We find that in contradiction to the weak paramagnetic properties characterizing bulk ruthenium, the synthesized samples are ferromagnetic as predicted for nanosized particles of nonmagnetic materials. At low pressure, the very small ruthenium catalyst particles are able to catalyze growth of SWCNTs. Their yield decreases with increasing reaction pressure. Transmission electron microscopy, selected area energy-dispersive X-ray analysis, Raman spectroscopy, and magnetic measurements were used to analyze and confirm properties of the synthesized NPs and nanotubes. A discussion on the growth mechanism of the Ru-containing nanostructures is presented.

  1. An active magnetic bearing with high Tc superconducting coils and ferromagnetic cores

    International Nuclear Information System (INIS)

    Brown, G.V.; DiRusso, E.; Provenza, A.J.

    1996-01-01

    A proof-of-feasibility demonstration showed that high-T c , superconductor (HTS) coils can be used in a high-load, active magnetic bearing in LN 2 . A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 890 N (200 lb) radial load capacity (measured nonrotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that for Cu in LN 2 . The bias coil, wound with nontwisted, multifilament HTS conductor, dissipated negligible power for its direct current. The control coils, wound with monofilament HTS sheathed in Ag, dissipated negligible power for direct current. AC losses increased rapidly with frequency and quadratically with AC amplitude. Above about 2 Hz, the effective resistance of the control coils exceeds that of the silver which is in electrical parallel with the oxide superconductor. These results show that twisted multifilament conductor is not needed for stable levitation but may be desired to reduce control power for sizable dynamic loads

  2. Functional quality of MR-compatible automatic biopsy guns compared with conventional ferromagnetic biopsy systems. An in vitro study

    International Nuclear Information System (INIS)

    Langen, H.J.; Landwehr, P.

    2001-01-01

    Comparative evaluation of specimens obtained with different MR-compatible biopsy systems and a conventional ferromagnetic system. Methods: Biopsies of a pig liver were performed post-mortem with three different MR-compatible (Somatex; E-Z-EM; Daum) and one conventional biopsy system (Somatex), five with each device. The specimens were measured and the histopathological quality was graded on a scale from 0 (no tissue) to 9 (best). The tip of the needle was examined with an electron microscope before and after biopsy to demonstrate abrasion. Results: The histopathological score between the first and fifth specimen taken with one biopsy device showed no significant difference. The conventional system yielded significantly better results in nearly all categories (p 2 ) were significantly smaller than those from the conventional system (9.98 mm 2 ). The needle tip abrasion of the different biopsy systems determined by electron microscopy showed no substantial difference. (orig.) [de

  3. High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

    International Nuclear Information System (INIS)

    Sirohi, Anshu; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Sheet, Goutam; Singh, Chandan K.; Kabir, Mukul; Thakur, Gohil S.; Haque, Zeba; Gupta, L. C.; Ganguli, Ashok K.

    2016-01-01

    CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (∼47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.

  4. High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

    Energy Technology Data Exchange (ETDEWEB)

    Sirohi, Anshu; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Sheet, Goutam, E-mail: goutam@iisermohali.ac.in [Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, S. A. S. Nagar, Manauli PO 140306 (India); Singh, Chandan K.; Kabir, Mukul [Department of Physics, Indian Institute of Science Education and Research, Pune 411008 (India); Thakur, Gohil S.; Haque, Zeba; Gupta, L. C. [Department of Chemistry, Indian Institute of Technology, New Delhi 110016 (India); Ganguli, Ashok K. [Department of Chemistry, Indian Institute of Technology, New Delhi 110016 (India); Institute of Nano Science & Technology, Mohali 160064 (India)

    2016-06-13

    CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (∼47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.

  5. An active homopolar magnetic bearing with high temperature superconductor (HTS) coils and ferromagnetic cores

    Science.gov (United States)

    Brown, G. V.; Dirusso, E.; Provenza, A. J.

    1995-01-01

    A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.

  6. Ferromagnetic nanorings

    International Nuclear Information System (INIS)

    Vaz, C A F; Hayward, T J; Llandro, J; Schackert, F; Morecroft, D; Bland, J A C; Klaeui, M; Laufenberg, M; Backes, D; Ruediger, U; Castano, F J; Ross, C A; Heyderman, L J; Nolting, F; Locatelli, A; Faini, G; Cherifi, S; Wernsdorfer, W

    2007-01-01

    Ferromagnetic metal rings of nanometre range widths and thicknesses exhibit fundamentally new spin states, switching behaviour and spin dynamics, which can be precisely controlled via geometry, material composition and applied field. Following the discovery of the 'onion state', which mediates the switching to and between vortex states, a range of fascinating phenomena has been found in these structures. In this overview of our work on ring elements, we first show how the geometric parameters of ring elements determine the exact equilibrium spin configuration of the domain walls of rings in the onion state, and we show how such behaviour can be understood as the result of the competition between the exchange and magnetostatic energy terms. Electron transport provides an extremely sensitive probe of the presence, spatial location and motion of domain walls, which determine the magnetic state in individual rings, while magneto-optical measurements with high spatial resolution can be used to probe the switching behaviour of ring structures with very high sensitivity. We illustrate how the ring geometry has been used for the study of a wide variety of magnetic phenomena, including the displacement of domain walls by electric currents, magnetoresistance, the strength of the pinning potential introduced by nanometre size constrictions, the effect of thermal excitations on the equilibrium state and the stochastic nature of switching events

  7. Ferromagnetism carried by highly delocalized hybrid states in Sc-doped ZnO thin films

    KAUST Repository

    Benali Kanoun, Mohammed; Goumri-Said, Souraya; Manchon, Aurelien; Schwingenschlö gl, Udo

    2012-01-01

    We present first-principles results for Sc-doped ZnOthin films. Neighboring Sc atoms in the surface and/or subsurface layers are found to be coupled ferromagnetically, where only two of the possible configurations induce spin polarization

  8. Feasibility of introducing ferromagnetic materials to onboard bulk high-T{sub c} superconductors to enhance the performance of present maglev systems

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Zigang, E-mail: zgdeng@gmail.com [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); State Key Laboratory of Traction Power (TPL), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Wang, Jiasu [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Zheng, Jun; Zhang, Ya [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); State Key Laboratory of Traction Power (TPL), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China); Wang, Suyu [Applied Superconductivity Laboratory (ASCLab), Southwest Jiaotong University (SWJTU), Chengdu, Sichuan 610031 (China)

    2013-02-14

    Highlights: ► Ferromagnetic materials guide the flux distribution of the PMG to bulk positions. ► With ferromagnetic materials, guidance performance can be enhanced greatly. ► A new HTS Maglev system with onboard ferromagnetic materials is designed. ► The design can meet large guidance force requirements for practical applications. -- Abstract: Performance improvement is a long-term research task for the promotion of practical application of promising high-temperature superconducting (HTS) magnetic levitation (maglev) vehicle technologies. We studied the feasibility to enhance the performance of present HTS Maglev systems by introducing ferromagnetic materials to onboard bulk superconductors. The principle here is to make use of the high magnetic permeability of ferromagnetic materials to alter the flux distribution of the permanent magnet guideway for the enhancement of magnetic field density at the position of the bulk superconductors. Ferromagnetic iron plates were added to the upper surface of bulk superconductors and their geometric and positioning effects on the maglev performance were investigated experimentally. Results show that the guidance performance (stability) was enhanced greatly for a particular setup when compared to the present maglev system which is helpful in the application where large guidance forces are needed such as maglev tracks with high degrees of curves.

  9. High-output microwave detector using voltage-induced ferromagnetic resonance

    International Nuclear Information System (INIS)

    Shiota, Yoichi; Suzuki, Yoshishige; Miwa, Shinji; Tamaru, Shingo; Nozaki, Takayuki; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji

    2014-01-01

    We investigated the voltage-induced ferromagnetic resonance (FMR) with various DC bias voltage and input RF power in magnetic tunnel junctions. We found that the DC bias monotonically increases the homodyne detection voltage due to the nonlinear FMR originating in an asymmetric magnetization-potential in the free layer. In addition, the linear increase of an output voltage to the input RF power in the voltage-induced FMR is more robust than that in spin-torque FMR. These characteristics enable us to obtain an output voltage more than ten times than that of microwave detectors using spin-transfer torque

  10. Spin spring behavior in exchange coupled soft and high-coercivity hard ferromagnets.

    Energy Technology Data Exchange (ETDEWEB)

    Shull, R. D.; Shapiro, A. J.; Gornakov, V. S.; Nikitenko, V. I.; Jiang, J. S.; Kaper, H.; Leaf, G.; Bader, S. D.

    2000-11-01

    The magnetization reversal processes in an epitaxial Fe/Sm{sub 2}Co{sub 7} structure were investigated using the magneto-optical indicator film technique. The dependence of the magnitude and the orientation of the structure average magnetization have been studied on both cycling and rotating the external magnetic field. It was discovered that the magnetization reversal of the soft ferromagnet can proceed by formation of not only one-dimensional, but also two-dimensional, exchange spin springs. Experimental data is compared with a theoretical estimation of the rotational hysteresis loop for a spin system containing a one-dimensional exchange spring.

  11. Prospects of high temperature ferromagnetism in (Ga, Mn)As semiconductors

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Wang, K. Y.; Mašek, Jan; Edmonds, K. W.; König, J.; Sinova, J.; Polini, M.; Goncharuk, Natalya; MacDonald, A. H.; Sawicki, M.; Campion, R. P.; Zhao, L.X.; Foxon, C. T.; Gallagher, B. L.

    2005-01-01

    Roč. 72, č. 16 (2005), 165204/1-165204/13 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GA202/05/0575; GA MŠk(CZ) LC510 Grant - others:EU FENIKS(XE) EC:G5RD-CT-2001-00535; EPSRC(GB) GR/S81407/01; Welch Foundation(GB) DE-FG03-02ER45958; Deutsche Forschungsgemeinschaft(DE) SFB 491 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic semiconductors * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.185, year: 2005

  12. High-Temperature Ferromagnetism in Transition Metal Implanted Wide-Bandgap Semiconductors

    Science.gov (United States)

    2005-07-01

    Mn)As and Its Heterostructures,” Acta Physica Polonica A, 94 (2):155–164 (August 1998). 79. Ohno, Y., D. K. Young, B. Beschoten, F. Matsukura, H. Ohno...reactive molecular-beam epitaxy,” Physical Review B , 67 (16):16205 (April 2003). 26. Dietl, T. “From Magnetic Polarons to Ferromagnetism,” Acta Physica ...samples,” Physica B , 308-310 :985–988 (December 2001). 15. Bradley, F. N. Materials for Magnetic Functions (First Edition). New York: Hayden, 1971. 16

  13. Anisotropic ferromagnetic behaviors in highly orientated epitaxial NiO-based thin films

    Directory of Open Access Journals (Sweden)

    Yu-Jun Zhang

    2015-07-01

    Full Text Available Antiferromagnetic materials attract a great amount of attention recently for promising antiferromagnet-based spintronics applications. NiO is a conventional antiferromagnetic semiconductor material and can show ferromagnetism by doping other magnetic elements. In this work, we synthesized epitaxial Fe-doped NiO thin films on SrTiO3 substrates with various crystal orientations by pulsed laser deposition. The room-temperature ferromagnetism of these films is anisotropic, including the saturated magnetization and the coercive field. The anisotropic magnetic behaviors of Fe-doped NiO diluted magnetic oxide system should be closely correlated to the magnetic structure of antiferromagnetic NiO base. Within the easy plane of NiO, the coercive field of the films becomes smaller, and larger coercive field while tested out of the easy plane of NiO. The saturated magnetization anisotropy is due to different strain applied by different substrates. These results lead us to more abundant knowledge of the exchange interactions in this conventional antiferromagnetic system.

  14. Nonlinear thermoelectric effects in high-field superconductor-ferromagnet tunnel junctions

    Directory of Open Access Journals (Sweden)

    Stefan Kolenda

    2016-11-01

    Full Text Available Background: Thermoelectric effects result from the coupling of charge and heat transport and can be used for thermometry, cooling and harvesting of thermal energy. The microscopic origin of thermoelectric effects is a broken electron–hole symmetry, which is usually quite small in metal structures. In addition, thermoelectric effects decrease towards low temperatures, which usually makes them vanishingly small in metal nanostructures in the sub-Kelvin regime.Results: We report on a combined experimental and theoretical investigation of thermoelectric effects in superconductor/ferromagnet hybrid structures. We investigate the dependence of thermoelectric currents on the thermal excitation, as well as on the presence of a dc bias voltage across the junction.Conclusion: Large thermoelectric effects are observed in superconductor/ferromagnet and superconductor/normal-metal hybrid structures. The spin-independent signals observed under finite voltage bias are shown to be reciprocal to the physics of superconductor/normal-metal microrefrigerators. The spin-dependent thermoelectric signals in the linear regime are due to the coupling of spin and heat transport, and can be used to design more efficient refrigerators.

  15. Biaxial stress driven tetragonal symmetry breaking and high-temperature ferromagnetic semiconductor from half-metallic CrO2

    Science.gov (United States)

    Xiao, Xiang-Bo; Liu, Bang-Gui

    2018-03-01

    It is highly desirable to combine the full spin polarization of carriers with modern semiconductor technology for spintronic applications. For this purpose, one needs good crystalline ferromagnetic (or ferrimagnetic) semiconductors with high Curie temperatures. Rutile CrO2 is a half-metallic spintronic material with Curie temperature 394 K and can have nearly full spin polarization at room temperature. Here, we find through first-principles investigation that when a biaxial compressive stress is applied on rutile CrO2, the density of states at the Fermi level decreases with the in-plane compressive strain, there is a structural phase transition to an orthorhombic phase at the strain of -5.6 % , and then appears an electronic phase transition to a semiconductor phase at -6.1 % . Further analysis shows that this structural transition, accompanying the tetragonal symmetry breaking, is induced by the stress-driven distortion and rotation of the oxygen octahedron of Cr, and the half-metal-semiconductor transition originates from the enhancement of the crystal field splitting due to the structural change. Importantly, our systematic total-energy comparison indicates the ferromagnetic Curie temperature remains almost independent of the strain, near 400 K. This biaxial stress can be realized by applying biaxial pressure or growing the CrO2 epitaxially on appropriate substrates. These results should be useful for realizing full (100%) spin polarization of controllable carriers as one uses in modern semiconductor technology.

  16. Energy gap of ferromagnet-superconductor bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Halterman, Klaus; Valls, Oriol T

    2003-10-15

    The excitation spectrum of clean ferromagnet-superconductor bilayers is calculated within the framework of the self-consistent Bogoliubov-de Gennes theory. Because of the proximity effect, the superconductor induces a gap in the ferromagnet spectrum, for thin ferromagnetic layers. The effect depends strongly on the exchange field in the ferromagnet. We find that as the thickness of the ferromagnetic layer increases, the gap disappears, and that its destruction arises from those quasiparticle excitations with wave vectors mainly along the interface. We discuss the influence that the interface quality and Fermi energy mismatch between the ferromagnet and superconductor have on the calculated energy gap. We also evaluate the density of states in the ferromagnet, and we find it in all cases consistent with the gap results.

  17. Superconducting Ferromagnetic Nanodiamond.

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Xu, Zheng; Jochum, Johanna K; Volodin, Alexander; Zhou, Shengqiang; May, Paul W; Onufriienko, Oleksandr; Kačmarčík, Jozef; Steele, Julian A; Li, Jun; Vanacken, Johan; Vacík, Jiri; Szabó, Pavol; Yuan, Haifeng; Roeffaers, Maarten B J; Cerbu, Dorin; Samuely, Peter; Hofkens, Johan; Moshchalkov, Victor V

    2017-06-27

    Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T c ∼ 3 K and a Curie temperature T Curie > 400 K. In spite of the high T Curie , our nanodiamond films demonstrate a decrease in the temperature dependence of magnetization below 100 K, in correspondence to an increase in the temperature dependence of resistivity. These anomalous magnetic and electrical transport properties reveal the presence of an intriguing precursor phase, in which spin fluctuations intervene as a result of the interplay between the two antagonistic states. Furthermore, the observations of high-temperature ferromagnetism, giant positive magnetoresistance, and anomalous Hall effect bring attention to the potential applications of our superconducting ferromagnetic nanodiamond films in magnetoelectronics, spintronics, and magnetic field sensing.

  18. Towards ferromagnet/superconductor junctions on graphene

    International Nuclear Information System (INIS)

    Pakkayil, Shijin Babu

    2015-01-01

    Ever since A. Aspect et al. performed the famous 1982 experiment to prove the violation of Bell's inequality, there have been suggestions to conduct the same experiment in a solid state system. Some of those proposals involve superconductors as the source of entangled electron pair and spin depended interfaces as the optical analogue of polariser/filter. Semiconductors can serve as the best medium for such an experiment due to their long relaxation lengths. So far there are no reports on a ferromagnet/superconductor junctions on a semiconductor even though such junctions has been successfully realised in metallic systems. This thesis reports the successful fabrication of ferromagnet/superconductor junction along with characterising measurements in a perfectly two dimensional zero-gap semiconductor known as graphene. Since it's discovery in 2004, graphene has attracted prodigious interest from both academia and industry due to it's inimitable physical properties: very high mobility, high thermal and electrical conductivity, a high Young's modulus and impermeability. Graphene is also expected to have very long spin relaxation length and high spin life time because of it's low spin orbit coupling. For this reason and since researchers are always looking for novel materials and devices to comply with the high demands for better and faster data storage devices, graphene has emanated as a brand new material system for spin based devices. The very first spin injection and detection in graphene was realised in 2007 and ever since, the focal point of the research has been to improve the spin transport properties. A part of this thesis discusses a new fabrication recipe which has a high yield for successfully contacting graphene with a ferromagnet. A high starting yield for ferromagnetic contacts is a irremissible condition for combining superconducting contacts to the device to fabricate ferromagnet/superconductor junctions. Any fabrication recipe

  19. Towards ferromagnet/superconductor junctions on graphene

    Energy Technology Data Exchange (ETDEWEB)

    Pakkayil, Shijin Babu

    2015-07-01

    Ever since A. Aspect et al. performed the famous 1982 experiment to prove the violation of Bell's inequality, there have been suggestions to conduct the same experiment in a solid state system. Some of those proposals involve superconductors as the source of entangled electron pair and spin depended interfaces as the optical analogue of polariser/filter. Semiconductors can serve as the best medium for such an experiment due to their long relaxation lengths. So far there are no reports on a ferromagnet/superconductor junctions on a semiconductor even though such junctions has been successfully realised in metallic systems. This thesis reports the successful fabrication of ferromagnet/superconductor junction along with characterising measurements in a perfectly two dimensional zero-gap semiconductor known as graphene. Since it's discovery in 2004, graphene has attracted prodigious interest from both academia and industry due to it's inimitable physical properties: very high mobility, high thermal and electrical conductivity, a high Young's modulus and impermeability. Graphene is also expected to have very long spin relaxation length and high spin life time because of it's low spin orbit coupling. For this reason and since researchers are always looking for novel materials and devices to comply with the high demands for better and faster data storage devices, graphene has emanated as a brand new material system for spin based devices. The very first spin injection and detection in graphene was realised in 2007 and ever since, the focal point of the research has been to improve the spin transport properties. A part of this thesis discusses a new fabrication recipe which has a high yield for successfully contacting graphene with a ferromagnet. A high starting yield for ferromagnetic contacts is a irremissible condition for combining superconducting contacts to the device to fabricate ferromagnet/superconductor junctions. Any fabrication recipe

  20. Coexistence of weak ferromagnetism and ferroelectricity in the high pressure LiNbO3-type phase of FeTiO3.

    Science.gov (United States)

    Varga, T; Kumar, A; Vlahos, E; Denev, S; Park, M; Hong, S; Sanehira, T; Wang, Y; Fennie, C J; Streiffer, S K; Ke, X; Schiffer, P; Gopalan, V; Mitchell, J F

    2009-07-24

    We report the magnetic and electrical characteristics of polycrystalline FeTiO_{3} synthesized at high pressure that is isostructural with acentric LiNbO_{3} (LBO). Piezoresponse force microscopy, optical second harmonic generation, and magnetometry demonstrate ferroelectricity at and below room temperature and weak ferromagnetism below approximately 120 K. These results validate symmetry-based criteria and first-principles calculations of the coexistence of ferroelectricity and weak ferromagnetism in a series of transition metal titanates crystallizing in the LBO structure.

  1. Histopathologic quality of prostate core biopsy specimens: comparison of an MR-compatible biopsy needle and a ferromagnetic biopsy needle used for ultrasound-guided prostate biopsy

    International Nuclear Information System (INIS)

    Franiel, T.; Hamm, B.; Beyersdorff, D.; Fritzsche, F.; Staack, A.; Rost, J.

    2006-01-01

    Purpose: The histopathologic quality of core biopsy specimens obtained via MRI-guided prostate biopsy using a 16G MR-compatible needle was compared to that of biopsies obtained via ultrasound-guided biopsy using a conventional 18G stainless steel biopsy needle. Material and Methods: A retrospective analysis was performed for a total of 247 transrectal prostate biopsy specimens obtained from 32 patients. A total of 117 tissue cores were obtained from 15 patients (PSA of 10.8 ng/ml, age 64 years) who underwent an MRI-guided prostate biopsy using a 16G (1.7 mm) MR-compatible biopsy needle made of titanium alloy. The remaining 130 tissue cores were obtained from 17 patients (PSA of 6.7 ng/ml, age 68 years) who underwent a transrectal ultrasound-guided prostate biopsy using an 18G (1.3 mm) ferromagnetic stainless steel biopsy needle. The length and width of the histologic sections prepared from the tissue cores were measured to calculate the area. The histopathologic quality of the specimens was assessed microscopically using tissue fragmentation, the presence of crush artifacts, and the overall assessability as criteria. Each of these features was assigned a score from 0 to 3. All 3 features contributed equally to the overall score which ranged from 0 (no tissue) to 9 (optimal quality). Results: The overall quality scores assigned to the biopsies obtained with a 16G MR-compatible needle and an 18G ferromagnetic needle can be considered to be equivalent to a mean difference between patient related median scores of the specimens of -0.05 (95% confidence interval [-0.46; 0.36]) and a given equivalence limit of 1. The MRI biopsies showed more tissue fragmentation (p=0.001) but fewer crush artifacts (p=0.022) while the assessability did not differ significantly between the two needle types (p=0.064). There was also no significant difference in the calculated areas of the tissue cores (p=0.236). According to the different calibers of the biopsy needles, the lengths (p=0

  2. STM observations of ferromagnetic clusters

    International Nuclear Information System (INIS)

    Wawro, A.; Kasuya, A.

    1998-01-01

    Co, Fe and Ni clusters of nanometer size, deposited on silicon and graphite (highly oriented pyrolytic graphite), were observed by a scanning tunneling microscope. Deposition as well as the scanning tunneling microscope measurements were carried out in an ultrahigh vacuum system at room temperature. Detailed analysis of Co cluster height was done with the scanning tunneling microscope equipped with a ferromagnetic tip in a magnetic field up to 70 Oe. It is found that bigger clusters (few nanometers in height) exhibit a dependence of their apparent height on applied magnetic field. We propose that such behaviour originates from the ferromagnetic ordering of cluster and associate this effect to spin polarized tunneling. (author)

  3. Ferromagnetic resonance frequency increase and resonance line broadening of a ferromagnetic Fe–Co–Hf–N film with in-plane uniaxial anisotropy by high-frequency field perturbation

    International Nuclear Information System (INIS)

    Seemann, K.; Leiste, H.; Krüger, K.

    2013-01-01

    Soft ferromagnetic Fe-Co-Hf-N films, produced by reactive r.f. magnetron sputtering, are useful to study the ferromagnetic resonance (FMR) by means of frequency domain permeability measurements up to the GHz range. Films with the composition Fe 33 Co 43 Hf 10 N 14 exhibit a saturation polarisation J s of around 1.35 T. They are consequently considered as being uniformly magnetised due to an in-plane uniaxial anisotropy of approximately μ 0 H u ≈4.5 m T after annealing them, e.g., at 400 °C in a static magnetic field for 1 h. Being exposed to a high-frequency field, the precession of magnetic moments leads to a marked frequency-dependent permeability with a sharp Lorentzian shaped imaginary part at around 2.33 GHz (natural resonance peak), which is in a very good agreement with the modified Landau–Lifschitz–Gilbert (LLG) differential equation. A slightly increased FMR frequency and a clear increase in the resonance line broadening due to an increase of the exciting high-frequency power (1–25.1 mW), considered as an additional perturbation of the precessing system of magnetic moments, could be discovered. By solving the homogenous LLG differential equation with respect to the in-plane uniaxial anisotropy, it was revealed that the high-frequency field perturbation impacts the resonance peak position f FMR and resonance line broadening Δf FMR characterised by a completed damping parameter α=α eff +Δα. Adapted from this result, the increase in f FMR and decrease in lifetime of the excited level of magnetic moments associated with Δf FMR , similar to a spin-½ particle in a static magnetic field, was theoretically elaborated as well as compared with experimental data. - Highlights: • Impact on the resonance frequency and resonance line by the high-frequency power. • Theoretic approach by solving the LLG differential equation. • Experimental verification and magnon processes. • Theoretical and experimental determination of the resonance state

  4. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous

  5. Fast High-Quality Noise

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall; Wyvill, Geoff

    2007-01-01

    At the moment the noise functions available in a graphics programmer's toolbox are either slow to compute or they involve grid-line artifacts making them of lower quality. In this paper we present a real-time noise computation with no grid-line artifacts or other regularity problems. In other words......, we put a new tool in the box that computes fast high-quality noise. In addition to being free of artifacts, the noise we present does not rely on tabulated data (everything is computed on the fly) and it is easy to adjust quality vs. quantity for the noise. The noise is based on point rendering (like...... spot noise), but it extends to more than two dimensions. The fact that it is based on point rendering makes art direction of the noise much easier....

  6. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    Science.gov (United States)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed.

  7. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    Energy Technology Data Exchange (ETDEWEB)

    Pasanai, K., E-mail: krisakronmsu@gmail.com

    2017-01-15

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  8. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    International Nuclear Information System (INIS)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  9. The Physics of Ferromagnetism

    CERN Document Server

    Miyazaki, Terunobu

    2012-01-01

    This book covers both basic physics of ferromagnetism such as magnetic moment, exchange coupling, magnetic anisotropy and recent progress in advanced ferromagnetic materials. Special interests are focused on NdFeB permanent magnets and the materials studied in the field of spintronics. In the latter, development of tunnel magnetoresistance effect through so called giant magnetoresistance effect is explained.

  10. Ferromagnet / superconductor oxide superlattices

    Science.gov (United States)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  11. Ferromagnetic shape memory materials

    Science.gov (United States)

    Tickle, Robert Jay

    Ferromagnetic shape memory materials are a new class of active materials which combine the properties of ferromagnetism with those of a diffusionless, reversible martensitic transformation. These materials have been the subject of recent study due to the unusually large magnetostriction exhibited in the martensitic phase. In this thesis we report the results of experiments which characterize the magnetic and magnetomechanical properties of both austenitic and martensitic phases of ferromagnetic shape memory material Ni2MnGa. In the high temperature cubic phase, anisotropy and magnetostriction constants are determined for a range of temperatures from 50°C down to the transformation temperature, with room temperature values of K1 = 2.7 +/- 104 ergs/cm3 and lambda100 = -145 muepsilon. In the low temperature tetragonal phase, the phenomenon of field-induced variant rearrangement is shown to produce anomalous results when traditional techniques for determining anisotropy and magnetostriction properties are employed. The requirement of single variant specimen microstructure is explained, and experiments performed on such a specimen confirm a uniaxial anisotropy within each martensitic variant with anisotropy constant Ku = 2.45 x 106 ergs/cm3 and a magnetostriction constant of lambdasv = -288 +/- 73 muepsilon. A series of magnetomechanical experiments investigate the effects of microstructure bias, repeated field cycling, varying field ramp rate, applied load, and specimen geometry on the variant rearrangement phenomenon in the martensitic phase. In general, the field-induced strain is found to be a function of the variant microstructure. Experiments in which the initial microstructure is biased towards a single variant state with an applied load generate one-time strains of 4.3%, while those performed with a constant bias stress of 5 MPa generate reversible strains of 0.5% over a period of 50 cycles. An increase in the applied field ramp rate is shown to reduce the

  12. Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

    Science.gov (United States)

    Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

    2018-05-01

    High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

  13. Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Si, M. S.; Gao, Daqiang, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn; Yang, Dezheng; Peng, Yong; Zhang, Z. Y.; Xue, Desheng, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Yushen [Jiangsu Laboratory of Advanced Functional Materials and College of Physics and Engineering, Changshu Institute of Technology, Changshu 215500 (China); Deng, Xiaohui [Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008 (China); Zhang, G. P. [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States)

    2014-05-28

    Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

  14. Ferromagnetic properties of manganese doped iron silicide

    Science.gov (United States)

    Ruiz-Reyes, Angel; Fonseca, Luis F.; Sabirianov, Renat

    We report the synthesis of high quality Iron silicide (FeSi) nanowires via Chemical Vapor Deposition (CVD). The materials exhibits excellent magnetic response at room temperature, especially when doped with manganese showing values of 2.0 X 10-04 emu for the FexMnySi nanowires. SEM and TEM characterization indicates that the synthesized nanowires have a diameter of approximately 80nm. MFM measurements present a clear description of the magnetic domains when the nanowires are doped with manganese. Electron Diffraction and XRD measurements confirms that the nanowires are single crystal forming a simple cubic structure with space group P213. First-principle calculations were performed on (111) FeSi surface using the Vienna ab initio simulation package (VASP). The exchange correlations were treated under the Ceperley-Alder (CA) local density approximation (LDA). The Brillouin Zone was sampled with 8x8x1 k-point grid. A total magnetic moment of about 10 μB was obtained for three different surface configuration in which the Iron atom nearest to the surface present the higher magnetization. To study the effect of Mn doping, Fe atom was replaced for a Mn. Stronger magnetization is presented when the Mn atom is close to the surface. The exchange coupling constant have been evaluated calculating the energy difference between the ferromagnetic and anti-ferromagnetic configurations.

  15. Ferromagnetic artificial pinning centers in multifilamentary superconducting wires

    International Nuclear Information System (INIS)

    Wang, J.Q.; Rizzo, N.D.; Prober, D.E.

    1997-01-01

    The authors fabricated multifilamentary NbTi wires with ferromagnetic (FM) artificial pinning centers (APCs) to enhance the critical current density (J c ) in magnetic fields. They used a bundle and draw technique to process the APC wires with either Ni or Fe as the pinning centers. Both wires produced higher J c in the high field range (5-9 T) than previous non-magnetic APC wires similarly processed, even though the authors have not yet optimized pin percentage. Using a magnetometer they found that the pins remained ferromagnetic for the wires with maximum J c . However, they did observe a substantial loss of FM material for the wires where the pin diameter approached 3 nm. Thus, they expect further enhancement of J c with better pin quality

  16. Understanding the Room Temperature Ferromagnetism in GaN Nanowires with Pd Doping

    International Nuclear Information System (INIS)

    Manna, S; De, S K

    2011-01-01

    We report the first synthesis and characterization of 4d transition metal palladium-doped GaN nanowires (NWs). Room temperature ferromagnetism has been observed in high quality Vapor Liquid Solid (VLS) epitaxy grown undoped n-type GaN nanowires. It was proposed that this type of magnetism is due to defects which are not observed in Bulk GaN because of large formation energy of defects in bulk GaN. Here we have successfully doped 4d transition metal Pd in GaN NWs. We find fairly strong and long-range ferromagnetic coupling between Pd substituted for Ga in GaN . The results suggest that 4d metals such as Pd may also be considered as candidates for ferromagnetic dopants in semiconductors.

  17. Anisotropy of the ferromagnetic L10 phase in the Mn-Al-C alloys induced by high-pressure spark plasma sintering

    Science.gov (United States)

    Tyrman, Muriel; Ahmim, Smail; Pasko, Alexandre; Etgens, Victor; Mazaleyrat, Frédéric; Quetel-Weben, Simon; Perrière, Loïc; Guillot, Ivan

    2018-05-01

    The metastable τ-phase of MnAl equi-atomic compound belongs to a family of ferromagnetic alloys with L10 crystal structure. Stabilization of the phase by adding 2 at. % using manganese carbide (Mn23C6) enhances the magnetization in relation with the increase in lattice volume. It is thus a promising candidate for rare-earth-free permanent magnets. Coercivity of Mn-Al-C alloys being still weak, there is an interest to see to which extend sintering/transformation of the ɛ-phase by Spark Plasma Sintering (SPS) can increase the coercivity and the anisotropy. The structural and the magnetic properties were studied for samples sintered at 550 °C under uniaxial pressure of 100, 200, 300 and 400 MPa. Coercivity, remanence and anistotropy appears with the sintering pressure. The high pressure applied while sintering produces preferential orientation of the flake-shaped grains which influences the remanence.

  18. Granular and layered ferroelectric–ferromagnetic thin-film nanocomposites as promising materials with high magnetotransmission effect

    Energy Technology Data Exchange (ETDEWEB)

    Akbashev, A.R. [Department of Materials Science, Moscow State University, 119992 Moscow (Russian Federation); Telegin, A.V., E-mail: telegin@imp.uran.ru [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620990 Ekaterinburg (Russian Federation); Kaul, A.R. [Department of Chemistry, Moscow State University, 119992 Moscow (Russian Federation); Sukhorukov, Yu.P. [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620990 Ekaterinburg (Russian Federation)

    2015-06-15

    Epitaxial thin films of granular and layered nanocomposites consisting of ferromagnetic perovskite Pr{sub 1–x}Sr{sub x}MnO{sub 3} and ferroelectric hexagonal LuMnO{sub 3} were grown on ZrO{sub 2}(Y{sub 2}O{sub 3}) substrates using metal-organic chemical vapor deposition (MOCVD). A self-organized growth of the granular composite took place in situ as a result of phase separation of the Pr–Sr–Lu–Mn–O system into the perovskite and hexagonal phases. Optical transmission measurements revealed a large negative magnetotransmission effect in the layered nanocomposite over a wide spectral and temperature range. The granular nanocomposite unexpectedly showed an even larger, but positive, magnetotransmission effect at room temperature. - Highlights: • Thin-film ferromagnetic–ferroelectric nanocomposites have been prepared by MOCVD. • Giant change of optical transparency of nanocomposites in magnetic field was detected. • Positive magnetotransmission in the granular nanocomposite was discovered in the IR. • Negative magnetotransmission in the layered nanocomposite was revealed in the IR. • Ferroelectric–ferromangetic nanocomposite is a promising material for optoelectronics.

  19. Granular and layered ferroelectric–ferromagnetic thin-film nanocomposites as promising materials with high magnetotransmission effect

    International Nuclear Information System (INIS)

    Akbashev, A.R.; Telegin, A.V.; Kaul, A.R.; Sukhorukov, Yu.P.

    2015-01-01

    Epitaxial thin films of granular and layered nanocomposites consisting of ferromagnetic perovskite Pr 1–x Sr x MnO 3 and ferroelectric hexagonal LuMnO 3 were grown on ZrO 2 (Y 2 O 3 ) substrates using metal-organic chemical vapor deposition (MOCVD). A self-organized growth of the granular composite took place in situ as a result of phase separation of the Pr–Sr–Lu–Mn–O system into the perovskite and hexagonal phases. Optical transmission measurements revealed a large negative magnetotransmission effect in the layered nanocomposite over a wide spectral and temperature range. The granular nanocomposite unexpectedly showed an even larger, but positive, magnetotransmission effect at room temperature. - Highlights: • Thin-film ferromagnetic–ferroelectric nanocomposites have been prepared by MOCVD. • Giant change of optical transparency of nanocomposites in magnetic field was detected. • Positive magnetotransmission in the granular nanocomposite was discovered in the IR. • Negative magnetotransmission in the layered nanocomposite was revealed in the IR. • Ferroelectric–ferromangetic nanocomposite is a promising material for optoelectronics

  20. Self-assembly of linear [Mn II 2 Mn III ] units with end-on azido bridges: the construction of a ferromagnetic chain using S T = 7 high-spin trimers

    KAUST Repository

    Jiang, Yuan; Qin, Lei; Li, Guanghua; Abbas, Ghulam; Cao, Yaqun; Wu, Gang; Han, Tian; Zheng, Yan-Zhen; Qiu, Shilun

    2015-01-01

    © The Royal Society of Chemistry 2015. The controlled organization of high-spin complexes into 1D coordination polymers is a challenge in molecular magnetism. In this work, we report a ferromagnetic Mn trimer Mn3(HL)2(CH3OH)6(Br)4·Br·(CH3OH)21 (H2L

  1. Carrier concentration induced ferromagnetism in semiconductors

    International Nuclear Information System (INIS)

    Story, T.

    2007-01-01

    In semiconductor spintronics the key materials issue concerns ferromagnetic semiconductors that would, in particular, permit an integration (in a single multilayer heterostructure) of standard electronic functions of semiconductors with magnetic memory function. Although classical semiconductor materials, such as Si or GaAs, are nonmagnetic, upon substitutional incorporation of magnetic ions (typically of a few atomic percents of Mn 2+ ions) and very heavy doping with conducting carriers (at the level of 10 20 - 10 21 cm -3 ) a ferromagnetic transition can be induced in such diluted magnetic semiconductors (also known as semimagnetic semiconductors). In the lecture the spectacular experimental observations of carrier concentration induced ferromagnetism will be discussed for three model semiconductor crystals. p - Ga 1-x Mn x As currently the most actively studied and most perspective ferromagnetic semiconductor of III-V group, in which ferromagnetism appears due to Mn ions providing both local magnetic moments and acting as acceptor centers. p - Sn 1-x Mn x Te and p - Ge 1-x Mn x Te classical diluted magnetic semiconductors of IV-VI group, in which paramagnet-ferromagnet and ferromagnet-spin glass transitions are found for very high hole concentration. n - Eu 1-x Gd x Te mixed magnetic crystals, in which the substitution of Gd 3+ ions for Eu 2+ ions creates very high electron concentration and transforms antiferromagnetic EuTe (insulating compound) into ferromagnetic n-type semiconductor alloy. For each of these materials systems the key physical features will be discussed concerning: local magnetic moments formation, magnetic phase diagram as a function of magnetic ions and carrier concentration as well as Curie temperature and magnetic anisotropy engineering. Various theoretical models proposed to explain the effect of carrier concentration induced ferromagnetism in semiconductors will be briefly discussed involving mean field approaches based on Zener and RKKY

  2. Thermodynamic-state and kinetic-process dependent dual ferromagnetic states in high-Si content FeMn(PSi) alloys

    International Nuclear Information System (INIS)

    Li, Guijiang; Eriksson, Olle; Johansson, Börje; Vitos, Levente

    2015-01-01

    We have found that thermodynamic state and kinetic process co-determine the dual ferromagnetic (FM) orders in high-Si content FeMnP 1−x Si x (0.25 < x < 0.5). Alloys undergoing high temperature annealing and quenching process prefer a high magnetic moment FM state in a chemically partial disordered structure with low c/a ratio. This mechanism is suggested to be responsible for the often discussed virgin effect as well. A chemically ordered structure obtained by a slow cooling process from a relatively low annealing temperature and the increase in Si content stabilize a metastable lattice with high c/a ratio and FM order with low magnetic moment. The non-simultaneity of the magnetic and structural transitions can be responsible for the occurrence of FM state in the high c/a range. Thus, a c/a ratio that changes from high to low is physically plausible to stabilize the metastable FM order at low temperature. Our theoretical observations indicate that suitable thermodynamic state and kinetic diffusion process is crucial for optimizing magnetocaloric properties and exploring feasible magnetocaloric materials

  3. PREFACE: Half Metallic Ferromagnets

    Science.gov (United States)

    Dowben, Peter

    2007-08-01

    surface and interface reconstructions. Thus spin injection, i.e. the spin polarization of the current through the interface, may be effectively reduced to very low values, although the non-equilibrium spin polarization of the electron density can have very high values in select devices. Underlying these issues is the need to consider the definition of polarization: not all polarizations are equal. Polarization depends on the measurement. We do not always measure a polarization that follows the usual definition of spin polarization, and in many cases, it is not exactly clear what polarization has been measured. For example, there are corrections for the Fermi velocity ν↓,↑ and spin relaxation τ↓,↑: equation 1 where n = 1 applies to the ballistic regime and n = 2 applies to the diffuse regime [3]. Neglecting interfaces and other complications, the diffuse regime (n = 2) should be the spin polarization of the bulk conductivity while ballistic regime (n = 1) is the polarization of the tunnel current and, in principle, Andreev reflection. As a result, suitable spin dependent Fermi velocity corrections might overcome an otherwise lackluster polarization for some device structures. Even measurements of polarization that are Fermi velocity independent (n = 0) may still depend on the wave vector and details of the interface band structure: as in the case of spin polarized photoemission and inverse photoemission. This special issue cannot possibly give due justice to all the various aspects of the physics of half metallic systems. By including both advocates and critics of half metallic ferromagnetism, the special issue should provide at least a taste of the controversies and challenges that exist in the study of half metallic ferromagnets. It may be that 'nature abhors half-metallicity' [2], and that relatively minor structural and thermal perturbations have a disproportionally strong effect on the density of states at the Fermi level, but in spite of much study half

  4. Availability of high quality weather data measurements

    DEFF Research Database (Denmark)

    Andersen, Elsa; Johansen, Jakob Berg; Furbo, Simon

    In the period 2016-2017 the project “Availability of high quality weather data measurements” is carried out at Department of Civil Engineering at the Technical University of Denmark. The aim of the project is to establish measured high quality weather data which will be easily available...... for the building energy branch and the solar energy branch in their efforts to achieve energy savings and for researchers and students carrying out projects where measured high quality weather data are needed....

  5. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng; Xia, Chuan; Zhu, Zhiyong; Wen, Yan; Zhang, Qiang; Alshareef, Husam N.; Zhang, Xixiang

    2016-01-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin

  6. Magnetic pinning in superconductor-ferromagnet multilayers

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.; Maley, M. P.

    2000-01-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10 6 -10 7 A/cm 2 at high temperatures (but not very close to T c ) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics

  7. Magnetic pinning in superconductor-ferromagnet multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N. [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chudnovsky, E. M. [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Maley, M. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2000-05-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10{sup 6}-10{sup 7} A/cm{sup 2} at high temperatures (but not very close to T{sub c}) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics.

  8. Hall effect measurements of high-quality M n3CuN thin films and the electronic structure

    Science.gov (United States)

    Matsumoto, Toshiki; Hatano, Takafumi; Urata, Takahiro; Iida, Kazumasa; Takenaka, Koshi; Ikuta, Hiroshi

    2017-11-01

    The physical properties of M n3CuN were studied using thin films. We found that an annealing process was very effective to improve the film quality, the key of which was the use of Ti that prevented the formation of oxide impurities. Using these high-quality thin films, we found strong strain dependence for the ferromagnetic transition temperature (TC) and a sign change of the Hall coefficient at TC. The analysis of Hall coefficient data revealed a sizable decrease of hole concentration and a large increase of electron mobility below TC, which is discussed in relation to the electronic structure of this material.

  9. Zerodur polishing process for high surface quality and high efficiency

    International Nuclear Information System (INIS)

    Tesar, A.; Fuchs, B.

    1992-08-01

    Zerodur is a glass-ceramic composite importance in applications where temperature instabilities influence optical and mechanical performance, such as in earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Polished surface quality of substrates affects performance of high reflection coatings. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing. With the proper control of polishing parameters, such surfaces exhibit roughnesses of < l Angstrom rms. Zerodur polishing was studied to recommend a high surface quality polishing process which could be easily adapted to standard planetary continuous polishing machines and spindles. This summary contains information on a polishing process developed at LLNL which reproducibly provides high quality polished Zerodur surfaces at very high polishing efficiencies

  10. Giant magnetotransmission and magnetoreflection in ferromagnetic materials

    International Nuclear Information System (INIS)

    Telegin, A.V.; Sukhorukov, Yu.P.; Loshkareva, N.N.; Mostovshchikova, E.V.; Bebenin, N.G.; Gan'shina, E.A.; Granovsky, A.B.

    2015-01-01

    We present a brief review on magnetotransmission (magnetoabsorption) and magnetoreflection of natural (unpolarized) light in ferromagnetic chromium chalcogenide spinel, manganites with perovskite structure and thin-film metallic nanostructures in the middle infrared spectral range. The magnetooptical effects under discussion are of high interest for numerous and promising applications in the infrared optoelectronics. - Highlights: • Magnetotransmission and magnetoreflection of light in ferromagnetic are presented. • The effects are greater than common magnetooptical phenomena in the infrared. • The effects may have a different origin depending on a material or spectral range. • Possible applications of the magnetotransmission and magnetoreflection are discussed

  11. Giant magnetotransmission and magnetoreflection in ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, A.V., E-mail: telegin@imp.uran.ru [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620137 Yekaterinburg (Russian Federation); Sukhorukov, Yu.P.; Loshkareva, N.N.; Mostovshchikova, E.V.; Bebenin, N.G. [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620137 Yekaterinburg (Russian Federation); Gan' shina, E.A.; Granovsky, A.B. [Moscow State University, 119991 Moscow (Russian Federation)

    2015-06-01

    We present a brief review on magnetotransmission (magnetoabsorption) and magnetoreflection of natural (unpolarized) light in ferromagnetic chromium chalcogenide spinel, manganites with perovskite structure and thin-film metallic nanostructures in the middle infrared spectral range. The magnetooptical effects under discussion are of high interest for numerous and promising applications in the infrared optoelectronics. - Highlights: • Magnetotransmission and magnetoreflection of light in ferromagnetic are presented. • The effects are greater than common magnetooptical phenomena in the infrared. • The effects may have a different origin depending on a material or spectral range. • Possible applications of the magnetotransmission and magnetoreflection are discussed.

  12. Nonlinear nuclear magnetic resonance in ferromagnets

    International Nuclear Information System (INIS)

    Nurgaliev, T.

    1988-01-01

    The properties of nonlinear nuclear magnetic resonance (NMR) have been studied theoretically by taking into account the interaction between NMR and FMR in the ferromagnets. The Landau-Lifshitz-Bloch equations, describing the electron and nuclear magnetization behaviour in ferromagnets are presented in an integral form for a weakly excited electronic system. The stationary solution of these equations has been analysed in the case of equal NMR and FMR frequencies: the criteria for the appearance of two stable dynamic states is found and the high-frequency magnetic susceptibility for these systems is investigated. 2 figs., 8 refs

  13. Engineering high quality medical software

    CERN Document Server

    Coronato, Antonio

    2018-01-01

    This book focuses on high-confidence medical software in the growing field of e-health, telecare services and health technology. It covers the development of methodologies and engineering tasks together with standards and regulations for medical software.

  14. Superconducting Ferromagnetic Nanodiamond

    Czech Academy of Sciences Publication Activity Database

    Zhang, G.; Samuely, T.; Xu, Z.; Jochum, J. K.; Volodin, A.; Zhou, S. Q.; May, P. W.; Onufriienko, O.; Kacmarik, J.; Steele, J. A.; Li, J.; Vanacken, J.; Vacík, Jiří; Szabo, P.; Yuan, H. F.; Roeffaers, M. B. J.; Cerbu, D.; Samuely, P.; Hofkens, J.; Moshchalkov, V.V.

    2017-01-01

    Roč. 11, č. 6 (2017), s. 5358-5366 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : nanodiamond * superconductivity and ferromagnetism * spin fluctuations * giant positive magnetoresistance * anamalous Hall effect Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nano-materials (production and properties ) Impact factor: 13.942, year: 2016

  15. Voltage control of ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    Ziyao Zhou

    2016-06-01

    Full Text Available Voltage control of magnetism in multiferroics, where the ferromagnetism and ferroelectricity are simultaneously exhibiting, is of great importance to achieve compact, fast and energy efficient voltage controllable magnetic/microwave devices. Particularly, these devices are widely used in radar, aircraft, cell phones and satellites, where volume, response time and energy consumption is critical. Researchers realized electric field tuning of magnetic properties like magnetization, magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk, thin films and nanostructure by different magnetoelectric (ME coupling mechanism: strain/stress, interfacial charge, spin–electromagnetic (EM coupling and exchange coupling, etc. In this review, we focus on voltage control of ferromagnetic resonance (FMR in multiferroics. ME coupling-induced FMR change is critical in microwave devices, where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices. Experimentally, FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics, especially, voltage control of magnetism in novel mechanisms like interfacial charge, spin–EM coupling and exchange coupling.

  16. Effects of high pressure on the structural, magnetic, and transport properties of the itinerant 5f ferromagnet U.sub.2./sub.Fe.sub.3./sub.Ge

    Czech Academy of Sciences Publication Activity Database

    Henriques, M.S.; Gorbunov, Denis; Andreev, Alexander V.; Arnold, Zdeněk; Surblé, S.; Heathman, S.; Griveau, J.C.; Lopes, E.B.; Prchal, J.; Havela, L.; Gonçalves, A.P.

    2014-01-01

    Roč. 89, č. 5 (2014), "054407-1"-"054407-9" ISSN 1098-0121 R&D Projects: GA ČR GAP204/12/0150; GA ČR(CZ) GAP204/10/0330 Grant - others:AVČR(CZ) M100101203 Institutional support: RVO:68378271 Keywords : actinide intermetallics * ferromagnetism * magnetoelasticity * high pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  17. Quality management manual for production of high quality cassava flour

    DEFF Research Database (Denmark)

    Dziedzoave, Nanam Tay; Abass, Adebayo Busura; Amoa-Awua, Wisdom K.

    The high quality cassava flour (HQCF) industry has just started to evolve in Africa and elsewhere. The sustainability of the growing industry, the profitability of small- and medium-scale enterprises (SMEs) that are active in the industry and good-health of consumers can best be guaranteed through...... the adoption of proper quality and food safety procedures. Cassava processing enterprises involved in the productionof HQCF must therefore be commited to the quality and food safety of the HQCF. They must have the right technology, appropriate processing machhinery, standard testing instruments...... and the necessary technical expertise. This quality manual was therefore developed to guide small- to medium-scale cassava in the design and implematation of Hazard Analysis Critical Control Point (HACCP) system and Good manufacturing Practices (GMP) plans for HQCF production. It describes the HQCF production...

  18. High quality-factor optical resonators

    International Nuclear Information System (INIS)

    Henriet, Rémi; Salzenstein, Patrice; Coillet, Aurélien; Saleh, Khaldoun; Chembo, Yanne K; Ristic, Davor; Ferrari, Maurizio; Mortier, Michel; Rasoloniaina, Alphonse; Dumeige, Yannick; Féron, Patrice; Cibiel, Gilles; Llopis, Olivier

    2014-01-01

    Various resonators are investigated for microwave photonic applications. Micro-sphere, disk and fiber ring resonators were designed, realized and characterized. Obtained quality factors are as high as Q = 10 10 . (paper)

  19. High-quality compressive ghost imaging

    Science.gov (United States)

    Huang, Heyan; Zhou, Cheng; Tian, Tian; Liu, Dongqi; Song, Lijun

    2018-04-01

    We propose a high-quality compressive ghost imaging method based on projected Landweber regularization and guided filter, which effectively reduce the undersampling noise and improve the resolution. In our scheme, the original object is reconstructed by decomposing of regularization and denoising steps instead of solving a minimization problem in compressive reconstruction process. The simulation and experimental results show that our method can obtain high ghost imaging quality in terms of PSNR and visual observation.

  20. Note: a high-sensitivity current sensor based on piezoelectric ceramic Pb(Zr,Ti)O3 and ferromagnetic materials.

    Science.gov (United States)

    He, Wei; Li, Ping; Wen, Yumei; Zhang, Jitao; Yang, Aichao; Lu, Caijiang

    2014-02-01

    An electric current sensor using piezoelectric ceramic Pb(Zr,Ti)O3 (PZT) sandwiched between two high permeability cuboids and two NdFeB magnets is presented. The magnetic field originating from an electric wire is augmented by the high permeability cuboids. The PZT plate experiences an enhanced magnetic force and generates voltage output. When placed with a distance of d = 5.0 mm from the wire, the sensor shows a flat sensitivity of ∼5.7 mV/A in the frequency range of 30 Hz-80 Hz and an average sensitivity of 5.6 mV/A with highly linear behavior in the current range of 1 A-10 A at 50 Hz.

  1. Transition Metal Dopants Essential for Producing Ferromagnetism in Metal Oxide Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Lydia; Thurber, Aaron P.; Anghel, Josh; Sabetian, Maryam; Engelhard, Mark H.; Tenne, D.; Hanna, Charles; Punnoose, Alex

    2010-08-13

    Recent claims that ferromagnetism can be produced in nanoparticles of metal oxides without the presence of transition metal dopants has been refuted in this work by investigating 62 high quality well-characterized nanoparticle samples of both undoped and Fe doped (0-10% Fe) ZnO. The undoped ZnO nanoparticles showed zero or negligible magnetization, without any dependence on the nanoparticle size. However, chemically synthesized Zn₁₋xFexO nanoparticles showed clear ferromagnetism, varying systematically with Fe concentration. Furthermore, the magnetic properties of Zn₁₋xFexO nanoparticles showed strong dependence on the reaction media used to prepare the samples. The zeta potentials of the Zn₁₋xFexO nanoparticles prepared using different reaction media were significantly different, indicating strong differences in the surface structure. Electron paramagnetic resonance studies clearly showed that the difference in the ferromagnetic properties of Zn₁₋xFexO nanoparticles with different surface structures originate from differences in the fraction of the doped Fe³⁺ ions that are coupled ferromagnetically.

  2. Hysteresis in conducting ferromagnets

    International Nuclear Information System (INIS)

    Schneider, Carl S.; Winchell, Stephen D.

    2006-01-01

    Maxwell's magnetic diffusion equation is solved for conducting ferromagnetic cylinders to predict a magnetic wave velocity, a time delay for flux penetration and an eddy current field, one of five fields in the linear unified field model of hysteresis. Measured Faraday voltages for a thin steel toroid are shown to be proportional to magnetic field step amplitude and decrease exponentially in time due to maximum rather than average permeability. Dynamic permeabilities are a field convolution of quasistatic permeability and the delay function from which we derive and observe square root dependence of coercivity on rate of field change

  3. Effect of Mg{sup 2+} and Ti{sup 4+} dopants on the structural, magnetic and high-frequency ferromagnetic properties of barium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Shams, Mohammad H. [Department of Physics, University of Isfahan, Hezar Jarib Street, Isfahan 81746-73441 (Iran, Islamic Republic of); Rozatian, Amir S.H., E-mail: a.s.h.rozatian@phys.ui.ac.ir [Department of Physics, University of Isfahan, Hezar Jarib Street, Isfahan 81746-73441 (Iran, Islamic Republic of); Yousefi, Mohammad H. [Department of Physics, University of Isfahan, Hezar Jarib Street, Isfahan 81746-73441 (Iran, Islamic Republic of); Valíček, Jan [Institute of Physics, Faculty of Mining and Geology, VŠB – Technical University of Ostrava, 17. Listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Šepelák, Vladimir [Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany); Slovak Academy of Sciences, Watsonova 45, 04001 Košice (Slovakia)

    2016-02-01

    The doped barium hexaferrite, BaFe{sub 12−x}(Mg{sub 0.5}Ti{sub 0.5}){sub x}O{sub 19} with 1≤x≤5, is synthesized by a solid state ceramic method. Its crystalline structure, morphology, as well as static and dynamic magnetic properties are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry, and vector network analysis, respectively. The cation distribution of Mg{sup 2+} and Ti{sup 4+} in the hexagonal structure of BaFe{sub 12−x}(Mg{sub 0.5}Ti{sub 0.5}){sub x}O{sub 19} is investigated by {sup 57}Fe Mössbauer spectroscopy. The effect of Mg{sup 2+} and Ti{sup 4+} dopants on static and high-frequency magnetic properties of the ferrite is studied. - Highlights: • The BaFe{sub 12−x}(MgTi){sub 0.5x}O{sub 19} (x =1– 5) are synthesized by a solid state reaction method. • The Mg{sup 2+} and Ti{sup 4+} dopants take positions 12k for x=1 and 4f{sub 1} and 4f{sub 2} for x=5. • The coercivity and magnetization are decreased with an increase in Mg–Ti content. • The ferromagnetic resonance frequency is decreased with increase of x. • The FMR is shifted to lower frequencies due to the reduction of the anisotropy field.

  4. Magnetic profiles in ferromagnetic/superconducting superlattices.

    Energy Technology Data Exchange (ETDEWEB)

    te Velthuis, S. G. E.; Hoffmann, A.; Santamaria, J.; Materials Science Division; Univ. Complutense de Madrid

    2007-02-28

    The interplay between ferromagnetism and superconductivity has been of longstanding fundamental research interest to scientists, as the competition between these generally mutually exclusive types of long-range order gives rise to a rich variety of physical phenomena. A method of studying these exciting effects is by investigating artificially layered systems, i.e. alternating deposition of superconducting and ferromagnetic thin films on a substrate, which enables a straight-forward combination of the two types of long-range order and allows the study of how they compete at the interface over nanometer length scales. While originally studies focused on low temperature superconductors interchanged with metallic ferromagnets, in recent years the scope has broadened to include superlattices of high T{sub c} superconductors and colossal magnetoresistance oxides. Creating films where both the superconducting as well as the ferromagnetic layers are complex oxide materials with similar crystal structures (Figure 1), allows the creation of epitaxial superlattices, with potentially atomically flat and ordered interfaces.

  5. Lattice effects on ferromagnetism in perovskite ruthenates

    Science.gov (United States)

    Cheng, J.-G.; Zhou, J.-S.; Goodenough, John B.

    2013-01-01

    Ferromagnetism and its evolution in the orthorhombic perovskite system Sr1–xCaxRuO3 have been widely believed to correlate with structural distortion. The recent development of high-pressure synthesis of the Ba-substituted Sr1–yBayRuO3 makes it possible to study ferromagnetism over a broader phase diagram, which includes the orthorhombic Imma and the cubic phases. However, the chemical substitutions introduce the A-site disorder effect on Tc, which complicates determination of the relationship between ferromagnetism and structural distortion. By clarifying the site disorder effect on Tc in several unique series of ruthenates in which the average bond length 〈A–O〉 remains the same but the bond-length variance varies, we are able to demonstrate a parabolic curve of Tc versus mean bond length 〈A–O〉. A much higher Tc ∼ 177 K than that found in orthorhombic SrRuO3 can be obtained from the curve at a bond length 〈A–O〉, which makes the geometric factor t = 〈A–O〉/(√2〈Ru–O〉) ∼ 1. This result reveals not only that the ferromagnetism in the ruthenates is extremely sensitive to the lattice strain, but also that it has an important implication for exploring the structure–property relationship in a broad range of oxides with perovskite or a perovskite-related structure. PMID:23904477

  6. Fabrication of high-quality brazed joints

    International Nuclear Information System (INIS)

    Orlov, A.V.

    1980-01-01

    Problem of ensuring of joint high-quality when brazing different parts in power engineering is considered. To obtain high-quality joints it is necessary to correctly design brazed joint and to choose a gap width, overlap length and fillet radius; to clean up carefully the surfaces to be brazed and fix them properly one relative to another; to apply a solder so as to provide its flowing into the gap and sticking in it; to exactly regulate thermal conditions of brazing. High quality and reliability of brazed joints are ensured by the application of solders based on noble metals, and cheap solders based on nickel, manganese and copper. Joints brazed with nickel base solders may operate at temperatures as high as 888 deg C

  7. TOTAL QUALITY MANAGEMENT IN HIGH EDUCATION

    Directory of Open Access Journals (Sweden)

    Hasan SERİN, Alper AYTEKİN

    2009-01-01

    Full Text Available The approach of Total Quality Management (TQM has been even more common and most recently its use in high education has been discussed. Likewise the enterprises producing various products, universities have also inputs, processes, and outputs. Due to conditions of competition, universities have to improve the qualities of these inputs, processes, and outputs, according to satisfaction, demands, and expectations of internal and external customers. If the TQM has been implemented in the universities with a manner that aims for customer satisfaction (students, lecturers, public and private establishments, and families, supports constant development, ensures participatory approach, and encourages working in groups, it will provide universities with effectiveness, efficiency, dynamics, and economics. In this study, common problems of universities, definitions of quality and TQM in high education, customer concept at universities, and factors affecting the quality of education have been explained. Besides, in order TQM approach to be successfully implemented in the universities, various suggestions have been presented.

  8. Silicon spintronics with ferromagnetic tunnel devices

    International Nuclear Information System (INIS)

    Jansen, R; Sharma, S; Dash, S P; Min, B C

    2012-01-01

    In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

  9. Magnetic nesting and co-existence of ferromagnetism and superconductivity

    International Nuclear Information System (INIS)

    Elesin, V.F.; Kapaev, V.V.; Kopaev, Yu.V.

    2004-01-01

    In the case of providing for the magnetic nesting conditions of the electron spin dispersion law the co-existence of ferromagnetism and superconductivity is possible by any high magnetization. The co-existence of ferromagnetism and superconductivity in the layered cuprate compounds of the RuSr 2 GdCu 2 O 8 -type is explained on this basis, wherein due to the nonstrict provision of the magnetic nesting condition there exists the finite but sufficiently high critical magnetization [ru

  10. Spin-dependent transport and functional design in organic ferromagnetic devices

    Directory of Open Access Journals (Sweden)

    Guichao Hu

    2017-09-01

    Full Text Available Organic ferromagnets are intriguing materials in that they combine ferromagnetic and organic properties. Although challenges in their synthesis still remain, the development of organic spintronics has triggered strong interest in high-performance organic ferromagnetic devices. This review first introduces our theory for spin-dependent electron transport through organic ferromagnetic devices, which combines an extended Su–Schrieffer–Heeger model with the Green’s function method. The effects of the intrinsic interactions in the organic ferromagnets, including strong electron–lattice interaction and spin–spin correlation between π-electrons and radicals, are highlighted. Several interesting functional designs of organic ferromagnetic devices are discussed, specifically the concepts of a spin filter, multi-state magnetoresistance, and spin-current rectification. The mechanism of each phenomenon is explained by transmission and orbital analysis. These works show that organic ferromagnets are promising components for spintronic devices that deserve to be designed and examined in future experiments.

  11. Raman characterization of bulk ferromagnetic nanostructured graphite

    International Nuclear Information System (INIS)

    Pardo, Helena; Divine Khan, Ngwashi; Faccio, Ricardo; Araújo-Moreira, F.M.; Fernández-Werner, Luciana

    2012-01-01

    Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm -1 showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.

  12. Effect of forage quality in faeces from different ruminant species fed high and low quality forage

    DEFF Research Database (Denmark)

    Jalali, A R; Nørgaard, P; Nielsen, M O

    2010-01-01

    Effect of forage quality in faeces from different ruminant species fed high and low quality forage......Effect of forage quality in faeces from different ruminant species fed high and low quality forage...

  13. Assuring quality in high-consequence engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hoover, Marcey L.; Kolb, Rachel R.

    2014-03-01

    In high-consequence engineering organizations, such as Sandia, quality assurance may be heavily dependent on staff competency. Competency-dependent quality assurance models are at risk when the environment changes, as it has with increasing attrition rates, budget and schedule cuts, and competing program priorities. Risks in Sandia's competency-dependent culture can be mitigated through changes to hiring, training, and customer engagement approaches to manage people, partners, and products. Sandia's technical quality engineering organization has been able to mitigate corporate-level risks by driving changes that benefit all departments, and in doing so has assured Sandia's commitment to excellence in high-consequence engineering and national service.

  14. Producing high-quality slash pine seeds

    Science.gov (United States)

    James Barnett; Sue Varela

    2003-01-01

    Slash pine is a desirable species. It serves many purposes and is well adapted to poorly drained flatwoods and seasonally flooded areas along the lower Coastal Plain of the Southeastern US. The use of high-quality seeds has been shown to produce uniform seedlings for outplanting, which is key to silvicultural success along the Coastal Plain and elsewhere. We present...

  15. Endorectal high dose rate brachytherapy quality assurance

    International Nuclear Information System (INIS)

    Devic, S.; Vuong, T.; Evans, M.; Podgorsak, E.

    2008-01-01

    We describe our quality assurance method for preoperative high dose rate (HDR) brachytherapy of endorectal tumours. Reproduction of the treatment planning dose distribution on a daily basis is crucial for treatment success. Due to the cylindrical symmetry, two types of adjustments are necessary: applicator rotation and dose distribution shift along the applicator axis. (author)

  16. Understanding lattice defects to influence ferromagnetic order of ZnO nanoparticles by Ni, Cu, Ce ions

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Kuldeep Chand, E-mail: dkuldeep.physics@gmail.com [Department of Physics, Panjab University, Chandigarh 160014 (India); Kotnala, R.K., E-mail: rkkotnala@gmail.com [CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2017-02-15

    Future spintronics technologies based on diluted magnetic semiconductors (DMS) will rely heavily on a sound understanding of the microscopic origins of ferromagnetism in such materials. It remains unclear, however, whether the ferromagnetism in DMS is intrinsic - a precondition for spintronics - or due to dopant clustering. For this, we include a simultaneous doping from transition metal (Ni, Cu) and rare earth (Ce) ions in ZnO nanoparticles that increase the antiferromagnetic ordering to achieve high-T{sub c} ferromagnetism. Rietveld refinement of XRD patterns indicate that the dopant ions in ZnO had a wurtzite structure and the dopants, Ni{sup 2+}, Cu{sup 2+}, Ce{sup 3+} ions, are highly influenced the lattice constants to induce lattice defects. The Ni, Cu, Ce ions in ZnO have nanoparticles formation than nanorods was observed in pure sample. FTIR involve some organic groups to induce lattice defects and the metal-oxygen bonding of Zn, Ni, Cu, Ce and O atoms to confirm wurtzite structure. Raman analysis evaluates the crystalline quality, structural disorder and defects in ZnO lattice with doping. Photoluminescence spectra have strong near-band-edge emission and visible emission bands responsible for defects due to oxygen vacancies. The energy band gap is calculated using Tauc relation. Room temperature ferromagnetism has been described due to bound magnetic polarons formation with Ni{sup 2+}, Cu{sup 2+}, Ce{sup 3+} ions in ZnO via oxygen vacancies. The zero field and field cooling SQUID measurement confirm the strength of antiferromagnetism in ZnO. The field cooling magnetization is studied by Curie-Weiss law that include antiferromagnetic interactions up to low temperature. The XPS spectra have involve +3/+4 oxidation states of Ce ions to influence the observed ferromagnetism. - Graphical abstract: The lattice defects/vacancies attributed by Ni and Ce ions in the wurtzite ZnO structure are responsible in high T{sub c} -ferromagnetism due to long-range magnetic

  17. Pressure-induced weak ferromagnetism in uranium dioxide, UO2

    International Nuclear Information System (INIS)

    Sakai, H; Kato, H; Tokunaga, Y; Kambe, S; Walstedt, R E; Nakamura, A; Tateiwa, N; Kobayashi, T C

    2003-01-01

    The dc magnetization of insulating UO 2 under high pressure up to ∼1 GPa has been measured using a piston-cylinder cell. Pressure-induced weak ferromagnetism appeared at low pressure (∼0.2 GPa). Both the remanent magnetization and the coercive force increase as pressure increases. This weak ferromagnetism may come from spin canting or from uncompensated moments around grain boundaries

  18. High Quality Virtual Reality for Architectural Exhibitions

    DEFF Research Database (Denmark)

    Kreutzberg, Anette

    2016-01-01

    This paper will summarise the findings from creating and implementing a visually high quality Virtual Reality (VR) experiment as part of an international architecture exhibition. It was the aim to represent the architectural spatial qualities as well as the atmosphere created from combining natural...... and artificial lighting in a prominent not yet built project. The outcome is twofold: Findings concerning the integration of VR in an exhibition space and findings concerning the experience of the virtual space itself. In the exhibition, an important aspect was the unmanned exhibition space, requiring the VR...... experience to be self-explanatory. Observations of different visitor reactions to the unmanned VR experience compared with visitor reactions at guided tours with personal instructions are evaluated. Data on perception of realism, spatial quality and light in the VR model were collected with qualitative...

  19. Optical orientation in ferromagnet/semiconductor hybrids

    International Nuclear Information System (INIS)

    Korenev, V L

    2008-01-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin–spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism

  20. Optical orientation in ferromagnet/semiconductor hybrids

    Science.gov (United States)

    Korenev, V. L.

    2008-11-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin-spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism.

  1. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  2. Ferromagnetic Objects Magnetovision Detection System.

    Science.gov (United States)

    Nowicki, Michał; Szewczyk, Roman

    2013-12-02

    This paper presents the application of a weak magnetic fields magnetovision scanning system for detection of dangerous ferromagnetic objects. A measurement system was developed and built to study the magnetic field vector distributions. The measurements of the Earth's field distortions caused by various ferromagnetic objects were carried out. The ability for passive detection of hidden or buried dangerous objects and the determination of their location was demonstrated.

  3. Ferromagnetic Objects Magnetovision Detection System

    Directory of Open Access Journals (Sweden)

    Michał Nowicki

    2013-12-01

    Full Text Available This paper presents the application of a weak magnetic fields magnetovision scanning system for detection of dangerous ferromagnetic objects. A measurement system was developed and built to study the magnetic field vector distributions. The measurements of the Earth’s field distortions caused by various ferromagnetic objects were carried out. The ability for passive detection of hidden or buried dangerous objects and the determination of their location was demonstrated.

  4. Non-ferromagnetic overburden casing

    Science.gov (United States)

    Vinegar, Harold J.; Harris, Christopher Kelvin; Mason, Stanley Leroy

    2010-09-14

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one system for electrically insulating an overburden portion of a heater wellbore is described. The system may include a heater wellbore located in a subsurface formation and an electrically insulating casing located in the overburden portion of the heater wellbore. The casing may include at least one non-ferromagnetic material such that ferromagnetic effects are inhibited in the casing.

  5. Ferromagnetism in doped or undoped spintronics nanomaterials

    Science.gov (United States)

    Qiang, You

    2010-10-01

    Much interest has been sparked by the discovery of ferromagnetism in a range of oxide doped and undoped semiconductors. The development of ferromagnetic oxide semiconductor materials with giant magnetoresistance (GMR) offers many advantages in spintronics devices for future miniaturization of computers. Among them, TM-doped ZnO is an extensively studied n-type wide-band-gap (3.36 eV) semiconductor with a tremendous interest as future mini-computer, blue light emitting, and solar cells. In this talk, Co-doped ZnO and Co-doped Cu2O semiconductor nanoclusters are successfully synthesized by a third generation sputtering-gas-aggregation cluster technique. The Co-doped nanoclusters are ferromagnetic with Curie temperature above room temperature. Both of Co-doped nanoclusters show positive magnetoresistance (PMR) at low temperature, but the amplitude of the PMRs shows an anomalous difference. For similar Co doping concentration at 5 K, PMR is greater than 800% for Co-doped ZnO but only 5% for Co-doped Cu2O nanoclusters. Giant PMR in Co-doped ZnO which is attributed to large Zeeman splitting effect has a linear dependence on applied magnetic field with very high sensitivity, which makes it convenient for the future spintronics applications. The small PMR in Co-doped Cu2O is related to its vanishing density of states at Fermi level. Undoped Zn/ZnO core-shell nanoparticle gives high ferromagnetic properties above room temperature due to the defect induced magnetization at the interface.

  6. High quality transportation fuels from renewable feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Lindfors, Lars Peter

    2010-09-15

    Hydrotreating of vegetable oils is novel process for producing high quality renewable diesel. Hydrotreated vegetable oils (HVO) are paraffinic hydrocarbons. They are free of aromatics, have high cetane numbers and reduce emissions. HVO can be used as component or as such. HVO processes can also be modified to produce jet fuel. GHG savings by HVO use are significant compared to fossil fuels. HVO is already in commercial production. Neste Oil is producing its NExBTL diesel in two plants. Production of renewable fuels will be limited by availability of sustainable feedstock. Therefore R and D efforts are made to expand feedstock base further.

  7. Boiling curve in high quality flow boiling

    International Nuclear Information System (INIS)

    Shiralkar, B.S.; Hein, R.A.; Yadigaroglu, G.

    1980-01-01

    The post dry-out heat transfer regime of the flow boiling curve was investigated experimentally for high pressure water at high qualities. The test section was a short round tube located downstream of a hot patch created by a temperature controlled segment of tubing. Results from the experiment showed that the distance from the dryout point has a significant effect on the downstream temperatures and there was no unique boiling curve. The heat transfer coefficients measured sufficiently downstream of the dryout point could be correlated using the Heineman correlation for superheated steam, indicating that the droplet deposition effects could be neglected in this region

  8. Flocking ferromagnetic colloids.

    Science.gov (United States)

    Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S

    2017-02-01

    Assemblages of microscopic colloidal particles exhibit fascinating collective motion when energized by electric or magnetic fields. The behaviors range from coherent vortical motion to phase separation and dynamic self-assembly. Although colloidal systems are relatively simple, understanding their collective response, especially under out-of-equilibrium conditions, remains elusive. We report on the emergence of flocking and global rotation in the system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms, leading to the emergence of large-scale collective motion: spontaneous symmetry breaking of the clockwise/counterclockwise particle rotation, collisional alignment of particle velocities, and random particle reorientations due to shape imperfections. We have also shown that hydrodynamic interactions between the particles do not have a qualitative effect on the collective dynamics. Our findings shed light on the onset of spatial and temporal coherence in a large class of active systems, both synthetic (colloids, swarms of robots, and biopolymers) and living (suspensions of bacteria, cell colonies, and bird flocks).

  9. Ab initio and Monte Carlo investigations of structural, electronic and magnetic properties of new ferromagnetic Heusler alloys with high Curie temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Dannenberg, Antje

    2011-08-30

    The mechanism which causes many of the unusual thermomechanical properties of martensitic alloys, as for example, superelasticity and the shape-memory effect, is the martensitic transformation. The prototype ferromagnetic shape memory alloy (FSMA) is Ni{sub 2}MnGa. But a technological breakthrough is missing due to its poor ductility and low operation temperatures. The goal of this thesis is the proposal of new FSMA appropriate for future technological applications. I focus on X{sub 2}YZ Heusler alloys which are mainly based on Mn, Fe, Co, and Ni for the X and Y sites and Z=Ga or Zn. The big challenge of this work is to find material classes which combine the unique magnetomechanical properties of FSMA which are large recoverable magnetostrictive strains, high magnetocrystalline anisotropy energy, and highly mobile twin boundaries with transformation temperatures clearly above room temperature and a reduced brittleness. Such a study, providing material classes which from a theoretical point of view are promising candidates for future FSMA, will help the experimental physicists to select interesting subgroups in the vast number of possible chemical compositions of X{sub 2}YZ Heusler alloys. I have systematically varied the composition in the new Heusler alloys in order to find trends indicating generic tendencies of the material properties, for instance, as a function of the valence electron concentration e/a. A main feature of this thesis is the attempt to find the origin of the competing structural ordering tendencies between conventional X{sub 2}YZ and inverse (XY)XZ Heusler structures which are observed for all systems investigated. In the first part of this work the accuracy and predictive power of ab initio and Monte Carlo simulations is demonstrated by reproducing the experimental phase diagram of Ni-Mn-(Ga,In,Sn,Sb). The linear increasing and decreasing slopes of T{sub M} and T{sub C} can be reproduced by total and free energy calculations and the analysis

  10. Eddy current inspection of mildly ferromagnetic tubing

    International Nuclear Information System (INIS)

    Mayo, W.R.; Carter, J.R.

    1984-02-01

    The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence inspect, the duplex stainless steel Sandvik 3RE60, which has saturation induction more than twice that of Monel 400. Prototypes of these probes have been tested in three ways: saturation capability, quality of typical eddy current data, and ability to eliminate permeability induced signals. Successful laboratory testing, potential applications, and limitations of these type probes are discussed

  11. Breeding and maintaining high-quality insects

    DEFF Research Database (Denmark)

    Jensen, Kim; Kristensen, Torsten Nygård; Heckmann, Lars-Henrik

    2017-01-01

    Insects have a large potential for sustainably enhancing global food and feed production, and commercial insect production is a rising industry of high economic value. Insects suitable for production typically have fast growth, short generation time, efficient nutrient utilization, high...... reproductive potential, and thrive at high density. Insects may cost-efficiently convert agricultural and industrial food by-products into valuable protein once the technology is finetuned. However, since insect mass production is a new industry, the technology needed to efficiently farm these animals is still...... in a starting phase. Here, we discuss the challenges and precautions that need to be considered when breeding and maintaining high-quality insect populations for food and feed. This involves techniques typically used in domestic animal breeding programs including maintaining genetically healthy populations...

  12. Inductive measurements of ferromagnetic resonance

    International Nuclear Information System (INIS)

    Woodward, R.C.; Kennewell, K.; Crew, D.C.; Stamps, R.L.

    2004-01-01

    Full text: The rapid advance in magnetic data storage has driven groundbreaking work in the science that underpins the properties of ferromagnetic materials at high frequencies. Recent work in this area has included the use of precession in order to produce ultra-high speed switching of magnetic elements, the generation of excited dynamical structures by application of inhomogeneous field pulses, and examination of the propagation of localized spin waves. This paper describes explorations of ultra-fast magnetization dynamics being undertaken at The University of Western Australia. We have studied the differences in magnetization dynamics in simple permalloy films when a sample is excited with sharp pulse compared to the to the dynamics generated by the application of a small amplitude continuous wave signal. We have observed a difference in the resonant frequency determined from these two excitations and will propose reasons for the different resonance responses of the system. Using the ultra-fast techniques described above we have measured dynamical properties that are significantly different to the static properties. These results are explained by the dynamical measurements being made on time scales smaller than the characteristic relaxation time. Future applications of these devices will be to examine broadening of line widths and frequency shifts associated with the excitation of magnetostatic modes, factors limiting quasiballistic reversal and differences between the dynamic and static properties of magnetic materials

  13. A simple one step solid state synthesis of nanocrystalline ferromagnetic α-Fe{sub 2}O{sub 3} with high surface area and catalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Shete, Madhavi D.; Fernandes, J.B., E-mail: julio@unigoa.ac.in

    2015-09-01

    α-Fe{sub 2}O{sub 3} is obtained by a simple route involving solvent free solid state decomposition of ferric nitrate in presence of urea. The samples were characterized by X-ray diffraction, infra-red and UV–Vis spectral studies, TEM, BET surface area measurements and TG–DTA analysis. Magnetic measurements were done from M–H hysteresis profiles. By changing the ratio of ferric nitrate and urea, α-phase was obtained in all the synthesized samples and was accompanied with increase in ferromagnetic behavior. The samples showed good photocatalytic activity for decomposition of H{sub 2}O{sub 2} and could be correlated with surface area values. The results were interpreted in terms of activity for the heterogeneous photo-Fenton reaction. - Highlights: • α-Fe{sub 2}O{sub 3} were synthesized by a solid state method. • These oxides showed large surface area and ferromagnetic behavior. • The catalysts showed good heterogeneous photo-Fenton activity.

  14. Conceptual study of ferromagnetic pebbles for heat exhaust in fusion reactors with short power decay length

    Directory of Open Access Journals (Sweden)

    N. Gierse

    2015-03-01

    The key results of this study are that very high heat fluxes are accessible in the operation space of ferromagnetic pebbles, that ferromagnetic pebbles are compatible with tokamak operation and current divertor designs, that the heat removal capability of ferromagnetic pebbles increases as λq decreases and, finally, that for fusion relevant values of q∥ pebble diameters below 100 μm are required.

  15. Self-assembly of linear [Mn II 2 Mn III ] units with end-on azido bridges: the construction of a ferromagnetic chain using S T = 7 high-spin trimers

    KAUST Repository

    Jiang, Yuan

    2015-01-01

    © The Royal Society of Chemistry 2015. The controlled organization of high-spin complexes into 1D coordination polymers is a challenge in molecular magnetism. In this work, we report a ferromagnetic Mn trimer Mn3(HL)2(CH3OH)6(Br)4·Br·(CH3OH)21 (H2L = 2-[(9H-fluoren-9-yl)amino]propane-1,3-diol) with the ground spin state of ST = 7 that can be assembled into a one-dimensional coordination chain [Mn3(HL)2(CH3OH)2(Br)4(N3)(H2O)·CH3OH]∞2 using azido bridging ligands. Interestingly, the ferromagnetic nature of 1 is well retained in 2. However, due to the negligible magnetic anisotropy in 1, both 1 and 2 do not show slow-relaxation of magnetization, which indicates that during the process of molecular assembly not only the intratrimer magnetic interaction but also the magnetic anisotropy of the trimer can be reserved.

  16. Dynamical response of vibrating ferromagnets

    CERN Document Server

    Gaganidze, E; Ziese, M

    2000-01-01

    The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of t...

  17. Magnetic excitations in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Furdyna, J.K.; Liu, X.; Zhou, Y.Y.

    2009-01-01

    Magnetic excitations in a series of GaMnAs ferromagnetic semiconductor films were studied by ferromagnetic resonance (FMR). Using the FMR approach, multi-mode spin wave resonance spectra have been observed, whose analysis provides information on magnetic anisotropy (including surface anisotropy), distribution of magnetization precession within the GaMnAs film, dynamic surface spin pinning (derived from surface anisotropy), and the value of exchange stiffness constant D. These studies illustrate a combination of magnetism and semiconductor physics that is unique to magnetic semiconductors

  18. Method for synthesis of high quality graphene

    Science.gov (United States)

    Lanzara, Alessandra [Piedmont, CA; Schmid, Andreas K [Berkeley, CA; Yu, Xiaozhu [Berkeley, CA; Hwang, Choonkyu [Albany, CA; Kohl, Annemarie [Beneditkbeuern, DE; Jozwiak, Chris M [Oakland, CA

    2012-03-27

    A method is described herein for the providing of high quality graphene layers on silicon carbide wafers in a thermal process. With two wafers facing each other in close proximity, in a first vacuum heating stage, while maintained at a vacuum of around 10.sup.-6 Torr, the wafer temperature is raised to about 1500.degree. C., whereby silicon evaporates from the wafer leaving a carbon rich surface, the evaporated silicon trapped in the gap between the wafers, such that the higher vapor pressure of silicon above each of the wafers suppresses further silicon evaporation. As the temperature of the wafers is raised to about 1530.degree. C. or more, the carbon atoms self assemble themselves into graphene.

  19. High quality data: An evaluation of AIM data quality and data quality procedures

    Science.gov (United States)

    The goal of every monitoring program is to collect high-quality data which can then be used to provide information to decision makers. The Bureau of Land Management (BLM) Assessment, Inventory, and Monitoring (AIM) program is one such data set which provides rangeland status, condition, and trend in...

  20. High-picture quality industrial CT scanner

    International Nuclear Information System (INIS)

    Shoji, Takao; Nishide, Akihiko; Fujii, Masashi.

    1989-01-01

    Industrial X-ray-CT-scanners, which provide cross-sectional images of a tested sample without destroying it, are attracting attention as a new nondestructive inspection device. In 1982, Toshiba commenced the development of industrial CT scanners, and introduced the 'TOSCANER' -3000 and-4000 series. Now, the state of the art 'TOSCANER'-20000 series of CT systems has been developed incorporating the latest computer tomography and image processing technology, such as the T9506 image processor. One of the advantages of this system is its applicability to a wide range of X-ray energy . The 'TOSCANER'-20000 series can be utilized for inspecting castings and other materials with relatively low-transparency to X-rays, as well as ceramics, composite materials and other materials with high X-ray transparency. A further feature of the new system is its high-picture quality, with a high-spatial resolution resulting from a pixel size of 0.2x0.2(mm). (author)

  1. [Quality management is associated with high quality services in health care].

    Science.gov (United States)

    Nielsen, Tenna Hassert; Riis, Allan; Mainz, Jan; Jensen, Anne-Louise Degn

    2013-12-09

    In these years, quality management has been the focus in order to meet high quality services for the patients in Danish health care. This article provides information on quality management and quality improvement and it evaluates its effectiveness in achieving better organizational structures, processes and results in Danish health-care organizations. Our findings generally support that quality management is associated with high quality services in health care.

  2. Optical studies of high quality synthetic diamond

    International Nuclear Information System (INIS)

    Sharp, S.J.

    1999-01-01

    This thesis is concerned with the study of fundamental and defect induced optical properties of synthetic diamond grown using high pressure, high temperature (HPHT) synthesis or chemical vapour deposition (CVD). The primary technique used for investigation is cathodoluminescence (including imaging and decay-time measurements) in addition to other forms of optical spectroscopy. This thesis is timely in that the crystallinity and purity of synthetic diamond has increased ten fold over the last few years. The diamond exciton emission, which is easily quenched by the presence of defects, is studied in high quality samples in detail. In addition the ability now exists to engineer the isotopic content of synthetic diamond to a high degree of accuracy. The experimental chapters are divided as follows: Chapter 2: High resolution, low temperature spectra reveal a splitting of the free-exciton phonon recombination emission peaks and the bound-exciton zero phonon line. Included are measurements of the variation in intensity and decay-time as a function of temperature. Chapter 3: The shift in energy of the phonon-assisted free-exciton phonon replicas with isotopic content has been measured. The shift is in agreement with the results of interatomic force model for phonon scattering due to isotope disorder. Chapter 4: A study of the shift in energy with isotopic content of the diamond of the GR1 band due to the neutral vacancy has allowed a verification of the theoretical predictions due to the Jahn Teller effect. Chapter 5: The spatial distribution of the free-exciton luminescence is studied in HPHT synthetic and CVD diamond. A variation in intensity with distance from the surface is interpreted as a significant non-radiative loss of excitons to the surface. Chapter 6: The decay-times of all known self-interstitial related centres have been measured in order to calculate the concentration of these centres present in electron irradiated diamond. (author)

  3. High Quality Data for Grid Integration Studies

    Energy Technology Data Exchange (ETDEWEB)

    Clifton, Andrew; Draxl, Caroline; Sengupta, Manajit; Hodge, Bri-Mathias

    2017-01-22

    As variable renewable power penetration levels increase in power systems worldwide, renewable integration studies are crucial to ensure continued economic and reliable operation of the power grid. The existing electric grid infrastructure in the US in particular poses significant limitations on wind power expansion. In this presentation we will shed light on requirements for grid integration studies as far as wind and solar energy are concerned. Because wind and solar plants are strongly impacted by weather, high-resolution and high-quality weather data are required to drive power system simulations. Future data sets will have to push limits of numerical weather prediction to yield these high-resolution data sets, and wind data will have to be time-synchronized with solar data. Current wind and solar integration data sets are presented. The Wind Integration National Dataset (WIND) Toolkit is the largest and most complete grid integration data set publicly available to date. A meteorological data set, wind power production time series, and simulated forecasts created using the Weather Research and Forecasting Model run on a 2-km grid over the continental United States at a 5-min resolution is now publicly available for more than 126,000 land-based and offshore wind power production sites. The National Solar Radiation Database (NSRDB) is a similar high temporal- and spatial resolution database of 18 years of solar resource data for North America and India. The need for high-resolution weather data pushes modeling towards finer scales and closer synchronization. We also present how we anticipate such datasets developing in the future, their benefits, and the challenges with using and disseminating such large amounts of data.

  4. Room Temperature Ferromagnetic Mn:Ge(001

    Directory of Open Access Journals (Sweden)

    George Adrian Lungu

    2013-12-01

    Full Text Available We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001, heated at relatively high temperature (starting with 250 °C. The samples were characterized by low energy electron diffraction (LEED, scanning tunneling microscopy (STM, high resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, superconducting quantum interference device (SQUID, and magneto-optical Kerr effect (MOKE. Samples deposited at relatively elevated temperature (350 °C exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001 crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001. The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

  5. Ferromagnetic Swimmers - Devices and Applications

    Science.gov (United States)

    Hamilton, Joshua; Petrov, Peter; Winlove, C. Peter; Gilbert, Andrew; Bryan, Matthew; Ogrin, Feodor

    2017-11-01

    Microscopic swimming devices hold promise for radically new applications in lab-on-a-chip and microfluidic technology, diagnostics and drug delivery etc. We propose a new class of autonomous ferromagnetic swimming devices, actuated and controlled solely by an oscillating magnetic field. Experimentally, these devices (3.6 mm) are based on a pair of interacting ferromagnetic particles of different size and different anisotropic properties joined by an elastic link and actuated by an external time-dependent magnetic field. The net motion is generated through a combination of dipolar interparticle gradient forces, time-dependent torque and hydrodynamic coupling. We investigate the dynamic performance of a prototype (3.6 mm) of the ferromagnetic swimmer in fluids of different viscosity as a function of the external field parameters and demonstrate stable propulsion over a wide range of Reynolds numbers. Manipulation of the external magnetic field resulted in robust control over the speed and direction of propulsion. We also demonstrate our ferromagnetic swimmer working as a macroscopic prototype of a microfluidic pump. By physically tethering the swimmer, instead of swimming, the swimmer generates a directional flow of liquid around itself.

  6. Collapse of ferromagnetism in itinerant-electron system: A magnetic, transport properties, and high pressure study of (Hf,Ta)Fe2 compounds

    Science.gov (United States)

    Diop, L. V. B.; Kastil, J.; Isnard, O.; Arnold, Z.; Kamarad, J.

    2014-10-01

    The magnetism and transport properties were studied for Laves (Hf,Ta)Fe2 itinerant-electron compounds, which exhibit a temperature-induced first-order transition from the ferromagnetic (FM) to the antiferromagnetic (AFM) state upon heating. At finite temperatures, the field-induced metamagnetic phase transition between the AFM and FM has considerable effects on the transport properties of these model metamagnetic compounds. A large negative magnetoresistance of about 14% is observed in accordance with the metamagnetic transition. The magnetic phase diagram is determined for the Laves Hf1-xTaxFe2 series and its Ta concentration dependence discussed. An unusual behavior is revealed in the paramagnetic state of intermediate compositions, it gives rise to the rapid increase and saturation of the local spin fluctuations of the 3d electrons. This new result is analysed in the frame of the theory of Moriya. For a chosen composition Hf0.825Ta0.175Fe2, exhibiting such remarkable features, a detailed investigation is carried out under hydrostatic pressure up to 1 GPa in order to investigate the volume effect on the magnetic properties. With increasing pressure, the magnetic transition temperature TFM-AFM from ferromagnetic to antiferromagnetic order decreases strongly non-linearly and disappears at a critical pressure of 0.75 GPa. In the pressure-induced AFM state, the field-induced first-order AFM-FM transition appears and the complex temperature dependence of the AFM-FM transition field is explained by the contribution from both the magnetic and elastic energies caused by the significant temperature variation of the amplitude of the local Fe magnetic moment. The application of an external pressure leads also to the progressive decrease of the Néel temperature TN. In addition, a large pressure effect on the spontaneous magnetization MS for pressures below 0.45 GPa, dln(Ms)/dP = -6.3 × 10-2 GPa-1 was discovered. The presented results are consistent with Moriya

  7. Ferromagnetic Film on a Superconducting Substrate

    OpenAIRE

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2000-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic (FM) film with perpendicular magnetization M_0 on a superconducting (SC) substrate. At 4{\\pi}M_0> 1. Here \\lambda_L is the London penetration length. For 4{\\pi}M_0 > H_{c1} and l_{N} in excess of about 35 {\\lambda}_{L}, the domains are connected by SC vortices. We argue that pinning of vortices by magnetic domains in FM/SC multilayers can provide high critical currents.

  8. Carbon Nanotubes Filled with Ferromagnetic Materials

    Directory of Open Access Journals (Sweden)

    Albrecht Leonhardt

    2010-08-01

    Full Text Available Carbon nanotubes (CNT filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology.

  9. Carbon Nanotubes Filled with Ferromagnetic Materials

    Science.gov (United States)

    Weissker, Uhland; Hampel, Silke; Leonhardt, Albrecht; Büchner, Bernd

    2010-01-01

    Carbon nanotubes (CNT) filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD) methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology. PMID:28883334

  10. Formation of quadrupolar phase in non-Heisenberg ferromagnets with half-integer spin

    International Nuclear Information System (INIS)

    Fridman, Yu.A.; Kosmachev, O.A.; Spirin, D.V.

    2005-01-01

    Possibility of realization of quadrupolar phase in non-Heisenberg ferromagnet with magnetic ion spin 32 is studied. It is shown that such phase state exists only in ferromagnets with high value of biquadratic exchange when external magnetic field is not applied. Phase diagram of the system is built

  11. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe2Mn1−xCuxAl (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    International Nuclear Information System (INIS)

    Thanh, Tran Dang; Nanto, Dwi; Tuyen, Ngo Thi Uyen; Nan, Wen-Zhe; Yu, YiKyung; Tartakovsky, Daniel M.; Yu, S.C.

    2015-01-01

    In this work, we prepared nanocrystalline Fe 2 Mn 1−x Cu x Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe 2 Mn 1−x Cu x Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe 2 Mn 1−x Cu x Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS m (T, H) data are followed a universal master curve

  12. Chemical solution synthesis and ferromagnetic resonance of epitaxial thin films of yttrium iron garnet

    Science.gov (United States)

    Lucas, Irene; Jiménez-Cavero, Pilar; Vila-Fungueiriño, J. M.; Magén, Cesar; Sangiao, Soraya; de Teresa, José Maria; Morellón, Luis; Rivadulla, Francisco

    2017-12-01

    We report the fabrication of epitaxial Y3F e5O12 (YIG) thin films on G d3G a5O12 (111) using a chemical solution method. Cubic YIG is a ferrimagnetic material at room temperature, with excellent magneto-optical properties, high electrical resistivity, and a very narrow ferromagnetic resonance, which makes it particularly suitable for applications in filters and resonators at microwave frequencies. But these properties depend on the precise stoichiometry and distribution of F e3 + ions among the octahedral/tetrahedral sites of a complex structure, which hampered the production of high-quality YIG thin films by affordable chemical methods. Here we report the chemical solution synthesis of YIG thin films, with excellent chemical, crystalline, and magnetic homogeneity. The films show a very narrow ferromagnetic resonance (long spin relaxation time), comparable to that obtained from high-vacuum physical deposition methods. These results demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic devices and other high-frequency applications.

  13. Dirac Magnons in Honeycomb Ferromagnets

    Directory of Open Access Journals (Sweden)

    Sergey S. Pershoguba

    2018-01-01

    Full Text Available The discovery of the Dirac electron dispersion in graphene [A. H. Castro Neto, et al., The Electronic Properties of Graphene, Rev. Mod. Phys. 81, 109 (2009RMPHAT0034-686110.1103/RevModPhys.81.109] led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching [T. O. Wehling, et al., Dirac Materials, Adv. Phys. 63, 1 (2014ADPHAH0001-873210.1080/00018732.2014.927109], the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of van der Waals-bonded stacks of honeycomb layers, e.g., chromium trihalides CrX_{3} (X=F, Cl, Br and I, that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single-particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory [F. J. Dyson, General Theory of Spin-Wave Interactions, Phys. Rev. 102, 1217 (1956PHRVAO0031-899X10.1103/PhysRev.102.1217, F. J. Dyson, Thermodynamic Behavior of an Ideal Ferromagnet, Phys. Rev. 102, 1230 (1956PHRVAO0031-899X10.1103/PhysRev.102.1230] to the case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in nearly half-century-old magnetic neutron-scattering data for CrBr_{3} [W. B. Yelon and R. Silberglitt, Renormalization of Large-Wave-Vector Magnons in

  14. Dirac Magnons in Honeycomb Ferromagnets

    Science.gov (United States)

    Pershoguba, Sergey S.; Banerjee, Saikat; Lashley, J. C.; Park, Jihwey; Ågren, Hans; Aeppli, Gabriel; Balatsky, Alexander V.

    2018-01-01

    The discovery of the Dirac electron dispersion in graphene [A. H. Castro Neto, et al., The Electronic Properties of Graphene, Rev. Mod. Phys. 81, 109 (2009), 10.1103/RevModPhys.81.109] led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching [T. O. Wehling, et al., Dirac Materials, Adv. Phys. 63, 1 (2014), 10.1080/00018732.2014.927109], the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of van der Waals-bonded stacks of honeycomb layers, e.g., chromium trihalides CrX3 (X =F , Cl, Br and I), that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single-particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory [F. J. Dyson, General Theory of Spin-Wave Interactions, Phys. Rev. 102, 1217 (1956), 10.1103/PhysRev.102.1217, F. J. Dyson, Thermodynamic Behavior of an Ideal Ferromagnet, Phys. Rev. 102, 1230 (1956), 10.1103/PhysRev.102.1230] to the case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in nearly half-century-old magnetic neutron-scattering data for CrBr3 [W. B. Yelon and R. Silberglitt, Renormalization of Large-Wave-Vector Magnons in Ferromagnetic CrBr3 Studied by Inelastic Neutron Scattering: Spin-Wave Correlation

  15. Ensuring High-Quality Learning for All

    Science.gov (United States)

    Núñez, Elsa M.

    2018-01-01

    The Association of American Colleges and Universities (AAC&U) has embarked on a sustained program to enhance the quality of student learning on campuses, while also supporting AAC&U members' efforts to bring liberal education to all sectors of society. This commitment to quality and equity in service to democracy forms the basis for…

  16. Exchange bias in nearly perpendicularly coupled ferromagnetic/ferromagnetic system

    International Nuclear Information System (INIS)

    Bu, K.M.; Kwon, H.Y.; Oh, S.W.; Won, C.

    2012-01-01

    Exchange bias phenomena appear not only in ferromagnetic/antiferromagnetic systems but also in ferromagnetic/ferromagnetic systems in which two layers are nearly perpendicularly coupled. We investigated the origin of the symmetry-breaking mechanism and the relationship between the exchange bias and the system's energy parameters. We compared the results of computational Monte Carlo simulations with those of theoretical model calculation. We found that the exchange bias exhibited nonlinear behaviors, including sign reversal and singularities. These complicated behaviors were caused by two distinct magnetization processes depending on the interlayer coupling strength. The exchange bias reached a maximum at the transition between the two magnetization processes. - Highlights: ► Exchange bias phenomena are found in perpendicularly coupled F/F systems. ► Exchange bias exhibits nonlinear behaviors, including sign reversal and singularities. ► These complicated behaviors were caused by two distinct magnetization processes. ► Exchange bias reached a maximum at the transition between the two magnetization processes. ► We established an equation to maximize the exchange bias in perpendicularly coupled F/F system.

  17. Superconducting magnetoresistance in ferromagnet/superconductor/ferromagnet trilayers.

    Science.gov (United States)

    Stamopoulos, D; Aristomenopoulou, E

    2015-08-26

    Magnetoresistance is a multifaceted effect reflecting the diverse transport mechanisms exhibited by different kinds of plain materials and hybrid nanostructures; among other, giant, colossal, and extraordinary magnetoresistance versions exist, with the notation indicative of the intensity. Here we report on the superconducting magnetoresistance observed in ferromagnet/superconductor/ferromagnet trilayers, namely Co/Nb/Co trilayers, subjected to a parallel external magnetic field equal to the coercive field. By manipulating the transverse stray dipolar fields that originate from the out-of-plane magnetic domains of the outer layers that develop at coercivity, we can suppress the supercurrent of the interlayer. We experimentally demonstrate a scaling of the magnetoresistance magnitude that we reproduce with a closed-form phenomenological formula that incorporates relevant macroscopic parameters and microscopic length scales of the superconducting and ferromagnetic structural units. The generic approach introduced here can be used to design novel cryogenic devices that completely switch the supercurrent 'on' and 'off', thus exhibiting the ultimate magnetoresistance magnitude 100% on a regular basis.

  18. Magnetic excitations in amorphous ferromagnets

    International Nuclear Information System (INIS)

    Continentino, M.A.

    The propagation of magnetic excitations in amorphous ferromagnets is studied from the point of view of the theory of random frequency modulation. It is shown that the spin waves in the hydrodynamic limit are well described by perturbation theory while the roton-like magnetic excitations with wavevector about the peak in the structure factor are not. A criterion of validity of perturbation theory is found which is identical to a narrowing condition in magnetic resonance. (author) [pt

  19. Unexpected large room-temperature ferromagnetism in porous Cu{sub 2}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-05-15

    Porous Cu{sub 2}O films have been fabricated on porous anodic alumina substrates using DC-reactive magnetron sputtering with pure Cu targets, and unexpectedly large room temperature ferromagnetism has been observed in the films. The maximum saturation magnetic moment along the out-of-plane direction was as high as 94 emu/cm{sup 3}. Photoluminescence spectra show that the ferromagnetism originates with oxygen vacancies. The ferromagnetism could be adjusted by changing the concentration of oxygen vacancies through annealing in an oxygen atmosphere. These observations suggest that the origin of the ferromagnetism is due to coupling between oxygen vacancies with local magnetic moments in the porous Cu{sub 2}O films, which can occur either directly through exchange interactions between oxygen vacancies, or through the mediation of conduction electrons. Such a ferromagnet without the presence of any ferromagnetic dopant may find applications in spintronic devices. - Highlights: • Porous Cu{sub 2}O films were deposited on porous anodic alumina (PAA) substrates. • Significant room-temperature ferromagnetism has been observed in porous Cu{sub 2}O films. • Ferromagnetism of Cu{sub 2}O films exhibited different magnetic signals with the field. • The saturation magnetization is 94 emu/cm{sup 3} with an out-of-plane.

  20. Calibration of Hall sensor array for critical current measurement of YBCO tape with ferromagnetic substrate

    International Nuclear Information System (INIS)

    Zhu, Yunpeng; Wang, Gang; Liu, Liyuan; Yang, Xinsheng; Zhao, Yong

    2015-01-01

    Abstract : HAS (Hall sensor array) is a powerful tool to detect the uniformity of HTS (high temperature superconductor) tape through mapping the distribution of remanent or shielding field along the surface of the tape. However, measurement of HTS tape with ferromagnetic parts by HSA is still an issue because the ferromagnetic substrate has influence on the magnetic field around the HTS layer. In this work, a continuous HSA system has been designed to measure the critical current of the YBCO tape with ferromagnetic substrate. The relationship between the remanent field and critical current was calibrated by the finite element method. The result showed that the HSA is an effective method for evaluating the critical current of the HTS tape with ferromagnetic substrate. - Highlight: • A continuous Hall sensor array system has been designed. • The inhomogeneity of YBCO tape with ferromagnetic substrate can be detected by HAS. • Finite element method is an effective method for calibrating the remanent field.

  1. Calibration of Hall sensor array for critical current measurement of YBCO tape with ferromagnetic substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yunpeng; Wang, Gang; Liu, Liyuan [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Yang, Xinsheng, E-mail: xsyang@swjtu.edu.cn [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Zhao, Yong [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney 2052, NSW (Australia)

    2015-12-15

    Abstract : HAS (Hall sensor array) is a powerful tool to detect the uniformity of HTS (high temperature superconductor) tape through mapping the distribution of remanent or shielding field along the surface of the tape. However, measurement of HTS tape with ferromagnetic parts by HSA is still an issue because the ferromagnetic substrate has influence on the magnetic field around the HTS layer. In this work, a continuous HSA system has been designed to measure the critical current of the YBCO tape with ferromagnetic substrate. The relationship between the remanent field and critical current was calibrated by the finite element method. The result showed that the HSA is an effective method for evaluating the critical current of the HTS tape with ferromagnetic substrate. - Highlight: • A continuous Hall sensor array system has been designed. • The inhomogeneity of YBCO tape with ferromagnetic substrate can be detected by HAS. • Finite element method is an effective method for calibrating the remanent field.

  2. High Efficiency, Illumination Quality OLEDs for Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Shiang; James Cella; Kelly Chichak; Anil Duggal; Kevin Janora; Chris Heller; Gautam Parthasarathy; Jeffery Youmans; Joseph Shiang

    2008-03-31

    The goal of the program was to demonstrate a 45 lumen per watt white light device based upon the use of multiple emission colors through the use of solution processing. This performance level is a dramatic extension of the team's previous 15 LPW large area illumination device. The fundamental material system was based upon commercial polymer materials. The team was largely able to achieve these goals, and was able to deliver to DOE a 90 lumen illumination source that had an average performance of 34 LPW a 1000 cd/m{sup 2} with peak performances near 40LPW. The average color temperature is 3200K and the calculated CRI 85. The device operated at a brightness of approximately 1000cd/m{sup 2}. The use of multiple emission colors particularly red and blue, provided additional degrees of design flexibility in achieving white light, but also required the use of a multilayered structure to separate the different recombination zones and prevent interconversion of blue emission to red emission. The use of commercial materials had the advantage that improvements by the chemical manufacturers in charge transport efficiency, operating life and material purity could be rapidly incorporated without the expenditure of additional effort. The program was designed to take maximum advantage of the known characteristics of these material and proceeded in seven steps. (1) Identify the most promising materials, (2) assemble them into multi-layer structures to control excitation and transport within the OLED, (3) identify materials development needs that would optimize performance within multilayer structures, (4) build a prototype that demonstrates the potential entitlement of the novel multilayer OLED architecture (5) integrate all of the developments to find the single best materials set to implement the novel multilayer architecture, (6) further optimize the best materials set, (7) make a large area high illumination quality white OLED. A photo of the final deliverable is shown

  3. Analysis of high-quality modes in open chaotic microcavities

    International Nuclear Information System (INIS)

    Fang, W.; Yamilov, A.; Cao, H.

    2005-01-01

    We present a numerical study of the high-quality modes in two-dimensional dielectric stadium microcavities. Although the classical ray mechanics is fully chaotic in a stadium billiard, all of the high-quality modes show a 'strong scar' around unstable periodic orbits. When the deformation (ratio of the length of the straight segments over the diameter of the half circles) is small, the high-quality modes correspond to whispering-gallery-type trajectories and their quality factors decrease monotonically with increasing deformation. At large deformation, each high-quality mode is associated with multiple unstable periodic orbits. Its quality factor changes nonmonotonically with the deformation, and there exists an optimal deformation for each mode at which its quality factor reaches a local maximum. This unusual behavior is attributed to the interference of waves propagating along different constituent orbits that could minimize light leakage out of the cavity

  4. High quality steel casting for energy technics

    International Nuclear Information System (INIS)

    Schuster, F.; Koefler, G.

    1982-01-01

    The casting of several chromium-molybdenum steels for steam and hydraulic turbines is discussed. Non-destructive testing of the castings is performed demonstrating the safety for use in nuclear technology. The effect of metallurgical parameters on steel casting quality, the heat treatment, and the effect of construction design on costs for fettling and repair weldings are considered. (Auth.)

  5. Heteroepitaxial Growth of Ferromagnetic MnSb(0001) Films on Ge/Si(111) Virtual Substrates.

    Science.gov (United States)

    Burrows, Christopher W; Dobbie, Andrew; Myronov, Maksym; Hase, Thomas P A; Wilkins, Stuart B; Walker, Marc; Mudd, James J; Maskery, Ian; Lees, Martin R; McConville, Christopher F; Leadley, David R; Bell, Gavin R

    2013-11-06

    Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent.

  6. Efficiency of homopolar generators without ferromagnetic circuit

    International Nuclear Information System (INIS)

    Kharitonov, V.V.

    1982-01-01

    E.m.f. and weights of homopolar generators (HG) without a ferromagnetic circuit and of similar generator with a ferromagnetic circuit are compared at equal armature diameters and armature rotative speed. HG without ferromagnetic cuircuit of disk and cylinder types with hot and superconducting excitation winding are considered. Areas of the most reasonable removal of a ferromagnetic circuit in the HG layout are found. The plots of relationships between the e.m.f. and HG weight that permit to estimate the efficiency of ''nonferrite'' HG constructions are presented

  7. Ferromagnetic nanoparticles for magnetic hyperthermia and thermoablation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Kita, Eiji; Kayano, Takeru; Sato, Suguru; Minagawa, Makoto; Yanagihara, Hideto; Kishimoto, Mikio [Institute of Applied Physics, University of Tsukuba, Tsukuba 305-8573 (Japan); Oda, Tatsuya; Hashimoto, Shinji; Yamada, Keiichi; Ohkohchi, Nobuhiro [Department of Surgery, Advanced Biomedical Applications, Graduate School of Comprehensive Human Science, University of Tsukuba, Tsukuba 305-8575 (Japan); Mitsumata, Chiharu, E-mail: kita@bk.tsukuba.ac.j [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2010-12-01

    The use of ferromagnetic nanoparticles for hyperthermia and thermoablation therapies has shown great promise in the field of nanobiomedicine. Even local hyperthermia offers numerous advantages as a novel cancer therapy; however, it requires a remarkably high heating power of more than 1 kW g{sup -1} for heat agents. As a candidate for high heat generation, we focus on ferromagnetic nanoparticles and compare their physical properties with those of superparamagnetic substances. Numerical simulations for ideal single-domain ferromagnetic nanoparticles with cubic and uniaxial magnetic symmetries were carried out and MH curves together with minor loops were obtained. From the simulation, the efficient use of an alternating magnetic field (AMF) having a limited amplitude was discussed. Co-ferrite nanoparticles with various magnitudes of coercive force were produced by co-precipitation and a hydrothermal process. A maximum specific loss power of 420 W g{sup -1} was obtained using an AMF at 117 kHz with H{sub 0} = 51.4 kA m{sup -1} (640 Oe). The relaxation behaviour in the ferromagnetic state below the superparamagnetic blocking temperature was examined by Moessbauer spectroscopy.

  8. Effects of geometrical frustration on ferromagnetism in the Hubbard model on the generalised Shastry-Sutherland lattice

    Science.gov (United States)

    Farkašovský, Pavol

    2018-05-01

    The small-cluster exact-diagonalization calculations and the projector quantum Monte Carlo method are used to examine the competing effects of geometrical frustration and interaction on ferromagnetism in the Hubbard model on the generalised Shastry-Sutherland lattice. It is shown that the geometrical frustration stabilizes the ferromagnetic state at high electron concentrations ( n ≳ 7/4), where strong correlations between ferromagnetism and the shape of the noninteracting density of states are observed. In particular, it is found that ferromagnetism is stabilized for these values of frustration parameters, which lead to the single-peaked noninterating density of states at the band edge. Once, two or more peaks appear in the noninteracting density of states at the band edge the ferromagnetic state is suppressed. This opens a new route towards the understanding of ferromagnetism in strongly correlated systems.

  9. Indoor Air Quality in High Performance Schools

    Science.gov (United States)

    High performance schools are facilities that improve the learning environment while saving energy, resources, and money. The key is understanding the lifetime value of high performance schools and effectively managing priorities, time, and budget.

  10. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

    2000-01-01

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  11. Radioactive Probes on Ferromagnetic Surfaces

    CERN Multimedia

    2002-01-01

    On the (broad) basis of our studies of nonmagnetic radioactive probe atoms on magnetic surfaces and at interfaces, we propose to investigate the magnetic interaction of magnetic probe atoms with their immediate environment, in particular of rare earth (RE) elements positioned on and in ferromagnetic surfaces. The preparation and analysis of the structural properties of such samples will be performed in the UHV chamber HYDRA at the HMI/Berlin. For the investigations of the magnetic properties of RE atoms on surfaces Perturbed Angular Correlation (PAC) measurements and Mössbauer Spectroscopy (MS) in the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) are proposed.

  12. Superconductor-ferromagnet-superconductor nanojunctions from perovskite materials

    International Nuclear Information System (INIS)

    Štrbík, V.; Beňačka, Š.; Gaži, Š.; Španková, M.; Šmatko, V.; Knoška, J.; Gál, N.; Chromik, Š.; Sojková, M.; Pisarčík, M.

    2017-01-01

    Highlights: • Superconductor-ferromagnet-superconductor nanojunction. • Nanojunctions prepared by Ga"3"+ focused ion beam patterning. • Indication of triplet Cooper pair component in junction superconducting current. • Qualitative agreement with theoretical model. - Abstract: The lateral superconductor-ferromagnet–superconductor (SFS) nanojunctions based on high critical temperature superconductor YBa_2Cu_3O_x (YBCO) and half-metallic ferromagnet La_0_._6_7Sr_0_._3_3MnO_3 (LSMO) thin films were prepared to investigate a possible presence of long range triplet component (LRTC) of Cooper pairs in the LSMO. We applied Ga"3"+ focused ion beam patterning to create YBCO/LSMO/YBCO lateral type nanojunctions with LSMO length as small as 40 nm. The resistivity vs. temperature, critical current density vs. temperature and resistance vs. magnetic field dependence were studied to recognize the LRTC of Cooper pairs in the LSMO. A non-monotonic temperature dependence of junction critical current density and a decrease of the SFS nanojunction resistance in increased magnetic field were observed. Only weak manifestations of LRTC and some qualitative agreement with theory were found out in SFS nanojunctions realized from the perovskite materials. The presence of equal-spin triplet component of Cooper pairs in half-metallic LSMO ferromagnet is not such apparent as in SFS junctions prepared from low temperature superconductors NbTiN and half-metallic ferromagnet CrO_2.

  13. Superconductor-ferromagnet-superconductor nanojunctions from perovskite materials

    Energy Technology Data Exchange (ETDEWEB)

    Štrbík, V., E-mail: vladimir.strbik@savba.sk [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia); Beňačka, Š.; Gaži, Š.; Španková, M.; Šmatko, V. [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia); Knoška, J. [Center for Free-Electron Laser Science, DESY, Notkestraße 85, 22607, Hamburg (Germany); Department of Physics, University of Hamburg, Luruper Chaussee 149, 22607, Hamburg (Germany); Gál, N.; Chromik, Š.; Sojková, M.; Pisarčík, M. [Institute of Electrical Engineering, SAS, Dúbravská Cesta 9, Bratislava (Slovakia)

    2017-02-15

    Highlights: • Superconductor-ferromagnet-superconductor nanojunction. • Nanojunctions prepared by Ga{sup 3+} focused ion beam patterning. • Indication of triplet Cooper pair component in junction superconducting current. • Qualitative agreement with theoretical model. - Abstract: The lateral superconductor-ferromagnet–superconductor (SFS) nanojunctions based on high critical temperature superconductor YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) and half-metallic ferromagnet La{sub 0.67}Sr{sub 0.33}MnO{sub 3} (LSMO) thin films were prepared to investigate a possible presence of long range triplet component (LRTC) of Cooper pairs in the LSMO. We applied Ga{sup 3+} focused ion beam patterning to create YBCO/LSMO/YBCO lateral type nanojunctions with LSMO length as small as 40 nm. The resistivity vs. temperature, critical current density vs. temperature and resistance vs. magnetic field dependence were studied to recognize the LRTC of Cooper pairs in the LSMO. A non-monotonic temperature dependence of junction critical current density and a decrease of the SFS nanojunction resistance in increased magnetic field were observed. Only weak manifestations of LRTC and some qualitative agreement with theory were found out in SFS nanojunctions realized from the perovskite materials. The presence of equal-spin triplet component of Cooper pairs in half-metallic LSMO ferromagnet is not such apparent as in SFS junctions prepared from low temperature superconductors NbTiN and half-metallic ferromagnet CrO{sub 2}.

  14. Onset of itinerant ferromagnetism associated with semiconductor ...

    Indian Academy of Sciences (India)

    In this paper, the magnetic and transport properties of the TiNb1−CoSn solid solution compounds with half Heusler cubic MgAgAs-type structure have been studied. This work shows the onset of ferromagnetism associated with a semiconductor to metal transition. The transition occurs directly from ferromagnetic metal to ...

  15. Quantum stability for the Heisenberg ferromagnet

    International Nuclear Information System (INIS)

    Bargheer, Till; Beisert, Niklas; Gromov, Nikolay

    2008-01-01

    Highly spinning classical strings on RxS 3 are described by the Landau-Lifshitz model or equivalently by the Heisenberg ferromagnet in the thermodynamic limit. The spectrum of this model can be given in terms of spectral curves. However, it is a priori not clear whether any given admissible spectral curve can actually be realized as a solution to the discrete Bethe equations, a property which can be referred to as stability. In order to study the issue of stability, we find and explore the general two-cut solution or elliptic curve. It turns out that the moduli space of this elliptic curve shows a surprisingly rich structure. We present the various cases with illustrations and thus gain some insight into the features of multi-cut solutions. It appears that all admissible spectral curves are indeed stable if the branch cuts are positioned in a suitable, non-trivial fashion.

  16. Quality Assurance Strategy for Existing Homes: Final Quality Management Primer for High Performing Homes

    Energy Technology Data Exchange (ETDEWEB)

    Del Bianco, M.; Taggart, J.; Sikora, J.; Wood, A.

    2012-12-01

    This guide is designed to help Building America (BA) Teams understand quality management and its role in transitioning from conventional to high performance home building and remodeling. It explains what quality means, the value of quality management systems, the unique need for QMS when building high performing homes, and the first steps to a implementing a comprehensive QMS. This document provides a framework and context for BA teams when they encounter builders and remodelers.

  17. Quality Assurance Strategy for Existing Homes. Final Quality Management Primer for High Performing Homes

    Energy Technology Data Exchange (ETDEWEB)

    Del Bianco, M. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Taggart, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Sikora, J. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States); Wood, A. [NAHB Research Center Industry Partnership, Upper Marlboro, MD (United States)

    2012-12-01

    This guide is designed to help Building America (BA) teams understand quality management and its role in transitioning from conventional to high performance home building and remodeling. It explains what quality means, the value of quality management systems, the unique need for QMS when building high performing homes, and the first steps to a implementing a comprehensive QMS. This document provides a framework and context for BA teams when they encounter builders and remodelers.

  18. Ferromagnetic spin coupling as the origin of 0.7 anomaly in quantum point contacts.

    Science.gov (United States)

    Aryanpour, K; Han, J E

    2009-02-06

    We study one-dimensional itinerant electron models with ferromagnetic coupling to investigate the origin of the 0.7 anomaly in quantum point contacts. Linear conductance calculations from the quantum Monte Carlo technique for spin interactions of different spatial range suggest that 0.7(2e;{2}/h) anomaly results from a strong interaction of low-density conduction electrons to ferromagnetic fluctuations formed across the potential barrier. The conductance plateau appears due to the strong incoherent scattering at high temperature when the electron traversal time matches the time scale of dynamic ferromagnetic excitations.

  19. Strain-Induced Ferromagnetism in Antiferromagnetic LuMnO3 Thin Films

    Science.gov (United States)

    White, J. S.; Bator, M.; Hu, Y.; Luetkens, H.; Stahn, J.; Capelli, S.; Das, S.; Döbeli, M.; Lippert, Th.; Malik, V. K.; Martynczuk, J.; Wokaun, A.; Kenzelmann, M.; Niedermayer, Ch.; Schneider, C. W.

    2013-07-01

    Single phase and strained LuMnO3 thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

  20. Inequality in Preschool Quality? Community-Level Disparities in Access to High-Quality Learning Environments

    Science.gov (United States)

    Bassok, Daphna; Galdo, Eva

    2016-01-01

    In recent years, unequal access to high-quality preschool has emerged as a growing public policy concern. Because of data limitations, it is notoriously difficult to measure disparities in access to early learning opportunities across communities and particularly challenging to quantify gaps in access to "high-quality" programs. Research…

  1. Positron annihilation study of the interfacial defects in ZnO nanocrystals: Correlation with ferromagnetism

    Science.gov (United States)

    Wang, Dong; Chen, Z. Q.; Wang, D. D.; Qi, N.; Gong, J.; Cao, C. Y.; Tang, Z.

    2010-01-01

    High purity ZnO nanopowders were pressed into pellets and annealed in air between 100 and 1200 °C. The crystal quality and grain size of the ZnO nanocrystals were investigated by x-ray diffraction 2θ scans. Annealing induces an increase in the grain size from 25 to 165 nm with temperature increasing from 400 to 1200 °C. Scanning electron microscopy and high-resolution transmission electron microscopy observations also confirm the grain growth during annealing. Positron annihilation measurements reveal vacancy defects including Zn vacancies, vacancy clusters, and voids in the grain boundary region. The voids show an easy recovery after annealing at 100-700 °C. However, Zn vacancies and vacancy clusters observed by positrons remain unchanged after annealing at temperatures below 500 °C and begin to recover at higher temperatures. After annealing at temperatures higher than 1000 °C, no positron trapping by the interfacial defects can be observed. Raman spectroscopy studies confirm the recovery of lattice disorder after annealing. Hysteresis loops are observed for the 100 and 400 °C annealed samples, which indicate ferromagnetism in ZnO nanocrystals. However, the ferromagnetism disappears after annealing above 700 °C, suggesting that it might originate from the surface defects such as Zn vacancies.

  2. Optimization of a superconducting linear levitation system using a soft ferromagnet

    International Nuclear Information System (INIS)

    Agramunt-Puig, Sebastia; Del-Valle, Nuria; Navau, Carles; Sanchez, Alvaro

    2013-01-01

    Highlights: ► Study of the levitation of a superconducting bar over different magnetic guideways. ► A soft ferromagnet within permanent magnets improves levitation stability. ► We study the best geometry for large levitation force with full stability. -- Abstract: The use of guideways that combine permanent magnets and soft ferromagnetic materials is a common practice in magnetic levitation transport systems (maglevs) with bulk high-temperature superconductors. Theoretical tools to simulate in a realistic way both the behavior of all elements (permanent magnets, soft ferromagnet and superconductor) and their mutual effects are helpful to optimize the designs of real systems. Here we present a systematic study of the levitation of a maglev with translational symmetry consisting of a superconducting bar and a guideway with two identic permanent magnets and a soft ferromagnetic material between them. The system is simulated with a numerical model based on the energy minimization method that allows to analyze the mutual interaction of the superconductor, assumed to be in the critical state, and a soft ferromagnet with infinite susceptibility. Results indicate that introducing a soft ferromagnet within the permanent magnets not only increases the levitation force but also improves the stability. Besides, an estimation of the relative sizes and shapes of the soft ferromagnet, permanent magnets and the superconductor in order to obtain large levitation force with full stability is provided

  3. Optimization of a superconducting linear levitation system using a soft ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Agramunt-Puig, Sebastia; Del-Valle, Nuria; Navau, Carles, E-mail: carles.navau@uab.cat; Sanchez, Alvaro

    2013-04-15

    Highlights: ► Study of the levitation of a superconducting bar over different magnetic guideways. ► A soft ferromagnet within permanent magnets improves levitation stability. ► We study the best geometry for large levitation force with full stability. -- Abstract: The use of guideways that combine permanent magnets and soft ferromagnetic materials is a common practice in magnetic levitation transport systems (maglevs) with bulk high-temperature superconductors. Theoretical tools to simulate in a realistic way both the behavior of all elements (permanent magnets, soft ferromagnet and superconductor) and their mutual effects are helpful to optimize the designs of real systems. Here we present a systematic study of the levitation of a maglev with translational symmetry consisting of a superconducting bar and a guideway with two identic permanent magnets and a soft ferromagnetic material between them. The system is simulated with a numerical model based on the energy minimization method that allows to analyze the mutual interaction of the superconductor, assumed to be in the critical state, and a soft ferromagnet with infinite susceptibility. Results indicate that introducing a soft ferromagnet within the permanent magnets not only increases the levitation force but also improves the stability. Besides, an estimation of the relative sizes and shapes of the soft ferromagnet, permanent magnets and the superconductor in order to obtain large levitation force with full stability is provided.

  4. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO -- a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Arenholz, Elke; Zhou, S.; Potzger, K.; Talut, G.; Reuther, H.; Kuepper, K.; Grenzer, J.; Xu, Q.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.

    2008-01-01

    We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  5. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO: a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Zhou Shengqiang; Potzger, K; Talut, G; Reuther, H; Kuepper, K; Grenzer, J; Xu Qingyu; Muecklich, A; Helm, M; Fassbender, J; Arenholz, E

    2008-01-01

    We investigated ZnO(0 0 0 1) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  6. Long range anti-ferromagnetic spin model for prebiotic evolution

    International Nuclear Information System (INIS)

    Nokura, Kazuo

    2003-01-01

    I propose and discuss a fitness function for one-dimensional binary monomer sequences of macromolecules for prebiotic evolution. The fitness function is defined by the free energy of polymers in the high temperature random coil phase. With repulsive interactions among the same kind of monomers, the free energy in the high temperature limit becomes the energy function of the one-dimensional long range anti-ferromagnetic spin model, which is shown to have a dynamical phase transition and glassy states

  7. Analysis of ultra-narrow ferromagnetic domain walls

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, Catherine; Paul, David

    2012-01-10

    New materials with high magnetic anisotropy will have domains separated by ultra-narrow ferromagnetic walls with widths on the order of a few unit cells, approaching the limit where the elastic continuum approximation often used in micromagnetic simulations is accurate. The limits of this approximation are explored, and the static and dynamic interactions with intrinsic crystalline defects and external driving elds are modeled. The results developed here will be important when considering the stability of ultra-high-density storage media.

  8. Prediction of bread-making quality using size exclusion high ...

    African Journals Online (AJOL)

    Variation in the distribution of protein molecular weight in wheat (Triticum aestivum), influences breadmaking quality of wheat cultivars, resulting in either poor or good bread. The objective of this study was to predict breadmaking quality of wheat cultivars using size exclusion high performance liquid chromatography.

  9. Adoption and impact of high quality bambara flour (HQBF ...

    African Journals Online (AJOL)

    Adoption and impact of high quality bambara flour (HQBF) technology in the ... consumer acceptability/quality of products, credit, availability of raw materials, and ... as a result of 12.5 per cent increase in demand for bambara-based products.

  10. Inhomogeneous superconductivity in a ferromagnet

    International Nuclear Information System (INIS)

    Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Boursier, R.; Grison, X.

    2003-01-01

    We have studied a new superconducting state where the condensate wave function resulting from conventional pairing, is modified by an exchange field. Superconductivity is induced into a ferromagnetic thin film (F) by the proximity effect with a superconducting reservoir (S). We observed oscillations of the superconducting order parameter induced in F as a function of the distance from the S/F interface. They originate from the finite momentum transfer provided to Cooper pairs by the splitting of the spin up and down bands. We measured the superconducting density of states in F by tunneling spectroscopy and the Josephson critical current when F is coupled with a superconducting counter-electrode. Negative values of the superconducting order parameter are revealed by capsized tunneling spectra in F and a negative Josephson coupling (π-junction)

  11. Dipolar ferromagnets and glasses (invited)

    International Nuclear Information System (INIS)

    Rosenbaum, T.F.; Wu, W.; Ellman, B.; Yang, J.; Aeppli, G.; Reich, D.H.

    1991-01-01

    What is the ground state and what are the dynamics of 10 23 randomly distributed Ising spins? We have attempted to answer these questions through magnetic susceptibility, calorimetric, and neutron scattering studies of the randomly diluted dipolar-coupled Ising magnet LiHo x Y 1-x F 4 . The material is ferromagnetic for dipole concentrations at least as low as x=0.46, with a Curie temperature obeying mean-field scaling relative to that of pure LiHoF 4 . In the dilute spin limit, an x=0.045 crystal shows very unusual glassy properties characterized by decreasing barriers to relaxation as T→0. Its properties are consistent with a single low degeneracy ground state with a large gap for excitations. A slightly more concentrated x=0.167 sample, however, supports a complex ground state with no appreciable gap, in accordance with prevailing theories of spin glasses. The underlying causes of such disparate behavior are discussed in terms of random clusters as probed by neutron studies of the x=0.167 sample. In addition to tracing the evolution of the glassy and ferromagnetic states with dipole concentration, we investigate the effects of a transverse magnetic field on the Ising spin glass, LiHo 0.167 Y 0.833 F 4 . The transverse field mixes the eigenfunctions of the ground-state Ising doublet with the otherwise inaccessible excited-state levels. We observe a rapid decrease in the characteristic relaxation times, large changes in the spectral form of the relaxation, and a depression of the spin-glass transition temperature with the addition of quantum fluctuations

  12. Quack: A quality assurance tool for high throughput sequence data.

    Science.gov (United States)

    Thrash, Adam; Arick, Mark; Peterson, Daniel G

    2018-05-01

    The quality of data generated by high-throughput DNA sequencing tools must be rapidly assessed in order to determine how useful the data may be in making biological discoveries; higher quality data leads to more confident results and conclusions. Due to the ever-increasing size of data sets and the importance of rapid quality assessment, tools that analyze sequencing data should quickly produce easily interpretable graphics. Quack addresses these issues by generating information-dense visualizations from FASTQ files at a speed far surpassing other publicly available quality assurance tools in a manner independent of sequencing technology. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Innovative and high quality education through Open Education and OER

    OpenAIRE

    Stracke, Christian M.

    2017-01-01

    Online presentation and webinar by Stracke, C. M. (2017, 18 December) on "Innovative and high quality education through Open Education and OER" for the Belt and Road Open Education Learning Week by the Beijing Normal University, China.

  14. Improving high quality, equitable maternal health services in Malawi ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Improving high quality, equitable maternal health services in Malawi (IMCHA) ... In response, the Ministry of Health implemented a Standards-Based Management and Recognition for Reproductive Health initiative to improve ... Total funding.

  15. High Quality Education and Learning for All through Open Education

    NARCIS (Netherlands)

    Stracke, Christian M.

    2016-01-01

    Keynote at the International Lensky Education Forum 2016, Yakutsk, Republic of Sakha, Russian Federation, by Stracke, C. M. (2016, 16 August): "High Quality Education and Learning for All through Open Education"

  16. Valley and spin resonant tunneling current in ferromagnetic/nonmagnetic/ferromagnetic silicene junction

    Directory of Open Access Journals (Sweden)

    Yaser Hajati

    2016-02-01

    Full Text Available We study the transport properties in a ferromagnetic/nonmagnetic/ferromagnetic (FNF silicene junction in which an electrostatic gate potential, U, is attached to the nonmagnetic region. We show that the electrostatic gate potential U is a useful probe to control the band structure, quasi-bound states in the nonmagnetic barrier as well as the transport properties of the FNF silicene junction. In particular, by introducing the electrostatic gate potential, both the spin and valley conductances of the junction show an oscillatory behavior. The amplitude and frequency of such oscillations can be controlled by U. As an important result, we found that by increasing U, the second characteristic of the Klein tunneling is satisfied as a result of the quasiparticles chirality which can penetrate through a potential barrier. Moreover, it is found that for special values of U, the junction shows a gap in the spin and valley-resolve conductance and the amplitude of this gap is only controlled by the on-site potential difference, Δz. Our findings of high controllability of the spin and valley transport in such a FNF silicene junction may improve the performance of nano-electronics and spintronics devices.

  17. Nonthermal Photocoercivity Effect in Low-Doped (Ga,Mn)As Ferromagnetic Semiconductor

    Science.gov (United States)

    Kiessling, T.; Astakhov, G. V.; Hoffmann, H.; Korenev, V. L.; Schwittek, J.; Schott, G. M.; Gould, C.; Ossau, W.; Brunner, K.; Molenkamp, L. W.

    2011-12-01

    We report a photoinduced change of the coercive field of a low doped Ga1-xMnxAs ferromagnetic semiconductor under very low intensity illumination. This photocoercivity effect (PCE) is local and reversible, which enables the controlled formation of localized magnetization domains. The PCE arises from a light induced lowering of the domain wall pinning energy as confirmed by test experiments on high doped, fully metallic ferromagnetic Ga1-xMnxAs.

  18. Design and installation of a ferromagnetic wall in tokamak geometry

    International Nuclear Information System (INIS)

    Hughes, P. E.; Levesque, J. P.; Rivera, N.; Mauel, M. E.; Navratil, G. A.

    2015-01-01

    Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective component test facility and DEMO power reactor. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these facilities. In order to study ferromagnetic effects in toroidal geometry, a ferritic wall upgrade was designed and installed in the High Beta Tokamak–Extended Pulse (HBT-EP). Several material options were investigated based on conductivity, magnetic permeability, vacuum compatibility, and other criteria, and the material of choice (high-cobalt steel) is characterized. Installation was accomplished quickly, with minimal impact on existing diagnostics and overall machine performance, and initial results demonstrate the effects of the ferritic wall on plasma stability

  19. Design and installation of a ferromagnetic wall in tokamak geometry

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, P. E., E-mail: peh2109@columbia.edu; Levesque, J. P.; Rivera, N.; Mauel, M. E.; Navratil, G. A. [Columbia University Plasma Physics Laboratory, Columbia University, 102 S.W. Mudd, 500 W. 120th St., New York, New York 10027 (United States)

    2015-10-15

    Low-activation ferritic steels are leading material candidates for use in next-generation fusion development experiments such as a prospective component test facility and DEMO power reactor. Understanding the interaction of plasmas with a ferromagnetic wall will provide crucial physics for these facilities. In order to study ferromagnetic effects in toroidal geometry, a ferritic wall upgrade was designed and installed in the High Beta Tokamak–Extended Pulse (HBT-EP). Several material options were investigated based on conductivity, magnetic permeability, vacuum compatibility, and other criteria, and the material of choice (high-cobalt steel) is characterized. Installation was accomplished quickly, with minimal impact on existing diagnostics and overall machine performance, and initial results demonstrate the effects of the ferritic wall on plasma stability.

  20. High-field magnetic behavior and forced-ferromagnetic state in an ErFe.sub.11./sub.TiH single crystal

    Czech Academy of Sciences Publication Activity Database

    Kostyuchenko, N.V.; Zvezdin, A. K.; Tereshina, Evgeniya; Skourski, Y.; Doerr, M.; Drulis, H.; Pelevin, I.A.; Tereshina, I. S.

    2015-01-01

    Roč. 92, č. 10 (2015), "104423-1"-"104423-5" ISSN 1098-0121 Institutional support: RVO:68378271 Keywords : high field magnetization * crystal field effects * hamiltonian * rare- earth intermetallics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  1. Collapse of ferromagnetism in itinerant-electron system: a magnetic, transport properties, and high pressure study of (Hf,Ta)Fe.sub.2./sub. compounds

    Czech Academy of Sciences Publication Activity Database

    Diop, L.; Kaštil, Jiří; Isnard, O.; Arnold, Zdeněk; Kamarád, Jiří

    2014-01-01

    Roč. 116, č. 16 (2014), "163907-1"-"163907-10" ISSN 0021-8979 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : high pressure * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.183, year: 2014

  2. Emblems of Quality in Higher Education. Developing and Sustaining High-Quality Programs.

    Science.gov (United States)

    Haworth, Jennifer Grant; Conrad, Clifton F.

    This book proposes an "engagement" theory of program quality to evaluate and improve higher education programs at all degree levels. Based on interviews with 781 participants in a national study of Masters degree programs, it focuses on the interactive roles of students, faculty, and administrators in developing high-quality programs…

  3. Ferromagnetic clusters in polycrystalline BaCoO3

    International Nuclear Information System (INIS)

    Botta, P.M.; Pardo, V.; Calle, C. de la; Baldomir, D.; Alonso, J.A.; Rivas, J.

    2007-01-01

    Polycrystalline BaCoO 3 was synthesized by a citrate technique using thermal treatments at high oxygen pressure. Magnetic susceptibility measurements on the compound were carried out under AC conditions. The magnetic properties of the material at low temperatures were found to be determined by the appearance of nanoscale ferromagnetic (FM) regions and not by a true magnetic phase transition. These clusters have a mean size of about 1 nm in diameter and obey an Arrhenius-like thermal relaxation

  4. Assessment of defects in ferromagnetic metals with eddy currents

    OpenAIRE

    Oaten, Susan Rosemary

    1989-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University. A study was made to identify and size surface breaking defects in ferromagnetic materials with eddy currents, whilst eliminating unwanted signals due to changes in magnetic permeability and probe lift-off. The former was overcome by the use of high frequencies and the latter by utilising the lift-off to characterise the defects. The lift- off or "touch" method was shown to be advantageous in ...

  5. Heat dissipation due to ferromagnetic resonance in a ferromagnetic metal monitored by electrical resistance measurement

    International Nuclear Information System (INIS)

    Yamanoi, Kazuto; Yokotani, Yuki; Kimura, Takashi

    2015-01-01

    The heat dissipation due to the resonant precessional motion of the magnetization in a ferromagnetic metal has been investigated. We demonstrated that the temperature during the ferromagnetic resonance can be simply detected by the electrical resistance measurement of the Cu strip line in contact with the ferromagnetic metal. The temperature change of the Cu strip due to the ferromagnetic resonance was found to exceed 10 K, which significantly affects the spin-current transport. The influence of the thermal conductivity of the substrate on the heating was also investigated

  6. Modification of critical current in HTSC tape conductors by a ferromagnetic layer

    International Nuclear Information System (INIS)

    Goemoery, F; Souc, J; Seiler, E; Vojenciak, M; Granados, X

    2008-01-01

    In some applications of tape conductors from high temperature superconductors (HTSC) the magnetic field is created by the transported current itself. This is e.g. the case of power transmission cables or current leads. Quite complex distribution of local magnetic field determines then the ability of the superconducting element to carry electrical current. We have investigated how much the critical current of a tape conductor can be changed by putting a ferromagnetic layer in the vicinity of the HTSC material. Numerical procedure has been developed to resolve the current and field distribution in such superconductor-ferromagnet composite tape. Theoretical predictions have been confirmed by experiments on sample made from Bi-2223/Ag composite tape. The critical current of such tape can be improved by placing a soft ferromagnetic material at the tape's edges. On the other hand, the calculations show that the ferromagnetic substrate of YBCO coated tape reduces its self-field critical current

  7. Synthesis, characterization, properties, and applications of nanosized ferroelectric, ferromagnetic, or multiferroic materials

    International Nuclear Information System (INIS)

    Dhak, Debasis; Das, Soma; Communication Engineering.); Dhak, Prasanta

    2015-01-01

    Recently, there has been an enormous increase in research activity in the field of ferroelectrics and ferromagnetics especially in multiferroic materials which possess both ferroelectric and ferromagnetic properties simultaneously. However, the ferroelectric, ferromagnetic, and multiferroic properties should be further improved from the utilitarian and commercial viewpoints. Nanostructural materials are central to the evolution of future electronics and information technologies. Ferroelectrics and ferromagnetics have already been established as a dominant branch in electronics sector because of their diverse applications. The ongoing dimensional downscaling of materials to allow packing of increased numbers of components into integrated circuits provides the momentum for evolution of nanostructural devices. Nanoscaling of the above materials can result in a modification of their functionality. Furthermore, nanoscaling can be used to form high density arrays of nanodomain nanostructures, which is desirable for miniaturization of devices

  8. Coexistence of Superconductivity and Ferromagnetism in ...

    African Journals Online (AJOL)

    KBHEEMA

    Ferromagnetic alignment can be expected to be strongly opposed by superconductivity. .... To obtain temperature dependent of energy gap of equation (23), we used the same techniques to solve the integral .... band metal ZrZn2. Nature, 412: ...

  9. Ferromagnetic and twin domains in LCMO manganites

    International Nuclear Information System (INIS)

    Jung, G.; Markovich, V.; Mogilyanski, D.; Beek, C. van der; Mukovskii, Y.M.

    2005-01-01

    Ferromagnetic and twin domains in lightly Ca-doped La 1-x Ca x MnO 3 single crystals have been visualized and investigated by means of the magneto-optical technique. Both types of domains became visible below the Curie temperature. The dominant structures seen in applied magnetic field are associated with magneto-crystalline anisotropy and twin domains. In a marked difference to the twin domains which appear only in applied magnetic field, ferromagnetic domains show up in zero applied field and are characterized by oppositely oriented spontaneous magnetization in adjacent domains. Ferromagnetic domains take form of almost periodic, corrugated strip-like structures. The corrugation of the ferromagnetic domain pattern is enforced by the underlying twin domains

  10. Dimensionality Driven Enhancement of Ferromagnetic Superconductivity in URhGe

    Science.gov (United States)

    Braithwaite, Daniel; Aoki, Dai; Brison, Jean-Pascal; Flouquet, Jacques; Knebel, Georg; Nakamura, Ai; Pourret, Alexandre

    2018-01-01

    In most unconventional superconductors, like the high-Tc cuprates, iron pnictides, or heavy-fermion systems, superconductivity emerges in the proximity of an electronic instability. Identifying unambiguously the pairing mechanism remains nevertheless an enormous challenge. Among these systems, the orthorhombic uranium ferromagnetic superconductors have a unique position, notably because magnetic fields couple directly to ferromagnetic order, leading to the fascinating discovery of the reemergence of superconductivity in URhGe at a high field. Here we show that uniaxial stress is a remarkable tool allowing the fine-tuning of the pairing strength. With a relatively small stress, the superconducting phase diagram is spectacularly modified, with a merging of the low- and high-field superconducting states and a significant enhancement of the superconductivity. The superconducting critical temperature increases both at zero field and under a field, reaching 1 K, more than twice higher than at ambient pressure. This enhancement of superconductivity is shown to be directly related to a change of the magnetic dimensionality detected from an increase of the transverse magnetic susceptibility: In addition to the Ising-type longitudinal ferromagnetic fluctuations, transverse magnetic fluctuations also play an important role in the superconducting pairing.

  11. High quality, high efficiency welding technology for nuclear power plants

    International Nuclear Information System (INIS)

    Aoki, Shigeyuki; Nagura, Yasumi

    1996-01-01

    For nuclear power plants, it is required to ensure the safety under the high reliability and to attain the high rate of operation. In the manufacture and installation of the machinery and equipment, the welding techniques which become the basis exert large influence to them. For the purpose of improving joint performance and excluding human errors, welding heat input and the number of passes have been reduced, the automation of welding has been advanced, and at present, narrow gap arc welding and high energy density welding such as electron beam welding and laser welding have been put to practical use. Also in the welding of pipings, automatic gas metal arc welding is employed. As for the welding of main machinery and equipment, there are the welding of the joints that constitute pressure boundaries, the build-up welding on the internal surfaces of pressure vessels for separating primary water from them, and the sealing welding of heating tubes and tube plates in steam generators. These weldings are explained. The welding of pipings and the state of development and application of new welding methods are reported. (K.I.)

  12. Influence of soft ferromagnetic sections on the magnetic flux density profile of a large grain, bulk Y–Ba–Cu–O superconductor

    International Nuclear Information System (INIS)

    Philippe, M P; Wéra, L; Fagnard, J-F; Vanderheyden, B; Vanderbemden, P; Ainslie, M D; Dennis, A R; Shi, Y-H; Cardwell, D A

    2015-01-01

    Bulk, high temperature superconductors have significant potential for use as powerful permanent magnets in a variety of practical applications due to their ability to trap record magnetic fields. In this paper, soft ferromagnetic sections are combined with a bulk, large grain Y–Ba–Cu–O high temperature superconductor to form superconductor/ferromagnet hybrid structures. We study how the ferromagnetic sections influence the shape of the profile of the trapped magnetic induction at the surface of each structure and report the surface magnetic flux density measured by Hall probe mapping. These configurations have been modelled using a 2D axisymmetric finite element method based on the H-formulation and the results show excellent qualitative and quantitative agreement with the experimental measurements. The model has also been used to study the magnetic flux distribution and predict the behaviour for other constitutive laws and geometries. The results show that the ferromagnetic material acts as a magnetic shield, but the flux density and its gradient are enhanced on the face opposite to the ferromagnet. The thickness and saturation magnetization of the ferromagnetic material are important and a characteristic ferromagnet thickness d* is derived: below d*, saturation of the ferromagnet occurs, and above d*, a weak thickness-dependence is observed. The influence of the ferromagnet is observed even if its saturation magnetization is lower than the trapped flux density of the superconductor. Conversely, thin ferromagnetic discs can be driven to full saturation even though the outer magnetic field is much smaller than their saturation magnetization. (paper)

  13. Concrete Waste Recycling Process for High Quality Aggregate

    International Nuclear Information System (INIS)

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-01

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  14. Josephson tunnel junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    Weides, M.P.

    2006-01-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al 2 O 3 tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or π coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, π) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-π Josephson junction. At a certain temperature this 0-π junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum Φ 0 . Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T → 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  15. Josephson tunnel junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M.P.

    2006-07-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  16. Room temperature ferromagnetism in a phthalocyanine based carbon material

    International Nuclear Information System (INIS)

    Honda, Z.; Sato, K.; Sakai, M.; Fukuda, T.; Kamata, N.; Hagiwara, M.; Kida, T.

    2014-01-01

    We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T c  = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material

  17. The paramagnetic properties of ferromagnetic mixed-spin chain system

    International Nuclear Information System (INIS)

    Hu, Ai-Yuan; Wu, Zhi-Min; Cui, Yu-Ting; Qin, Guo-Ping

    2015-01-01

    The double-time Green's function method is used to investigate the paramagnetic properties of ferromagnetic mixed-spin chain system within the random-phase approximation and Anderson–Callen's decoupling approximation. The analytic expressions of the transverse susceptibility, longitudinal susceptibility and correlation length are obtained under transverse and longitudinal magnetic field. Using the analytic expressions of the transverse and longitudinal susceptibility to fit the experimental results, our results well agree with experimental data and the results from the high temperature series expansion within a simple Padé approximation. - Highlights: • We investigate the magnetic properties of a ferromagnetic mixed-spin chain system. • We use the double-time temperature-dependent Green's function technique. • Different single-ion anisotropy values for different spin values are considered. • Our results agree with experimental data and the results from the other theoretical methods

  18. Room temperature ferromagnetism in a phthalocyanine based carbon material

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Z., E-mail: honda@fms.saitama-u.ac.jp; Sato, K.; Sakai, M.; Fukuda, T.; Kamata, N. [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Hagiwara, M.; Kida, T. [KYOKUGEN (Center for Quantum Science and Technology under Extreme Conditions), Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2014-02-07

    We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T{sub c} = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material.

  19. Influence of lattice defects on criticality of Potts ferromagnet

    International Nuclear Information System (INIS)

    Souza Costa, U.M. de.

    1985-01-01

    The critical properties of the q-state Potts ferromagnet and the anisotropic Heisenberg model on hypercubic lattices (d = 2,3); emphasis is given to the free surface and the interface effects, the Real Space Renormalization Group approach. The criticality of the quenched bond-mixed q-state Potts ferromagnet on square lattice is discussed. It is shown that, the crossover from the pure fixed point to the random one occurs, while q increases, through a pitchfork bifurcation; the relation-ship with the Harris criterion is analyzed. High precision numerical values for the critical temperatures corresponding to arbitrary concentrations of the coupling constants J sub(1) and J sub(2), and arbitrary ratios J sub(1)/J sub(2) are presented.(author)

  20. Topological magnon bands in ferromagnetic star lattice

    International Nuclear Information System (INIS)

    Owerre, S A

    2017-01-01

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1–3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii–Moriya (DM) spin–orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases. (paper)

  1. Topological magnon bands in ferromagnetic star lattice.

    Science.gov (United States)

    Owerre, S A

    2017-05-10

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1-3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii-Moriya (DM) spin-orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases.

  2. High Quality Zinc Oxide Thin films and Nanostructures Prepared by Pulsed Laser Deposition for Photodetectors

    KAUST Repository

    Flemban, Tahani H.

    2017-12-11

    Zinc oxide (ZnO) semiconductors have been utilized by many researchers, due to its unique properties beneficial for functional devices. In particular, gadolinium (Gd)–doped ZnO exhibits high ferromagnetic and electrical properties, which is attributed to defect/impurity bands mediated by Gd dopants. In this dissertation, I study the effects of Gd concentration, oxygen pressure using pulsed laser deposition (PLD), and thermal annealing on the optical and structural properties of undoped and Gd-doped ZnO films and nanostructures. Moreover, as the growth of practical ZnO nanostructures-based devices without catalyst, while presently challenging, is highly important for many applications. Thus, for the first time, a novel method is developed for growing well aligned ZnO nanorods (NRs) by optimizing PLD conditions using Gd-doped ZnO target without any catalyst in a single step. This study shows that, both the lattice orientation of the substrate and the Gd characteristics are significant in enhancing the NR growth. Our findings reveal that precise control of the NR density can be achieved by changing the oxygen partial pressure. Furthermore, due to the Gd incorporation, these NRs possess favorable electrical properties with a significant mobility of 177 cm2 (V.s)-1 compared to that reported in literature. Nonetheless significant challenges need to be overcome to achieve reproducible and stable p-type ZnO for commercial applications. Hence, several attempts based on n-type ZnO grown on foreign p-type substrates were made to achieve high-performance devices and overcome the issues arising when p-type doped ZnO is employed. Moreover, Growth of ZnO nanostructures on a foreign p-type substrates does not require a lattice-matched p-type substrate. Thus, for the first time, PLD conditions are improved to grow high quality ZnO nanotubes (NTs) with high optical, structural and electrical properties on a p-type Si (100) substrate without catalyst for high-performance devices. A

  3. High-quality planar high-Tc Josephson junctions

    International Nuclear Information System (INIS)

    Bergeal, N.; Grison, X.; Lesueur, J.; Faini, G.; Aprili, M.; Contour, J.P.

    2005-01-01

    Reproducible high-T c Josephson junctions have been made in a rather simple two-step process using ion irradiation. A microbridge (1 to 5 μm wide) is firstly designed by ion irradiating a c-axis-oriented YBa 2 Cu 3 O 7-δ film through a gold mask such as the nonprotected part becomes insulating. A lower T c part is then defined within the bridge by irradiating with a much lower fluence through a narrow slit (20 nm) opened in a standard electronic photoresist. These planar junctions, whose settings can be finely tuned, exhibit reproducible and nearly ideal Josephson characteristics. This process can be used to produce complex Josephson circuits

  4. Research Update: Strain and composition effects on ferromagnetism of Mn0.05Ge0.95 quantum dots

    Directory of Open Access Journals (Sweden)

    Liming Wang

    2016-04-01

    Full Text Available Mn0.05Ge0.95 quantum dots (QDs samples were grown by molecular beam epitaxy on Si substrates and 15-nm-thick fully strained Si0.8Ge0.2 virtual substrates, respectively. The QDs samples grown on the Si0.8Ge0.2 virtual substrates show a significant ferromagnetism with a Curie temperature of 227 K, while the QDs samples grown on the Si substrates are non-ferromagnetic. Microstructures of the QDs samples were characterized by high resolution transmission electron microscopy and synchrotron radiation X-ray diffraction. Interdependence between microstructure and ferromagnetism of Mn-doped Ge QDs was investigated. For the QDs sample grown on the strained Si0.8Ge0.2 virtual substrate, although the ferromagnetic phase Mn5Ge3 clusters were found to be formed in small dome-shaped dots, the significant ferromagnetism observed in that sample is attributed to ferromagnetic phase Mn-doped large dome-shaped Ge QDs, rather than to the ferromagnetic phase Mn5Ge3 clusters. The fully strained Si0.8Ge0.2 virtual substrates would result in a residual strain into the QDs and an increase in Ge composition in the QDs. Both consequences favor the formations of ferromagnetic phase Mn-doped Ge QDs from points of view of quantum confinement effect as well as Mn doping at substitutional sites.

  5. Two-fold origin of the deformation-induced ferromagnetism in bulk Fe60Al40 (at.%) alloys

    International Nuclear Information System (INIS)

    Menendez, E; Surinach, S; Baro, M D; Sort, J; Liedke, M O; Fassbender, J; Nogues, J

    2008-01-01

    The transition from the atomically ordered B2-phase to the chemically disordered A2-phase and the concomitant deformation-induced ferromagnetism have been investigated in bulk polycrystalline Fe 60 Al 40 (at.%) alloys subjected to compression processes. A detailed correlation between structural, magnetic and mechanical properties reveals that the generated ferromagnetism depends on the stress level but is virtually independent of the loading rate. The mechanisms governing the induced ferromagnetism also vary as the stress level is increased. Namely, in the low-stress regime both lattice cell expansion and atomic intermixing play a role in the induced ferromagnetic behavior. Conversely, lattice expansion seems to become the main mechanism contributing to the generated ferromagnetism in the high-stress regime. Furthermore, a correlation is also observed between the order-disorder transition and the mechanical hardness. Hence, a combination of magnetic and mechanical measurements can be used, in synergetic manner, to investigate this deformation-induced phase transition.

  6. Transport properties of Josephson contacts with ferromagnetic tunnel barriers; Transporteigenschaften von Josephson-Kontakten mit ferromagnetischer Tunnelbarriere

    Energy Technology Data Exchange (ETDEWEB)

    Sprungmann, Dirk

    2010-01-28

    The combination of the Josephson and the proximity effect is possible by the introduction of a ferromagnetic barrier into a Josephson contact resulting in a so called π coupling. The supra current through these contacts is flowing in the reverse direction. Specific new electronic circuits such as phase shifting devices are possible, for instance for high-speed analog-digital transducers. In the frame of this thesis SIFS Josephson contacts were studied, with a barrier consisting of a thin insulating Al2Ox barrier layer and a ferromagnetic thin film. For the ferromagnetic material weak ferromagnetic Ni(0.6)Cu(0.4), the strong ferromagnetic Fe(0.25)Co(0.75) and the ternary Heusler alloys Co2MnSn and Cu2MnAl were used. Josephson contacts with π coupling were realized with the NiCu alloy, triplet superconductivity seems to appear with the Heusler systems.

  7. Key factors for a high-quality VR experience

    Science.gov (United States)

    Champel, Mary-Luc; Doré, Renaud; Mollet, Nicolas

    2017-09-01

    For many years, Virtual Reality has been presented as a promising technology that could deliver a truly new experience to users. The media and entertainment industry is now investigating the possibility to offer a video-based VR 360 experience. Nevertheless, there is a substantial risk that VR 360 could have the same fate as 3DTV if it cannot offer more than just being the next fad. The present paper aims at presenting the various quality factors required for a high-quality VR experience. More specifically, this paper will focus on the main three VR quality pillars: visual, audio and immersion.

  8. Process to Continuously Melt, Refine and Cast High Quality Steel

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-09-01

    The purpose of this project is to conduct research and development targeted at designing a revolutionary steelmaking process. This process will deliver high quality steel from scrap to the casting mold in one continuous process and will be safer, more productive, and less capital intensive to build and operate than conventional steelmaking. The new process will produce higher quality steel faster than traditional batch processes while consuming less energy and other resources.

  9. Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

    Energy Technology Data Exchange (ETDEWEB)

    Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel; Tobar, Michael E. [ARC Centre of Excellence for Engineered Quantum Systems, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 (Australia); Bushev, Pavel [Experimentalphysik, Universität des Saarlandes, D-66123 Saarbrücken (Germany)

    2015-09-21

    This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of the phenomenon is demonstrated.

  10. High-quality cardiopulmonary resuscitation: current and future directions.

    Science.gov (United States)

    Abella, Benjamin S

    2016-06-01

    Cardiopulmonary resuscitation (CPR) represents the cornerstone of cardiac arrest resuscitation care. Prompt delivery of high-quality CPR can dramatically improve survival outcomes; however, the definitions of optimal CPR have evolved over several decades. The present review will discuss the metrics of CPR delivery, and the evidence supporting the importance of CPR quality to improve clinical outcomes. The introduction of new technologies to quantify metrics of CPR delivery has yielded important insights into CPR quality. Investigations using CPR recording devices have allowed the assessment of specific CPR performance parameters and their relative importance regarding return of spontaneous circulation and survival to hospital discharge. Additional work has suggested new opportunities to measure physiologic markers during CPR and potentially tailor CPR delivery to patient requirements. Through recent laboratory and clinical investigations, a more evidence-based definition of high-quality CPR continues to emerge. Exciting opportunities now exist to study quantitative metrics of CPR and potentially guide resuscitation care in a goal-directed fashion. Concepts of high-quality CPR have also informed new approaches to training and quality improvement efforts for cardiac arrest care.

  11. Optimization of a superconducting linear levitation system using a soft ferromagnet

    Science.gov (United States)

    Agramunt-Puig, Sebastia; Del-Valle, Nuria; Navau, Carles; Sanchez, Alvaro

    2013-04-01

    The use of guideways that combine permanent magnets and soft ferromagnetic materials is a common practice in magnetic levitation transport systems (maglevs) with bulk high-temperature superconductors. Theoretical tools to simulate in a realistic way both the behavior of all elements (permanent magnets, soft ferromagnet and superconductor) and their mutual effects are helpful to optimize the designs of real systems. Here we present a systematic study of the levitation of a maglev with translational symmetry consisting of a superconducting bar and a guideway with two identic permanent magnets and a soft ferromagnetic material between them. The system is simulated with a numerical model based on the energy minimization method that allows to analyze the mutual interaction of the superconductor, assumed to be in the critical state, and a soft ferromagnet with infinite susceptibility. Results indicate that introducing a soft ferromagnet within the permanent magnets not only increases the levitation force but also improves the stability. Besides, an estimation of the relative sizes and shapes of the soft ferromagnet, permanent magnets and the superconductor in order to obtain large levitation force with full stability is provided.

  12. Next Generation High Quality Videoconferencing Service for the LHC

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    In recent times, we have witnessed an explosion of video initiatives in the industry worldwide. Several advancements in video technology are currently improving the way we interact and collaborate. These advancements are forcing tendencies and overall experiences: any device in any network can be used to collaborate, in most cases with an overall high quality. To cope with this technology progresses, CERN IT Department has taken the leading role to establish strategies and directions to improve the user experience in remote dispersed meetings and remote collaboration at large in the worldwide LHC communities. Due to the high rate of dispersion in the LHC user communities, these are critically dependent of videoconferencing technology, with a need of robustness and high quality for the best possible user experience. We will present an analysis of the factors that influenced the technical and strategic choices to improve the reliability, efficiency and overall quality of the LHC remote sessions. In particular, ...

  13. IMPACT OF RESILIENCE, ICT SUPPORT AND QUALITY OF STUDENT'S LIFE ON QUALITY OF HIGH EDUCATION PROCESS

    Directory of Open Access Journals (Sweden)

    Zorica Lazic

    2016-12-01

    Full Text Available Answers to the questions of how and in what way the quality of life of students, resilience and ICT support affects the quality of high education we will get through this work where main objective is to define a network of processes and process management ensuring more quality and more innovative managing and service provision, therefore satisfying the needs of service users - in this case the students of the university. To collect the relevant data in the thematic analysis of this paper, the method of interviewing by questionnaires was applied. The sample survey was conducted among undergraduate students, teachers and staff of the Teacher Training Faculty in Uzice.

  14. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan)

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  15. Learning Disabilities and Achieving High-Quality Education Standards

    Science.gov (United States)

    Gartland, Debi; Strosnider, Roberta

    2017-01-01

    This is an official document of the National Joint Committee on Learning Disabilities (NJCLD), of which Council for Learning Disabilities is a long-standing, active member. With this position paper, NJCLD advocates for the implementation of high-quality education standards (HQES) for students with learning disabilities (LD) and outlines the…

  16. extraction of high quality dna from polysaccharides-secreting ...

    African Journals Online (AJOL)

    cistvr

    A DNA extraction method using CTAB was used for the isolation of genomic DNA from ten. Xanthomonas campestris pathovars, ten isolates of Xanthomonas albilineans and one isolate of. Pseudomonas rubrisubalbicans. High quality DNA was obtained that was ideal for molecular analy- ses. Extracellular polysaccharides ...

  17. Negative Binomial charts for monitoring high-quality processes

    NARCIS (Netherlands)

    Albers, Willem/Wim

    Good control charts for high quality processes are often based on the number of successes between failures. Geometric charts are simplest in this respect, but slow in recognizing moderately increased failure rates p. Improvement can be achieved by waiting until r > 1 failures have occurred, i.e. by

  18. Synthesis and spectroscopic study of high quality alloy Cdx S ...

    Indian Academy of Sciences (India)

    Wintec

    In the present study, we report the synthesis of high quality CdxZn1–xS nanocrystals alloy at. 150°C with .... (XRD) using a Siemens model D 500, powder X-ray ... decays were analysed using IBH DAS6 software. 3. ... This alloying process is.

  19. Methods and systems for fabricating high quality superconducting tapes

    Science.gov (United States)

    Majkic, Goran; Selvamanickam, Venkat

    2018-02-13

    An MOCVD system fabricates high quality superconductor tapes with variable thicknesses. The MOCVD system can include a gas flow chamber between two parallel channels in a housing. A substrate tape is heated and then passed through the MOCVD housing such that the gas flow is perpendicular to the tape's surface. Precursors are injected into the gas flow for deposition on the substrate tape. In this way, superconductor tapes can be fabricated with variable thicknesses, uniform precursor deposition, and high critical current densities.

  20. Managing quality inside a high-technology project organization

    OpenAIRE

    Jokinen, T. (Tauno)

    2004-01-01

    Abstract This action research addresses the deployment of Total Quality Management (TQM) principles in a high-technology new product development organisation. During the period of study, the organisation grew fast. High-technology product development and hypergrowth provided a unique combination of extreme conditions for the study. The existing concepts of TQM are presented as an organised map enabling strategic analysis for an implementation plan. The history of TQM dates back to the ...

  1. [Quality of sleep and academic performance in high school students].

    Science.gov (United States)

    Bugueño, Maithe; Curihual, Carolina; Olivares, Paulina; Wallace, Josefa; López-AlegrÍa, Fanny; Rivera-López, Gonzalo; Oyanedel, Juan Carlos

    2017-09-01

    Sleeping and studying are the day-to-day activities of a teenager attending school. To determine the quality of sleep and its relationship to the academic performance among students attending morning and afternoon shifts in a public high school. Students of the first and second year of high school answered an interview about socio-demographic background, academic performance, student activities and subjective sleep quality; they were evaluated using the Pittsburgh Sleep Quality Index (PSQI). The interview was answered by 322 first year students aged 15 ± 5 years attending the morning shift and 364 second year students, aged 16 ± 0.5 years, attending the afternoon shift. The components: sleep latency, habitual sleep efficiency, sleep disturbance, drug use and daytime dysfunction were similar and classified as good in both school shifts. The components subjective sleep quality and duration of sleep had higher scores among students of the morning shift. The mean grades during the first semester of the students attending morning and afternoon shifts were 5.9 and 5.8, respectively (of a scale from 1 to 7). Among students of both shifts, the PSQI scale was associated inversely and significantly with academic performance. A bad sleep quality influences academic performance in these students.

  2. Highly qualified does not equal high quality: A study of urban stakeholders' perceptions of quality in science teaching

    Science.gov (United States)

    Miranda, Rommel Joseph

    By employing qualitative methods, this study sought to determine the perceptions that urban stakeholders hold about what characteristics should distinguish a high school science teacher whom they would consider to demonstrate high quality in science teaching. A maximum variation sample of six science teachers, three school administrators, six parents and six students from a large urban public school district were interviewed using semi-structured, in-depth interview techniques. From these data, a list of observable characteristics which urban stakeholders hold as evidence of high quality in science teaching was generated. Observational techniques were utilized to determine the extent to which six urban high school science teachers, who meet the NCLB Act criteria for being "highly qualified", actually possessed the characteristics which these stakeholders hold as evidence of high quality in science teaching. Constant comparative analysis was used to analyze the data set. The findings suggest that urban stakeholders perceive that a high school science teacher who demonstrates high quality in science teaching should be knowledgeable about their subject matter, their student population, and should be resourceful; should possess an academic background in science and professional experience in science teaching; should exhibit professionalism, a passion for science and teaching, and a dedication to teaching and student learning; should be skillful in planning and preparing science lessons and in organizing the classroom, in presenting the subject matter to students, in conducting a variety of hands-on activities, and in managing a classroom; and should assess whether students complete class goals and objectives, and provide feedback about grades for students promptly. The findings further reveal that some of the urban high school science teachers who were deemed to be "highly qualified", as defined by the NCLB Act, engaged in practices that threatened quality in science

  3. High quality digital holographic reconstruction on analog film

    Science.gov (United States)

    Nelsen, B.; Hartmann, P.

    2017-05-01

    High quality real-time digital holographic reconstruction, i.e. at 30 Hz frame rates, has been at the forefront of research and has been hailed as the holy grail of display systems. While these efforts have produced a fascinating array of computer algorithms and technology, many applications of reconstructing high quality digital holograms do not require such high frame rates. In fact, applications such as 3D holographic lithography even require a stationary mask. Typical devices used for digital hologram reconstruction are based on spatial-light-modulator technology and this technology is great for reconstructing arbitrary holograms on the fly; however, it lacks the high spatial resolution achievable by its analog counterpart, holographic film. Analog holographic film is therefore the method of choice for reconstructing highquality static holograms. The challenge lies in taking a static, high-quality digitally calculated hologram and effectively writing it to holographic film. We have developed a theoretical system based on a tunable phase plate, an intensity adjustable high-coherence laser and a slip-stick based piezo rotation stage to effectively produce a digitally calculated hologram on analog film. The configuration reproduces the individual components, both the amplitude and phase, of the hologram in the Fourier domain. These Fourier components are then individually written on the holographic film after interfering with a reference beam. The system is analogous to writing angularly multiplexed plane waves with individual component phase control.

  4. Seed layer technique for high quality epitaxial manganite films

    Directory of Open Access Journals (Sweden)

    P. Graziosi

    2016-08-01

    Full Text Available We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening temperature, strain profile and chemical states are derived.

  5. Long quantum channels for high-quality entanglement transfer

    International Nuclear Information System (INIS)

    Banchi, L; Apollaro, T J G; Cuccoli, A; Verrucchi, P; Vaia, R

    2011-01-01

    High-quality quantum-state and entanglement transfer can be achieved in an unmodulated spin bus operating in the ballistic regime, which occurs when the endpoint qubits A and B are nonperturbatively coupled to the chain by a suitable exchange interaction j 0 . Indeed, the transition amplitude characterizing the transfer quality exhibits a maximum for a finite optimal value j opt 0 (N), where N is the channel length. We show that j opt 0 (N) scales as N -1/6 for large N and that it ensures a high-quality entanglement transfer even in the limit of arbitrarily long channels, almost independently of the channel initialization. For instance, for any chain length the average quantum-state transmission fidelity exceeds 90% and decreases very little in a broad neighbourhood of j opt 0 (N). We emphasize that, taking the reverse point of view, should j 0 be experimentally constrained, high-quality transfer can still be obtained by adjusting the channel length to its optimal value. (paper)

  6. Integration study of high quality teaching resources in universities

    Directory of Open Access Journals (Sweden)

    Honglu Liu

    2012-12-01

    Full Text Available Purpose: The development level and quality of education depend on the merits and efficiency in the use of teaching resources, especially in the case of obvious contradiction between the demand and supply of teaching resources. So to integrate teaching resources, improve the efficiency in the use of high quality teaching resources, and take the road of content development to enhance the competitiveness of education has become very important and urgent.Design/methodology/approach: On the basis of analysis on the teaching resources of universities and the problems they faced, this paper introduced the basic concepts of cloud storage, and built the integration architecture of high quality teaching resources in universities based on the cloud storage.Findings and Originality/value: The HDFS-based cloud storage proposed in this paper is a dynamically adjustable and Internet-based storage solution, and the users can access storage targets using the network through a common and easy-to-use protocol and application programming interfaces. This new technology is useful for end users benefits. With the continuous development and improvement of cloud storage, it will necessarily result in more and more applications in the institutions of higher learning and education network.Originality/value: This paper introduced the cloud storage into the integration of high quality teaching resources in universities first and as a new form of service, it can be a good solution.

  7. Analysis of ferromagnetic shielding of the ITER NBI

    International Nuclear Information System (INIS)

    Roccella, M.; Lucca, F.; Roccella, R.; Cocilovo, V.; Ramogida, G.; Portone, A.; Tanga, A.; Formisano, A.; Martone, R.

    2006-01-01

    In ITER two heating and one diagnostic Neutral Beam Injectors (NBIs) are foreseen [P. L. Mondino et al., ''ITER neutral beam system '', Nucl. Fus., vol. 40, p. 501 (2000)]. Inside these components there are very stringent limits on the magnetic field (the flux density must be below some Gauss (G) along the ion path and below 20 G in the neutralizing region). To achieve these performances in an environment with high stray field due to the plasma and the poloidal field coils, both passive and active shielding systems are foreseen. The present design of the Magnetic Field Reduction System (MFRS) is made of seven active coils and of a box surrounding the NBI region, consisting of ferromagnetic plates 15 cm thick. The electromagnetic analysis of the effectiveness of these shields has been performed by a full 3D FEM model using the ANSYS code. To perform the FEM modeling of the component special care has been used to face the particular geometrical features of the component (a box of about 15 x 5 x 5 m vs. a ferromagnetic layer of only 15 cm thick). To insert an adequate number of FEM elements (at least 5) in the thickness of the ferromagnetic layer, without a prohibitive increase in the total FEM elements number, a particular modeling approach (a sort of '' Chinese boxes '' technique) has been developed. Due to this technique the FEM model enclosing the ferromagnetic box results completely independent on the fine FEM structure inside the shielding layer. It has been even possible, using this technique, introducing a thin (below 1 cm thick) slot all through the shielding plates, without perturbing the rest of the model. This slot has been used to analyze the effects of possible manufacturing lacks on the residual magnetic field inside the component. This technique has allowed the use of only structured meshes made by brick elements, much more accurate than the tetra elements, needed in the usual free meshing techniques. To have the possibility of changing the shielding

  8. Examination of Operation Quality for High-frequent Railway Operation

    DEFF Research Database (Denmark)

    Landex, Alex; Kaas, Anders H.

    2009-01-01

    take the first train in their direction. The article examines four different approaches to examine operation quality for high-frequent operation that are based on the experiences of the passengers. These approaches are the service frequency of the operation, travel time extension, a combination......The examination of operation quality for high-frequent operation requires other approaches than the typical evaluation of punctuality (trains on time) and reliability (operated trains). This is because passengers in high-frequent railway systems do not necessarily notice train delays as they just...... of the service frequency and travel time approaches, and passenger delays. The service frequency and travel time approaches are simple measurements with low complexity and complement each other. Therefore, the article recommends combining the service frequency and travel time approaches to get a more accurate...

  9. Spectrum of ferromagnetic transition metal magnetic excitations and neutron scattering

    International Nuclear Information System (INIS)

    Kuzemskij, A.L.

    1979-01-01

    Quantum statistical models of ferromagnetic transition metals as well as methods of their solutions are reviewed. The correspondence of results on solving these models and the data on scattering thermal neutrons in ferromagnetic is discussed

  10. Ferromagnetic Josephson Junctions for Cryogenic Memory

    Science.gov (United States)

    Niedzielski, Bethany M.; Gingrich, Eric C.; Khasawneh, Mazin A.; Loloee, Reza; Pratt, William P., Jr.; Birge, Norman O.

    2015-03-01

    Josephson junctions containing ferromagnetic materials are of interest for both scientific and technological purposes. In principle, either the amplitude of the critical current or superconducting phase shift across the junction can be controlled by the relative magnetization directions of the ferromagnetic layers in the junction. Our approach concentrates on phase control utilizing two junctions in a SQUID geometry. We will report on efforts to control the phase of junctions carrying either spin-singlet or spin-triplet supercurrent for cryogenic memory applications. Supported by Northorp Grumman Corporation and by IARPA under SPAWAR Contract N66001-12-C-2017.

  11. Itinerant Ferromagnetism in Ultracold Fermi Gases

    DEFF Research Database (Denmark)

    Heiselberg, Henning

    2012-01-01

    Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature a second order transition is found at akF ≃ 0.90 compatible with QMC. Thermodyna......Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature a second order transition is found at akF ≃ 0.90 compatible with QMC...

  12. Proximity effects in ferromagnet/superconductor structures

    International Nuclear Information System (INIS)

    Yu, H.L.; Sun, G.Y.; Yang, L.Y.; Xing, D.Y.

    2004-01-01

    The Nambu spinor Green's function approach is applied to study proximity effects in ferromagnet/superconductor (FM/SC) structures. They include the induced superconducting order parameter and density of states (DOS) with superconducting feature on the FM side, and spin-dependent DOS within the energy gap on the SC side. The latter indicates an appearance of gapless superconductivity and a coexistence of ferromagnetism and superconductivity in a small regime near the interface. The influence of exchange energy in FM and barrier strength at interface on the proximity effects is discussed

  13. Magnon-photon interaction in ferromagnets

    International Nuclear Information System (INIS)

    Shrivastava, K.N.

    1980-01-01

    A magnon-photon interaction for the magnetic vector of the electromagnetic wave perpendicular to the direction of magnetization in a ferromagnet is constructed with the use of Bogoliubov transformation. The resulting magnon-photon interaction is found to contain several interesting new radiation effects. The self-energy of the magnon is calculated and life times arising from the radiation scattering are predicted. The magnon frequency shift due to the radiation field is found. One of the terms arising from the one-magnon one-photon scattering gives a line width that is in reasonable agreement with the experimentally measured value of ferromagnetic resonance line width in yttrium iron garnet. (orig.)

  14. Wellhead with non-ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Hinson, Richard A [Houston, TX; Vinegar, Harold J [Bellaire, TX

    2009-05-19

    Wellheads for coupling to a heater located in a wellbore in a subsurface formation are described herein. At least one wellhead may include a heater located in a wellbore in a subsurface formation; and a wellhead coupled to the heater. The wellhead may be configured to electrically couple the heater to one or more surface electrical components. The wellhead may include at least one non-ferromagnetic material such that ferromagnetic effects are inhibited in the wellhead. Systems and methods for using such wellheads for treating a subsurface formation are described herein.

  15. Vortex dynamics in ferromagnetic/superconducting bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cieplak, M.Z.; Adamus, Z. [Polish Acad Sci, Inst Phys, PL-02668 Warsaw, (Poland); Konczykowski, M. [CEA, DSM, DRECAM, Lab Solides Irradies, Ecole Polytechnique, CNRS-UMR 7642, F-91128 Palaiseau (France); Zhu, L.Y.; Chien, C.L. [Johns Hopkins Univ, Dept Phys and Astron, Baltimore, MD 21218 (United States)

    2008-07-01

    The dependence of vortex dynamics on the geometry of magnetic domain pattern is studied in the superconducting/ferromagnetic bilayers, in which niobium is a superconductor, and Co/Pt multilayer with perpendicular magnetic anisotropy serves as a ferromagnetic layer. Magnetic domain patterns with different density of domains per surface area and different domain size, w, are obtained for Co/Pt with different thickness of Pt. The dense patterns of domains with the size comparable to the magnetic penetration depth (w {>=} {lambda}) produce large vortex pinning and smooth vortex penetration, while less dense patterns with larger domains (w {>=}{>=} {lambda}) enhance pinning less effectively and result in flux jumps during flux motion. (authors)

  16. High quality Y-type hexaferrite thick films for microwave applications by an economical and environmentally benign crystal growth technique

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bolin; Chen, Yajie, E-mail: y.chen@neu.edu; Gillette, Scott; Su, Zhijuan; Harris, Vincent G. [Center for Microwave Magnetic Materials and Integrated Circuits and Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Wolf, Jason; McHenry, Michael E. [Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

    2014-02-17

    Thick barium hexaferrite Ba{sub 2}Zn{sub 2}Fe{sub 12}O{sub 22} (i.e., Zn{sub 2}Y) films having thicknesses of ∼100 μm were epitaxially grown on MgO (111) substrates using an environmentally benign ferrite-salt mixture by vaporizing the salt. X-ray diffraction pole figure analyses showed (00l) crystallographic alignment with little in plane dispersion confirming epitaxial growth. Saturation magnetization, 4πM{sub s}, was measured for as-grown films to be 2.51 ± 0.1 kG with an out of plane magnetic anisotropy field H{sub A} of 8.9 ± 0.1 kOe. Ferromagnetic resonance linewidth, as the peak-to-peak power absorption derivative at 9.6 GHz, was measured to be 62 Oe. These properties demonstrate a rapid, convenient, cost-effective, and nontoxic method of growing high quality thick crystalline ferrite films which could be used widely for microwave device applications.

  17. Quality and efficiency in high dimensional Nearest neighbor search

    KAUST Repository

    Tao, Yufei; Yi, Ke; Sheng, Cheng; Kalnis, Panos

    2009-01-01

    Nearest neighbor (NN) search in high dimensional space is an important problem in many applications. Ideally, a practical solution (i) should be implementable in a relational database, and (ii) its query cost should grow sub-linearly with the dataset size, regardless of the data and query distributions. Despite the bulk of NN literature, no solution fulfills both requirements, except locality sensitive hashing (LSH). The existing LSH implementations are either rigorous or adhoc. Rigorous-LSH ensures good quality of query results, but requires expensive space and query cost. Although adhoc-LSH is more efficient, it abandons quality control, i.e., the neighbor it outputs can be arbitrarily bad. As a result, currently no method is able to ensure both quality and efficiency simultaneously in practice. Motivated by this, we propose a new access method called the locality sensitive B-tree (LSB-tree) that enables fast highdimensional NN search with excellent quality. The combination of several LSB-trees leads to a structure called the LSB-forest that ensures the same result quality as rigorous-LSH, but reduces its space and query cost dramatically. The LSB-forest also outperforms adhoc-LSH, even though the latter has no quality guarantee. Besides its appealing theoretical properties, the LSB-tree itself also serves as an effective index that consumes linear space, and supports efficient updates. Our extensive experiments confirm that the LSB-tree is faster than (i) the state of the art of exact NN search by two orders of magnitude, and (ii) the best (linear-space) method of approximate retrieval by an order of magnitude, and at the same time, returns neighbors with much better quality. © 2009 ACM.

  18. Temperature limited heater utilizing non-ferromagnetic conductor

    Science.gov (United States)

    Vinegar,; Harold J. , Harris; Kelvin, Christopher [Houston, TX

    2012-07-17

    A heater is described. The heater includes a ferromagnetic conductor and an electrical conductor electrically coupled to the ferromagnetic conductor. The ferromagnetic conductor is positioned relative to the electrical conductor such that an electromagnetic field produced by time-varying current flow in the ferromagnetic conductor confines a majority of the flow of the electrical current to the electrical conductor at temperatures below or near a selected temperature.

  19. High quality flux control system for electron gun evaporation

    International Nuclear Information System (INIS)

    Appelbloom, A.M.; Hadley, P.; van der Marel, D.; Mooij, J.E.

    1991-01-01

    This paper reports on a high quality flux control system for electron gun evaporation developed and tested for the MBE growth of high temperature superconductors. The system can be applied to any electron gun without altering the electron gun itself. Essential elements of the system are a high bandwidth mass spectrometer, control electronics and a high voltage modulator to sweep the electron beam over the melt at high frequencies. the sweep amplitude of the electron beam is used to control the evaporation flux at high frequencies. The feedback loop of the system has a bandwidth of over 100 Hz, which makes it possible to grow superlattices and layered structures in a fast and precisely controlled manner

  20. Safety and quality management at the high flux reactor Petten

    International Nuclear Information System (INIS)

    Zurita, A.; Ahlf, J.

    1995-01-01

    The High Flux Reactor (HFR) is one high power multi-purpose materials testing research reactor of the tank-in-pool type, cooled and moderated by light-water. It is operated at 45 MW at a prescribed schedule of 11 cycles per year, each comprising 25 operation days and three shut-down days. Since the licence for the operation of HFR was granted in 1962, a total of 14 amendments to the original licence have been made following different modifications in the installations. In the meantime, international nuclear standards were developed, especially in the framework of the NUSS programme of the IAEA, which were adopted by the Dutch Licensing Authorities. In order to implement the new standards, the situation at the HFR was comprehensively reviewed in the course of an audit performed by the Dutch Licensing Authorities in 1988. This also resulted in formulating the task of setting-up an 'HFR - Integral Quality Assurance Handbook' (HFR-IQAD) involving both organizations JRCIAM and ECN, which had the unique framework and basic guideline to assure the safe and efficient operation and exploitation of the HFR and to promote safety and quality in all aspects of HFR related activities. The assurance of safe and efficient operation and exploitation of the HFR is condensed together under the concepts of safety and quality of services and is achieved through the safety and quality management. (orig.)

  1. Ferromagnets as pure spin current generators and detectors

    Science.gov (United States)

    Qu, Danru; Miao, Bingfeng; Chien, Chia -Ling; Huang, Ssu -Yen

    2015-09-08

    Provided is a spintronics device. The spintronics can include a ferromagnetic metal layer, a positive electrode disposed on a first surface portion of the ferromagnetic metal layer, and a negative electrode disposed on a second surface portion of the ferromagnetic metal.

  2. Ferromagnetic resonance study of the half-Heusler alloy NiMnSb. The benefit of using NiMnSb as a ferromagnetic layer in pseudo-spin-valve based spin-torque oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Riegler, Andreas

    2011-11-25

    -beam lithography and measured by ferromagnetic resonance. The damping remains in the low 10{sup -3} range as determined directly by extracting the Gilbert damping from the line width. Additionally magnetostatic modes are observed in arrays of elements, which is further evidence of high material quality of the samples. By sputtering various metals on top of the NiMnSb, spin pumping from the ferromagnet into the non-magnetic layer is investigated. After these material investigations, pseudo-spin-valves using NiMnSb as one of the ferromagnet, in combination with Permalloy were fabricating using a self-aligned lithography process. These samples show a GMR ratio of 3.4% at room temperature and almost double at low temperature, comparing favourably to the best single stack GMR structures reported to date. Moreover, current induced switching measurements show promisingly low current densities are necessary to change the magnetic orientation of the free layer. These current densities compete with state-of-the-art GMR devices for metal based structures and almost with tunnel junction devices. The true potential of these devices however comes to light when they are operated as spin torque oscillators to emit high frequency, tunable, narrow spectrum electromagnetic waves. These Heusler based STOs show an outstanding q-factor of 4180, even when operating in the absence of an external field, a value which bests the highest value in the literature by more than an order of magnitude. While these devices currently still suffer from the same limited output power as all STO reported to date, their sub-micron lateral dimensions make the fabrication of an on-chip array of coupled oscillators, which is a promising path forward towards industrially relevant output power.

  3. Wellbeing Understanding in High Quality Healthcare Informatics and Telepractice.

    Science.gov (United States)

    Fiorini, Rodolfo A; De Giacomo, Piero; L'Abate, Luciano

    2016-01-01

    The proper use of healthcare informatics technology and multidimensional conceptual clarity are fundamental to create and boost outstanding clinical and telepractice results. Avoiding even terminology ambiguities is mandatory for high quality of care service. For instance, well-being or wellbeing is a different way to write the same concept only, or there is a good deal of ambiguity around the meanings of these terms the way they are written. In personal health, healthcare and healthcare informatics, this kind of ambiguity and lack of conceptual clarity has been called out repeatedly over the past 50 years. It is time to get the right, terse scenario. We present a brief review to develop and achieve ultimate wellbeing understanding for practical high quality healthcare informatics and telepractice application. This article presents an innovative point of view on deeper wellbeing understanding towards its increased clinical effective application.

  4. Electric-field controlled ferromagnetism in MnGe magnetic quantum dots

    Directory of Open Access Journals (Sweden)

    Faxian Xiu

    2011-03-01

    Full Text Available Electric-field control of ferromagnetism in magnetic semiconductors at room temperature has been actively pursued as one of the important approaches to realize practical spintronics and non-volatile logic devices. While Mn-doped III-V semiconductors were considered as potential candidates for achieving this controllability, the search for an ideal material with high Curie temperature (Tc>300 K and controllable ferromagnetism at room temperature has continued for nearly a decade. Among various dilute magnetic semiconductors (DMSs, materials derived from group IV elements such as Si and Ge are the ideal candidates for such materials due to their excellent compatibility with the conventional complementary metal-oxide-semiconductor (CMOS technology. Here, we review recent reports on the development of high-Curie temperature Mn0.05Ge0.95 quantum dots (QDs and successfully demonstrate electric-field control of ferromagnetism in the Mn0.05Ge0.95 quantum dots up to 300 K. Upon the application of gate-bias to a metal-oxide-semiconductor (MOS capacitor, the ferromagnetism of the channel layer (i.e. the Mn0.05Ge0.95 quantum dots was modulated as a function of the hole concentration. Finally, a theoretical model based upon the formation of magnetic polarons has been proposed to explain the observed field controlled ferromagnetism.

  5. Hole-induced d"0 ferromagnetism enhanced by Na-doping in GaN

    International Nuclear Information System (INIS)

    Zhang, Yong; Li, Feng

    2017-01-01

    The d"0 ferromagnetism in wurtzite GaN is investigated by the first-principle calculations. It is found that spontaneous magnetization occurs if sufficient holes are injected in GaN. Both Ga vacancy and Na doping can introduce holes into GaN. However, Ga vacancy has a high formation energy, and is thus unlikely to occur in a significant concentration. In contrast, Na doping has relatively low formation energy. Under N-rich growth condition, Na doping with a sufficient concentration can be achieved, which can induce half-metallic ferromagnetism in GaN. Moreover, the estimated Curie temperature of Na-doped GaN is well above the room temperature. - Highlights: • Hole-induced ferromagnetism in GaN is confirmed. • Both Ga Vacancy and Na-doping can introduce hole into GaN. • The concentration of Ga vacancy is too low to induce detectable ferromagnetism. • Na-doped GaN is a possible ferromagnet with a high curie-temperature.

  6. Quality assurance system for sitting high risk facilities

    International Nuclear Information System (INIS)

    Rodriguez, Aymee; Peralta, Jose L.; Fernandez, Manuel

    1999-01-01

    The paper shows how we have conceived and designed the quality assurance system for the site selection process of an area for sitting the facility of high risk in correspondence with the approved methodology. The results obtained in the implementation of the system have permitted the satisfactory performance of each one the expected stage, defining the most favorable sectors in order to continue the studies of the repository site for the disposal of low and intermedium. (author)

  7. High-quality uniform dry transfer of graphene to polymers.

    Science.gov (United States)

    Lock, Evgeniya H; Baraket, Mira; Laskoski, Matthew; Mulvaney, Shawn P; Lee, Woo K; Sheehan, Paul E; Hines, Daniel R; Robinson, Jeremy T; Tosado, Jacob; Fuhrer, Michael S; Hernández, Sandra C; Walton, Scott G

    2012-01-11

    In this paper we demonstrate high-quality, uniform dry transfer of graphene grown by chemical vapor deposition on copper foil to polystyrene. The dry transfer exploits an azide linker molecule to establish a covalent bond to graphene and to generate greater graphene-polymer adhesion compared to that of the graphene-metal foil. Thus, this transfer approach provides a novel alternative route for graphene transfer, which allows for the metal foils to be reused. © 2011 American Chemical Society

  8. Coupling of high-quality-factor optical resonators

    International Nuclear Information System (INIS)

    Salzenstein, Patrice; Henriet, Rémi; Coillet, Aurélien; Chembo, Yanne K; Mortier, Michel; Sérier-Brault, Hélène; Rasoloniaina, Alphonse; Dumeige, Yannick; Féron, Patrice

    2013-01-01

    We improve theoretically and experimentally the problem of the coupling between a high Q-factor resonator and its external coupler. We have observed oscillations of ringing induced by the sweeping of the excitation frequency of an active microsphere. Thanks to this approach, the quality factor of an optical resonator was measured and we obtained Q = 5.8 × 10 8 . (paper)

  9. Tunneling Conductance in Ferromagnetic Metal/Normal Metal/Spin-Singlet -Wave Ferromagnetic Superconductor Junctions

    Directory of Open Access Journals (Sweden)

    Hamidreza Emamipour

    2013-01-01

    Full Text Available In the framework of scattering theory, we study the tunneling conductance in a system including two junctions, ferromagnetic metal/normal metal/ferromagnetic superconductor, where ferromagnetic superconductor is in spin-singlet -wave pairing state. The non-magnetic normal metal is placed in the intermediate layer with the thickness ( which varies from 1 nm to 10000 nm. The interesting result which we have found is the existence of oscillations in conductance curves. The period of oscillations is independent of FS and FN exchange field while it depends on . The obtained results can serve as a useful tool to determine the kind of pairing symmetry in ferromagnetic superconductors.

  10. A high throughput DNA extraction method with high yield and quality

    Directory of Open Access Journals (Sweden)

    Xin Zhanguo

    2012-07-01

    Full Text Available Abstract Background Preparation of large quantity and high quality genomic DNA from a large number of plant samples is a major bottleneck for most genetic and genomic analyses, such as, genetic mapping, TILLING (Targeting Induced Local Lesion IN Genome, and next-generation sequencing directly from sheared genomic DNA. A variety of DNA preparation methods and commercial kits are available. However, they are either low throughput, low yield, or costly. Here, we describe a method for high throughput genomic DNA isolation from sorghum [Sorghum bicolor (L. Moench] leaves and dry seeds with high yield, high quality, and affordable cost. Results We developed a high throughput DNA isolation method by combining a high yield CTAB extraction method with an improved cleanup procedure based on MagAttract kit. The method yielded large quantity and high quality DNA from both lyophilized sorghum leaves and dry seeds. The DNA yield was improved by nearly 30 fold with 4 times less consumption of MagAttract beads. The method can also be used in other plant species, including cotton leaves and pine needles. Conclusion A high throughput system for DNA extraction from sorghum leaves and seeds was developed and validated. The main advantages of the method are low cost, high yield, high quality, and high throughput. One person can process two 96-well plates in a working day at a cost of $0.10 per sample of magnetic beads plus other consumables that other methods will also need.

  11. Ferromagnetism in poly(N-perfluorophenylpyrrole)

    Energy Technology Data Exchange (ETDEWEB)

    Čík, G., E-mail: gabriel.cik@stuba.sk [Department of Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Šeršeň, F. [Institute of Chemistry, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava (Slovakia); Dlháň, L. [Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Zálupský, P. [Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Rapta, P. [Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Hrnčariková, K. [Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Plecenik, T. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava (Slovakia)

    2015-10-01

    Magnetic properties of the synthesized poly(N-perfluorophenylpyrrole) were studied. The synthesized polymer dissolves in common organic solvents. By the zero-field cooling-field cooling method (ZFC–FC) we found that at low temperatures (T{sub b}<50 K) the synthetic polymer reaches a state with prevailing ferromagnetism. The synthesized polymer retained ferromagnetism even at 300 K. The anomalous magnetic behavior was explained in terms of spin–spin interaction of triplet polarons. As can be seen from the calculated spin density of SOMO and SOMO 1 such a state arise as a consequence of 1-D spin interactions of polarons. Based on the calculated and visualized spin density (SOMO) on the polymer chain such interactions can be explained by the theory of flat-band-ferromagnetism. - Highlights: • We synthesized a new conducting polymer poly(N-perfluorophenylpyrrole). • By the ZFC–FC and EPR methods we measured magnetic properties of the prepared polymer. • We discussed stability and interactions of the polarons in triplet states. • At low temperatures the synthesized polymer reached ferromagnetism.

  12. On piezomagnetism at viscoplasticity of ferromagnetics

    International Nuclear Information System (INIS)

    Micunovic, M.

    2001-01-01

    The paper deals with viscoplasticity of ferromagnetic materials. Tensor representation is applied to a set of evolution equations comprising the plastic stretching and residual magnetization tensors. Small magnetoelastic strains of isotropic insulators are considered in detail in two special cases of finite as well as small plastic strain. A special emphasis is given to piezomagnetism effects in the case of uniaxial cycling strain (author)

  13. Angular and linear momentum of excited ferromagnets

    NARCIS (Netherlands)

    Yan, P.; Kamra, A.; Cao, Y.; Bauer, G.E.W.

    2013-01-01

    The angular momentum vector of a Heisenberg ferromagnet with isotropic exchange interaction is conserved, while under uniaxial crystalline anisotropy the projection of the total spin along the easy axis is a constant of motion. Using Noether's theorem, we prove that these conservation laws persist

  14. Ferromagnetic hysteresis and the effective field

    NARCIS (Netherlands)

    Naus, H.W.L.

    2002-01-01

    The Jiles-Atherton model of the behavior of ferromagnetic materials determines the irreversible magnetization from the effective field by using a differential equation. This paper presents an exact, analytical solution to the equation, one displaying hysteresis. The inclusion of magnetomechanical

  15. Ferromagnetism in diluted magnetic semiconductor heterojunction systems

    Czech Academy of Sciences Publication Activity Database

    Lee, B.; Jungwirth, Tomáš; MacDonald, A. H.

    2002-01-01

    Roč. 17, - (2002), s. 393-403 ISSN 0268-1242 R&D Projects: GA ČR GA202/98/0085; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * heterostructures Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.241, year: 2002

  16. Pseudospin anisotropy classification of quantum Hall ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; MacDonald, A. H.

    2000-01-01

    Roč. 63, č. 3 (2000), s. 035305-1 - 035305-9 ISSN 0163-1829 R&D Projects: GA ČR GA202/98/0085 Institutional research plan: CEZ:AV0Z1010914 Keywords : quantum Hall ferromagnets * anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.065, year: 2000

  17. Skyrmion physics in Bose-Einstein ferromagnets

    NARCIS (Netherlands)

    Al Khawaja, U.; Stoof, H.T.C.

    2001-01-01

    We show that a ferromagnetic Bose-Einstein condensate has not only line-like vortex excitations, but in general, also allows for pointlike topological excitations, i.e., skyrmions. We discuss the thermodynamic stability and the dynamic properties of these skyrmions for both spin-1/2 and

  18. Nonmonotonic critical temperature in superconductor ferromagnet bilayers

    NARCIS (Netherlands)

    Fominov, Ya. V.; Fominov, I.V.; Chtchelkatchev, N.M.; Golubov, Alexandre Avraamovitch

    2002-01-01

    The critical temperature Tc of a superconductor/ferromagnet (SF) bilayer can exhibit nonmonotonic dependence on the thickness df of the F layer. SF systems have been studied for a long time; according to the experimental situation, a ¿dirty¿ limit is often considered which implies that the mean free

  19. Magnetization dissipation in ferromagnets from scattering theory

    NARCIS (Netherlands)

    Brataas, A.; Tserkovnyak, Y.; Bauer, G.E.W.

    2011-01-01

    The magnetization dynamics of ferromagnets is often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the dissipative part is parametrized by the Gilbert damping

  20. Room-temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    the ferromagnetic nature of ITO and the strength of magnetization is superior to those of In2O3 and SnO2. However, ... ties in the spintronic devices, the materials suitable for such devices ... into suitable quartz test tubes (10mm) whose interior was enclosed in .... related to metal indium In0 with binding energy 443.6 eV was.

  1. Neutron Depolarization in Submicron Ferromagnetic Materials

    NARCIS (Netherlands)

    Rekveldt, M.Th.

    1989-01-01

    The neutron depolarization technique is based on the loss of polarization of a polarized neutron beam after transmission through ferromagnetic substances. This loss, caused by Larmor precession in individual domains, determines the mean domain size, the mean square direction cosines of the domains

  2. Methods and systems for fabricating high quality superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Majkic, Goran; Selvamanickam, Venkat

    2018-02-13

    An MOCVD system fabricates high quality superconductor tapes with variable thicknesses. The MOCVD system can include a gas flow chamber between two parallel channels in a housing. A substrate tape is heated and then passed through the MOCVD housing such that the gas flow is perpendicular to the tape's surface. Precursors are injected into the gas flow for deposition on the substrate tape. In this way, superconductor tapes can be fabricated with variable thicknesses, uniform precursor deposition, and high critical current densities.

  3. High quality mask storage in an advanced Logic-Fab

    Science.gov (United States)

    Jähnert, Carmen; Fritsche, Silvio

    2012-02-01

    High efficient mask logistics as well as safe and high quality mask storage are essential requirements within an advanced lithography area of a modern logic waferfab. Fast operational availability of the required masks at the exposure tool with excellent mask condition requires a safe mask handling, safeguarding of high mask quality over the whole mask usage time without any quality degradation and an intelligent mask logistics. One big challenge is the prevention of haze on high advanced phase shift masks used in a high volume production line for some thousands of 248nm or 193nm exposures. In 2008 Infineon Dresden qualified a customer specific developed semi-bare mask storage system from DMSDynamic Micro Systems in combination with a high advanced mask handling and an interconnected complex logistic system. This high-capacity mask storage system DMS M1900.22 for more than 3000 masks with fully automated mask and box handling as well as full-blown XCDA purge has been developed and adapted to the Infineon Lithotoollandscape using Nikon and SMIF reticle cases. Advanced features for ESD safety and mask security, mask tracking via RFID and interactions with the exposure tools were developed and implemented. The stocker is remote controlled by the iCADA-RSM system, ordering of the requested mask directly from the affected exposure tool allows fast access. This paper discusses the advantages and challenges for this approach as well as the practical experience gained during the implementation of the new system which improves the fab performance with respect to mask quality, security and throughput. Especially the realization of an extremely low and stable humidity level in addition with a well controlled air flow at each mask surface, preventing masks from haze degradation and particle contamination, turns out to be a notable technical achievement. The longterm stability of haze critical masks has been improved significantly. Relevant environmental parameters like

  4. Resistive switching via the converse magnetoelectric effect in ferromagnetic multilayers on ferroelectric substrates.

    Science.gov (United States)

    Pertsev, N A; Kohlstedt, H

    2010-11-26

    A voltage-controlled resistive switching is predicted for ferromagnetic multilayers and spin valves mechanically coupled to a ferroelectric substrate. The switching between low- and high-resistance states results from the strain-driven magnetization reorientations by about 90°, which are shown to occur in ferromagnetic layers with a high magnetostriction and weak cubic magnetocrystalline anisotropy. Such reorientations, not requiring external magnetic fields, can be realized experimentally by applying moderate electric field to a thick substrate (bulk or membrane type) made of a relaxor ferroelectric having ultrahigh piezoelectric coefficients. The proposed multiferroic hybrids exhibiting giant magnetoresistance may be employed as electric-write nonvolatile magnetic memory cells with nondestructive readout.

  5. Magnetic and electronic properties of half-metallic ferromagnetic Mn-stabilised zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Maznichenko, Igor; Daene, Markus; Hergert, Wolfram; Mertig, Ingrid [Martin-Luther-Univ. Halle-Wittenberg, Inst. Phys., 06099 Halle (Germany); Ernst, Arthur; Ostanin, Sergey; Sandratskii, Leonid; Bruno, Patrick [Max-Planck-Inst. Mikrostrukturphys., Weinberg 2, 06120 Halle (Germany); Bergqvist, Lars [Dept. Phys., Uppsala Univ., Box 530, 751 21 Uppsala (Sweden); Hughes, Ian; Staunton, Julie [Dept. Phys., Univ. Warwick, Coventry CV4 7AL (United Kingdom); Kudrnovsky, Josef [Max-Planck-Inst. Mikrostrukturphys., Weinberg 2, 06120 Halle (Germany); Inst. Phys., Acad. Sci. of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic)

    2007-07-01

    The investigations of the manganese stabilised cubic zirconia (Mn-SZ) show that this dilute magnetic semiconductors possess unique magnetic properties. Based on ab-initio electronic structure calculations which include the effects of thermally excited magnetic fluctuations, the autors predict Mn-SZ to be ferromagnetic for a wide range of Mn concentration up to high T{sub C}. It was found that this material, which is well known both as a diamond imitation and as a catalyst, is halfmetallic with majority and minority spin states of the Mn impurities lying in the wide band gap of zirconia. The high T{sub C} ferromagnetism is robust against oxygen vacancies and against the distribution of Mn impurities on the Zr fcc sublattice. This work responds to the question concerning the key electronic and structure factors behind an optimal doping. The autors propose this stable half-metallic ferromagnet to be a promising candidate for future spintronics applications.

  6. Magneto-optical Kerr-effect at low temperatures. Investigation of superconductor/ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Stahl, Claudia; Ruoss, Stephen; Graefe, Joachim; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Albrecht, Joachim [Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

    2016-07-01

    With XMCD microscopy it is possible to visualize the critical current density of the superconductor YBCO with high spatial resolution. Therefore, soft magnetic CoFeB is introduced as sensor layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which are then imaged via X-ray microscopy. These experiments have to be carried out at the scanning X-ray microscope MAXYMUS at the synchrotron Bessy II in Berlin. For that purpose pre-characterization of the sensor is highly desirable: Magnetic interactions between the superconductor and the ferromagnetic sensor layer have been investigated at low temperatures using Kerr-effect measurements. Therefore hysteresis loops are obtained by a sophisticated magnet and field ramping setup within the NanoMOKE3 system. The results are used to optimize the ferromagnetic sensor layer for XMCD microscopy of superconductors.

  7. Spin Transport in Mesoscopic Superconducting-Ferromagnetic Hybrid Conductor

    Directory of Open Access Journals (Sweden)

    Zein W. A.

    2008-01-01

    Full Text Available The spin polarization and the corresponding tunneling magnetoresistance (TMR for a hybrid ferromagnetic / superconductor junction are calculated. The results show that these parameters are strongly depends on the exchange field energy and the bias voltage. The dependence of the polarization on the angle of precession is due to the spin flip through tunneling process. Our results could be interpreted as due to spin imbalance of carriers resulting in suppression of gap energy of the superconductor. The present investigation is valuable for manufacturing magnetic recording devices and nonvolatile memories which imply a very high spin coherent transport for such junction.

  8. Potts ferromagnet correlation length in hypercubic lattices: Renormalization - group approach

    International Nuclear Information System (INIS)

    Curado, E.M.F.; Hauser, P.R.

    1984-01-01

    Through a real space renormalization group approach, the q-state Potts ferromagnet correlation length on hierarchical lattices is calculated. These hierarchical lattices are build in order to simulate hypercubic lattices. The high-and-low temperature correlation length asymptotic behaviours tend (in the Ising case) to the Bravais lattice correlation length ones when the size of the hierarchical lattice cells tends to infinity. It is conjectured that the asymptotic behaviours several values of q and d (dimensionality) so obtained are correct. Numerical results are obtained for the full temperature range of the correlation length. (Author) [pt

  9. Competing interactions in ferromagnetic/antiferromagnetic perovskite superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Takamura, Y.; Biegalski, M.B.; Christen, H.M.

    2009-10-22

    Soft x-ray magnetic dichroism, magnetization, and magnetotransport measurements demonstrate that the competition between different magnetic interactions (exchange coupling, electronic reconstruction, and long-range interactions) in La{sub 0.7}Sr{sub 0.3}FeO{sub 3}(LSFO)/La{sub 0.7}Sr{sub 0.3}MnO{sub 3}(LSMO) perovskite oxide superlattices leads to unexpected functional properties. The antiferromagnetic order parameter in LSFO and ferromagnetic order parameter in LSMO show a dissimilar dependence on sublayer thickness and temperature, illustrating the high degree of tunability in these artificially layered materials.

  10. Spin Transport in Mesoscopic Superconducting-Ferromagnetic Hybrid Conductor

    Directory of Open Access Journals (Sweden)

    Zein W. A.

    2008-01-01

    Full Text Available The spin polarization and the corresponding tunneling magnetoresistance (TMR for a hybrid ferromagnetic/superconductor junction are calculated. The results show that these parameters are strongly depends on the exchange field energy and the bias voltage. The dependence of the polarization on the angle of precession is due to the spin flip through tunneling process. Our results could be interpreted as due to spin imbalance of carriers resulting in suppression of gap energy of the superconductor. The present investigation is valuable for manufacturing magnetic recording devices and nonvolatile memories which imply a very high spin coherent transport for such junction.

  11. Spin-wave damping in ferromagnets in the ordered regime

    International Nuclear Information System (INIS)

    Reinecke, T.L.; Stinchcombe, R.B.

    1978-01-01

    Theoretical results based on a high-density approach are compared with experimental measurements for the damping of long-wavelength spin waves in the nearly isotropic ferromagnet for temperatures up to the critical regime. The theory, which has no adjustable parameters, is shown to account well for the overall magnitude of the spin-wave widths measured in recent neutron scattering experiments on EuO, and it is also in satisfactory agreement with the measured wave vector and temperature dependence of these widths. An estimate is also given for the contribution of dipolar coupling to the spin-wave widths

  12. Ferromagnetic alloy material CoFeC with high thermal tolerance in MgO/CoFeC/Pt structure and comparable intrinsic damping factor with CoFeB

    Science.gov (United States)

    Chen, Shaohai; Zhou, Jing; Lin, Weinan; Yu, Jihang; Guo, Rui; Poh, Francis; Shum, Danny; Chen, Jingsheng

    2018-02-01

    The thermal tolerance and perpendicular magnetic anisotropy (PMA) of ferromagnetic alloy Co40Fe40C20 in the structure MgO/CoFeC/Pt (or Ta) were investigated and compared with the commonly used CoFeB alloy. It is found that the PMA of CoFeC with {{K}i,CoFeC}=2.21 erg c{{m}-2} , which is 59% higher than that of CoFeB, can be obtained after proper post-annealing treatment. Furthermore, CoFeC alloy provides better thermal tolerance to temperature of 400 °C than CoFeB. The studies on ferromagnetic resonance show that the intrinsic damping constant α in of Co40Fe40C20 alloy is 0.0047, which is similar to the reported value of 0.004 for Co40Fe40B20 alloy. The comprehensive comparisons indicate that CoFeC alloy is a promising candidate for the application of the integration of spin torque transfer magnetic random access memory with complementary metal-oxide semiconductor processes.

  13. Construction of High-Quality Camel Immune Antibody Libraries.

    Science.gov (United States)

    Romão, Ema; Poignavent, Vianney; Vincke, Cécile; Ritzenthaler, Christophe; Muyldermans, Serge; Monsion, Baptiste

    2018-01-01

    Single-domain antibodies libraries of heavy-chain only immunoglobulins from camelids or shark are enriched for high-affinity antigen-specific binders by a short in vivo immunization. Thus, potent binders are readily retrieved from relatively small-sized libraries of 10 7 -10 8 individual transformants, mostly after phage display and panning on a purified target. However, the remaining drawback of this strategy arises from the need to generate a dedicated library, for nearly every envisaged target. Therefore, all the procedures that shorten and facilitate the construction of an immune library of best possible quality are definitely a step forward. In this chapter, we provide the protocol to generate a high-quality immune VHH library using the Golden Gate Cloning strategy employing an adapted phage display vector where a lethal ccdB gene has to be substituted by the VHH gene. With this procedure, the construction of the library can be shortened to less than a week starting from bleeding the animal. Our libraries exceed 10 8 individual transformants and close to 100% of the clones harbor a phage display vector having an insert with the length of a VHH gene. These libraries are also more economic to make than previous standard approaches using classical restriction enzymes and ligations. The quality of the Nanobodies that are retrieved from immune libraries obtained by Golden Gate Cloning is identical to those from immune libraries made according to the classical procedure.

  14. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    Energy Technology Data Exchange (ETDEWEB)

    Aravindh, S. Assa; Schwingenschloegl, Udo, E-mail: udo.schwingenschloegl@kaust.edu.sa, E-mail: iman.roqan@kaust.edu.sa; Roqan, Iman S., E-mail: udo.schwingenschloegl@kaust.edu.sa, E-mail: iman.roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)

    2014-12-21

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn{sub 48}O{sub 48} nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high T{sub C} in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  15. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    KAUST Repository

    Aravindh, S. Assa

    2014-12-19

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  16. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    KAUST Repository

    Aravindh, S. Assa; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  17. Magnetization reversal of ferromagnetic nanoparticles induced by a stream of polarized electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kozhushner, M.A.; Gatin, A.K.; Grishin, M.V.; Shub, B.R. [Semenov Institute of Chemical Physics of RAS, 4, Kosygin Street, Moscow 119991 (Russian Federation); Kim, V.P.; Khomutov, G.B. [Faculty of Physics, Lomonosov Moscow State University, Lenin Gory 1-2, Moscow 119991 (Russian Federation); Ilegbusi, O.J. [University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816-2450 (United States); Trakhtenberg, L.I. [Semenov Institute of Chemical Physics of RAS, 4, Kosygin Street, Moscow 119991 (Russian Federation)

    2016-09-15

    The remagnetization of ferromagnetic Fe{sub 3}O{sub 4} nanoparticles of several thousand cubic nanometers by spin-polarized current is investigated. For this purpose, magnetite nanoparticles are synthesized and deposited on a conductive nonmagnetic substrate. The remagnetization is conducted in high-vacuum scanning tunneling microscope (STM). The STM tip from magnetized iron wire constitutes one electrode while the ferromagnetic nanoparticle on the graphite surface represents the second electrode. The measured threshold value of remagnetization current (I{sub thresh}=9 nA) is the lowest value of current at which remagnetization occurs. The change in nanoparticle magnetization is detected by the effect of giant magnetic resistance, specifically, the dependence of the weak polarized current (Iferromagnetic nanoclusters. The peculiarities of size dependence of the observed effects are explained. - Highlights: • Ferromagnetic nanoparticle in STM with ferromagnetic tip. • Change of the direction of nanoparticle magnetization by current I>I{sub cr}=9 nA. • GMR effect used to control change of magnetization.

  18. Magnetic damping phenomena in ferromagnetic thin-films and multilayers

    Science.gov (United States)

    Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

    2017-11-01

    Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

  19. High beam quality and high energy short-pulse laser with MOPA

    Science.gov (United States)

    Jin, Quanwei; Pang, Yu; Jiang, JianFeng; Tan, Liang; Cui, Lingling; Wei, Bin; Sun, Yinhong; Tang, Chun

    2018-03-01

    A high energy, high beam quality short-pulse diode-pumped Nd:YAG master oscillator power-amplifier (MOPA) laser with two amplifier stages is demonstrated. The two-rod birefringence compensation was used as beam quality controlling methods, which presents a short-pulse energy of 40 mJ with a beam quality value of M2 = 1.2 at a repetition rate of 400Hz. The MOPA system delivers a short-pulse energy of 712.5 mJ with a pulse width of 12.4 ns.The method of spherical aberration compensation is improved the beam quality, a M2 factor of 2.3 and an optical-to-optical efficiency of 27.7% is obtained at the maximum laser out power.The laser obtained 1.4J out energy with polarization integration.

  20. Magnetic characterisation of large grain, bulk Y–Ba–Cu–O superconductor–soft ferromagnetic alloy hybrid structures

    International Nuclear Information System (INIS)

    Philippe, M.P.; Fagnard, J.-F.; Kirsch, S.; Xu, Z.; Dennis, A.R.; Shi, Y.-H.; Cardwell, D.A.; Vanderheyden, B.; Vanderbemden, P.

    2014-01-01

    Highlights: • Large grain, bulk YBaCuO superconductor (SC) combined with ferromagnetic elements. • The flux lines curve outwards through the ferromagnet in the remanent state. • The trapped field in the SC is enhanced by the presence of the ferromagnet. • The effects of the SC and the ferromagnet add when the ferromagnet is saturated. - Abstract: Large grain, bulk Y–Ba–Cu–O (YBCO) high temperature superconductors (HTS) have significant potential for use in a variety of practical applications that incorporate powerful quasi-permanent magnets. In the present work, we investigate how the trapped field of such magnets can be improved by combining bulk YBCO with a soft FeNi, ferromagnetic alloy. This involves machining the alloy into components of various shapes, such as cylinders and rings, which are attached subsequently to the top surface of a solid, bulk HTS cylinder. The effect of these modifications on the magnetic hysteresis curve and trapped field of the bulk superconductor at 77 K are then studied using pick-up coil and Hall probe measurements. The experimental data are compared to finite element modelling of the magnetic flux distribution using Campbell’s algorithm. Initially we establish the validity of the technique involving pick-up coils wrapped around the bulk superconductor to obtain its magnetic hysteresis curve in a non-destructive way and highlight the difference between the measured signal and the true magnetization of the sample. We then consider the properties of hybrid ferromagnet/superconductor (F/S) structures. Hall probe measurements, together with the results of the model, establish that flux lines curve outwards through the ferromagnet, which acts, effectively, like a magnetic short circuit. Magnetic hysteresis curves show that the effects of the superconductor and the ferromagnet simply add when the ferromagnet is saturated fully by the applied field. The trapped field of the hybrid structure is always larger than that of the

  1. Development of nuclear quality high pressure valve bellows in Canada

    International Nuclear Information System (INIS)

    Janzen, P.; Astill, C.J.

    1978-06-01

    Concurrent with the decision to use bellows stem sealed nuclear valves where feasible in commercial-scale CANDU plants, AECL undertook to develop an indigenous high pressure valve bellows technology. This program included developing the capability to fabricate improved high pressure valve bellows in conjunction with a Canadian manufacturer. This paper describes the evolution of a two-stage bellows fabrication process involving: (1) manufacture of discrete lengths of precision thin wall telescoping tubes - from preparation of strip blanks through edge grinding and edge forming to longitudinal welding; (2) forming of bellows from tube assemblies using a novel combination of mechanical inward forming followed by hydraulic outward forming. Bellows of Inconel 600 and Inconel 625 have been manufactured and evaluated. Test results indicate comparable to improved performance over alternative high quality bellows. (author)

  2. Fat Quality Influences the Obesogenic Effect of High Fat Diets

    Directory of Open Access Journals (Sweden)

    Raffaella Crescenzo

    2015-11-01

    Full Text Available High fat and/or carbohydrate intake are associated with an elevated risk for obesity and chronic diseases such as diabetes and cardiovascular diseases. The harmful effects of a high fat diet could be different, depending on dietary fat quality. In fact, high fat diets rich in unsaturated fatty acids are considered less deleterious for human health than those rich in saturated fat. In our previous studies, we have shown that rats fed a high fat diet developed obesity and exhibited a decrease in oxidative capacity and an increase in oxidative stress in liver mitochondria. To investigate whether polyunsaturated fats could attenuate the above deleterious effects of high fat diets, energy balance and body composition were assessed after two weeks in rats fed isocaloric amounts of a high-fat diet (58.2% by energy rich either in lard or safflower/linseed oil. Hepatic functionality, plasma parameters, and oxidative status were also measured. The results show that feeding on safflower/linseed oil diet attenuates the obesogenic effect of high fat diets and ameliorates the blood lipid profile. Conversely, hepatic steatosis and mitochondrial oxidative stress appear to be negatively affected by a diet rich in unsaturated fatty acids.

  3. Spin supercurrent in Josephson contacts with noncollinear ferromagnets

    International Nuclear Information System (INIS)

    Shomali, Zahra; Zareyan, Malek; Belzig, Wolfgang

    2011-01-01

    We present a theoretical study of the Josephson coupling of two superconductors that are connected through a diffusive contact consisting of noncollinear ferromagnetic domains. The leads are conventional s-wave superconductors with a phase difference of ψ. Firstly, we consider a contact with two domains with magnetization vectors misoriented by an angle θ. Using the quantum circuit theory, we found that in addition to the charge supercurrent, which shows a 0-π transition relative to the angle θ, a spin supercurrent with a spin polarization normal to the magnetization vectors flows between the domains. While the charge supercurrent is odd in ψ and even in θ, the spin supercurrent is even in ψ and odd in θ. Furthermore, with asymmetric insulating barriers at the interfaces of the junction, the system may experience an antiferromagnetic-ferromagnetic phase transition for ψ=π. Secondly, we discuss the spin supercurrent in an extended magnetic texture with multiple domain walls. We find the position-dependent spin supercurrent. While the direction of the spin supercurrent is always perpendicular to the plane of the magnetization vectors, the magnitude of the spin supercurrent strongly depends on the phase difference between the superconductors and the number of domain walls. In particular, our results reveal the high sensitivity of spin- and charge-transport in the junction to the number of domain walls in the ferromagnet. We show that superconductivity in coexistence with noncollinear magnetism can be used in a Josephson nanodevice to create a controllable spin supercurrent acting as a spin transfer torque on a system. Our results demonstrate the possibility of coupling the superconducting phase to the magnetization dynamics and, hence, constituting a quantum interface, for example between the magnetization and a superconducting qubit.

  4. High quality electron beams from a laser wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, S M; Issac, R C; Welsh, G H; Brunetti, E; Shanks, R P; Anania, M P; Cipiccia, S; Manahan, G G; Aniculaesei, C; Ersfeld, B; Islam, M R; Burgess, R T L; Vieux, G; Jaroszynski, D A [SUPA, Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Gillespie, W A [SUPA, Division of Electronic Engineering and Physics, University of Dundee, Dundee (United Kingdom); MacLeod, A M [School of Computing and Creative Technologies, University of Abertay Dundee, Dundee (United Kingdom); Van der Geer, S B; De Loos, M J, E-mail: m.wiggins@phys.strath.ac.u [Pulsar Physics, Burghstraat 47, 5614 BC Eindhoven (Netherlands)

    2010-12-15

    High quality electron beams have been produced in a laser-plasma accelerator driven by femtosecond laser pulses with a peak power of 26 TW. Electrons are produced with an energy up to 150 MeV from the 2 mm gas jet accelerator and the measured rms relative energy spread is less than 1%. Shot-to-shot stability in the central energy is 3%. Pepper-pot measurements have shown that the normalized transverse emittance is {approx}1{pi} mm mrad while the beam charge is in the range 2-10 pC. The generation of high quality electron beams is understood from simulations accounting for beam loading of the wakefield accelerating structure. Experiments and self-consistent simulations indicate that the beam peak current is several kiloamperes. Efficient transportation of the beam through an undulator is simulated and progress is being made towards the realization of a compact, high peak brilliance free-electron laser operating in the vacuum ultraviolet and soft x-ray wavelength ranges.

  5. Precipitation of ferromagnetic phase induced by defect energies during creep deformation in Type 304 austenitic steel

    International Nuclear Information System (INIS)

    Tsukada, Yuhki; Shiraki, Atsuhiro; Murata, Yoshinori; Takaya, Shigeru; Koyama, Toshiyuki; Morinaga, Masahiko

    2010-01-01

    The correlation of defect energies with precipitation of the ferromagnetic phase near M 23 C 6 carbide during creep tests at high temperature in Type 304 austenitic steel was examined by estimating the defect energies near the carbide, based on micromechanics. As one of the defect energies, the precipitation energy was calculated by assuming M 23 C 6 carbide to be a spherical inclusion. The other defect energy, creep dislocation energy, was calculated based on dislocation density data obtained from transmission electron microscopy observations of the creep samples. The dislocation energy density was much higher than the precipitation energy density in the initial stage of the creep process, when the ferromagnetic phase started to increase. Creep dislocation energy could be the main driving force for precipitation of the ferromagnetic phase.

  6. Precipitation of ferromagnetic phase induced by defect energies during creep deformation in Type 304 austenitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Tsukada, Yuhki, E-mail: tsukada@silky.numse.nagoya-u.ac.j [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Shiraki, Atsuhiro; Murata, Yoshinori [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Takaya, Shigeru [Japan Atomic Energy Agency, 4002 Narita-cho, O-arai-machi, Higashi-ibaraki-gun, Ibaraki 311-1393 (Japan); Koyama, Toshiyuki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Morinaga, Masahiko [Department of Materials, Physics and Energy Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2010-06-15

    The correlation of defect energies with precipitation of the ferromagnetic phase near M{sub 23}C{sub 6} carbide during creep tests at high temperature in Type 304 austenitic steel was examined by estimating the defect energies near the carbide, based on micromechanics. As one of the defect energies, the precipitation energy was calculated by assuming M{sub 23}C{sub 6} carbide to be a spherical inclusion. The other defect energy, creep dislocation energy, was calculated based on dislocation density data obtained from transmission electron microscopy observations of the creep samples. The dislocation energy density was much higher than the precipitation energy density in the initial stage of the creep process, when the ferromagnetic phase started to increase. Creep dislocation energy could be the main driving force for precipitation of the ferromagnetic phase.

  7. Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals

    International Nuclear Information System (INIS)

    Ray, Sugata; Kolen'ko, Yury V; Watanabe, Tomoaki; Yoshimura, Masahiro; Itoh, Mitsuru; Kovnir, Kirill A; Lebedev, Oleg I; Turner, Stuart; Erni, Rolf; Tendeloo, Gustaaf Van; Chakraborty, Tanushree

    2012-01-01

    Defect mediated high temperature ferromagnetism in oxide nanocrystallites is the central feature of this work. Here, we report the development of room temperature ferromagnetism in nanosized Co-doped barium titanate particles with a size of around 14 nm, synthesized by a solvothermal drying method. A combination of x-ray diffraction with state-of-the-art electron microscopy techniques confirms the intrinsic doping of Co into BaTiO 3 . The development of the room temperature ferromagnetism was tracked down to the different donor defects, namely hydroxyl groups at the oxygen site and oxygen vacancies and their relative concentrations at the surface and the core of the nanocrystal, which could be controlled by post-synthesis drying and thermal treatments.

  8. Anion vacancy-mediated ferromagnetism in atomic-thick Ni3N nanosheets

    Science.gov (United States)

    Xia, Baorui; Wang, Tongtong; Chi, Xiao; Yu, Xiaojiang; Liu, Peitao; Zhang, Jingyan; Xi, Shibo; Du, Yonghua; Gao, Daqiang

    2017-12-01

    Realizing spin and electronic behavior of two-dimensional ultrathin nanosheets is significant to construct next generation nanoelectronics. Here, atomic-thick Ni3N nanosheets with clear room temperature ferromagnetism and high saturation magnetization (1.2 emu/g) are reported. X-ray magnetic circular dichroism and first-principles calculation results give the evidence that the observed intrinsic ferromagnetism in Ni3N nanosheets originates from the surface N-deficiency, where alignments of localized large magnetic moments of Ni in the vicinity of the N defect can be aligned parallel to activate macroscopic ferromagnetism. These ultrathin Ni3N nanosheets show great potential application in next-generation electron devices.

  9. Sleep quality and its relationship with quality of life among high-risk pregnant women (gestational diabetes and hypertension).

    Science.gov (United States)

    Saadati, Fatemeh; Sehhatiei Shafaei, Fahimeh; Mirghafourvand, Mozhgan

    2018-01-01

    Sleep is one of the most basic human requirements. This research aims at determining the status of sleep quality and its relationship with quality of life among high-risk pregnant women in Tabriz, Iran, in 2015. This research was a sectional study done on 364 qualified women in 28-36 weeks of pregnancy suffering from mild preeclampsia and gestational diabetes. The sampling was done as convenience. Personal-social-midwifery questionnaire, Pittsburg sleep quality, and quality of life in pregnancy (QOL-ORAV) were used for gathering data. Multivariate linear regression model was used for determining the relationship between sleep quality and its subsets with quality of life and controlling confounders. In the current study, the prevalence of sleep disturbance was 96.4%. Mean (SD) of the total score of sleep quality was 10.1 (4.1) and the total score of quality of life was 61.7 (17.3). According to Pearson's correlation test, there was statistically significant relationship between quality of life and sleep quality and all its subsets except sleep duration and use of sleep medication (p quality of life. The findings of current research show that sleep quality is low among high-risk pregnant women and quality of life is medium. So, it is necessary that required training is given by health cares for improving sleep quality and quality of life to mothers.

  10. Present status of high quality beam facility at Waseda University

    International Nuclear Information System (INIS)

    Washio, M.; Kawai, H.; Hama, Y.; Kudo, N.; Kobayashi, M.; Kuribayasi, T.; Kawaguchi, M.; Kuroda, R.; Maeda, K.; Nagasawa, F.; Ueyama, D.; Hizume, K.; Wang, X.J.; Hayano, H.; Urakawa, J.; Kashiwagi, S.

    2004-01-01

    A research project named High-Tech Research Center Project has been conducted at Waseda University. In this project, an RF gun system has been used for production of low emittance and short bunched electron beam. The experiments for the electron beam quality measurement have been carried out by slit scan techniques, etc. Short pulsed x-ray with the energy range of so-called water window has been generation by the inverse compton scattering. Further, the pulse radiolysis system has been constructed, and the stroboscopic pulse radiolysis has been applied for the detection of hydrated electron in picosecond time region. (author)

  11. Anti-Stokes Luminescence in High Quality Quantum Wells

    Science.gov (United States)

    Vinattieri, A.; Bogani, F.; Miotto, A.; Ceccherini, S.

    1997-11-01

    We present a detailed investigation of the anti-Stokes (AS) luminescence which originates from exciton recombination when below gap excitation is used, in a set of high quality quantum well structures. We observe strong excitonic resonances in the AS signal as measured from photoluminescence and photoluminescence excitation spectra. We demonstrate that neither the electromagnetic coupling between the wells nor the morphological disorder can explain this up-conversion effect. Time-resolved luminescence data after ps excitation and fs correlation spectroscopy results provide clear evidence of the occurrence of a two-step absorption which is assisted by the exciton population resonantly excited by the first photon.

  12. The quality of high-energy X-ray beams

    International Nuclear Information System (INIS)

    LaRiviere, P.D.

    1989-01-01

    Supplement 17 of the British Journal of Radiology is a survey of central-axis depth doses for radiotherapy machines, patterned largely on BJR Supplement 11 (1972). Inspection of high-energy X-ray depth doses for a 10 x 10 cm field at an SSD of 100 cm disclosed large differences between the two sets of data, especially for qualities above 8 MV, e.g. a depth dose of 80% at 10 cm is rated at about 19 MV according to BJR Supplement 11, and 23 MV according to BJR Supplement 17. It was found that Supplement 17 depth-dose data above 8 MV were erratic, but Supplement 11 data could be represented by an analytical expression, providing a unique means of assigning MV quality. It was also found that dose-weighted average energy of the filtered beam plotted smoothly against depth dose. For dosimetric purposes, it is suggested that this parameter be used as a true measure of beam quality, removing discrepancies introduced by the use of nominal MV for this purpose. (author)

  13. CCD Astrophotography High-Quality Imaging from the Suburbs

    CERN Document Server

    Stuart, Adam

    2006-01-01

    This is a reference book for amateur astronomers who have become interested in CCD imaging. Those glorious astronomical images found in astronomy magazines might seem out of reach to newcomers to CCD imaging, but this is not the case. Great pictures are attainable with modest equipment. Adam Stuart’s many beautiful images, reproduced in this book, attest to the quality of – initially – a beginner’s efforts. Chilled-chip astronomical CCD-cameras and software are also wonderful tools for cutting through seemingly impenetrable light-pollution. CCD Astrophotography from the Suburbs describes one man’s successful approach to the problem of getting high-quality astronomical images under some of the most light-polluted conditions. Here is a complete and thoroughly tested program that will help every CCD-beginner to work towards digital imaging of the highest quality. It is equally useful to astronomers who have perfect observing conditions, as to those who have to observe from light-polluted city skies.

  14. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    Science.gov (United States)

    Li, Dong-Xiang; Qin, Xiu-Bo; Zheng, Li-Rong; Li, Yu-Xiao; Cao, Xing-Zhong; Li, Zhuo-Xin; Yang, Jing; Wang, Bao-Yi

    2013-03-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti3+—VO defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.

  15. Large-scale calculation of ferromagnetic spin systems on the pyrochlore lattice

    Energy Technology Data Exchange (ETDEWEB)

    Soldatov, Konstantin, E-mail: soldatov_ks@students.dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Nefedev, Konstantin, E-mail: nefedev.kv@dvfu.ru [School of Natural Sciences, Far Eastern Federal University, Vladivostok (Russian Federation); Institute of Applied Mathematics, Far Eastern Branch, Russian Academy of Science, Vladivostok (Russian Federation); Komura, Yukihiro [CIJ-solutions, Chuo-ku, Tokyo 103-0023 (Japan); Okabe, Yutaka, E-mail: okabe@phys.se.tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan)

    2017-02-19

    We perform the high-performance computation of the ferromagnetic Ising model on the pyrochlore lattice. We determine the critical temperature accurately based on the finite-size scaling of the Binder ratio. Comparing with the data on the simple cubic lattice, we argue the universal finite-size scaling. We also calculate the classical XY model and the classical Heisenberg model on the pyrochlore lattice. - Highlights: • Calculations of the ferromagnetic models on the pyrochlore lattice were performed. • Precise critical temperatures were determined using Binder ratio finite-size scaling. • The universal finite-size scaling was argued.

  16. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    International Nuclear Information System (INIS)

    Li Dong-Xiang; Cao Xing-Zhong; Li Zhuo-Xin; Yang Jing; Wang Bao-Yi; Qin Xiu-Bo; Zheng Li-Rong; Li Yu-Xiao

    2013-01-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO 2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti 3+ —V O defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti 3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO 2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments

  17. Theory for disordered phase in Heisenberg and non-Heisenberg two-dimensional S=1 ferromagnets

    International Nuclear Information System (INIS)

    Spirin, D.V.; Fridman, Yu.A.

    2003-01-01

    We apply a modification of self-consistent spin-wave theory to investigation of two-dimensional S=1 isotropic Heisenberg and non-Heisenberg ferromagnets at nonzero temperatures. We use Hubbard operators method and bosonization technique. We calculated chemical potential and found dependence of correlation length on temperature. Specific heat has Schottky-type peak and decreases at high temperatures. Disordered phase in non-Heisenberg ferromagnet is also studied. The results for such a model differ from those of Heisenberg one

  18. Percutaneous vertebroplasty with a high-quality rotational angiographic unit

    Energy Technology Data Exchange (ETDEWEB)

    Pedicelli, Alessandro [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: apedicelli@rm.unicatt.it; Rollo, Massimo [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: mrollo@rm.unicatt.it; Piano, Mariangela [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: mariangela.piano@gmail.com; Re, Thomas J. [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: tomjre@gmail.com; Cipriani, Maria C. [Department of Gerontology, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: alexped@yahoo.com; Colosimo, Cesare [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: colosimo@rm.unicatt.it; Bonomo, Lorenzo [Department of Bioimaging and Radiological Sciences, Catholic University of Sacred Heart, Policl. A.Gemelli, l.go Gemelli 1, 00168 Rome (Italy)], E-mail: lbonomo@rm.unicatt.it

    2009-02-15

    We evaluated the reliability of a rotational angiographic unit (RA) with flat-panel detector as a single technique to guide percutaneous vertebroplasty (PVP) and for post-procedure assessment by 2D and 3D reformatted images. Fifty-five consecutive patients (104 vertebral bodies) were treated under RA fluoroscopy. Rotational acquisitions with 2D and 3D reconstruction were obtained in all patients for immediate post-procedure assessment. In complex cases, this technique was also used to evaluate the needle position during the procedure. All patients underwent CT scan after the procedure. RA and CT findings were compared. In all cases, a safe trans-pedicular access and an accurate control of the bone-cement injection were successfully performed with high-quality fluoroscopy, even at the thoracic levels and in case of vertebra plana. 2D and 3D rotational reconstructions permitted CT-like images that clearly showed needle position and were similar to CT findings in depicting intrasomatic implant-distribution. RA detected 40 cement leakages compared to 42 demonstrated by CT and showed overall 95% sensitivity and 100% specificity compared to CT for final post-procedure assessment. Our preliminary results suggest that high-quality RA is reliable and safe as a single technique for PVP guidance, control and post-procedure assessment. It permits fast and cost-effective procedures avoiding multi-modality imaging.

  19. Computer-aided control of high-quality cast iron

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2008-04-01

    Full Text Available The study discusses the possibility of control of the high-quality grey cast iron and ductile iron using the author’s genuine computer programs. The programs have been developed with the help of algorithms based on statistical relationships that are said to exist between the characteristic parameters of DTA curves and properties, like Rp0,2, Rm, A5 and HB. It has been proved that the spheroidisation and inoculation treatment of cast iron changes in an important way the characteristic parameters of DTA curves, thus enabling a control of these operations as regards their correctness and effectiveness, along with the related changes in microstructure and mechanical properties of cast iron. Moreover, some examples of statistical relationships existing between the typical properties of ductile iron and its control process were given for cases of the melts consistent and inconsistent with the adopted technology.A test stand for control of the high-quality cast iron and respective melts has been schematically depicted.

  20. Automated high speed volume computed tomography for inline quality control

    International Nuclear Information System (INIS)

    Hanke, R.; Kugel, A.; Troup, P.

    2004-01-01

    Increasing complexity of innovative products as well as growing requirements on quality and reliability call for more detailed knowledge about internal structures of manufactured components rather by 100 % inspection than just by sampling test. A first-step solution, like radioscopic inline inspection machines, equipped with automated data evaluation software, have become state of the art in the production floor during the last years. However, these machines provide just ordinary two-dimensional information and deliver no volume data e.g. to evaluate exact position or shape of detected defects. One way to solve this problem is the application of X-ray computed tomography (CT). Compared to the performance of the first generation medical scanners (scanning times of many hours), today, modern Volume CT machines for industrial applications need about 5 minutes for a full object scan depending on the object size. Of course, this is still too long to introduce this powerful method into the inline production quality control. In order to gain acceptance, the scanning time including subsequent data evaluation must be decreased significantly and adapted to the manufacturing cycle times. This presentation demonstrates the new technical set up, reconstruction results and the methods for high-speed volume data evaluation of a new fully automated high-speed CT scanner with cycle times below one minute for an object size of less than 15 cm. This will directly create new opportunities in design and construction of more complex objects. (author)

  1. Production of high quality water for oil sands application

    Energy Technology Data Exchange (ETDEWEB)

    Beaudette-Hodsman, C.; Macleod, B. [Pall Corp., Mississauga, ON (Canada); Venkatadri, R. [Pall Corp., East Hills, NY (United States)

    2008-10-15

    This paper described a pressurized microfiltration membrane system installed at an oil sands extraction site in Alberta. The system was designed to complement a reverse osmosis (RO) system installed at the site to produce the high quality feed water required by the system's boilers. Groundwater in the region exhibited moderate total suspended solids and high alkalinity and hardness levels, and the RO system required feed water with a silt density index of 3 or less. The conventional pretreatment system used at the site was slowing down production due to the severe fouling of the RO membranes. The new microfiltration system contained an automated PVDF hollow fiber microfiltration membrane system contained in a trailer. Suspended particles and bacteria were captured within the filter, and permeate was sent to the RO unit. Within 6 hours of being installed, the unit was producing water with SDI values in the range of 1.0 to 2.5. It was concluded that the microfiltration system performed reliably regardless of wide variations in feed water quality and flow rates. 3 refs., 1 tab., 8 figs.

  2. Topological Aspects of Solitons in Ferromagnets

    International Nuclear Information System (INIS)

    Ren Jirong; Wang Jibiao; Li Ran; Xu Donghui; Duan Yishi

    2008-01-01

    Two kinds of topological soliton (skyrmion and magnetic vortex ring) in ferromagnets are studied. They have the common topological origin, a tensor H αβ = n-vector · (∂ α n-vector x ∂ β n-vector ), which describes the non-trivial distribution of local orientation of magnetization n-vector at large distances in space. The topological stability of skyrmion is protected by the winding number. Knot-like topological defect as magnetic vortex rings is also studied. On the assumption that magnetic vortex rings are geometric lines, we present their δ-function distribution in ferromagnetic materials. Furthermore, it is briefly shown that Hopf invariant is a proper topological invariant to describe the topology of magnetic vortex rings

  3. Ferromagnetism of Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Jitendra Pal Singh

    2017-11-01

    Full Text Available Magnetism without d-orbital electrons seems to be unrealistic; however, recent observations of magnetism in non-magnetic oxides, such as ZnO, HfO2, and MgO, have opened new avenues in the field of magnetism. Magnetism exhibited by these oxides is known as d° ferromagnetism, as these oxides either have completely filled or unfilled d-/f-orbitals. This magnetism is believed to occur due to polarization induced by p-orbitals. Magnetic polarization in these oxides arises due to vacancies, the excitation of trapped spin in the triplet state. The presence of vacancies at the surface and subsurface also affects the magnetic behavior of these oxides. In the present review, origins of magnetism in magnesium oxide are discussed to obtain understanding of d° ferromagnetism.

  4. Ising ferromagnet: zero-temperature dynamic evolution

    International Nuclear Information System (INIS)

    Oliveira, P M C de; Newman, C M; Sidoravicious, V; Stein, D L

    2006-01-01

    The dynamic evolution at zero temperature of a uniform Ising ferromagnet on a square lattice is followed by Monte Carlo computer simulations. The system always eventually reaches a final, absorbing state, which sometimes coincides with a ground state (all spins parallel), and sometimes does not (parallel stripes of spins up and down). We initiate here the numerical study of 'chaotic time dependence' (CTD) by seeing how much information about the final state is predictable from the randomly generated quenched initial state. CTD was originally proposed to explain how nonequilibrium spin glasses could manifest an equilibrium pure state structure, but in simpler systems such as homogeneous ferromagnets it is closely related to long-term predictability and our results suggest that CTD might indeed occur in the infinite volume limit

  5. On the critical frontiers of Potts ferromagnets

    International Nuclear Information System (INIS)

    Magalhaes, A.C.N. de; Tsallis, C.

    1981-01-01

    A conjecture concerning the critical frontiers of q- state Potts ferromagnets on d- dimensional lattices (d > 1) which generalize a recent one stated for planar lattices is formulated. The present conjecture is verified within satisfactory accuracy (exactly in some cases) for all the lattices or arrays whose critical points are known. Its use leads to the prediction of: a) a considerable amount of new approximate critical points (26 on non-planar regular lattices, some others on Husimi trees and cacti); b) approximate critical frontiers for some 3- dimensional lattices; c) the possibly asymptotically exact critical point on regular lattices in the limit d→infinite for all q>=1; d) the possibly exact critical frontier for the pure Potts model on fully anisotropic Bethe lattices; e) the possibly exact critical frontier for the general quenched random-bond Potts ferromagnet (any P(J)) on isotropic Bethe lattices. (Author) [pt

  6. High Framingham risk score decreases quality of life in adults

    Directory of Open Access Journals (Sweden)

    Christian Yosaputra

    2010-04-01

    Full Text Available Cardiovascular disease (CVD risk factors, such as diabetes, hypertension, hypercholesterolemia, smoking, and obesity tend to occur together in the general population. Increasing prevalence of multiple CVD risk factors has been related to increased risk of death from coronary heart disease and stroke. Studies have suggested that people with several risk factors of CVD may have impaired health-related quality of life. The objective of this study was to assess the association of CVD risk factors with quality of life (QOL among adults aged 40 to 65 years. A cross-sectional study was conducted involving 220 subjects 40 - 65 years of age at a health center. The CVD risk factors were assessed using the Framingham risk score that is the standard instrument for assessment of the risk of a first cardiac event. The risk factors assessed were age, smoking, blood pressure, total cholesterol and high density lipoprotein cholesterol concentrations. QOL was assessed by means of the WHOQOL-BREF instrument that had been prevalidated. The results of the study showed that 28.2% of subjects were smokers, 56.4% had stage 1 hypertension, 42.8% high total cholesterol and 13.6% low HDL cholesterol. The high risk group amounted to 45.5% and 42.3% constitued an intermediate risk group. High CVD risk scores were significantly associated with a low QOL for all domains (physical, psychological, social and environment (p=0.000. Preventing or reducing the multiple CVD risk factors to improve QOL is necessary among adults.

  7. Fractal effects on excitations in diluted ferromagnets

    International Nuclear Information System (INIS)

    Kumar, D.

    1981-08-01

    The low energy spin-wave like excitations in diluted ferromagnets near percolation threshold are studied. For this purpose an explicit use of the fractal model for the backbone of the infinite percolating cluster due to Kirkpatrick is made. Three physical effects are identified, which cause the softening of spin-waves as the percolation point is approached. The importance of fractal effects in the calculation of density of states and the low temperature thermodynamics is pointed out. (author)

  8. Anomalous hall effect in ferromagnetic semiconductors

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Niu, Q.; MacDonald, A. H.

    2002-01-01

    Roč. 88, č. 20 (2002), s. 207208-1-207208-4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0912; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * anomalous Hall effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.323, year: 2002

  9. Magnon squeezing states in a ferromagnet

    International Nuclear Information System (INIS)

    Wang Junfeng; Cheng Ze; Ping Yunxia; Wan Jinyin; Zhang Yanmin

    2006-01-01

    In this Letter we discuss squeezing state of magnon in ferromagnet, which permits a reduction in the quantum fluctuation of the spin component to below the zero-point quantum noise level of coherent magnon states. We investigate the generation of squeezed magnon state through calculating the expectation values of spin component fluctuation. The mean field theory is introduced in dealing with the nonlinear interaction terms of Hamiltonian of magnon system

  10. The Kondo effect in ferromagnetic atomic contacts.

    Science.gov (United States)

    Calvo, M Reyes; Fernández-Rossier, Joaquín; Palacios, Juan José; Jacob, David; Natelson, Douglas; Untiedt, Carlos

    2009-04-30

    Iron, cobalt and nickel are archetypal ferromagnetic metals. In bulk, electronic conduction in these materials takes place mainly through the s and p electrons, whereas the magnetic moments are mostly in the narrow d-electron bands, where they tend to align. This general picture may change at the nanoscale because electrons at the surfaces of materials experience interactions that differ from those in the bulk. Here we show direct evidence for such changes: electronic transport in atomic-scale contacts of pure ferromagnets (iron, cobalt and nickel), despite their strong bulk ferromagnetism, unexpectedly reveal Kondo physics, that is, the screening of local magnetic moments by the conduction electrons below a characteristic temperature. The Kondo effect creates a sharp resonance at the Fermi energy, affecting the electrical properties of the system; this appears as a Fano-Kondo resonance in the conductance characteristics as observed in other artificial nanostructures. The study of hundreds of contacts shows material-dependent log-normal distributions of the resonance width that arise naturally from Kondo theory. These resonances broaden and disappear with increasing temperature, also as in standard Kondo systems. Our observations, supported by calculations, imply that coordination changes can significantly modify magnetism at the nanoscale. Therefore, in addition to standard micromagnetic physics, strong electronic correlations along with atomic-scale geometry need to be considered when investigating the magnetic properties of magnetic nanostructures.

  11. Tunable Magnon Weyl Points in Ferromagnetic Pyrochlores.

    Science.gov (United States)

    Mook, Alexander; Henk, Jürgen; Mertig, Ingrid

    2016-10-07

    The dispersion relations of magnons in ferromagnetic pyrochlores with Dzyaloshinskii-Moriya interaction are shown to possess Weyl points, i. e., pairs of topologically nontrivial crossings of two magnon branches with opposite topological charge. As a consequence of their topological nature, their projections onto a surface are connected by magnon arcs, thereby resembling closely Fermi arcs of electronic Weyl semimetals. On top of this, the positions of the Weyl points in reciprocal space can be tuned widely by an external magnetic field: rotated within the surface plane, the Weyl points and magnon arcs are rotated as well; tilting the magnetic field out of plane shifts the Weyl points toward the center Γ[over ¯] of the surface Brillouin zone. The theory is valid for the class of ferromagnetic pyrochlores, i. e., three-dimensional extensions of topological magnon insulators on kagome lattices. In this Letter, we focus on the (111) surface, identify candidates of established ferromagnetic pyrochlores which apply to the considered spin model, and suggest experiments for the detection of the topological features.

  12. Ferroelectricity with Ferromagnetic Moment in Orthoferrites

    Science.gov (United States)

    Tokunaga, Yusuke

    2010-03-01

    Exotic multiferroics with gigantic magnetoelectric (ME) coupling have recently been attracting broad interests from the viewpoints of both fundamental physics and possible technological application to next-generation spintronic devices. To attain a strong ME coupling, it would be preferable that the ferroelectric order is induced by the magnetic order. Nevertheless, the magnetically induced ferroelectric state with the spontaneous ferromagnetic moment is still quite rare apart from a few conical-spin multiferroics. To further explore multiferroic materials with both the strong ME coupling and spontaneous magnetization, we focused on materials with magnetic structures other than conical structure. In this talk we present that the most orthodox perovskite ferrite systems DyFeO3 and GdFeO3 have ``ferromagnetic-ferroelectric,'' i.e., genuinely multiferroic states in which weak ferromagnetic moment is induced by Dzyaloshinskii-Moriya interaction working on Fe spins and electric polarization originates from the striction due to symmetric exchange interaction between Fe and Dy (Gd) spins [1] [2]. Both materials showed large electric polarization (>0.1 μC/cm^2) and strong ME coupling. In addition, we succeeded in mutual control of magnetization and polarization with electric- and magnetic-fields in GdFeO3, and attributed the controllability to novel, composite domain wall structure. [4pt] [1] Y. Tokunaga et al., Phys. Rev. Lett. 101, 097205 (2008). [0pt] [2] Y. Tokunaga et al., Nature Mater. 8, 558 (2009).

  13. Spin-polarized transport in a two-dimensional electron gas with interdigital-ferromagnetic contacts

    DEFF Research Database (Denmark)

    Hu, C.-M.; Nitta, Junsaku; Jensen, Ane

    2001-01-01

    Ferromagnetic contacts on a high-mobility, two-dimensional electron gas (2DEG) in a narrow gap semiconductor with strong spin-orbit interaction are used to investigate spin-polarized electron transport. We demonstrate the use of magnetized contacts to preferentially inject and detect specific spi...

  14. Epitaxial ferromagnetic Fe3Si on GaAs(111)A with atomically smooth surface and interface

    International Nuclear Information System (INIS)

    Liu, Y. C.; Hung, H. Y.; Kwo, J.; Chen, Y. W.; Lin, Y. H.; Cheng, C. K.; Hong, M.; Tseng, S. C.; Hsu, C. H.; Chang, M. T.; Lo, S. C.

    2015-01-01

    Single crystal ferromagnetic Fe 3 Si(111) films were grown epitaxially on GaAs(111)A by molecular beam epitaxy. These hetero-structures possess extremely low surface roughness of 1.3 Å and interfacial roughness of 1.9 Å, measured by in-situ scanning tunneling microscope and X-ray reflectivity analyses, respectively, showing superior film quality, comparing to those attained on GaAs(001) in previous publications. The atomically smooth interface was revealed by the atomic-resolution Z (atomic number)-contrast scanning transmission electron microscopy (STEM) images using the correction of spherical aberration (Cs)-corrected electron probe. Excellent crystallinity and perfect lattice match were both confirmed by high resolution x-ray diffraction. Measurements of magnetic property for the Fe 3 Si/GaAs(111) yielded a saturation moment of 990 emu/cm 3 with a small coercive field ≤1 Oe at room temperature

  15. Automated Theorem Proving in High-Quality Software Design

    Science.gov (United States)

    Schumann, Johann; Swanson, Keith (Technical Monitor)

    2001-01-01

    The amount and complexity of software developed during the last few years has increased tremendously. In particular, programs are being used more and more in embedded systems (from car-brakes to plant-control). Many of these applications are safety-relevant, i.e. a malfunction of hardware or software can cause severe damage or loss. Tremendous risks are typically present in the area of aviation, (nuclear) power plants or (chemical) plant control. Here, even small problems can lead to thousands of casualties and huge financial losses. Large financial risks also exist when computer systems are used in the area of telecommunication (telephone, electronic commerce) or space exploration. Computer applications in this area are not only subject to safety considerations, but also security issues are important. All these systems must be designed and developed to guarantee high quality with respect to safety and security. Even in an industrial setting which is (or at least should be) aware of the high requirements in Software Engineering, many incidents occur. For example, the Warshaw Airbus crash, was caused by an incomplete requirements specification. Uncontrolled reuse of an Ariane 4 software module was the reason for the Ariane 5 disaster. Some recent incidents in the telecommunication area, like illegal "cloning" of smart-cards of D2GSM handies, or the extraction of (secret) passwords from German T-online users show that also in this area serious flaws can happen. Due to the inherent complexity of computer systems, most authors claim that only a rigorous application of formal methods in all stages of the software life cycle can ensure high quality of the software and lead to real safe and secure systems. In this paper, we will have a look, in how far automated theorem proving can contribute to a more widespread application of formal methods and their tools, and what automated theorem provers (ATPs) must provide in order to be useful.

  16. Spin transport in diffusive ferromagnetic Josephson junctions with noncollinear magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Shomali, Zahra; Zareyan, Malek [Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45195 (Iran, Islamic Republic of); Belzig, Wolfgang [Fachbereich Physik, Universitaet Konstanz, D-78457 Konstanz (Germany)

    2011-07-01

    We numerically study the Josephson coupling of two s-wave superconductors which are connected through a diffusive contact made of two ferromagnetic domains with the magnetization vectors misoriented by an angle {theta}. The assumed superconducting leads are conventional s-wave type with the phase difference of {phi}. Using the quantum circuit theory, we find that in addition to the charge supercurrent, which shows a 0-{pi} transition relative to the angle {theta}, the spin supercurrent with a spin polarization normal to the magnetization vectors will flow through the contact. Our results present a 0-{pi} quantum phase transition as a function of the wave vector, Q{xi}. Finally, we investigate the spin supercurrent in an extended magnetic texture with multiple domain walls. We find the behavior of spin supercurrent is highly sensitive to the barrier. When asymmetric barriers don't change the value of the spin supercurrent, the symmetric ones decrease the value of it notably. We also investigate some other interesting effects for these systems. In addition, we present when Q{xi} is the even multiple of {pi}, the spin-current which is penetrated into the nonhomogeneous ferromagnets is nearly zero, how ever the odd ones show the large amount of penetrated spin supercurrent.

  17. Preparation and characterization of flexible ferromagnetic nanocomposites for microwave applications

    International Nuclear Information System (INIS)

    Thomas, Teena; Kanoth, Bipinbal P.; Nijas, C.M.; Joy, P.A.; Joseph, Joseph M.; Kuthirummal, Narayanan; Thachil, Eby T.

    2015-01-01

    Highlights: • Fe 3 O 4 nanoparticles (∼20 nm) were synthesised by co-precipitation method. • Nanoparticles were homogeneously distributed in natural rubber through latex stage processing. • Mechanical properties and magnetic properties of composites improved with loading Fe 3 O 4 nanoparticles. • Imaginary part of permeability increases with nanoparticle loading improving the microwave absorption characteristics. • Infrared spectra reveal strong interaction between NR and iron oxide nanoparticles. - Abstract: Magnetic Fe 3 O 4 nanoparticles (∼20 nm) were synthesized using the chemical co-precipitation method with a view of developing flexible and easily processable ferromagnetic materials with high mouldability to be used as microwave absorbers. The nanoparticles prepared were incorporated into natural rubber through latex stage processing. This novel processing method gives better dispersion of particles in the rubber matrix. The composites were characterized using XRD, SEM, vibrating sample magnetometer, dynamic mechanical analyzer, cavity perturbation, thermogravimetry (TGA), and Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). A notable improvement in the mechanical properties of composites was observed upon adding Fe 3 O 4 particles. Magnetic and microwave characteristics of the composites indicate the formation of a flexible ferromagnetic material with good microwave absorption characteristics

  18. Preparation and characterization of flexible ferromagnetic nanocomposites for microwave applications

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Teena; Kanoth, Bipinbal P. [Department of Polymer Science & Rubber Technology, Cochin University of Science & Technology, Cochin, 682022, Kerala (India); Nijas, C.M. [Department of Electronics, Cochin University of Science & Technology, Cochin, 682022, Kerala (India); Joy, P.A. [Physical and Materials Chemistry Division, National Chemical Laboratory, Pune 411008 (India); Joseph, Joseph M. [Inter University Centre for Nanomaterials and Devices, Cochin University of Science & Technology, Cochin 682022, Kerala (India); Kuthirummal, Narayanan, E-mail: kuthirummaln@cofc.edu [Department of Physics and Astronomy, College of Charleston, Charleston, SC 29424 (United States); Thachil, Eby T., E-mail: ethachil@gmail.com [Department of Polymer Science & Rubber Technology, Cochin University of Science & Technology, Cochin, 682022, Kerala (India)

    2015-10-15

    Highlights: • Fe{sub 3}O{sub 4} nanoparticles (∼20 nm) were synthesised by co-precipitation method. • Nanoparticles were homogeneously distributed in natural rubber through latex stage processing. • Mechanical properties and magnetic properties of composites improved with loading Fe{sub 3}O{sub 4} nanoparticles. • Imaginary part of permeability increases with nanoparticle loading improving the microwave absorption characteristics. • Infrared spectra reveal strong interaction between NR and iron oxide nanoparticles. - Abstract: Magnetic Fe{sub 3}O{sub 4} nanoparticles (∼20 nm) were synthesized using the chemical co-precipitation method with a view of developing flexible and easily processable ferromagnetic materials with high mouldability to be used as microwave absorbers. The nanoparticles prepared were incorporated into natural rubber through latex stage processing. This novel processing method gives better dispersion of particles in the rubber matrix. The composites were characterized using XRD, SEM, vibrating sample magnetometer, dynamic mechanical analyzer, cavity perturbation, thermogravimetry (TGA), and Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). A notable improvement in the mechanical properties of composites was observed upon adding Fe{sub 3}O{sub 4} particles. Magnetic and microwave characteristics of the composites indicate the formation of a flexible ferromagnetic material with good microwave absorption characteristics.

  19. Magnetic excitations in ferromagnetic phase of MnP

    International Nuclear Information System (INIS)

    Yano, Shin-ichiro; Itoh, Shinichi; Yokoo, Tetsuya; Satoh, Setsuo; Kawana, Daichi; Kousaka, Yusuke; Akimitsu, Jun; Endoh, Yasuo

    2013-01-01

    Inelastic neutron scattering experiments were performed on an intermetallic compound, MnP. We used a newly developed High Resolution Chopper Spectrometer, HRC, for energy transfers E≤75meV, besides various triple axis spectrometers; LTAS for energy transfers E≤2meV, TOPAN for E≤7.5meV and TAS-1 for E≤35meV. Spin wave excitations were observed in the ferromagnetic phase of MnP in the entire Brillouin zone along the a ⁎ - and b ⁎ -axes. The zone boundary energies of spin waves were determined to be around 60 meV along the a ⁎ -axis and around 75 meV along the b ⁎ -axis, and the dispersion relations showed two branches for both axes. The observed dispersion relations of spin waves were well described by an isotropic Heisenberg interaction adding a single ion anisotropy with two sub-lattices. - Highlights: • Inelastic neutron scattering experiments were performed mainly using pulsed neutrons. • Spin waves were observed in the ferromagnetic phase of an intermetallic compound MnP. • The dispersion relations were determined entirely along the a ⁎ - and b ⁎ -axes. • We could describe the observed dispersion relations by a two sub-lattice model

  20. Phase diagrams of site diluted ferromagnetic thin film

    International Nuclear Information System (INIS)

    Hamedoun, M.; Bouslykhane, K.; Bakrim, H.; Hourmatallah, A.; Benzakour, N.; Masrour, R.

    2006-01-01

    The phase transition properties of Ising, classical XY and Heisenberg of diluted ferromagnetic thin film are studied by the method of exact high-temperature series expansions extrapolated with the Pade approximants method. The reduced critical temperature τ c of the diluted ferromagnetic thin films is studied as a function of film thickness L and the exchange interactions in the bulk J b , in the surface J s and between surface and nearest-neighbour layer J - bar . It is found that τ c increases with the exchange interactions of surface and L. The magnetic phase diagram (τ c versus dilution x) is obtained. A critical value of the surface exchange interaction above which the surface magnetism appears is obtained. The dependence of the critical parameter of surface reduced coupling R 2 c as a function of the dilution x and the ratio of the exchange interaction between the surface and nearest-neighbour layer to the bulk one R 1 for the three studied models has been investigated. The percolation threshold is defined as the concentration x p at which τ c =0. The obtained values are x p ∼0.2 in the bulk and x p ∼0.4 at the surface

  1. Spin Funneling for Enhanced Spin Injection into Ferromagnets

    Science.gov (United States)

    Sayed, Shehrin; Diep, Vinh Q.; Camsari, Kerem Yunus; Datta, Supriyo

    2016-07-01

    It is well-established that high spin-orbit coupling (SOC) materials convert a charge current density into a spin current density which can be used to switch a magnet efficiently and there is increasing interest in identifying materials with large spin Hall angle for lower switching current. Using experimentally benchmarked models, we show that composite structures can be designed using existing spin Hall materials such that the effective spin Hall angle is larger by an order of magnitude. The basic idea is to funnel spins from a large area of spin Hall material into a small area of ferromagnet using a normal metal with large spin diffusion length and low resistivity like Cu or Al. We show that this approach is increasingly effective as magnets get smaller. We avoid unwanted charge current shunting by the low resistive NM layer utilizing the newly discovered phenomenon of pure spin conduction in ferromagnetic insulators via magnon diffusion. We provide a spin circuit model for magnon diffusion in FMI that is benchmarked against recent experiments and theory.

  2. Magnetoresistance at artificial interfaces in epitaxial ferromagnetic thin films

    International Nuclear Information System (INIS)

    Fontcuberta, J.; Bibes, M.; Martinez, B.; Trtik, V.; Ferrater, C.; Sanchez, F.; Varela, M.

    2000-01-01

    Epitaxial La 2/3 Sr 1/3 MnO 3 and SrRuO 3 thin films have been grown by laser ablation on single-crystalline SrTiO 3 substrates. Prior to manganite or ruthenate deposition tracks have been patterned on the SrTiO 3 substrate by using an appropriately focused laser beam. In the experiments here reported linear tracks have been formed. The magnetotransport properties of the films, particularly the magnetoresistance, along paths parallel and perpendicular to the track have been extensively investigated and compared to similar data recorded on films grown on bicrystalline STO substrates. Whereas in LSMO a significant low-field tunnel magnetoresistance develops across the artificial interface, in SRO this tunnel contribution is absent. However, a significant high-field magnetoresistance is observed for both metallic and ferromagnetic systems. The results are analysed and discussed within the framework of the current understanding of double exchange and itinerant ferromagnets. Magnetoresistance data for various configurations of the track array are presented

  3. Recruiting and retaining high-quality teachers in rural areas.

    Science.gov (United States)

    Monk, David H

    2007-01-01

    In examining recruitment and retention of teachers in rural areas, David Monk begins by noting the numerous possible characteristics of rural communities--small size, sparse settlement, distance from population concentrations, and an economic reliance on agricultural industries that are increasingly using seasonal and immigrant workers to minimize labor costs. Many, though not all, rural areas, he says, are seriously impoverished. Classes in rural schools are relatively small, and teachers tend to report satisfaction with their work environments and relatively few problems with discipline. But teacher turnover is often high, and hiring can be difficult. Monk observes that rural schools have a below-average share of highly trained teachers. Compensation in rural schools tends to be low, perhaps because of a lower fiscal capacity in rural areas, thus complicating efforts to attract and retain teachers. Several student characteristics, including relatively large shares of students with special needs and with limited English skills and lower shares of students attending college, can also make it difficult to recruit and retain high-quality teachers. Other challenges include meeting the needs of highly mobile children of low-income migrant farm workers. With respect to public policy, Monk asserts a need to focus on a subcategory of what might be called hard-to-staff rural schools rather than to develop a blanket set of policies for all rural schools. In particular, he recommends a focus on such indicators as low teacher qualifications, teaching in fields far removed from the area of training, difficulty in hiring, high turnover, a lack of diversity among teachers in the school, and the presence of migrant farm workers' children. Successful efforts to stimulate economic growth in these areas would be highly beneficial. He also calls attention to the potential for modern telecommunication and computing technologies to offset some of the drawbacks associated with teaching

  4. An electromagnetically actuated fiber optic switch using magnetized ferromagnetic materials

    Science.gov (United States)

    Pandojirao-S, Praveen; Dhaubanjar, Naresh; Phuyal, Pratibha C.; Chiao, Mu; Chiao, J.-C.

    2008-03-01

    This paper presents the design, fabrication and testing of a fiber optic switch actuated electromagnetically. The ferromagnetic gel coated optical fiber is actuated using external electromagnetic fields. The ferromagnetic gel consists of ferromagnetic powders dispersed in epoxy. The fabrication utilizes a simple cost-effective coating setup. A direct fiberto-fiber alignment eliminates the need for complementary optical parts and the displacement of fiber switches the laser coupling. The magnetic characteristics of magnetized ferromagnetic materials are performed using alternating gradient magnetometer and the magnetic hysteresis curves are measured for different ferromagnetic materials including iron, cobalt, and nickel. Optical fiber switches with various fiber lengths are actuated and their static and dynamic responses for the same volume of ferromagnetic gel are summarized. The highest displacement is 1.345 mm with an input current of 260mA. In this paper, the performance of fiber switches with various coating materials is presented.

  5. Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Remes, Zdenek [Institute of Physics ASCR v.v.i., Cukrovarnicka 10, 162 00 Prague 6 (Czech Republic); Sun, Shih-Jye, E-mail: sjs@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Varga, Marian [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Chou, Hsiung [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hsu, Hua-Shu [Department of Applied Physics, National Pingtung University of Education, Pingtung 900, Taiwan (China); Kromka, Alexander [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Horak, Pavel [Nuclear Physics Institute, 250 68 Rez (Czech Republic)

    2015-11-15

    The nanocrystalline diamond films turn to be ferromagnetic after implanting various nitrogen doses on them. Through this research, we confirm that the room-temperature ferromagnetism of the implanted samples is derived from the measurements of magnetic circular dichroism (MCD) and superconducting quantum interference device (SQUID). Samples with larger crystalline grains as well as higher implanted doses present more robust ferromagnetic signals at room temperature. Raman spectra indicate that the small grain-sized samples are much more disordered than the large grain-sized ones. We propose that a slightly large saturated ferromagnetism could be observed at low temperature, because the increased localization effects have a significant impact on more disordered structure. - Highlights: • Nitrogen implanted nanocrystalline diamond films exhibit ferromagnetism at room temperature. • Nitrogen implants made a Raman deviation from the typical nanocrystalline diamond films. • The ferromagnetism induced from the structure distortion is dominant at low temperature.

  6. Routine quality control of high dose rate brachytherapy equipment

    International Nuclear Information System (INIS)

    Guzman Calcina, Carmen S.; Almeida, Adelaide de; Rocha, Jose R. Oliveira

    2001-01-01

    A Quality Assurance program should be installed also for High Dose Rate brachytherapy, in the order to achieve a correct dose administration to the patient and for the safety to those involved directly with the treatment. The work presented here has the following purposes: Analyze the types of equipment tests presented by the official protocols (TG40, TG56 e ARCAL XXX), evaluate the brachytherapy routine tests of protocols from various national and international radiotherapy services and compare the latter with those presented in the official protocols. As a result, we conclude the following: TG56 presents a higher number of tests when compared to the other official protocols and most of the tests presented by the analyzed services are present in TG56. A suggestion for a basic protocol is presented, emphasizing the periodicity and tolerance level of each of the tests. (author)

  7. High quality diesel fuels by VO-LSGO hydrotreatment

    Energy Technology Data Exchange (ETDEWEB)

    Stanica-Ezeanu, Dorin; Juganaru, Traian [Petroleum and Gas Univ. of Ploiesti (Romania)

    2013-06-01

    The aim of the paper is to obtain a high quality Diesel fuel by hydro-deoxigenation of vegetable oils (VO) mixed with a low sulfur gasoil (LSGO). The process is possible by using a bi-functional catalyst Ni-Mo supported by an activated Al{sub 2}O{sub 3} containing 2% Ultrastable Y-zeolite. The experimental conditions were: T =340 - 380 C, Pressure = 50 bar, LHSV = 1,5 h{sup -1}, H{sub 2}/Feed ratio = 15 mole H{sub 2} /mole liquid feed. The liquid product was separated in two fractions: a light distillate (similar to gasoline) and a heavy distillate (boiling point > 200 C) with very good characteristics for Diesel engines. The reaction chemistry is very complex, but the de-oxygenation process is decisive for the chemical structure of hydrocarbons from final product. Finally, a schema for the reaction mechanism is proposed. (orig.)

  8. Supercapacitors based on high-quality graphene scrolls

    Science.gov (United States)

    Zeng, Fanyan; Kuang, Yafei; Liu, Gaoqin; Liu, Rui; Huang, Zhongyuan; Fu, Chaopeng; Zhou, Haihui

    2012-06-01

    High-quality graphene scrolls (GSS) with a unique scrolled topography are designed using a microexplosion method. Their capacitance properties are investigated by cyclic voltammetry, galvanostatic charge-discharge and electrical impedance spectroscopy. Compared with the specific capacity of 110 F g-1 for graphene sheets, a remarkable capacity of 162.2 F g-1 is obtained at the current density of 1.0 A g-1 in 6 M KOH aqueous solution owing to the unique scrolled structure of GSS. The capacity value is increased by about 50% only because of the topological change of graphene sheets. Meanwhile, GSS exhibit excellent long-term cycling stability along with 96.8% retained after 1000 cycles at 1.0 A g-1. These encouraging results indicate that GSS based on the topological structure of graphene sheets are a kind of promising material for supercapacitors.

  9. A roadmap to high quality chemically prepared graphene

    Energy Technology Data Exchange (ETDEWEB)

    Gengler, Regis Y N; Spyrou, Konstantinos; Rudolf, Petra, E-mail: r.gengler@rug.n, E-mail: p.rudolf@rug.n [Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG Groningen (Netherlands)

    2010-09-22

    Graphene was discovered half a decade ago and proved the existence of a two-dimensional system which becomes stable as a result of 3D corrugation. It appeared very quickly that this exceptional material had truly outstanding electronic, mechanical, thermal and optical properties. Consequently a broad range of applications appeared, as the graphene science speedily moved forward. Since then, a lot of effort has been devoted not only to the study of graphene but also to its fabrication. Here we review the chemical approaches to graphene production, their advantages as well as their downsides. Our aim is to draw a roadmap of today's most reliable path to high quality graphene via chemical preparation.

  10. High quality factor HTS Josephson junctions on low loss substrates

    Energy Technology Data Exchange (ETDEWEB)

    Stornaiuolo, D; Longobardi, L; Massarotti, D; Barone, A; Tafuri, F [CNR-SPIN Napoli, Complesso Universitario di Monte Sant' Angelo, via Cinthia, 80126 Napoli (Italy); Papari, G; Carillo, F [NEST, CNR-NANO and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa (Italy); Cennamo, N [Dipartimento Ingegneria dell' Informazione, Seconda Universita degli Studi di Napoli, via Roma 29, 81031 Aversa (Italy)

    2011-04-15

    We have extended the off-axis biepitaxial technique to produce YBCO grain boundary junctions on low loss substrates. Excellent transport properties have been reproducibly found, with remarkable values of the quality factor I{sub c}R{sub n} (with I{sub c} the critical current and R{sub n} the normal state resistance) above 10 mV, far higher than the values commonly reported in the literature for high temperature superconductor (HTS) based Josephson junctions. The outcomes are consistent with a picture of a more uniform grain boundary region along the current path. This work supports a possible implementation of grain boundary junctions for various applications including terahertz sensors and HTS quantum circuits in the presence of microwaves.

  11. A roadmap to high quality chemically prepared graphene

    International Nuclear Information System (INIS)

    Gengler, Regis Y N; Spyrou, Konstantinos; Rudolf, Petra

    2010-01-01

    Graphene was discovered half a decade ago and proved the existence of a two-dimensional system which becomes stable as a result of 3D corrugation. It appeared very quickly that this exceptional material had truly outstanding electronic, mechanical, thermal and optical properties. Consequently a broad range of applications appeared, as the graphene science speedily moved forward. Since then, a lot of effort has been devoted not only to the study of graphene but also to its fabrication. Here we review the chemical approaches to graphene production, their advantages as well as their downsides. Our aim is to draw a roadmap of today's most reliable path to high quality graphene via chemical preparation.

  12. CHOREOGRAPHIC METHODS FOR CREATING NOVEL, HIGH QUALITY DANCE

    Directory of Open Access Journals (Sweden)

    David Kirsh

    2016-02-01

    Full Text Available We undertook a detailed ethnographic study of the dance creation process of a noted choreographer and his distinguished troupe. All choreographer dancer interactions were videoed, the choreographer and dancers were interviewed extensively each day, as well as other observations and tests performed. The choreographer used three main methods to produce high quality and novel content: showing, making-on, and tasking. We present, analyze and evaluate these methods, and show how these approaches allow the choreographer to increase the creative output of the dancers and him. His methods, although designed for dance, apply more generally to other creative endeavors, especially where brainstorming is involved, and where the creative process is distributed over many individuals. His approach is also a case study in multi-modal direction, owing to the range of mechanisms he uses to communicate and direct.

  13. Biotransformation of Organic Waste into High Quality Fertilizer

    DEFF Research Database (Denmark)

    Bryndum, Sofie

    Agriculture faces several challenges of future provision of nutrients such as limited P reserves and increasing prices of synthetic fertilizers and recycling of nutrients from organic waste can be an important strategy for the long-term sustainability of the agricultural systems. Organically...... and S, is often low; and (3) the unbalanced composition of nutrients rarely matches crop demands. Therefore the objective of this project was to investigate the potential for (1) recycling nutrients from agro-industrial wastes and (2) compost biotransformation into high-quality organic fertilizers...... other uses into fertilizer use would be unlikely. An estimated ~50 % of the total organic waste pool, primarily consisting of animal manure and waste from the processing of sugar cane, coffee, oil palm and oranges, is currently being re-used as “fertilizers”, meaning it is eventually returned...

  14. Tunnel barrier and noncollinear magnetization effects on shot noise in ferromagnetic/semiconductor/ferromagnetic heterojunctions

    International Nuclear Information System (INIS)

    An Xingtao; Liu Jianjun

    2008-01-01

    Based on the scattering approach, we investigate transport properties of electrons in a one-dimensional waveguide that contains a ferromagnetic/semiconductor/ferromagnetic heterojunction and tunnel barriers in the presence of Rashba and Dresselhaus spin-orbit interactions. We simultaneously consider significant quantum size effects, quantum coherence, Rashba and Dresselhaus spin-orbit interactions and noncollinear magnetizations. It is found that the tunnel barrier plays a decisive role in the transmission coefficient and shot noise of the ballistic spin electron transport through the heterojunction. When the small tunnel barriers are considered, the transport properties of electrons are quite different from those without tunnel barriers

  15. Nonlinear nano-scale localized breather modes in a discrete weak ferromagnetic spin lattice

    International Nuclear Information System (INIS)

    Kavitha, L.; Parasuraman, E.; Gopi, D.; Prabhu, A.; Vicencio, Rodrigo A.

    2016-01-01

    We investigate the propagation dynamics of highly localized discrete breather modes in a weak ferromagnetic spin lattice with on-site easy axis anisotropy due to crystal field effect. We derive the discrete nonlinear equation of motion by employing boson mappings and p-representation. We explore the onset of modulational instability both analytically in the framework of linear stability analysis and numerically by means of molecular dynamics (MD) simulations, and a perfect agreement was demonstrated. It is also explored that how the antisymmetric nature of the canted ferromagnetic lattice supports highly localized discrete breather (DBs) modes as shown in the stability/instability windows. The energy exchange between low amplitude discrete breathers favours the growth of higher amplitude DBs, resulting eventually in the formation of few long-lived high amplitude DBs. - Highlights: • The effects of DM and anisotropy interaction on the DB modes are studied. • The antisymmetric nature of the canted ferromagnetic medium supports the DB modes. • Dynamics of ferromagnetic chain is governed by boson mappings and p-representation.

  16. Modelling characteristics of ferromagnetic cores with the influence of temperature

    International Nuclear Information System (INIS)

    Górecki, K; Rogalska, M; Zarȩbski, J; Detka, K

    2014-01-01

    The paper is devoted to modelling characteristics of ferromagnetic cores with the use of SPICE software. Some disadvantages of the selected literature models of such cores are discussed. A modified model of ferromagnetic cores taking into account the influence of temperature on the magnetizing characteristics and the core losses is proposed. The form of the elaborated model is presented and discussed. The correctness of this model is verified by comparing the calculated and the measured characteristics of the selected ferromagnetic cores.

  17. A method for measuring exchange stiffness in ferromagnetic films

    International Nuclear Information System (INIS)

    Girt, Erol; Huttema, W.; Montoya, E.; Kardasz, B.; Eyrich, C.; Heinrich, B.; Mryasov, O. N.; Dobin, A. Yu.; Karis, O.

    2011-01-01

    An exchange stiffness, A ex , in ferromagnetic films is obtained by fitting the M(H) dependence of two ferromagnetic layers antiferromagnetically coupled across a nonmagnetic spacer layer with a simple micromagnetic model. In epitaxial and textured structures this method allows measuring A ex between the crystallographic planes perpendicular to the growth direction of ferromagnetic films. Our results show that A ex between [0001] planes in textured Co grains is 1.54 ± 0.12 x 10 -11 J/m.

  18. Ferromagnetic bond of Li{sub 10} cluster: An alternative approach in terms of effective ferromagnetic sites

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, Roberto; Fuentealba, Patricio, E-mail: pfuentea@hotmail.es, E-mail: cardena@macul.ciencias.uchile.cl; Cárdenas, Carlos, E-mail: pfuentea@hotmail.es, E-mail: cardena@macul.ciencias.uchile.cl [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Avda. Ecuador 3493, Santiago 9170124 (Chile); Rössler, Jaime [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Llano-Gil, Sandra [Faculty of Engineering, Food Engineering Program, Corporación Universitaria Lasallista, Caldas, Antioquia (Colombia)

    2016-09-07

    In this work, a model to explain the unusual stability of atomic lithium clusters in their highest spin multiplicity is presented and used to describe the ferromagnetic bonding of high-spin Li{sub 10} and Li{sub 8} clusters. The model associates the (lack of-)fitness of Heisenberg Hamiltonian with the degree of (de-)localization of the valence electrons in the cluster. It is shown that a regular Heisenberg Hamiltonian with four coupling constants cannot fully explain the energy of the different spin states. However, a more simple model in which electrons are located not at the position of the nuclei but at the position of the attractors of the electron localization function succeeds in explaining the energy spectrum and, at the same time, explains the ferromagnetic bond found by Shaik using arguments of valence bond theory. In this way, two different points of view, one more often used in physics, the Heisenberg model, and the other in chemistry, valence bond, come to the same answer to explain those atypical bonds.

  19. Room temperature ferromagnetism in ZnO prepared by microemulsion

    Directory of Open Access Journals (Sweden)

    Qingyu Xu

    2011-09-01

    Full Text Available Clear room temperature ferromagnetism has been observed in ZnO powders prepared by microemulsion. The O vacancy (VO clusters mediated by the VO with one electron (F center contributed to the ferromagnetism, while the isolated F centers contributed to the low temperature paramagnetism. Annealing in H2 incorporated interstitial H (Hi in ZnO, and removed the isolated F centers, leading to the suppression of the paramagnetism. The ferromagnetism has been considered to originate from the VO clusters mediated by the Hi, leading to the enhancement of the coercivity. The ferromagnetism disappeared after annealing in air due to the reduction of Hi.

  20. Ferromagnetic pairing states on two-coupled chains

    International Nuclear Information System (INIS)

    Tanaka, Akinori

    2008-01-01

    We propose a concrete model which exhibits ferromagnetism and electron-pair condensation simultaneously. The model is defined on two chains and consists of the electron hopping term, the on-site Coulomb repulsion and a ferromagnetic interaction which describes ferromagnetic coupling between two electrons, one on a bond in a chain and the other on a site in the other chain. It is rigorously shown that the model has fully-polarized ferromagnetic pairing ground states. The higher dimensional version of the model is also presented

  1. Optimal thermoeconomic performance of an irreversible regenerative ferromagnetic Ericsson refrigeration cycle

    International Nuclear Information System (INIS)

    Xu, Zhichao; Guo, Juncheng; Lin, Guoxing; Chen, Jincan

    2016-01-01

    On the basis of the Langevin theory of classical statistical mechanics, the magnetization, entropy, and iso-field heat capacity of ferromagnetic materials are analyzed and their mathematical expressions are derived. An irreversible regenerative Ericsson refrigeration cycle by using a ferromagnetic material as the working substance is established, in which finite heat capacity rates of low and high temperature reservoirs, non-perfect regenerative heat of the refrigeration cycle, additional regenerative heat loss, etc. are taken into account. Based on the regenerative refrigeration cycle model, a thermoeconomic function is introduced as one objective function and optimized with respect to the temperatures of the working substance in the two iso-thermal processes. By means of numerical calculation, the effects of the effective factor of the heat exchangers in high/low temperature reservoir sides, efficiency of the regenerator, heat capacity rate of the low temperature reservoir, and applied magnetic field on the optimal thermoeconomic function as well as the corresponding cooling rate and coefficient of performance are revealed. The results obtained in this paper can provide some theoretical guidance for the optimal design of actual regenerative magnetic refrigerator cycle. - Highlights: • Thermodynamic performance of ferromagnetic material is analyzed. • An irreversible regenerative ferromagnetic Ericsson refrigeration cycle is set up. • The thermoeconomic objective function is introduced and optimized. • Impacts of the thermoeconomic and other parameters are discussed.

  2. Peculiar ferromagnetic insulator state in the low-hole-doped manganites

    International Nuclear Information System (INIS)

    Algarabel, P.A.; Teresa, J.M. de; Blasco, J.; Ibarra, M.R.; Kapusta, Cz.; Sikora, M.; Zajac, D.; Riedi, P.C.; Ritter, C.

    2003-01-01

    In this work we show the very different nature of the ferromagnetic state of the low-hole-doped manganites with respect to other manganites showing colossal magnetoresistance. High-field measurements definitively prove the coexistence of ferromagnetic-metallic and ferromagnetic-insulating regions even when the sample is magnetically saturated, with the ground state being inhomogeneous. We have investigated La 0.9 Ca 0.1 MnO 3 as a prototype compound. A wide characterization by means of magnetic and magnetotransport measurements, neutron diffraction, small-angle neutron scattering, and nuclear magnetic resonance has allowed us to establish that the ground state is based on the existence of disordered nanometric double-exchange metallic clusters that coexist with long-range superexchange-based ferromagnetic insulating regions. Under high magnetic field the system reaches magnetization saturation by aligning the magnetic clusters and the insulating matrix, but even if they grow in size, they do not reach the percolation limit

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

    Science.gov (United States)

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

    2009-04-01

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

  4. High quality protein microarray using in situ protein purification

    Directory of Open Access Journals (Sweden)

    Fleischmann Robert D

    2009-08-01

    Full Text Available Abstract Background In the postgenomic era, high throughput protein expression and protein microarray technologies have progressed markedly permitting screening of therapeutic reagents and discovery of novel protein functions. Hexa-histidine is one of the most commonly used fusion tags for protein expression due to its small size and convenient purification via immobilized metal ion affinity chromatography (IMAC. This purification process has been adapted to the protein microarray format, but the quality of in situ His-tagged protein purification on slides has not been systematically evaluated. We established methods to determine the level of purification of such proteins on metal chelate-modified slide surfaces. Optimized in situ purification of His-tagged recombinant proteins has the potential to become the new gold standard for cost-effective generation of high-quality and high-density protein microarrays. Results Two slide surfaces were examined, chelated Cu2+ slides suspended on a polyethylene glycol (PEG coating and chelated Ni2+ slides immobilized on a support without PEG coating. Using PEG-coated chelated Cu2+ slides, consistently higher purities of recombinant proteins were measured. An optimized wash buffer (PBST composed of 10 mM phosphate buffer, 2.7 mM KCl, 140 mM NaCl and 0.05% Tween 20, pH 7.4, further improved protein purity levels. Using Escherichia coli cell lysates expressing 90 recombinant Streptococcus pneumoniae proteins, 73 proteins were successfully immobilized, and 66 proteins were in situ purified with greater than 90% purity. We identified several antigens among the in situ-purified proteins via assays with anti-S. pneumoniae rabbit antibodies and a human patient antiserum, as a demonstration project of large scale microarray-based immunoproteomics profiling. The methodology is compatible with higher throughput formats of in vivo protein expression, eliminates the need for resin-based purification and circumvents

  5. The structure of high-quality aluminium cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2012-01-01

    Full Text Available In this study presents the analyse of aluminium iron cast structure (as-cast condition which are used in high temperature. While producing the casts of aluminium iron major influence has been preserve the structure of technological process parameters. The addition to Fe-C-Al alloy V, Ti, Cr leads to the improvement of functional and mechanical cast qualities. In this study, a method was investigated to eliminate the presence of undesirable Al4C3 phases in a aluminium cast iron structure and thus improve the production process. V and Ti additions in aluminium cast iron allows to development of FeAl - VC or TiC alloys. In particular, V or Ti contents above 5 wt.% were found to totally eliminate the presence of Al4C3. In addition, preliminary work indicates that the alloy with the FeAl - VC or TiC structure reveals high oxidation resistance. The introduction of 5 wt.% chromium to aluminium cast iron strengthened Al4C3 precipitate. Thus, the resultant alloy can be considered an intermetallic FeAl matrix strengthened by VC and TiC or modified Al4C3 reinforcements.

  6. High-Quality Seismic Observations of Sonic Booms

    Science.gov (United States)

    Wurman, Gilead; Haering, Edward A., Jr.; Price, Michael J.

    2011-01-01

    The SonicBREWS project (Sonic Boom Resistant Earthquake Warning Systems) is a collaborative effort between Seismic Warning Systems, Inc. and NASA Dryden Flight Research Center. This project aims to evaluate the effects of sonic booms on Earthquake Warning Systems in order to prevent such systems from experiencing false alarms due to sonic booms. The airspace above the Antelope Valley, California includes the High Altitude Supersonic Corridor and the Black Mountain Supersonic Corridor. These corridors are among the few places in the US where supersonic flight is permitted, and sonic booms are commonplace in the Antelope Valley. One result of this project is a rich dataset of high-quality accelerometer records of sonic booms which can shed light on the interaction between these atmospheric phenomena and the solid earth. Nearly 100 sonic booms were recorded with low-noise triaxial MEMS accelerometers recording 1000 samples per second. The sonic booms had peak overpressures ranging up to approximately 10 psf and were recorded in three flight series in 2010 and 2011. Each boom was recorded with up to four accelerometers in various array configurations up to 100 meter baseline lengths, both in the built environment and the free field. All sonic booms were also recorded by nearby microphones. We present the results of the project in terms of the potential for sonic-boom-induced false alarms in Earthquake Warning Systems, and highlight some of the interesting features of the dataset.

  7. High-quality remote interactive imaging in the operating theatre

    Science.gov (United States)

    Grimstead, Ian J.; Avis, Nick J.; Evans, Peter L.; Bocca, Alan

    2009-02-01

    We present a high-quality display system that enables the remote access within an operating theatre of high-end medical imaging and surgical planning software. Currently, surgeons often use printouts from such software for reference during surgery; our system enables surgeons to access and review patient data in a sterile environment, viewing real-time renderings of MRI & CT data as required. Once calibrated, our system displays shades of grey in Operating Room lighting conditions (removing any gamma correction artefacts). Our system does not require any expensive display hardware, is unobtrusive to the remote workstation and works with any application without requiring additional software licenses. To extend the native 256 levels of grey supported by a standard LCD monitor, we have used the concept of "PseudoGrey" where slightly off-white shades of grey are used to extend the intensity range from 256 to 1,785 shades of grey. Remote access is facilitated by a customized version of UltraVNC, which corrects remote shades of grey for display in the Operating Room. The system is successfully deployed at Morriston Hospital, Swansea, UK, and is in daily use during Maxillofacial surgery. More formal user trials and quantitative assessments are being planned for the future.

  8. Blueprint for action: steps toward a high-quality, high-value maternity care system.

    Science.gov (United States)

    Angood, Peter B; Armstrong, Elizabeth Mitchell; Ashton, Diane; Burstin, Helen; Corry, Maureen P; Delbanco, Suzanne F; Fildes, Barbara; Fox, Daniel M; Gluck, Paul A; Gullo, Sue Leavitt; Howes, Joanne; Jolivet, R Rima; Laube, Douglas W; Lynne, Donna; Main, Elliott; Markus, Anne Rossier; Mayberry, Linda; Mitchell, Lynn V; Ness, Debra L; Nuzum, Rachel; Quinlan, Jeffrey D; Sakala, Carol; Salganicoff, Alina

    2010-01-01

    Childbirth Connection hosted a 90th Anniversary national policy symposium, Transforming Maternity Care: A High Value Proposition, on April 3, 2009, in Washington, DC. Over 100 leaders from across the range of stakeholder perspectives were actively engaged in the symposium work to improve the quality and value of U.S. maternity care through broad system improvement. A multi-disciplinary symposium steering committee guided the strategy from its inception and contributed to every phase of the project. The "Blueprint for Action: Steps Toward a High Quality, High Value Maternity Care System", issued by the Transforming Maternity Care Symposium Steering Committee, answers the fundamental question, "Who needs to do what, to, for, and with whom to improve the quality of maternity care over the next five years?" Five stakeholder workgroups collaborated to propose actionable strategies in 11 critical focus areas for moving expeditiously toward the realization of the long term "2020 Vision for a High Quality, High Value Maternity Care System", also published in this issue. Following the symposium these workgroup reports and recommendations were synthesized into the current blueprint. For each critical focus area, the "Blueprint for Action" presents a brief problem statement, a set of system goals for improvement in that area, and major recommendations with proposed action steps to achieve them. This process created a clear sightline to action that if enacted could improve the structure, process, experiences of care, and outcomes of the maternity care system in ways that when anchored in the culture can indeed transform maternity care. Copyright 2010 Jacobs Institute of Women

  9. Stress and sleep quality in high school brazilian adolescents

    Directory of Open Access Journals (Sweden)

    Gema Mesquita

    2010-06-01

    Full Text Available OBJECTIVE: The objective of the present study is to analyze the effect of stress on sleep quality in a group of adolescents. METHOD: Two high schools in Alfenas, southern Minas Gerais State, Brazil, were chosen to participate in the study. The sample consisted of both genders (n=160 with 65.63% females. The age range of participants was 15 to18 years. The Pittsburgh Sleep Quality Index (PSQI was applied for collection of data to quantify sleep quality. The Lipp Inventory of Stress Symptoms that objectively identifies symptoms of stress was applied. RESULTS: It was observed that 23.53% of stressed students and 45.33% of unstressed ones sleep well; 76.47% of stressed pupils and 54.67% of those unstressed do not sleep well. With regard to school performance, a mean of 0.65 was found for stressed students and 0.60 for those without stress, Mann-Whitney (p=0.0596. CONCLUSION: Stress contributed to raising the percentage of poor sleepers, as ell as increasing ean school performance.OBJETIVO: O objetivo do presente estudo foi analisar a influência do stress sobre a qualidade do sono em um grupo de adolescentes. MÉTODO: Foram escolhidas duas instituições educacionais do ensino médio, na cidade de Alfenas, sul de Minas Gerais, Brasil. A amostra foi composta por ambos os sexos (n=160, com 65,63% do sexo feminino. A faixa etária dos participantes foi de 15 a 18 anos. Para a coleta de dados aplicou-se: Índice de Qualidade de Sono de Pittsburgh (IQSP utilizado para quantificar a qualidade do sono; o Inventário de Sintomas de Stress para Adultos de Lipp (ISSL que identifica de modo objetivo a sintomatologia de stress foi aplicado. RESULTADOS: Observou-se que 23,53% dos estressados dormem bem e 45,33% dos não estressados dormem bem; 76,47% dos estressados não dormem bem e 54,67% dos não estressados não dormem bem. Quanto ao rendimento escolar têm-se as médias 0,65 para os alunos estressados e 0,60 para aqueles que não sofrem de stress, Mann

  10. Ferromagnetic resonance in gigahertz magneto-impedance of multilayer systems

    International Nuclear Information System (INIS)

    Cos, D. de; Garcia-Arribas, A.; Barandiaran, J.M.

    2006-01-01

    The effect of ferromagnetic resonance (FMR) on magneto-impedance (MI) of multilayer thin films is investigated. We present impedance measurements of an insulated multilayer film as a function of the applied magnetic field both in the plane of the sample and perpendicular to it, for frequencies from 300 kHz to 3 GHz. These measurements have been made using RF techniques, and the data have been treated using high-frequency models in order to minimize the contribution to the impedance of the test fixture. The results confirm that the FMR dominates the MI behavior at high frequency, allowing to reach higher MI ratios than those achieved at the quasistatic regime. However, the broad resonance lines cause a considerable drop of the sensitivity of the curves, and therefore the optimum operation frequency of GMI devices lays in the sub-GHz range

  11. High-quality endoscope reprocessing decreases endoscope contamination.

    Science.gov (United States)

    Decristoforo, P; Kaltseis, J; Fritz, A; Edlinger, M; Posch, W; Wilflingseder, D; Lass-Flörl, C; Orth-Höller, D

    2018-02-24

    Several outbreaks of severe infections due to contamination of gastrointestinal (GI) endoscopes, mainly duodenoscopes, have been described. The rate of microbial endoscope contamination varies dramatically in literature. The aim of this multicentre prospective study was to evaluate the hygiene quality of endoscopes and automated endoscope reprocessors (AERs) in Tyrol/Austria. In 2015 and 2016, a total of 463 GI endoscopes and 105 AERs from 29 endoscopy centres were analysed by a routine (R) and a combined routine and advanced (CRA) sampling procedure and investigated for microbial contamination by culture-based and molecular-based analyses. The contamination rate of GI endoscopes was 1.3%-4.6% according to the national guideline, suggesting that 1.3-4.6 patients out of 100 could have had contacts with hygiene-relevant microorganisms through an endoscopic intervention. Comparison of R and CRA sampling showed 1.8% of R versus 4.6% of CRA failing the acceptance criteria in phase I and 1.3% of R versus 3.0% of CRA samples failing in phase II. The most commonly identified indicator organism was Pseudomonas spp., mainly Pseudomonas oleovorans. None of the tested viruses were detected in 40 samples. While AERs in phase I failed (n = 9, 17.6%) mainly due to technical faults, phase II revealed lapses (n = 6, 11.5%) only on account of microbial contamination of the last rinsing water, mainly with Pseudomonas spp. In the present study the contamination rate of endoscopes was low compared with results from other European countries, possibly due to the high quality of endoscope reprocessing, drying and storage. Copyright © 2018 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  12. 76 FR 45397 - Export Inspection and Weighing Waiver for High Quality Specialty Grain Transported in Containers

    Science.gov (United States)

    2011-07-29

    ...-AB18 Export Inspection and Weighing Waiver for High Quality Specialty Grain Transported in Containers... permanent a waiver due to expire on July 31, 2012, for high quality specialty grain exported in containers... of high quality specialty grain exported in containers are small entities that up until recently...

  13. Coexistence of short- and long-range ferromagnetic order in nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) synthesized by high-energy ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Thanh, Tran Dang, E-mail: thanhxraylab@yahoo.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam); Nanto, Dwi [Physics Education, Syarif Hidayatullah States Islamic University, Jakarta 15412 (Indonesia); Tuyen, Ngo Thi Uyen [Department of Natural Science, Nha Trang Pedagogic College, Nguyen Chanh, Nha Trang, Khanh Hoa (Viet Nam); Nan, Wen-Zhe [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Yu, YiKyung [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Tartakovsky, Daniel M., E-mail: dmt@ucsd.edu [Department of Mechanical and Aerospace Engineering, University of California, San Diego, CA 92093-0411 (United States); Yu, S.C., E-mail: scyu@cbnu.ac.kr [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi (Viet Nam)

    2015-11-15

    In this work, we prepared nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al (x=0.0, 0.1 and 0.3) powders by the high energy ball milling technique, and then studied their critical properties. Our analysis reveals that the increase of Cu-doping concentration (up to x=0.3) in these powders leads to a gradual increase of the ferromagnetic–paramagnetic transition temperature from 406 to 452 K. The Banerjee criterion suggests that all the samples considered undergo a second-order phase transition. A modified Arrott plot and scaling analysis indicate that the critical exponents (β=0.419 and 0.442, γ=1.082 and 1.116 for x=0.0 and 0.1, respectively) are located in between those expected for the 3D-Heisenberg and the mean-field models; the values of β=0.495 and γ=1.046 for x=0.3 sample are very close to those of the mean-field model. These features reveal the coexistence of the short- and long-range ferromagnetic order in the nanocrystalline Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al powders. Particularly, as the concentration of Cu increases, values of the critical exponent shift towards those of the mean-field model. Such results prove the Cu doping favors establishing a long-range ferromagnetic order. - Highlights: • Fe{sub 2}Mn{sub 1−x}Cu{sub x}Al nanocrystals were prepared by a high energy ball milling method. • A coexistence of the short- and long-range FM order in the nanocrystals. • Cu doping favors establishing a long-range FM order in the nanocrystals. • All the ΔS{sub m}(T, H) data are followed a universal master curve.

  14. Magnetic microstructure of nanocrystalline ferromagnets and nanocrystalline systems combining ferromagnetic and antiferromagnetic phases

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, J.; Wagner, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kostorz, G. [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Wiedenmann, A. [HMI Berlin (Germany)

    1997-09-01

    Magnetic small-angle neutron scattering measurements were performed on nanostructured ferromagnetic materials on the basis of Fe, Ni and Co, produced preferentially by the inert-gas condensation technique, with the aim to determine the magnetic microstructure of mesoscopic small-particle systems. (author) 1 fig., 3 refs.

  15. Competing ferromagnetic and anti-ferromagnetic interactions in iron nitride ζ-Fe2N

    Science.gov (United States)

    Rao, K. Sandeep; Salunke, H. G.

    2018-03-01

    The paper discusses the magnetic state of zeta phase of iron nitride viz. ζ-Fe2N on the basis of spin polarized first principles electronic structure calculations together with a review of already published data. Results of our first principles study suggest that the ground state of ζ-Fe2N is ferromagnetic (FM) with a magnetic moment of 1.528μB on the Fe site. The FM ground state is lower than the anti-ferromagnetic (AFM) state by 8.44 meV and non-magnetic (NM) state by 191 meV per formula unit. These results are important in view of reports which claim that ζ-Fe2N undergoes an AFM transition below 10 K and others which do not observe any magnetic transition up to 4.2 K. We argue that the experimental results of AFM transition below 10 K are inconclusive and we propose the presence of competing FM and AFM superexchange interactions between Fe sites mediated by nitrogen atoms, which are consistent with Goodenough-Kanamori-Anderson rules. We find that the anti-ferromagnetically coupled Fe sites are outnumbered by ferromagnetically coupled Fe sites leading to a stable FM ground state. A Stoner analysis of the results also supports our claim of a FM ground state.

  16. Dynamic detection of spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance (Conference Presentation)

    Science.gov (United States)

    Crowell, Paul A.; Liu, Changjiang; Patel, Sahil; Peterson, Tim; Geppert, Chad C.; Christie, Kevin; Stecklein, Gordon; Palmstrøm, Chris J.

    2016-10-01

    A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this new approach enables a measurement of short spin lifetimes (C. Liu, S. J. Patel, T. A. Peterson, C. C. Geppert, K. D. Christie, C. J. Palmstrøm, and P. A. Crowell, "Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance," Nature Communications 7, 10296 (2016). http://dx.doi.org/10.1038/ncomms10296

  17. Spin Transport in Ferromagnetic and Antiferromagnetic Textures

    KAUST Repository

    Akosa, Collins A.

    2016-12-07

    In this dissertation, we provide an accurate description of spin transport in magnetic textures and in particular, we investigate in detail, the nature of spin torque and magnetic damping in such systems. Indeed, as will be further discussed in this thesis, the current-driven velocity of magnetic textures is related to the ratio between the so-called non-adiabatic torque and magnetic damping. Uncovering the physics underlying these phenomena can lead to the optimal design of magnetic systems with improved efficiency. We identified three interesting classes of systems which have attracted enormous research interest (i) Magnetic textures in systems with broken inversion symmetry: We investigate the nature of magnetic damping in non-centrosymmetric ferromagnets. Based on phenomenological and microscopic derivations, we show that the magnetic damping becomes chiral, i.e. depends on the chirality of the magnetic texture. (ii) Ferromagnetic domain walls, skyrmions and vortices: We address the physics of spin transport in sharp disordered magnetic domain walls and vortex cores. We demonstrate that upon spin-independent scattering, the non-adiabatic torque can be significantly enhanced. Such an enhancement is large for vortex cores compared to transverse domain walls. We also show that the topological spin currents owing in these structures dramatically enhances the non-adiabaticity, an effect unique to non-trivial topological textures (iii) Antiferromagnetic skyrmions: We extend this study to antiferromagnetic skyrmions and show that such an enhanced topological torque also exist in these systems. Even more interestingly, while such a non-adiabatic torque inuences the undesirable transverse velocity of ferromagnetic skyrmions, in antiferromagnetic skyrmions, the topological non-adiabatic torque directly determines the longitudinal velocity. As a consequence, scaling down the antiferromagnetic skyrmion results in a much more efficient spin torque.

  18. The generalized spherical model of ferromagnetic films

    International Nuclear Information System (INIS)

    Costache, G.

    1977-12-01

    The D→ infinity of the D-vectorial model of a ferromagnetic film with free surfaces is exactly solved. The mathematical mechanism responsible for the onset of a phase transition in the system is a generalized sticking phenomenon. It is shown that the temperature at which the sticking appears, the transition temperature of the model is monotonously increasing with increasing the number of layers of the film, contrary to what happens in the spherical model with overall constraint. Certain correlation inequalities of Griffiths type are shown to hold. (author)

  19. Ferromagnetic film on a superconducting substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M{sub 0} on a superconducting (SC) substrate. At 4{pi}M{sub 0}>1; {lambda}{sub L} being the London penetration length.

  20. Ferromagnetic film on a superconducting substrate

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M 0 on a superconducting (SC) substrate. At 4πM 0 c1 the SC is in the Meissner state and the equilibrium domain width in the film, l, scales as (l/4πλ L )=(l N /4πλ L ) 2/3 with the domain width on a normal (nonsuperconducting) substrate, l N /4πλ L >>1; λ L being the London penetration length

  1. Itinerant ferromagnetism in the narrow band limit

    CERN Document Server

    Liu, S H

    2000-01-01

    It is shown that in the narrow band, strong interaction limit the paramagnetic state of an itinerant ferromagnet is described by the disordered local moment state. As a result, the Curie temperature is orders of magnitude lower than what is expected from the large exchange splitting of the spin bands. An approximate analysis has also been carried out for the partially ordered state, and the result explains the temperature evolvement of the magnetic contributions to the resistivity and low-energy optical conductivity of CrO sub 2.

  2. Excitation spectrum of ferromagnetic xxz-chains

    International Nuclear Information System (INIS)

    Schneider, T.; Stoll, E.

    1983-01-01

    In the history of xxz-Heisenberg spin chains, understanding of the dynamic form factors (DFF) is much less advanced. In this paper the DFF of ferromagnetic xxz chains as a tool to probe and interpret excitation spectrum is reviewed. The Isingheisenberg chain, and the Planar-Heisenberg chain (where HF approximations become exact) are studied. The results provide instructive connections between spin systems, interacting fermions and bosons. Various new aspects--thermally induced bound state effects in terms of central peaks in DFF for Isinglike xxz chains; the possibility to observe bound states in S /SUB zz/ (q,w) accessible by neutron scattering techniques, in the planar system--are found

  3. Spin transport in ferromagnetically contacted carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.; Morgan, C.; Schneider, C.M. [Peter Gruenberg Institut, PGI-6, Forschungszentrum Juelich and JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany)

    2011-11-15

    We present magnetoresistance (MR) measurements on carbon nanotubes (CNTs) with different ferromagnetic leads. A sample with permalloy (Ni{sub 80}Fe{sub 20}) contacts shows the expected tunneling-type MR effect. Measurements on devices with CoPd contacts show a larger change of resistance with magnetic field. However, only minor loops are observed, which is explained with domain wall pinning. This is supported by magnetic force microscopy (MFM) measurements, which reveal a complicated bubble and stripe domain pattern. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Long-Run Benefits from Universal High-Quality Preschooling

    DEFF Research Database (Denmark)

    Bauchmüller, Robert; Gørtz, Mette; Rasmussen, Astrid Würtz

    2014-01-01

    This paper investigates the role of preschool quality for children's school performance at the end of primary school. We construct five structural quality indicators based on unique Danish administrative register data. 30,444 children finishing primary school's 9th grade in 2008 and who attended ...... in children's test results in Danish. Boys benefit more from preschool quality than girls. Ethnic minority children benefit from higher staff stability....

  5. Low-quality birds do not display high-quality signals: The cysteine-pheomelanin mechanism of honesty

    Science.gov (United States)

    Galván, Ismael; Wakamatsu, Kazumasa; Camarero, Pablo R; Mateo, Rafael; Alonso-Alvarez, Carlos

    2015-01-01

    The mechanisms that make that the costs of producing high-quality signals are unaffordable to low-quality signalers are a current issue in animal communication. The size of the melanin-based bib of male house sparrows Passer domesticus honestly signals quality. We induced the development of new bibs while treating males with buthionine-sulfoximine (BSO), a substance that depletes the levels of the antioxidant glutathione (GSH) and the amino acid cysteine, two elements that switch melanogenesis from eumelanin to pheomelanin. Final bib size is negatively related to pheomelanin levels in the bib feathers. BSO reduced cysteine and GSH levels in all birds, but improved phenotypes (bibs larger than controls) were only expressed by high-quality birds (BSO birds with largest bibs initially). Negative associations between final bib size and cysteine levels in erythrocytes, and between pheomelanin and cysteine levels, were observed in high-quality birds only. These findings suggest that a mechanism uncoupling pheomelanin and cysteine levels may have evolved in low-quality birds to avoid producing bibs of size not corresponding to their quality and greater relative costs. Indeed, greater oxidative stress in cells was not observed in low-quality birds. This may represent the first mechanism maintaining signal honesty without producing greater relative costs on low-quality signalers. PMID:25330349

  6. Systems and processes that ensure high quality care.

    Science.gov (United States)

    Bassett, Sally; Westmore, Kathryn

    2012-10-01

    This is the second in a series of articles examining the components of good corporate governance. It considers how the structures and processes for quality governance can affect an organisation's ability to be assured about the quality of care. Complex information systems and procedures can lead to poor quality care, but sound structures and processes alone are insufficient to ensure good governance, and behavioural factors play a significant part in making sure that staff are enabled to provide good quality care. The next article in this series looks at how the information reporting of an organisation can affect its governance.

  7. Half-Metallic Ferromagnetism and Stability of Transition Metal Pnictides and Chalcogenides

    Science.gov (United States)

    Liu, Bang-Gui

    It is highly desirable to explore robust half-metallic ferromagnetic materials compatible with important semiconductors for spintronic applications. A state-of-the-art full potential augmented plane wave method within the densityfunctional theory is reliable enough for this purpose. In this chapter we review theoretical research on half-metallic ferromagnetism and structural stability of transition metal pnictides and chalcogenides. We show that some zincblende transition metal pnictides are half-metallic and the half-metallic gap can be fairly wide, which is consistent with experiment. Systematic calculations reveal that zincblende phases of CrTe, CrSe, and VTe are excellent half-metallic ferromagnets. These three materials have wide half-metallic gaps, are low in total energy with respect to the corresponding ground-state phases, and, importantly, are structurally stable. Halfmetallic ferromagnetism is also found in wurtzite transition metal pnictides and chalcogenides and in transition-metal doped semiconductors as well as deformed structures. Some of these half-metallic materials could be grown epitaxially in the form of ultrathin .lms or layers suitable for real spintronic applications.

  8. Prediction of Intrinsic Ferromagnetic Ferroelectricity in a Transition-Metal Halide Monolayer

    Science.gov (United States)

    Huang, Chengxi; Du, Yongping; Wu, Haiping; Xiang, Hongjun; Deng, Kaiming; Kan, Erjun

    2018-04-01

    The realization of multiferroics in nanostructures, combined with a large electric dipole and ferromagnetic ordering, could lead to new applications, such as high-density multistate data storage. Although multiferroics have been broadly studied for decades, ferromagnetic ferroelectricity is rarely explored, especially in two-dimensional (2D) systems. Here we report the discovery of 2D ferromagnetic ferroelectricity in layered transition-metal halide systems. On the basis of first-principles calculations, we reveal that a charged CrBr3 monolayer exhibits in-plane multiferroicity, which is ensured by the combination of orbital and charge ordering as realized by the asymmetric Jahn-Teller distortions of octahedral Cr - Br6 units. As an example, we further show that (CrBr3)2Li is a ferromagnetic ferroelectric multiferroic. The explored phenomena and mechanism of multiferroics in this 2D system not only are useful for fundamental research in multiferroics but also enable a wide range of applications in nanodevices.

  9. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A., E-mail: perumal@iitg.ernet.in [Department of Physics, Indian institute of Technology Guwahati, Guwahati 781 039 (India)

    2015-08-15

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μ{sub B}/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (T{sub C}) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high T{sub C} and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  10. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Directory of Open Access Journals (Sweden)

    Patta Ravikumar

    2015-08-01

    Full Text Available We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μB/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (TC around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high TC and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  11. Characterization of non equilibrium effects on high quality critical flows

    International Nuclear Information System (INIS)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J.

    1995-01-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness

  12. Characterization of non equilibrium effects on high quality critical flows

    Energy Technology Data Exchange (ETDEWEB)

    Camelo, E.; Lemonnier, H.; Ochterbeck, J. [Commissariat a l Energie Atomique, Grenoble (France)] [and others

    1995-09-01

    The appropriate design of various pieces of safety equipment such as relief systems, relies on the accurate description of critical flow phenomena. Most of the systems of industrial interest are willing to be described by one-dimensional area-averaged models and a large fraction of them involves multi-component high gas quality flows. Within these circumstances, the flow is very likely to be of an annular dispersed nature and its description by two-fluid models requires various closure relations. Among the most sensitive closures, there is the interfacial area and the liquid entrained fraction. The critical flowrate depends tremendously on the accurate description of the non equilibrium which results from the correctness of the closure equations. In this study, two-component flows are emphasized and non equilibrium results mainly form the differences in the phase velocities. It is therefore of the utmost importance to have reliable data to characterize non equilibrium phenomena and to assess the validity of the closure models. A comprehensive description of air-water nozzle flows, with emphasis on the effect of the nozzle geometry, has been undertaken and some of the results are presented here which helps understanding the overall flow dynamics. Besides the critical flowrate, the presented material includes pressure profiles, droplet size and velocity, liquid film flowrate and liquid film thickness.

  13. Nonlinear wave propagation through a ferromagnet with damping in ...

    Indian Academy of Sciences (India)

    magnetic waves in a ferromagnet can be reduced to an integro-differential equation. Keywords. Solitons; integro-differential equations; reductive perturbation method. PACS Nos 41.20 Jb; 05.45 Yv; 03.50 De; 78.20 Ls. 1. Introduction. The phenomenon of propagation of electromagnetic waves in ferromagnets are not only.

  14. Levitation properties of maglev systems using soft ferromagnets

    Science.gov (United States)

    Huang, Chen-Guang; Zhou, You-He

    2015-03-01

    Soft ferromagnets are widely used as flux-concentration materials in the design of guideways for superconducting magnetic levitation transport systems. In order to fully understand the influence of soft ferromagnets on the levitation performance, in this work we apply a numerical model based on the functional minimization method and the Bean’s critical state model to study the levitation properties of an infinitely long superconductor immersed in the magnetic field created by a guideway of different sets of infinitely long parallel permanent magnets with soft ferromagnets between them. The levitation force, guidance force, magnetic stiffness and magnetic pole density are calculated considering the coupling between the superconductor and soft ferromagnets. The results show that the levitation performance is closely associated with the permanent magnet configuration and with the location and dimension of the soft ferromagnets. Introducing the soft ferromagnet with a certain width in a few configurations always decreases the levitation force. However, for most configurations, the soft ferromagnets contribute to improve the levitation performance only when they have particular locations and dimensions in which the optimized location and thickness exist to increase the levitation force the most. Moreover, if the superconductor is laterally disturbed, the presence of soft ferromagnets can effectively improve the lateral stability for small lateral displacement and reduce the degradation of levitation force.

  15. Spin Heat Accumulation Induced by Tunneling from a Ferromagnet

    NARCIS (Netherlands)

    Vera-Marun, I.J.; Wees, B.J. van; Jansen, R.

    2014-01-01

    An electric current from a ferromagnet into a nonmagnetic material can induce a spin-dependent electron temperature. Here, it is shown that this spin heat accumulation, when created by tunneling from a ferromagnet, produces a non-negligible voltage signal that is comparable to that due to the

  16. Modelling the power losses in the ferromagnetic materials

    Directory of Open Access Journals (Sweden)

    Detka Kalina

    2017-07-01

    Full Text Available In this paper, the problem of describing power losses in ferromagnetic materials is considered. The limitations of Steinmetz formula are shown and a new analytical description of losses in a considered material is proposed. The correctness of the developed description is demonstrated experimentally by comparing the results of calculation with the catalogue characteristics for different ferromagnetic materials.

  17. Magnetic excitons in singlet-ground-state ferromagnets

    DEFF Research Database (Denmark)

    Birgeneau, R.J.; Als-Nielsen, Jens Aage; Bucher, E.

    1971-01-01

    The authors report measurements of the dispersion of singlet-triplet magnetic excitons as a function of temperature in the singlet-ground-state ferromagnets fcc Pr and Pr3Tl. Well-defined excitons are observed in both the ferromagnetic and paramagnetic regions, but with energies which are nearly...

  18. Image Quality in High-resolution and High-cadence Solar Imaging

    Science.gov (United States)

    Denker, C.; Dineva, E.; Balthasar, H.; Verma, M.; Kuckein, C.; Diercke, A.; González Manrique, S. J.

    2018-03-01

    Broad-band imaging and even imaging with a moderate bandpass (about 1 nm) provides a photon-rich environment, where frame selection (lucky imaging) becomes a helpful tool in image restoration, allowing us to perform a cost-benefit analysis on how to design observing sequences for imaging with high spatial resolution in combination with real-time correction provided by an adaptive optics (AO) system. This study presents high-cadence (160 Hz) G-band and blue continuum image sequences obtained with the High-resolution Fast Imager (HiFI) at the 1.5-meter GREGOR solar telescope, where the speckle-masking technique is used to restore images with nearly diffraction-limited resolution. The HiFI employs two synchronized large-format and high-cadence sCMOS detectors. The median filter gradient similarity (MFGS) image-quality metric is applied, among others, to AO-corrected image sequences of a pore and a small sunspot observed on 2017 June 4 and 5. A small region of interest, which was selected for fast-imaging performance, covered these contrast-rich features and their neighborhood, which were part of Active Region NOAA 12661. Modifications of the MFGS algorithm uncover the field- and structure-dependency of this image-quality metric. However, MFGS still remains a good choice for determining image quality without a priori knowledge, which is an important characteristic when classifying the huge number of high-resolution images contained in data archives. In addition, this investigation demonstrates that a fast cadence and millisecond exposure times are still insufficient to reach the coherence time of daytime seeing. Nonetheless, the analysis shows that data acquisition rates exceeding 50 Hz are required to capture a substantial fraction of the best seeing moments, significantly boosting the performance of post-facto image restoration.

  19. Quality Assurance Roadmap for High Performance Residential Buildings

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-10-05

    This report outlines the approach to quality assurance in the construction process for new residential construction, including seven process steps from the assessment of current construction practice, through design and documentation changes, to training and quality control for on-site personnel.

  20. Paying for High- and Low-Quality Teaching

    Science.gov (United States)

    Schacter, John; Thum, Yeow Meng

    2004-01-01

    The extensive research on teacher quality has led to two conclusions. First, there are large and significant differences among teachers in terms of their capacity to improve student achievement. Second, these differences are not captured by common measures of teacher qualifications (E.A. Hanushek, Teacher quality, in: L.T. Izumi, W.M. Evers…

  1. Some thermodynamical properties of normal (or ferromagnetic) metal / superconductor heterojunctions

    International Nuclear Information System (INIS)

    Cayssol, Jerome

    2003-01-01

    We have investigated the orbital magnetism of a ballistic hybrid normal-superconductor ring. We have obtained the flux dependent excitation spectrum for arbitrary normal and superconductor lengths. We have introduced a new method to evaluate the current harmonics. We have described the cross-over from the, 'h/eh/e-periodic persistent current to the', h/2e-periodic Josephson current. In a second study, we have calculated the effect of intrinsic ordinary reflexion on the Josephson current in a ballistic superconductor-ferromagnetic-superconductor. The spectrum is strongly modified by gap openings but the current and the 0-π transition are only slightly modified up to very high spin polarisation. In a third study, we analyse the contain of some solutions of Usadel equation. The standard perturbation theory dressed by cooperons enables us to interpret those solutions in terms of diffusive paths connecting Andreev reflexion events. (author) [fr

  2. Low frequency terahertz-induced demagnetization in ferromagnetic nickel

    Energy Technology Data Exchange (ETDEWEB)

    Shalaby, Mostafa, E-mail: most.shalaby@gmail.com; Vicario, Carlo, E-mail: carlo.vicario@psi.ch [SwissFEL, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Hauri, Christoph P., E-mail: christoph.hauri@psi.ch [SwissFEL, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); École Polytechnique Fédérale de Lausanne, 1015 Lausanne (Switzerland)

    2016-05-02

    A laser stimulus at terahertz (THz) frequency is expected to offer superior control over magnetization dynamics compared to an optical pulse, where ultrafast demagnetization is mediated by heat deposition. As a THz field cycle occurs on a timescale similar to the natural speed of spin motions, this can open a path for triggering precessional magnetization motion and ultimately ultrafast magnetic switching by the THz magnetic field component, without quenching. Here, we explore the ultrafast magnetic response of a ferromagnetic nickel thin film excited by a strong (33 MV/cm) terahertz transient in non-resonant conditions. While the magnetic laser pulse component induces ultrafast magnetic precessions, we experimentally found that at high pump fluence, the THz pulse leads to large quenching which dominates the precessional motion by far. Furthermore, degradation of magnetic properties sets in and leads to permanent modifications of the Ni thin film and damage.

  3. Room temperature luminescence and ferromagnetism of AlN:Fe

    Energy Technology Data Exchange (ETDEWEB)

    Li, H., E-mail: lihui@mail.iee.ac.cn, E-mail: wjwang@aphy.iphy.ac.cn [The Key Laboratory of Solar Thermal Energy and Photovoltaic System, Institute of Electrical engineering, Chinese Academy of Sciences, Beijing 100190 (China); Cai, G. M. [School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083 (China); Wang, W. J., E-mail: lihui@mail.iee.ac.cn, E-mail: wjwang@aphy.iphy.ac.cn [Research and Development Center for Functional Crystals, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-06-15

    AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR) method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe{sup 2+} state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV) and 598 nm (2.07 eV) are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  4. Room temperature luminescence and ferromagnetism of AlN:Fe

    Directory of Open Access Journals (Sweden)

    H. Li

    2016-06-01

    Full Text Available AlN:Fe polycrystalline powders were synthesized by a modified solid state reaction (MSSR method. Powder X-ray diffraction and transmission electron microscopy results reveal the single phase nature of the doped samples. In the doped AlN samples, Fe is in Fe2+ state. Room temperature ferromagnetic behavior is observed in AlN:Fe samples. Two photoluminescence peaks located at about 592 nm (2.09 eV and 598 nm (2.07 eV are observed in AlN:Fe samples. Our results suggest that AlN:Fe is a potential material for applications in spintronics and high power laser devices.

  5. Tunneling magnetoresistance in ferromagnetic planar hetero-nanojunctions

    KAUST Repository

    Useinov, Arthur

    2010-05-03

    We present a theoretical study of the tunneling magnetoresistance (TMR) in nanojunctions between non-identical ferromagnetic metals in the framework of the quasiclassical approach. The lateral size of a dielectric oxide layer, which is considered as a tunneling barrier between the metallic electrodes, is comparable with the mean-free path of electrons. The dependence of the TMR on the bias voltage, physical parameters of the dielectric barrier, and spin polarization of the electrodes is studied. It is demonstrated that a simple enough theory can give high TMR magnitudes of several hundred percent at bias voltages below 0.5 V. A qualitative comparison with the available experimental data is given. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Energy relaxation and heating of magnons in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Korenblit, I.Ya.; Tankhilevich, B.G.

    1976-01-01

    The warming-up of electrons and magnons by a high electrical field in ferromagnetic semiconductors with wide conduction bands has been considered. The warming-up of magnons determines the dependence of the magnetic characteristics of the semiconductor (for example, its magnetization) on the electric field and leads to some interesting peculiarities in the current-voltage characteristic (CVC). In some cases, owing to a rapid decrease of electrical conductivity with the increasing temperature of magnons, the CVC may contain a descending part. Since the energy relaxation of magnons occurs very slowly, the time during which the stationary state sets in, although varying widely as a function of the lattice temperature T and the electron gas concentration n, may reach values of the order of milliseconds

  7. Giant proximity effect in ferromagnetic bilayers

    Science.gov (United States)

    Ramos, Silvia; Charlton, Tim; Quintanilla, Jorge; Suter, Andreas; Moodera, Jagadeesh; Prokscha, Thomas; Salman, Zaher; Forgan, Ted

    2013-03-01

    The proximity effect is a phenomenon where an ordered state leaks from a material into an adjacent one over some finite distance, ξ. For superconductors, this distance is ~ the coherence length. Nevertheless much longer-range, ``giant'' proximity effects have been observed in cuprate junctions. This surprising effect can be understood as a consequence of critical opalescence. Since this occurs near all second order phase transitions, giant proximity effects should be very general and, in particular, they should be present in magnetic systems. The ferromagnetic proximity effect has the advantage that its order parameter (magnetization) can be observed directly. We investigate the above phenomenon in Co/EuS bilayer films, where both materials undergo ferromagnetic transitions but at rather different temperatures (bulk TC of 1400K for Co and 16.6K for EuS). A dramatic increase in the range of the proximity effect is expected near the TC of EuS. We present the results of our measurements of the magnetization profiles as a function of temperature, carried out using the complementary techniques of low energy muon rotation and polarized neutron reflectivity. Work supported by EPSRC, STFC and ONR grant N00014-09-1-0177 and NSF grant DMR 0504158.

  8. Titanium nitride room-temperature ferromagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Iu.G., E-mail: morozov@ism.ac.ru [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belyakov, O.A. [Ogarev Mordovia State University, Saransk, 68 Bol' shevistskaya Street, 430005 (Russian Federation); Parkin, I.P., E-mail: i.p.parkin@ucl.ac.uk [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Sathasivam, S. [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [All-Russian Research Institute on Problems of Civil Defense and Emergencies of Emergency Control Ministry of Russia (EMERCOM), 7 Davidkovskaya Street, Moscow, 121352 (Russian Federation)

    2016-08-05

    Cubic and near-spherical TiN nanoparticles ranging in average size from 20 to 125 nm were prepared by levitation-jet aerosol synthesis through condensation of titanium vapor in an inert gas flow with gaseous nitrogen injection. The nanoparticles were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET measurements, UV–Vis, FT-IR, Raman spectroscopy, XPS, and vibrating-sample magnetometry. Room-temperature ferromagnetism with maximum magnetization up to 2.5 emu/g was recorded for the nanoparticles. The results indicate that the observed ferromagnetic ordering was related to the defect Ti–N structures on the surface of nanoparticles. This suggestion is in good correlation with the measured spectroscopical data. - Highlights: • Levitation-jet aerosol synthesis of TiN nanoparticles (NPs). • SEM, XRD, BET, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between optical and XPS measurements data and maximum magnetization of the NPs.

  9. Teaching quality: High school students' autonomy and competence.

    Science.gov (United States)

    León, Jaime; Medina-Garrido, Elena; Ortega, Miriam

    2018-05-01

    How teachers manage class learning and interact with students affects students’ motivation and engagement. However, it could be that the effect of students’ representation of teaching quality on the students’ motivation varies between classes. Students from 90 classes participated in the study. We used multilevel random structural equation modeling to analyze whether the relationship of the students’ perception of teaching quality (as an indicator of the students’ mental representation) and students’ motivation varies between classes, and if this variability depends on the class assessment of teaching quality (as an indicator of teaching quality). The effect of teachers’ structure on the regression slope of student perception of student competence was .127. The effect of teachers’ autonomy support on the regression slope of student perception of student autonomy was .066. With this study we contribute a more detailed description of the relationship between teaching quality, competence and autonomy.

  10. Room-temperature ferromagnetism in cerium dioxide powders

    Energy Technology Data Exchange (ETDEWEB)

    Rakhmatullin, R. M., E-mail: rrakhmat@kpfu.ru; Pavlov, V. V.; Semashko, V. V.; Korableva, S. L. [Kazan Federal University, Institute of Physics (Russian Federation)

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  11. New developments in high quality grey cast irons

    Directory of Open Access Journals (Sweden)

    Iulian Riposan

    2014-07-01

    Full Text Available The paper reviews original data obtained by the present authors, revealed in recent separate publications, describing specific procedures for high quality grey irons, and reflecting the forecast needs of the worldwide iron foundry industry. High power, medium frequency coreless induction furnaces are commonly used in electric melting grey iron foundries. This has resulted in low sulphur (1,500 °C, contributing to unfavourable conditions for graphite nucleation. Thin wall castings are increasingly produced by these electric melt shops with a risk of greater eutectic undercooling during solidification. The paper focused on two groups of grey cast irons and their specific problems: carbides and graphite morphology control in lower carbon equivalent high strength irons (CE=3.4%-3.8%, and austenite dendrite promotion in eutectic and slightly hypereutectic irons (CE=4.1%-4.5%, in order to increase their strength characteristics. There are 3 stages and 3 steps involving graphite formation, iron chemistry and iron processing that appear to be important. The concept in the present paper sustains a threestage model for nucleating flake graphite [(Mn,XS type nuclei]. There are three important groups of elements (deoxidizer, Mn/S, and inoculant and three technological stages in electric melting of iron (superheat, pre-conditioning of base iron, final inoculation. Attention is drawn to a control factor (%Mn x (%S ensuring it equals to 0.03 – 0.06, accompanied by 0.005wt.%–0.010wt.% Al and/or Zr content in inoculated irons. It was found that iron powder addition promotes austenite dendrite formation in eutectic and slightly eutectic, acting as reinforcement for the eutectic cells. But, there is an accompanying possible negative influence on the characteristics of the (Mn,XS type graphite nuclei (change the morphology of nuclei from polygonal compact to irregular polygonal, and therefore promote chill tendency in treated irons. A double addition (iron

  12. A high yielding, better quality chickpea mutant variety 'NIFA-95'

    International Nuclear Information System (INIS)

    Hassan, S.; Javed, M.A.; Khattak, S.U.K.; Iqbal, M.M.

    2001-01-01

    Chickpea or gram (Cicer arietinum L.) is an important legume crop of Pakistan, grown on over one million hectares annually. The national average yield of the crop is very low (0.5 t/ha) and thus the country had to spent about 2 billion rupees ($ 50 million) on import of pulses. The main causes of low yield are non-availability of genetic sources for resistance to various diseases especially gram blight Ascochyta rabiei (Pass.) Lab., insect pest (Pod borer) and non-adoption of proper production technology by the farmers. This calls for earnest efforts of breeders to evolve high yielding and disease resistant varieties of chickpea for provision of quality seeds to the farming community to increase production of this important crop. Seeds of a highly blight susceptible variety '6153' were irradiated at 200 Gy dose of gamma radiation in 1985 and the promising mutant line CMN-446-4 was selected in M3 generation on the basis of disease resistance, greater number of pods and better plant type. After confirmation of its resistance to blight in M 4 and M 5 , the mutant line was evaluated in various trials at different locations. In the advanced and zonal yield trials during 1993-95, the line CMN-446-4 produced the highest grain yield of 2,600 kg/ha as compared to the rest of the mutants and varieties. The line was also evaluated in the chickpea national uniform yield trial, conducted on over 11 locations in the country during 1993-94. In this trial, the mutant line ranked 3rd by producing an average yield of 1,528 kg/ha as compared to the two check varieties 'Punjab-91' (1,316 kg/ha) and 'Paidar-91' (1,391 kg/ha). The mutant line CMN-446-4 is moderately resistant to gram blight, highly resistant to stored pest (pulse beetle), contains 25.3% more protein as compared to the parental variety 6153 and is also better in nitrogen fixing capacity.The proposal for release of the mutant line CMN-446-4 as a new variety under the name 'NIFA-95' for general cultivation in the rainfed

  13. Construction of an Overhauser magnetic gradiometer and the applications in geomagnetic observation and ferromagnetic target localization

    Science.gov (United States)

    Liu, H.; Dong, H.; Liu, Z.; Ge, J.; Bai, B.; Zhang, C.

    2017-10-01

    The proton precession magnetometer with single sensor is commonly used in geomagnetic observation and magnetic anomaly detection. Due to technological limitations, the measurement accuracy is restricted by several factors such as the sensor performance, frequency measurement precision, instability of polarization module, etc. Aimed to improve the anti-interference ability, an Overhauser magnetic gradiometer with dual sensor structure was designed. An alternative design of a geomagnetic sensor with differential dual-coil structure was presented. A multi-channel frequency measurement algorithm was proposed to increase the measurement accuracy. A silicon oscillator was adopted to resolve the instability of polarization system. This paper briefly discusses the design and development of the gradiometer and compares the data recorded by this instrument with a commonly used commercially Overhauser magnetometer in the world market. The proposed gradiometer records the earth magnetic field in 24 hours with measurement accuracy of ± 0.3 nT and a sampling rate of 3 seconds per sample. The quality of data recorded is excellent and consistent with the commercial instrument. In addition, experiments of ferromagnetic target localization were conducted. This gradiometer shows a strong ability in magnetic anomaly detection and localization. To sum up, it has the advantages of convenient operation, high precision, strong anti-interference, etc., which proves the effectiveness of the dual sensor structure Overhauser magnetic gradiometer.

  14. Construction of an Overhauser magnetic gradiometer and the applications in geomagnetic observation and ferromagnetic target localization

    International Nuclear Information System (INIS)

    Liu, H.; Dong, H.; Ge, J.; Zhang, C.; Liu, Z.; Bai, B.

    2017-01-01

    The proton precession magnetometer with single sensor is commonly used in geomagnetic observation and magnetic anomaly detection. Due to technological limitations, the measurement accuracy is restricted by several factors such as the sensor performance, frequency measurement precision, instability of polarization module, etc. Aimed to improve the anti-interference ability, an Overhauser magnetic gradiometer with dual sensor structure was designed. An alternative design of a geomagnetic sensor with differential dual-coil structure was presented. A multi-channel frequency measurement algorithm was proposed to increase the measurement accuracy. A silicon oscillator was adopted to resolve the instability of polarization system. This paper briefly discusses the design and development of the gradiometer and compares the data recorded by this instrument with a commonly used commercially Overhauser magnetometer in the world market. The proposed gradiometer records the earth magnetic field in 24 hours with measurement accuracy of ± 0.3 nT and a sampling rate of 3 seconds per sample. The quality of data recorded is excellent and consistent with the commercial instrument. In addition, experiments of ferromagnetic target localization were conducted. This gradiometer shows a strong ability in magnetic anomaly detection and localization. To sum up, it has the advantages of convenient operation, high precision, strong anti-interference, etc., which proves the effectiveness of the dual sensor structure Overhauser magnetic gradiometer.

  15. Fiber laser drilling of Ni46Mn27Ga27 ferromagnetic shape memory alloy

    Science.gov (United States)

    Biffi, C. A.; Tuissi, A.

    2014-11-01

    The interest in ferromagnetic shape memory alloys (SMAs), such as NiMnGa, is increasing, thanks to the functional properties of these smart and functional materials. One of the most evident properties of these systems is their brittleness, which makes attractive the study of unconventional manufacturing processes, such as laser machining. In this work the interaction of laser beam, once focalized on the surface of Ni46Mn27Ga27 [at%] alloy, has been studied. The experiments were performed with a single laser pulse, using a 1 kW continuous wave fiber laser. The morphology of the laser machined surfaces was evaluated using scanning electron microscopy, coupled with energetic dispersion spectroscopy for the measurement of the chemical composition. The results showed that the high quality of the laser beam, coupled with great irradiances available, allow for blind or through holes to be machined on 1.8 mm plates with a single pulse in the order of a few ms. Holes were produced with size in the range of 200-300 μm; despite the long pulse duration, low amount of melted material is produced around the hole periphery. No significant variation of the chemical composition has been detected on the entrance surfaces while the exit ones have been characterized by the loss of Ga content, due to its melting point being significantly lower with respect to the other alloying elements.

  16. Physics and quality assurance for high dose rate brachytherapy

    International Nuclear Information System (INIS)

    Anderson, Lowell L.

    1995-01-01

    Purpose: To review the physical aspects of high dose rate (HDR) brachytherapy, including commissioning and quality assurance, source calibration and dose distribution measurements, and treatment planning methods. Following the introduction of afterloading in brachytherapy, development efforts to make it 'remote' culminated in 1964 with the near-simultaneous appearance of remote afterloaders in five major medical centers. Four of these machines were 'high dose rate', three employing 60Co and one (the GammaMed) using a single, cable-mounted 192Ir source. Stepping-motor source control was added to the GammaMed in 1974, making it the precursor of modern remote afterloaders, which are now suitable for interstitial as well as intracavitary brachytherapy by virtue of small source-diameter and indexer-accessed multiple channels. Because the 192Ir sources currently used in HDR remote afterloaders are supplied at a nominal air-kerma strength of 11.4 cGy cm2 s-1 (10 Ci), are not collimated in clinical use, and emit a significant fraction (15%) of photons at energies greater than 600 keV, shielding and facility design must be undertaken as carefully and thoroughly as for external beam installations. Licensing requirements of regulatory agencies must be met with respect both to maximum permissible dose limits and to the existence and functionality of safety devices (door interlocks, radiation monitors, etc.). Commissioning and quality assurance procedures that must be documented for HDR remote afterloading relate to (1) machine, applicator, guide-tube, and facility functionality checks, (2) source calibration, (3) emergency response readiness, (4) planning software evaluation, and (5) independent checks of clinical dose calculations. Source calibration checks must be performed locally, either by in-air measurement of air kerma strength or with a well ionization chamber calibrated (by an accredited standards laboratory) against an in-air measurement of air kerma strength for the

  17. Twin pregnancy possibly associated with high semen quality

    DEFF Research Database (Denmark)

    Asklund, Camilla; Jensen, Tina Kold; Jørgensen, Niels

    2007-01-01

    BACKGROUND: Recent studies found an association between a long waiting time to pregnancy (TTP) and reduced probability of twinning and a reduced dizygotic (DZ) twinning rate in subfertile men. However, it remains unsolved whether semen quality is associated with twin offspring. We therefore studied...... the semen quality in a group of fathers of naturally conceived twins. METHODS: In this study, 37 fathers of DZ twins and 15 fathers of monozygotic (MZ) twins participated, and 349 normal fertile men served as a reference group. All men delivered a semen sample, underwent a physical examination and completed...... points higher than the reference group (P semen quality than the reference group, which supports...

  18. Interplay of dopants and defects in making Cu doped TiO{sub 2} nanoparticle a ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, Biswajit, E-mail: biswa.tezu@gmail.com [Department of Physics, Tezpur University, Napaam 784028, Assam (India); Choudhury, Amarjyoti [Department of Physics, Tezpur University, Napaam 784028, Assam (India); Borah, Debajit [Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam (India)

    2015-10-15

    Here we have studied the role of oxygen defects and Cu dopants on ferromagnetism in Cu doped TiO{sub 2} nanoparticles with nominal Cu concentration of 2%, 4% and 6 mol%. Electron paramagnetic resonance (EPR) spectra analysis reveals the presence of Cu{sup 2+} in the distorted octahedral coordination of TiO{sub 2}. Cu d-states undergo strong p-d coupling with the valence band O 2p state of TiO{sub 2} resulting the extended absorption hump in the visible region. Photoluminescence results reveal the presence of oxygen defect related emission peaks in Cu doped TiO{sub 2}. Room temperature ferromagnetism is observed in all the Cu doped TiO{sub 2} nanoparticles. Saturation magnetization is the highest at 4 mol% and then there is a decrease in magnetization at 6 mol%. Ferromagnetism completely disappears on calcinations of 4% Cu doped TiO{sub 2} in air at 450 °C for 8 h. It is speculated that both oxygen vacancies and Cu d-states are involved in the room temperature ferromagnetism. Spin polarization occurs by the formation of bound magnetic polaron between electrons in Cu{sup 2+}d-states and the unpaired spins in oxygen vacancies. Presence of Cu{sup 2+}-Cu{sup 2+}d-d exchange interaction and Cu{sup 2+}-O{sup 2−}-Cu{sup 2+} antiferromagnetic superexchange interactions might have resulted in the reduction in magnetization at 6 mol% Cu. - Graphical abstract: Ferromagnetism in Cu doped TiO{sub 2} requires presence of both Cu dopant and oxygen vacancies. - Highlights: • Cu doped TiO{sub 2} nanoparticle displays room temperature ferromagnetism. • Ferromagnetism requires presence of both Cu and oxygen vacancies. • Antiferromagnetic interaction persists at high Cu dopant concentration. • Paramagnetism appears on air annealing of the doped system for longer period.

  19. High quality ceramic coatings sprayed by high efficiency hypersonic plasma spraying gun

    International Nuclear Information System (INIS)

    Zhu Sheng; Xu Binshi; Yao JiuKun

    2005-01-01

    This paper introduced the structure of the high efficiency hypersonic plasma spraying gun and the effects of hypersonic plasma jet on the sprayed particles. The optimised spraying process parameters for several ceramic powders such as Al 2 O 3 , Cr 2 O 3 , ZrO 2 , Cr 3 C 2 and Co-WC were listed. The properties and microstructure of the sprayed ceramic coatings were investigated. Nano Al 2 O 3 -TiO 2 ceramic coating sprayed by using the high efficiency hypersonic plasma spraying was also studied. Compared with the conventional air plasma spraying, high efficiency hypersonic plasma spraying improves greatly the ceramic coatings quality but at low cost. (orig.)

  20. Spin-flip scattering effect on the current-induced spin torque in ferromagnet-insulator-ferromagnet tunnel junctions

    International Nuclear Information System (INIS)

    Zhu Zhengang; Su Gang; Jin Biao; Zheng Qingrong

    2003-01-01

    We have investigated the current-induced spin transfer torque of a ferromagnet-insulator-ferromagnet tunnel junction by taking the spin-flip scatterings into account. It is found that the spin-flip scattering can induce an additional spin torque, enhancing the maximum of the spin torque and giving rise to an angular shift compared to the case when the spin-flip scatterings are neglected. The effects of the molecular fields of the left and right ferromagnets on the spin torque are also studied. It is found that τ Rx /I e (τ Rx is the spin-transfer torque acting on the right ferromagnet and I e is the tunneling electrical current) does vary with the molecular fields. At two certain angles, τ Rx /I e is independent of the molecular field of the right ferromagnet, resulting in two crossing points in the curve of τ Rx /I e versus the relevant orientation for different molecular fields

  1. Safe and high quality food production using low quality waters and improved irrigation systems and management

    DEFF Research Database (Denmark)

    Plauborg, Finn; Andersen, Mathias Neumann; Liu, Fulai

    2010-01-01

    uneven irrigation patterns can increase the water use efficiency as well as the quality of vegetable crops. Furthermore, recent innovations in the water treatment and irrigation industry have shown potential for the use of low quality water resources, such as reclaimed water or surface water in peri...

  2. High throughput electrospinning of high-quality nanofibers via an aluminum disk spinneret

    Science.gov (United States)

    Zheng, Guokuo

    In this work, a simple and efficient needleless high throughput electrospinning process using an aluminum disk spinneret with 24 holes is described. Electrospun mats produced by this setup consisted of fine fibers (nano-sized) of the highest quality while the productivity (yield) was many times that obtained from conventional single-needle electrospinning. The goal was to produce scaled-up amounts of the same or better quality nanofibers under variable concentration, voltage, and the working distance than those produced with the single needle lab setting. The fiber mats produced were either polymer or ceramic (such as molybdenum trioxide nanofibers). Through experimentation the optimum process conditions were defined to be: 24 kilovolt, a distance to collector of 15cm. More diluted solutions resulted in smaller diameter fibers. Comparing the morphologies of the nanofibers of MoO3 produced by both the traditional and the high throughput set up it was found that they were very similar. Moreover, the nanofibers production rate is nearly 10 times than that of traditional needle electrospinning. Thus, the high throughput process has the potential to become an industrial nanomanufacturing process and the materials processed by it may be used as filtration devices, in tissue engineering, and as sensors.

  3. Improving the quality of pork and pork products for the consumer : development of innovative, integrated, and sustainable food production chains of high quality pork products matching consumer demands

    NARCIS (Netherlands)

    Heimann, B.; Christensen, M.; Rosendal Rasmussen, S.; Bonneau, M.; Grunert, K.G.; Arnau, J.; Trienekens, J.H.; Oksbjerg, N.; Greef, de K.H.; Petersen, B.

    2012-01-01

    Improving the quality of pork and pork products for the consumer: development of innovative, integrated, and sustainable food production chains of high quality pork products matching consumer demands.

  4. Ferromagnetic material inspection for feedwater heater and condenser tubes

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    In recent years, special ferritic stainless steels, such as AL29-4C/sup TM/, Sea-Cure/sup TM/, E-Brite/sup TM/, 439, and similar alloys have been introduced as tube material in condensers, feedwater heaters, moisture separator/reheaters, and other heat exchangers. In addition, carbon steel tubes are widely used in feedwater heaters and heat exchangers in chemical plants. The main problem with the in-service inspection of these ferritic alloys and carbon steel tubes lies in their highly ferromagnetic properties. These properties severely limit the application of the standard eddy current techniques. The effort was undertaken under EPRI sponsorship to develop a reliable technique for in-service inspection of ferromagnetic tubes. The new method combines the measurement of magnetic flux leakage generated around the defects with measurement of total flux in the tube wall. The heart of the inspection system is a special ID probe that magnetizes the tube and generates signals for any tube defect. A permanent record of inspection is provided with a strip-chart or magnetic tape recorder. The laboratory and field evaluation of this new system demonstrated its very good sensitivity to small defects, its reliability, and its ruggedness. Defects as small as 10% external wall loss in heavy wall carbon steel tube were detected. Tubes in the power plant were inspected at a rate of 300-500 tubes per eight-hour shift. The other advantages of this newly developed technique are its simplicity, low cost of instrumentation, easy data interpretation, and full portability

  5. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    Science.gov (United States)

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of AB and randomly stacked structures. Herein we report a rational approach to produce large-area high quality AB stacked bilayer graphene. We show that the self-limiting effect of graphene growth on Cu foil can be broken by using a high H2/CH4 ratio in a low pressure CVD process to enable the continued growth of bilayer graphene. A high temperature and low pressure nucleation step is found to be critical for the formation of bilayer graphene nuclei with high AB stacking ratio. A rational design of a two-step CVD process is developed for the growth of bilayer graphene with high AB stacking ratio (up to 90 %) and high coverage (up to 99 %). The electrical transport studies demonstrated that devices made of the as-grown bilayer graphene exhibit typical characteristics of AB stacked bilayer graphene with the highest carrier mobility exceeding 4,000 cm2/V·s at room temperature, comparable to that of the exfoliated bilayer graphene. PMID:22906199

  6. Perfect GMR effect in gapped graphene-based ferromagnetic normal ferromagnetic junctions

    Institute of Scientific and Technical Information of China (English)

    Hossein Karbaschi; Gholam Reza Rashedi

    2015-01-01

    We investigate the quantum transport property in gapped graphene-based ferromagnetic/normal/ferromagnetic (FG/NG/FG) junctions by using the Dirac–Bogoliubov–de Gennes equation. The graphene is fabricated on SiC and BN substrates separately, so carriers in FG/NG/FG structures are considered as massive relativistic particles. Transmission prob-ability, charge, and spin conductances are studied as a function of exchange energy of ferromagnets (h), size of graphene gap, and thickness of normal graphene region (L) respectively. Using the experimental values of Fermi energy in the normal graphene part (EFN∼400 meV) and energy gap in graphene (260 meV for SiC and 50 meV for BN substrate), it is shown that this structure can be used for both spin-up and spin-down polarized current. The latter case has different behavior of gapped FG/NG/FG from that of gapless FG/NG/FG structures. Also perfect charge giant magnetoresistance is observed in a range of EFN−mv2F

  7. Magnetic excitations in transition-metal ferromagnets

    International Nuclear Information System (INIS)

    Uemura, Y.J.

    1984-01-01

    A review is given on current neutron scattering experiments at Brookhaven National Laboratory on transition-metal ferromagnets Ni, Fe, Pd 2 MnSn and MnSi. The scattering intensity in constant-energy scans, observed above T/sub c/ in all of these materials, exhibited a clear peak at finite momentum transfers. Using a simple scattering function with double-Lorentzian shape, we demonstrate that this peak is a manifestation of simple diffusive spin fluctuations. Experimental results of several parameters are compared in the context of localized-moment and itinerant-electron pictures. The ratio of spin wave stiffness constant D and transition temperature kT/sub c/ is shown to be a good yardstick for the degree of itinerancy of d-electrons

  8. ''Soft'' Anharmonic Vortex Glass in Ferromagnetic Superconductors

    International Nuclear Information System (INIS)

    Radzihovsky, Leo; Ettouhami, A. M.; Saunders, Karl; Toner, John

    2001-01-01

    Ferromagnetic order in superconductors can induce a spontaneous vortex (SV) state. For external field H=0 , rotational symmetry guarantees a vanishing tilt modulus of the SV solid, leading to drastically different behavior than that of a conventional, external-field-induced vortex solid. We show that quenched disorder and anharmoinc effects lead to elastic moduli that are wave-vector dependent out to arbitrarily long length scales, and non-Hookean elasticity. The latter implies that for weak external fields H , the magnetic induction scales universally like B(H)∼B(0)+cH α , with α∼0.72 . For weak disorder, we predict the SV solid is a topologically ordered glass, in the ''columnar elastic glass'' universality class

  9. Room temperature ferromagnetic gadolinium silicide nanoparticles

    Science.gov (United States)

    Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

    2018-03-06

    A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.

  10. Muon spin relaxation in ferromagnets. Pt. 1

    International Nuclear Information System (INIS)

    Lovesey, S.W.; Karlsson, E.B.

    1991-04-01

    Expressions for the dipolar and hyperfine contributions to the relaxation rate of muons implanted in a ferromagnet are presented and analysed using the Heisenberg model of spin-waves including dipolar and Zeeman energies. Calculations for EuO indicate that relaxation is likely to be dominated by the hyperfine mechanism, even if the ratio of the hyperfine and dipolar coupling constants is small. The hyperfine mechanism is sensitive to the dipolar energy of the atomic spins, whereas the dipolar mechanisms depend essentially on the exchange energy. For both mechanisms there is an almost quadratic dependence on temperature, throughout much of the ordered magnetic phase, which reflects two-spin-wave difference events from the Raman-type relaxation processes. (author)

  11. Ferromagnetic rollers in a harmonic confinement

    Science.gov (United States)

    Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S.

    We present the emergence of flocking and global rotation in a system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field confined in a harmonic potential. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms leading to the emergence of large-scale collective motion: spontaneous symmetry breaking of the clock / counterclockwise particle rotation, collisional alignment of particle velocities, and random particle re-orientations due to shape imperfections. We also emphasize a subtle role of rotational noise: While the low-frequency flocking appears to be noise-insensitive, the reentrant flocking happens to be noise-activated. Moreover, we uncover a new relation between collective motion and synchronisation.

  12. Critical behavior of ferromagnetic Ising thin films

    International Nuclear Information System (INIS)

    Cossio, P.; Mazo-Zuluaga, J.; Restrepo, J.

    2006-01-01

    In the present work, we study the magnetic properties and critical behavior of simple cubic ferromagnetic thin films. We simulate LxLxd films with semifree boundary conditions on the basis of the Monte Carlo method and the Ising model with nearest neighbor interactions. A Metropolis dynamics was implemented to carry out the energy minimization process. For different film thickness, in the nanometer range, we compute the temperature dependence of the magnetization, the magnetic susceptibility and the fourth order Binder's cumulant. Bulk and surface contributions of these quantities are computed in a differentiated fashion. Additionally, according to finite size scaling theory, we estimate the critical exponents for the correlation length, magnetic susceptibility, and magnetization. Results reveal a strong dependence of critical temperature and critical exponents on the film thickness. The obtained critical exponents are finally compared to those reported in literature for thin films

  13. Surface effects in the Potts ferromagnet

    International Nuclear Information System (INIS)

    Tsallis, C.; Sarmento, E.F.

    1984-01-01

    Within a real space renormalisation group framework, the phase diagram of a semi-infinite cubic-lattice q-state Potts ferromagnet is studied, in which the free surface coupling constant J sub(S) = (1+Δ)J sub(B) might be different from the bulk one J sub(B). The starting value Δ sub(c) (q) is calculated above which surface order is possible even if bulk order is absent. Our results can be alternatively seen as approximate for the simple cubic lattice (as a matter of fact, the Ising value Δ sub(c) (2) obtained approaches the series result better than any other theory known consequently Δ sub(c) (q) is expected to be quite satisfactory even for q not= 2) or as exact for a well defined diamond-like hierarchical lattice. In the q →0 limit, Δ sub(c) diverges as 1/√q. (Author) [pt

  14. Heat exchanges in a quenched ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Corberi, Federico; Zannetti, Marco [Dipartimento di Fisica ' E.R. Caianiello' , and CNISM, Unita di Salerno, Universita di Salerno, via Ponte don Melillo, I-84084 Fisciano, SA (Italy); Gonnella, Giuseppe; Piscitelli, Antonio [Dipartimento di Fisica, Universita di Bari and INFN, Sezione di Bari, via Amendola 173, I-70126 Bari (Italy)

    2013-02-01

    The off-equilibrium probability distribution of the heat exchanged by a ferromagnet in a time interval after a quench below the critical point is calculated analytically in the large-N limit. The distribution is characterized by a singular threshold Q{sub C} < 0, below which a macroscopic fraction of heat is released by the k = 0 Fourier component of the order parameter. The mathematical structure producing this phenomenon is the same responsible for the order parameter condensation in the equilibrium low temperature phase. The heat exchanged by the individual Fourier modes follows a non-trivial pattern, with the unstable modes at small wave vectors warming up the modes around a characteristic finite wave vector k{sub M}. Two internal temperatures, associated with the k = 0 and k = k{sub M} modes, rule the heat currents through a fluctuation relation similar to the one for stationary systems in contact with two thermal reservoirs. (fast track communication)

  15. Consumers' expected quality and intention to purchase high quality pork meat.

    Science.gov (United States)

    Papanagiotou, P; Tzimitra-Kalogianni, I; Melfou, K

    2013-03-01

    Expected quality is believed to be one of the most important factors that influence consumers' intention to purchase food. The present study seeks to explore the concept of pork meat expected quality and compare it with self-stated consumer intention to purchase pork meat. The aim is attempted by means of a field research conducted in Greece, following a conjoint analytic procedure. Results show that quality expectations comply with intention to buy pork, in many aspects. However, several differences have been identified. More specifically, country of origin and marbling appear to be more important for respondents' purchase decisions than they are for their quality evaluations, while the opposite appears to be true for price. Finally, socio-demographic factors such as gender, level of education, place of purchase and consumption habits seem to influence perceptions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Safe and High Quality Food Production using Low Quality Waters and Improved Irrigation Systems and Management, EU Project

    DEFF Research Database (Denmark)

    Plauborg, Finn; Jensen, Christian Richardt; Dalsgaard, Anders

    2009-01-01

    : the safety and quality of food products, and the increasing competition for clean freshwater. SAFIR is funded for the period 2005-2009 under the Food Quality and Safety thematic area of the EU 6th Framework Research Programme. The challenge for the next years will be to produce safe and high quality foods...... a multi-disciplinary team, with food safety and quality experts, engineers, agronomists and economists from17 research institutes and private companies in Europe, Israel and China working together. The project assesses potential risks to farmers. Coupled with farm management and economic models, a new...... intelligent tool for efficient and safe use and re-use of low-quality water are being developed. Already published results indicate water saving in the order of 25-30% in agricultural crops as potatoes and tomatoes are possible without yield reduction. Slightly treated waste water can be used safely when...

  17. Neutron depolarization study of static and dynamic magnetic properties of ferromagnets

    International Nuclear Information System (INIS)

    Stuesser, N.

    1986-01-01

    In this thesis neutron depolarization experiments are performed on amorphous and crystalline ferromagnetic materials. The subjects studied are concerned with 'domain structure in magnetically weak uniaxial amorphous ferromagnetic ribbons', 'static critical behaviour at the ferromagnetic-paramagnetic phase transition', 'small magnetic anisotropy in nickel near T c ', and 'magnetization reversal in conducting ferromagnets'. 87 refs.; 37 figs.; 3 tabs

  18. Quality assessment and potential utilization of high amylolytic ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-03

    Dec 3, 2008 ... This study was carried out to compare the qualities of two acclaimed Nigerian amylolytic maize cultivars; SPMAT ... growing demand for usage as a gluten-free cereal. (Sweeny ... The grain was malted and the malting loss was calculated using the .... also confirmed that there was no significant difference in.

  19. Quality Alternative Certification Programs in Special Education Ensure High Retention

    Science.gov (United States)

    Karge, Belinda D.; McCabe, Marjorie

    2014-01-01

    Market driven alternative routes to teaching have evolved into a quality program option and not just an answer to the teacher shortage. Alternative certification is a viable means of recruiting, training, and certifying those who have a bachelor's degree and a strong desire to enter the field of teaching. California has been a leader in the…

  20. Innovation in Business Education: Developing a High Quality Online MBA

    Science.gov (United States)

    Roe, C. William; Toma, Alfred G.; Yallapragada, RamMohan R.

    2015-01-01

    Online degree programs were probably pioneered by for-profit universities such as University of Phoenix. Many online degree programs were initially considered low quality academic programs compared to traditional programs. Therefore, many public and private universities were slow to adopt the online programs. However, gradually more and more…

  1. Single-magnon tunneling through a ferromagnetic nanochain

    International Nuclear Information System (INIS)

    Petrov, E.G.; Ostrovsky, V.

    2010-01-01

    Magnon transmission between ferromagnetic contacts coupled by a linear ferromagnetic chain is studied at the condition when the chain exhibits itself as a tunnel magnon transmitter. It is shown that dependently on magnon energy at the chain, a distant intercontact magnon transmission occurs either in resonant or off-resonant tunneling regime. In the first case, a transmission function depends weakly on the number of chain sites whereas at off-resonant regime the same function manifests an exponential drop with the chain length. Change of direction of external magnetic field in one of ferromagnetic contacts blocks a tunnel transmission of magnon.

  2. Ferromagnetic properties of Mn-doped AlN

    International Nuclear Information System (INIS)

    Li, H.; Bao, H.Q.; Song, B.; Wang, W.J.; Chen, X.L.; He, L.J.; Yuan, W.X.

    2008-01-01

    Mn-doped AlN polycrystalline powders with a wurtzite structure were synthesized by solid-state reactions. A red-orange band at 600 nm, due to Mn 3+ incorporated into the AlN lattice, is observed in the photoluminescence (PL) spectrum at room temperature (RT). Magnetic measurements show the samples possess hysteresis loops up to 300 K, indicating that the obtained powders are ferromagnetic at around RT. The Mn concentration-induced RT ferromagnetism is less than 1 at%. Our results confirm that the RT ferromagnetism can be realized in Mn-doped AlN

  3. Flux penetration in a ferromagnetic/superconducting bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Adamus, Z.; Cieplak, M.Z.; Abal' Oshev, A. [Polish Acad Sci, Inst Phys, PL-02668 Warsaw, (Poland); Konczykowski, M. [CEA/DSM/DRECAM, Laboratoire des Solides Irradies, F-91191 Gif Sur Yvette, (France); Konczykowski, M. [Ecole Polytech, CNRS - UMR 7642, F-91128 Palaiseau, (France); Cheng, X.M.; Zhu, L.Y.; Chien, C.L. [Johns Hopkins Univ, Dept Phys and Astron, Baltimore, MD 21218 (United States)

    2007-07-01

    An array of miniature Hall sensors is used to study the magnetic flux penetration in a ferromagnetic/superconducting bilayer consisting of Nb as a superconducting layer and Co/Pt multilayer with perpendicular magnetic anisotropy as a ferromagnetic layer, separated by an amorphous Si layer to avoid the proximity effect. It is found that the magnetic domains in the ferromagnetic layer create a large edge barrier in the superconducting layer which delays flux penetration. The smooth flux profiles observed in the absence of magnetic pinning change into terraced profiles in the presence of domains. (authors)

  4. Effects of Rashba and Dresselhaus spin-orbit couplings on itinerant ferromagnetism

    Science.gov (United States)

    Liu, Mengnan; Xu, Liping; Wan, Yong; Yan, Xu

    2018-02-01

    Based on Stoner model for itinerant ferromagnet, effects of spin-orbit coupling (SOC) on ferromagnetism were investigated at zero temperature. It was found that SOC will enhance the critical ferromagnetic exchange interaction for spontaneous magnetization, and then suppress ferromagnetism. In case of the coexistence of Rashba and Dresselhaus SOCs, the mixture of the two spin-orbit couplings showed stronger suppressed effect on ferromagnetism than only one kind of SOC alone. When the two SOCs mixed with equal magnitude, ferromagnetism in itinerant ferromagnet was suppressed to minimum.

  5. Quality of life of people living with HIV/AIDS and on highly active ...

    African Journals Online (AJOL)

    Quality of life of people living with HIV/AIDS and on highly active ... the Short Form-36 Health Survey (SF-36) was used to measure quality of life among patients on ... instrument for use in Ethiopia to assess the quality of life of people living with ...

  6. Does High School Facility Quality Affect Student Achievement? A Two-Level Hierarchical Linear Model

    Science.gov (United States)

    Bowers, Alex J.; Urick, Angela

    2011-01-01

    The purpose of this study is to isolate the independent effects of high school facility quality on student achievement using a large, nationally representative U.S. database of student achievement and school facility quality. Prior research on linking school facility quality to student achievement has been mixed. Studies that relate overall…

  7. Manufacturing High-Quality Carbon Nanotubes at Lower Cost

    Science.gov (United States)

    Benavides, Jeanette M.; Lidecker, Henning

    2004-01-01

    A modified electric-arc welding process has been developed for manufacturing high-quality batches of carbon nanotubes at relatively low cost. Unlike in some other processes for making carbon nanotubes, metal catalysts are not used and, consequently, it is not necessary to perform extensive cleaning and purification. Also, unlike some other processes, this process is carried out at atmospheric pressure under a hood instead of in a closed, pressurized chamber; as a result, the present process can be implemented more easily. Although the present welding-based process includes an electric arc, it differs from a prior electric-arc nanotube-production process. The welding equipment used in this process includes an AC/DC welding power source with an integral helium-gas delivery system and circulating water for cooling an assembly that holds one of the welding electrodes (in this case, the anode). The cathode is a hollow carbon (optionally, graphite) rod having an outside diameter of 2 in. (approximately equal to 5.1 cm) and an inside diameter of 5/8 in. (approximately equal to 1.6 cm). The cathode is partly immersed in a water bath, such that it protrudes about 2 in. (about 5.1 cm) above the surface of the water. The bottom end of the cathode is held underwater by a clamp, to which is connected the grounding cable of the welding power source. The anode is a carbon rod 1/8 in. (approximately equal to 0.3 cm) in diameter. The assembly that holds the anode includes a thumbknob- driven mechanism for controlling the height of the anode. A small hood is placed over the anode to direct a flow of helium downward from the anode to the cathode during the welding process. A bell-shaped exhaust hood collects the helium and other gases from the process. During the process, as the anode is consumed, the height of the anode is adjusted to maintain an anode-to-cathode gap of 1 mm. The arc-welding process is continued until the upper end of the anode has been lowered to a specified height

  8. Growth of room temperature ferromagnetic Ge1-xMnx quantum dots on hydrogen passivated Si (100) surfaces

    Science.gov (United States)

    Gastaldo, Daniele; Conta, Gianluca; Coïsson, Marco; Amato, Giampiero; Tiberto, Paola; Allia, Paolo

    2018-05-01

    A method for the synthesis of room-temperature ferromagnetic dilute semiconductor Ge1-xMnx (5 % < x < 8 %) quantum dots by molecular beam epitaxy by selective growth on hydrogen terminated silicon (100) surface is presented. The functionalized substrates, as well as the nanostructures, were characterized in situ by reflection high-energy electron diffraction. The quantum dots density and equivalent radius were extracted from field emission scanning electron microscope pictures, obtained ex-situ. Magnetic characterizations were performed by superconducting quantum interference device vibrating sample magnetometry revealing that ferromagnetic order is maintained up to room temperature: two different ferromagnetic phases were identified by the analysis of the field cooled - zero field cooled measurements.

  9. Significant enhancement of room temperature ferromagnetism in surfactant coated polycrystalline Mn doped ZnO particles

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, O.D. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Gopalakrishnan, I.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)]. E-mail: ikgopal@barc.gov.in; Sudakar, C. [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201 (United States); Kadam, R.M. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kulshreshtha, S.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2007-07-12

    We report a surfactant assisted synthesis of Mn doped ZnO polycrystalline samples showing robust room temperature ferromagnetism as characterized by X-ray diffraction analysis, transmission electron microscopy, electron paramagnetic resonance and DC magnetization measurements. This surfactant assisted synthesis method, developed by us, is found to be highly reproducible. Further, it can also be extended to the synthesis of other transition metal doped ZnO.

  10. Numerical determination of injector design for high beam quality

    International Nuclear Information System (INIS)

    Boyd, J.K.

    1985-01-01

    The performance of a free electron laser strongly depends on the electron beam quality or brightness. The electron beam is transported into the free electron laser after it has been accelerated to the desired energy. Typically the maximum beam brightness produced by an accelerator is constrained by the beam brightness deliverd by the accelerator injector. Thus it is important to design the accelerator injector to yield the required electron beam brightness. The DPC (Darwin Particle Code) computer code has been written to numerically model accelerator injectors. DPC solves for the transport of a beam from emission through acceleration up to the full energy of the injector. The relativistic force equation is solved to determine particle orbits. Field equations are solved for self consistent electric and magnetic fields in the Darwin approximation. DPC has been used to investigate the beam quality consequences of A-K gap, accelerating stress, electrode configuration and axial magnetic field profile

  11. 'Radiooncology 2007: High quality of life, the ultimate goal'. Abstracts

    International Nuclear Information System (INIS)

    2007-01-01

    The 13th annual congress of Deutsche Gesellschaft fuer Radioonkologie e.V. discussed clinical radiotherapy, medical physics and radiation biology, as well as an extensive programme of working groups on radiology in medical technology, care, and office. The focus was on new equipment (from image-supported to image-guided radiotherapy) and new approaches of targeted tumour therapy. Aspects of life quality are coming to the fore and will get even more important in the future. (orig.)

  12. High image quality sub 100 picosecond gated framing camera development

    International Nuclear Information System (INIS)

    Price, R.H.; Wiedwald, J.D.

    1983-01-01

    A major challenge for laser fusion is the study of the symmetry and hydrodynamic stability of imploding fuel capsules. Framed x-radiographs of 10-100 ps duration, excellent image quality, minimum geometrical distortion (< 1%), dynamic range greater than 1000, and more than 200 x 200 pixels are required for this application. Recent progress on a gated proximity focused intensifier which meets these requirements is presented

  13. The High Flying Leadership Qualities: What Matters the Most

    Science.gov (United States)

    2016-04-01

    operational and functional background of its personnel steeped in both DoD and industry experience. Research Methodology Based on their experiences...DeLorean Motors, Levitz Furniture , Enron, and many other corporations like these learned what happens when key leadership qualities lose all lift...graduate of the Canadian Force Command and Staff College in Toronto, Ontario, Canada; and the U.S. Army War College in Carlisle Barracks

  14. Study of structure of HTS coated conductor with ferromagnetic substrate having low AC transport current loss using FEM

    International Nuclear Information System (INIS)

    Miyagi, D.; Amadutsumi, Y.; Takahashi, N.; Tsukamoto, O.

    2007-01-01

    AC transport current losses of coated conductors with ferromagnetic substrates are higher than the loss calculated by the Norris equation. In order to reduce the AC transport current loss we propose in this paper a structure of the coated conductor that has wider substrate than the SC (Superconducting) layer. The current distribution and AC loss of the proposed model are analyzed by means of FEM. The AC transport current loss is reduced due to the change of current density distribution near the edge of SC layer, consequent to the high value of magnetic permeability of the ferromagnetic substrate, that is wider than the SC layer

  15. Water Quality: A Field-Based Quality Testing Program for Middle Schools and High Schools.

    Science.gov (United States)

    Massachusetts State Water Resources Authority, Boston.

    This manual contains background information, lesson ideas, procedures, data collection and reporting forms, suggestions for interpreting results, and extension activities to complement a water quality field testing program. Information on testing water temperature, water pH, dissolved oxygen content, biochemical oxygen demand, nitrates, total…

  16. Tunneling time and Hartman effect in a ferromagnetic graphene superlattice

    Directory of Open Access Journals (Sweden)

    Farhad Sattari

    2012-03-01

    Full Text Available Using transfer-matrix and stationary phase methods, we study the tunneling time (group delay time in a ferromagnetic monolayer graphene superlattice. The system we peruse consists of a sequence of rectangular barriers and wells, which can be realized by putting a series of electronic gates on the top of ferromagnetic graphene. The magnetization in the two ferromagnetic layers is aligned parallel. We find out that the tunneling time for normal incident is independent of spin state of electron as well as the barrier height and electron Fermi energy while for the oblique incident angles the tunneling time depends on the spin state of electron and has an oscillatory behavior. Also the effect of barrier width on tunneling time is also investigated and shown that, for normal incident, the Hartman effect disappears in a ferromagnetic graphene superlattice but it appears for oblique incident angles when the x component of the electron wave vector in the barrier is imaginary.

  17. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects

    KAUST Repository

    Zhang, Zhenkui

    2014-01-01

    We examine the effects of several intrinsic defects on the magnetic behavior of ZnS nanostructures using hybrid density functional theory to gain insights into d0 ferromagnetism. Previous studies have predicted that the magnetism is due to a coupling between partially filled defect states. By taking into account the electronic correlations, we find an additional splitting of the defect states in Zn vacancies and thus the possibility of gaining energy by preferential filling of hole states, establishing ferromagnetism between spin polarized S 3p holes. We demonstrate a crucial role of neutral S vacancies in promoting ferromagnetism between positively charged S vacancies. S dangling bonds on the nanoparticle surface also induce ferromagnetism. This journal is

  18. Comment on ``Ferromagnetic film on a superconducting substrate''

    Science.gov (United States)

    Sonin, E. B.

    2002-10-01

    A superconducting substrate is not able to shrink drastically domains in a ferromagnetic film, contrary to the prediction of Bulaevskii and Chudnovsky. This is shown on the basis of the exact solution for the stripe domain structure.

  19. Polarised neutron diffraction studies on weak ferromagnetism - a survey

    International Nuclear Information System (INIS)

    Radhakrishna, P.

    1982-10-01

    The physical basis of the phenomenon of weak ferromagnetism in certain antiferromagnetic insulators is briefly discussed. A survey of the contributions of polarised neutron diffraction towards the elucidation of different aspects of this field is presented

  20. Penetration of magnetic field in ferromagnetic transformer sheet

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, R; Ziolkowski, M

    1981-01-12

    The paper deals with the penetration of magnetic field in a ferromagnetic transformer sheet. The flux-density distribution is computed using Galerkin's procedure. The different boundary conditions and the nonlinear B/H characteristic is taken into account.

  1. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects

    KAUST Repository

    Zhang, Zhenkui; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    We examine the effects of several intrinsic defects on the magnetic behavior of ZnS nanostructures using hybrid density functional theory to gain insights into d0 ferromagnetism. Previous studies have predicted that the magnetism is due to a

  2. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    International Nuclear Information System (INIS)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H 2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between “on” and “off” states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (V Zn  + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, V Zn  + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μ B . The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism

  3. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    Science.gov (United States)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between "on" and "off" states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (VZn + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, VZn + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μB. The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism.

  4. Micromagnetic simulation of exchange coupled ferri-/ferromagnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Oezelt, Harald, E-mail: harald.oezelt@fhstp.ac.at [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Kovacs, Alexander; Reichel, Franz; Fischbacher, Johann; Bance, Simon [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Gusenbauer, Markus [Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria); Schubert, Christian; Albrecht, Manfred [Institute of Physics, Chemnitz University of Technology, Reichenhainer Straße 70, D-09126 Chemnitz (Germany); Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86159 Augsburg (Germany); Schrefl, Thomas [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria)

    2015-05-01

    Exchange coupled ferri-/ferromagnetic heterostructures are a possible material composition for future magnetic storage and sensor applications. In order to understand the driving mechanisms in the demagnetization process, we perform micromagnetic simulations by employing the Landau–Lifshitz–Gilbert equation. The magnetization reversal is dominated by pinning events within the amorphous ferrimagnetic layer and at the interface between the ferrimagnetic and the ferromagnetic layer. The shape of the computed magnetization reversal loop corresponds well with experimental data, if a spatial variation of the exchange coupling across the ferri-/ferromagnetic interface is assumed. - Highlights: • We present a model for exchange coupled ferri-/ferromagnetic heterostructures. • We incorporate the microstructural features of the amorphous ferrimagnet. • A distribution of interface exchange coupling is assumed to fit experimental data. • The reversal is dominated by pinning within the ferrimagnet and at the interface.

  5. Real-World Solutions for Developing High-Quality PHP Frameworks and Applications

    CERN Document Server

    Bergmann, Sebastian

    2011-01-01

    Learn to develop high-quality applications and frameworks in PHP Packed with in-depth information and step-by-step guidance, this book escorts you through the process of creating, maintaining and extending sustainable software of high quality with PHP. World-renowned PHP experts present real-world case studies for developing high-quality applications and frameworks in PHP that can easily be adapted to changing business requirements. . They offer different approaches to solving  typical development and quality assurance problems that every developer needs to know and master.Details the process

  6. Remote field eddy current testing of ferromagnetic tubes

    International Nuclear Information System (INIS)

    David, B.

    1990-01-01

    In order to test ferromagnetic tubes using internal probes, Intercontrole and the CEA have carried out theoretical and experimental works and developed a method to adapt the Remote Field Eddy Current technique which has been known and used for 30 years now. This document briefly recalls the basic principles of the Remote Field Eddy Current technique, the various steps of the works carried out and mainly describes examples of field inspection of ferromagnetic tubes and pipes [fr

  7. Targets with thin ferromagnetic layers for transient field experiments

    International Nuclear Information System (INIS)

    Gallant, J.L.; Dmytrenko, P.

    1982-01-01

    Multilayer targets containing a central layer sufficiently thin so that all recoil nuclei can traverse it and subsequently stop in a suitable cubic environment have been prepared. Such targets are required in experiments making use of a magnetic field acting on an ion moving through a ferromagnetic material. The preparation and annealing of the ferromagnetic foils (iron and gadolinium) and the fabrication of the multilayer targets are described. (orig.)

  8. Evidence of weak ferromagnetism in chromium(III) oxide particles

    International Nuclear Information System (INIS)

    Vazquez-Vazquez, Carlos; Banobre-Lopez, Manuel; Lopez-Quintela, M.A.; Hueso, L.E.; Rivas, J.

    2004-01-01

    The low temperature (4< T(K)<350) magnetic properties of chromium(III) oxide particles have been studied. A clear evidence of the presence of weak ferromagnetism is observed below 250 K. The magnetisation curves as a function of the applied field show coercive fields due to the canted antiferromagnetism of the particles. Around 55 K a maximum is observed in the zero-field-cooled curves; this maximum can be assumed as a blocking temperature, similarly to ultrafine ferromagnetic particles

  9. Idea on patent ; It is high time to stress quality

    International Nuclear Information System (INIS)

    2012-03-01

    This book deals with patent stressing on the quality, which includes from idea to technical business, It's simple to register the computer program, why do patent lawyer appoint the patent attorney's office? construction of patent right range, a good patent and a bad patent, strong patent and weak patent. It doesn't allow for Dus to use as we like, each patent has different value, Let's write technical specifications, advice on talking for invention with a patent attorney's office and what kind of task do intellectual property division do?

  10. High-quality PWO crystals for the PANDA-EMC

    International Nuclear Information System (INIS)

    Novotny, R W; Bremer, D; Dormenev, V; Drexler, P; Eissner, T; Kuske, T; Moritz, M

    2011-01-01

    The paper provides a status report on the crystal production and quality control of a major part of the PbWO 4 crystals for the PANDA-EMC. The results confirm the excellent performance of the new generation of PWO-II. The mechanism of stimulated recovery provides an additional tool to recover radiation damage at room and low temperatures by applying an external infrared light source. Even on-line recovery can be considered if the photo sensor is insensitive in that particular wavelength region.

  11. Measurement system with high accuracy for laser beam quality.

    Science.gov (United States)

    Ke, Yi; Zeng, Ciling; Xie, Peiyuan; Jiang, Qingshan; Liang, Ke; Yang, Zhenyu; Zhao, Ming

    2015-05-20

    Presently, most of the laser beam quality measurement system collimates the optical path manually with low efficiency and low repeatability. To solve these problems, this paper proposed a new collimated method to improve the reliability and accuracy of the measurement results. The system accuracy controlled the position of the mirror to change laser beam propagation direction, which can realize the beam perpendicularly incident to the photosurface of camera. The experiment results show that the proposed system has good repeatability and the measuring deviation of M2 factor is less than 0.6%.

  12. Rehosting of Bacterial Chaperones for High-Quality Protein Production▿

    Science.gov (United States)

    Martínez-Alonso, Mónica; Toledo-Rubio, Verónica; Noad, Rob; Unzueta, Ugutz; Ferrer-Miralles, Neus; Roy, Polly; Villaverde, Antonio

    2009-01-01

    Coproduction of DnaK/DnaJ in Escherichia coli enhances solubility but promotes proteolytic degradation of their substrates, minimizing the yield of unstable polypeptides. Higher eukaryotes have orthologs of DnaK/DnaJ but lack the linked bacterial proteolytic system. By coexpression of DnaK and DnaJ in insect cells with inherently misfolding-prone recombinant proteins, we demonstrate simultaneous improvement of soluble protein yield and quality and proteolytic stability. Thus, undesired side effects of bacterial folding modulators can be avoided by appropriate rehosting in heterologous cell expression systems. PMID:19820142

  13. Health-Related Quality of Life in Children with High-Functioning Autism

    Science.gov (United States)

    Potvin, Marie-Christine; Snider, Laurie; Prelock, Patricia A.; Wood-Dauphinee, Sharon; Kehayia, Eva

    2015-01-01

    The health-related quality of life of school-aged children with high-functioning autism is poorly understood. The objectives of this study were to compare the health-related quality of life of children with high-functioning autism to that of typically developing peers and to compare child-self and parent-proxy reports of health-related quality of…

  14. Publishing high-quality climate data on the semantic web

    Science.gov (United States)

    Woolf, Andrew; Haller, Armin; Lefort, Laurent; Taylor, Kerry

    2013-04-01

    The effort over more than a decade to establish the semantic web [Berners-Lee et. al., 2001] has received a major boost in recent years through the Open Government movement. Governments around the world are seeking technical solutions to enable more open and transparent access to Public Sector Information (PSI) they hold. Existing technical protocols and data standards tend to be domain specific, and so limit the ability to publish and integrate data across domains (health, environment, statistics, education, etc.). The web provides a domain-neutral platform for information publishing, and has proven itself beyond expectations for publishing and linking human-readable electronic documents. Extending the web pattern to data (often called Web 3.0) offers enormous potential. The semantic web applies the basic web principles to data [Berners-Lee, 2006]: using URIs as identifiers (for data objects and real-world 'things', instead of documents) making the URIs actionable by providing useful information via HTTP using a common exchange standard (serialised RDF for data instead of HTML for documents) establishing typed links between information objects to enable linking and integration Leading examples of 'linked data' for publishing PSI may be found in both the UK (http://data.gov.uk/linked-data) and US (http://www.data.gov/page/semantic-web). The Bureau of Meteorology (BoM) is Australia's national meteorological agency, and has a new mandate to establish a national environmental information infrastructure (under the National Plan for Environmental Information, NPEI [BoM, 2012a]). While the initial approach is based on the existing best practice Spatial Data Infrastructure (SDI) architecture, linked-data is being explored as a technological alternative that shows great promise for the future. We report here the first trial of government linked-data in Australia under data.gov.au. In this initial pilot study, we have taken BoM's new high-quality reference surface

  15. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    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

  16. Data-driven techniques to estimate parameters in a rate-dependent ferromagnetic hysteresis model

    International Nuclear Information System (INIS)

    Hu Zhengzheng; Smith, Ralph C.; Ernstberger, Jon M.

    2012-01-01

    The quantification of rate-dependent ferromagnetic hysteresis is important in a range of applications including high speed milling using Terfenol-D actuators. There exist a variety of frameworks for characterizing rate-dependent hysteresis including the magnetic model in Ref. , the homogenized energy framework, Preisach formulations that accommodate after-effects, and Prandtl-Ishlinskii models. A critical issue when using any of these models to characterize physical devices concerns the efficient estimation of model parameters through least squares data fits. A crux of this issue is the determination of initial parameter estimates based on easily measured attributes of the data. In this paper, we present data-driven techniques to efficiently and robustly estimate parameters in the homogenized energy model. This framework was chosen due to its physical basis and its applicability to ferroelectric, ferromagnetic and ferroelastic materials.

  17. Critical current enhancement by Lorentz force reduction in superconductor-ferromagnet nanocomposites

    International Nuclear Information System (INIS)

    Blamire, M G; Dinner, R B; Wimbush, S C; MacManus-Driscoll, J L

    2009-01-01

    Ferromagnetic pinning centres in superconductors form much deeper potential wells than equivalent insulating or metallic non-superconducting inclusions. However, the resultant pinning forces arising from magnetic inclusions are low because the magnetic interaction takes place over the length scale of the magnetic penetration depth which is large in technological superconductors. Nonetheless, we show that a magnetic inclusion can also reduce the Lorentz force on a vortex, yielding a substantially enhanced critical current density for a given pinning force. We calculate this enhancement for a single vortex pinned by a paramagnetic cylinder as well as a vortex lattice interacting with magnetic inclusions, and find that the inclusion of ferromagnetic particles or rods offers a practical means of enhancing the critical currents in oxide high temperature superconductors.

  18. Study on the Road Traffic Survey System Based on Micro-ferromagnetic Induction Coil Sensor

    Directory of Open Access Journals (Sweden)

    Liang Tong

    2014-05-01

    Full Text Available Road traffic information is the basis of road traffic management and control. Due to the special design of the sensor coil and ferromagnetic core, traffic survey system which uses micro ferromagnetic inductive coil vehicle detector, not only has the features of small size, simple installation and little road surface damage, but also has the advantages of output signal strength, simple signal processing circuit and obvious characteristics for output waveform corresponding vehicle feature. Based on the introduction of the sensor working principle, the construction of hardware and signal processing circuit for the traffic survey system is described in detail in the paper. Combined with the characteristics of the sensor output waveform, adaptive nearest neighbor clustering RBF neural network algorithm used to classify the vehicles is proposed and verified by experimental method. The result has a high vehicle classification rate and demonstrates the feasibility of the system.

  19. Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

    International Nuclear Information System (INIS)

    Wang, D.D.; Chen, Z.Q.; Li, C.Y.; Li, X.F.; Cao, C.Y.; Tang, Z.

    2012-01-01

    High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 °C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 °C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 °C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 °C. However, after 1400 °C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

  20. Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.D. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Chen, Z.Q., E-mail: chenzq@whu.edu.cn [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Li, C.Y.; Li, X.F. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Cao, C.Y.; Tang, Z. [Department of Electronic and Engineering, East China Normal University, Shanghai 200241 (China)

    2012-07-15

    High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 Degree-Sign C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 Degree-Sign C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 Degree-Sign C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 Degree-Sign C. However, after 1400 Degree-Sign C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

  1. Formation of spin-polarons in the ferromagnetic Kondo lattice model away from half-filling

    International Nuclear Information System (INIS)

    Arredondo, Y; Navarro, O; Vallejo, E; Avignon, M

    2012-01-01

    Even though realistic one-dimensional experiments in the field of half-metallic semiconductors are not at hand yet, we are interested in the underlying fundamental physics. In this regard we study a one-dimensional ferromagnetic Kondo lattice model, a model in which a conduction band is coupled ferromagnetically to a background of localized d moments with coupling constant J H , and investigate the T = 0 phase diagram as a function of the antiferromagnetic interaction J between the localized moments and the band-filling n, since it has been observed that doping of the compounds has led to formation of magnetic domains. We explore the spin-polaron formation by looking at the nearest-neighbour correlation functions in the spin and charge regimes for which we use the density matrix renormalization group method, which is a highly efficient method to investigate quasi-one-dimensional strongly correlated systems. (paper)

  2. Rare earth doped M-type hexaferrites; ferromagnetic resonance and magnetization dynamics

    Directory of Open Access Journals (Sweden)

    Vipul Sharma

    2018-05-01

    Full Text Available M-type hexagonal barium ferrites come in the category of magnetic material that plays a key role in electromagnetic wave propagation in various microwave devices. Due to their large magnetic anisotropy and large magnetization, their operating frequency exceeds above 50 GHz. Doping is a way to vary its magnetic properties to such an extent that its ferromagnetic resonance (FMR response can be tuned over a broad frequency band. We have done a complete FMR study of rare earth elements neodymium (Nd and samarium (Sm, with cobalt (Co as base, doped hexaferrite nanoparticles (NPs. X-ray diffractometry, vibrating sample magnetometer (VSM, and ferromagnetic resonance (FMR techniques were used to characterize the microstructure and magnetic properties of doped hexaferrite nanoparticles. Using proper theoretical electromagnetic models, various parameters are extracted from FMR data which play important role in designing and fabricating high-frequency microwave devices.

  3. Correlation between ferromagnetism and defects in MgO nanocrystals studied by positron annihilation

    Science.gov (United States)

    Wang, D. D.; Chen, Z. Q.; Li, C. Y.; Li, X. F.; Cao, C. Y.; Tang, Z.

    2012-07-01

    High purity MgO nanopowders were pressed into pellets and annealed in air from 100 to 1400 °C. Variation of the microstructures was investigated by X-ray diffraction and positron annihilation spectroscopy. Annealing induces an increase in the MgO grain size from 27 to 60 nm with temperature increasing up to 1400 °C. Positron annihilation measurements reveal vacancy defects including Mg vacancies, vacancy clusters, microvoids and large pores in the grain boundary region. Rapid recovery of Mg monovacancies and vacancy clusters was observed after annealing above 1200 °C. Room temperature ferromagnetism was observed for MgO nanocrystals annealed at 100, 700, and 1000 °C. However, after 1400 °C annealing, MgO nanocrystals turn into diamagnetic. Our results suggest that the room temperature ferromagnetism in MgO nanocrystals might originate from the interfacial defects.

  4. Room-temperature ferromagnetism observed in C-/N-/O-implanted MgO single crystals

    Science.gov (United States)

    Li, Qiang; Ye, Bonian; Hao, Yingping; Liu, Jiandang; Zhang, Jie; Zhang, Lijuan; Kong, Wei; Weng, Huimin; Ye, Bangjiao

    2013-01-01

    MgO single crystals were implanted with 70 keV C/N/O ions at room temperature with respective doses of 2 × 1016 and 2 × 1017 ions/cm2. All samples with high-dose implantation showed room temperature hysteresis in magnetization loops. Magnetization and slow positron annihilation measurements confirmed that room temperature ferromagnetism in O-implanted samples was attributed to the presence of Mg vacancies. Furthermore, the introduction of C or N played more effective role in ferromagnetic performance than Mg vacancies. Moreover, the magnetic moment possibly occurred from the localized wave function of unpaired electrons and the exchange interaction formed a long-range magnetic order.

  5. The spin-s quantum Heisenberg ferromagnetic models in the physical magnon theory

    International Nuclear Information System (INIS)

    Liu, B.-G.; Pu, F.-C.

    2001-01-01

    The spin-s quantum Heisenberg ferromagnetic model is investigated in the physical magnon theory. The effect of the extra unphysical magnon states on every site is completely removed in the magnon Hamiltonian and during approximation procedure so that the condition †n i a n i >=0(n≥2s+1) is rigorously satisfied. The physical multi-magnon occupancy †n i a n i >(1≤n≤2s) is proportional to T 3n/2 at low temperature and is equivalent to 1/(2s+1) at the Curie temperature. The magnetization not only unified but also well-behaved from zero temperature to Curie temperature is obtained in the framework of the magnon theory for the spin-s quantum Heisenberg ferromagnetic model. The ill-behaved magnetizations at high temperature in earlier magnon theories are completely corrected. The relation of magnon (spin wave) theory with spin-operator decoupling theory is clearly understood

  6. Room temperature ferromagnetism in Fe-doped semiconductor ZrS2 single crystals

    Science.gov (United States)

    Muhammad, Zahir; Lv, Haifeng; Wu, Chuanqiang; Habib, Muhammad; Rehman, Zia ur; Khan, Rashid; Chen, Shuangming; Wu, Xiaojun; Song, Li

    2018-04-01

    Two dimensional (2D) layered magnetic materials have obtained much attention due to their intriguing properties with a potential application in the field of spintronics. Herein, room-temperature ferromagnetism with 0.2 emu g‑1 magnetic moment is realized in Fe-doped ZrS2 single crystals of millimeter size, in comparison with diamagnetic behaviour in ZrS2. The electron paramagnetic resonance spectroscopy reveals that 5.2wt% Fe-doping ZrS2 crystal exhibit high spin value of g-factor about 3.57 at room temperature also confirmed this evidence, due to the unpaired electrons created by doped Fe atoms. First principle static electronic and magnetic calculations further confirm the increased stability of long range ferromagnetic ordering and enhanced magnetic moment in Fe-doped ZrS2, originating from the Fe spin polarized electron near the Fermi level.

  7. Quality Improvement, Inventory Management, Lead Time Reduction and Production Scheduling in High-Mix Manufacturing Environments

    Science.gov (United States)

    2017-01-13

    Quality Improvement , Inventory Management, Lead Time Reduction and Production Scheduling in High-mix Manufacturing Environments by Sean Daigle B.S...Mechanical Engineering Chairman, Department Committee on Graduate Theses 2 Quality Improvement , Inventory Management, Lead Time Reduction and... Production Scheduling in High-mix Manufacturing Environments by Sean Daigle Submitted to the Department of Mechanical Engineering on January 13, 2017, in

  8. Optimization of nitridation conditions for high quality inter-polysilicon dielectric layers

    NARCIS (Netherlands)

    Klootwijk, J.H.; Bergveld, H.J.; van Kranenburg, H.; Woerlee, P.H.; Wallinga, Hans

    1996-01-01

    Nitridation of deposited high temperature oxides (HTO) was studied to form high quality inter-polysilicon dielectric layers for embedded non volatile memories. Good quality dielectric layers were obtained earlier by using an optimized deposition of polysilicon and by performing a post-dielectric

  9. Bridges to Excellence--recognizing high-quality care: analysis of physician quality and resource use.

    Science.gov (United States)

    Rosenthal, Meredith B; de Brantes, Francois S; Sinaiko, Anna D; Frankel, Matthew; Robbins, Russell D; Young, Sara

    2008-10-01

    To examine whether physicians who sought and received Bridges to Excellence (BTE) recognition performed better than similar physicians on a standardized set of population-based performance measures. Cross-sectional comparison of performance data. Using a claims dataset of all commercially insured members from 6 health plans in Massachusetts, we examined population-based measures of quality and resource use for physicians recognized by the BTE programs Physician Office Link and Diabetes Care Link, compared with nonrecognized physicians in the same specialties. Differences in performance were tested using generalized linear models. Physician Office Link-recognized physicians performed significantly better than their nonrecognized peers on measures of cervical cancer screening, mammography, and glycosylated hemoglobin testing. Diabetes Care Link-recognized physicians performed significantly better on all 4 diabetes process measures of quality, with the largest differences observed in microalbumin screening (17.7%). Patients of Physician Office Link-recognized physicians had a significantly greater percentage of their resource use accounted for by evaluation and management services (3.4%), and a smaller percentage accounted for by facility (-1.6%), inpatient ancillary (-0.1%), and nonmanagement outpatient services (-1.0%). After adjustment for patient age and sex, and case mix, Physician Office Link-recognized physicians had significantly fewer episodes per patient (0.13) and lower resource use per episode (dollars 130), but findings were mixed for Diabetes Care Link-recognized physicians. Our findings suggest that the BTE approach to ascertaining physician quality identifies physicians who perform better on claims-based quality measures and primary care physicians who use a less resource-intensive practice style.

  10. Scanning X-ray microscopy of superconductor/ferromagnet bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Claudia; Ruoss, Stephen; Weigand, Markus; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University (Germany)

    2016-07-01

    The magnetic flux distribution arising from a high-T{sub c} superconductor is detected and visualized with high spatial resolution using scanning x-ray microscopy (SXM). Therefore, we introduce a sensor layer, namely, an amorphous, soft-magnetic CoFeB cover layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which is visualized using the large x-ray magnetic circular dichroism (XMCD) effect of the Co and Fe L3-edge. We show that the XMCD contrast in the sensor layer corresponds to the in-plane magnetic flux distribution of the superconductor and can hence be used to image magnetic structures in superconductors with high spatial resolution. Using the total electron yield (TEY) mode the surface structure and the magnetic domains can be imaged simultaneously and can be correlated. The measurements are carried out at our scanning x-ray microscope MAXYMUS at Bessy II, Berlin with the new low temperature setup.

  11. Active and passive kink mode studies in a tokamak with a movable ferromagnetic wall

    Energy Technology Data Exchange (ETDEWEB)

    Levesque, J. P.; Hughes, P. E.; Bialek, J.; Byrne, P. J.; Mauel, M. E.; Navratil, G. A.; Peng, Q.; Rhodes, D. J.; Stoafer, C. C. [Department of Applied Physics and Applied Mathematics, Columbia University, 500 W. 120th Street, New York, New York 10027 (United States)

    2015-05-15

    High-resolution active and passive kink mode studies are conducted in a tokamak with an adjustable ferromagnetic wall near the plasma surface. Ferritic tiles made from 5.6 mm thick Hiperco{sup ®} 50 alloy have been mounted on the plasma-facing side of half of the in-vessel movable wall segments in the High Beta Tokamak-Extended Pulse device [D. A. Maurer et al., Plasma Phys. Controlled Fusion 53, 074016 (2011)] in order to explore ferritic resistive wall mode stability. Low-activation ferritic steels are a candidate for structural components of a fusion reactor, and these experiments examine MHD stability of plasmas with nearby ferromagnetic material. Plasma-wall separation for alternating ferritic and non-ferritic wall segments is adjusted between discharges without opening the vacuum vessel. Amplification of applied resonant magnetic perturbations and plasma disruptivity are observed to increase when the ferromagnetic wall is close to plasma surface instead of the standard stainless steel wall. Rapidly rotating m/n=3/1 external kink modes have higher growth rates with the nearby ferritic wall. Feedback suppression of kinks is still as effective as before the installation of ferritic material in vessel, in spite of increased mode growth rates.

  12. Tunneling magnetoresistance in junctions composed of ferromagnets and time-reversal invariant topological superconductors

    International Nuclear Information System (INIS)

    Yan, Zhongbo; Wan, Shaolong

    2016-01-01

    Tunneling magnetoresistance between two ferrromagnets is an issue of fundamental importance in spintronics. In this work, we show that tunneling magnetoresistance can also emerge in junctions composed of ferromagnets and time-reversal invariant topological superconductors without spin-rotation symmetry. Here the physical origin is that when the spin-polarization direction of an injected electron from the ferromagnet lies in the same plane of the spin-polarization direction of Majorana zero modes, the electron will undergo a perfect spin-equal Andreev reflection, while injected electrons with other spin-polarization directions will be partially Andreev reflected and partially normal reflected, which consequently has a lower conductance, and therefore, the magnetoresistance effect emerges. Compared to conventional magnetic tunnel junctions, an unprecedented advantage of the junctions studied here is that arbitrary high tunneling magnetoresistance can be obtained even when the magnetization of the ferromagnets are weak and the insulating tunneling barriers are featureless. Our findings provide a new fascinating mechanism to obtain high tunneling magnetoresistance. (paper)

  13. Control of spin-orbit torques through crystal symmetry in WTe2/ferromagnet bilayers

    Science.gov (United States)

    MacNeill, D.; Stiehl, G. M.; Guimaraes, M. H. D.; Buhrman, R. A.; Park, J.; Ralph, D. C.

    2017-03-01

    Recent discoveries regarding current-induced spin-orbit torques produced by heavy-metal/ferromagnet and topological-insulator/ferromagnet bilayers provide the potential for dramatically improved efficiency in the manipulation of magnetic devices. However, in experiments performed to date, spin-orbit torques have an important limitation--the component of torque that can compensate magnetic damping is required by symmetry to lie within the device plane. This means that spin-orbit torques can drive the most current-efficient type of magnetic reversal (antidamping switching) only for magnetic devices with in-plane anisotropy, not the devices with perpendicular magnetic anisotropy that are needed for high-density applications. Here we show experimentally that this state of affairs is not fundamental, but rather one can change the allowed symmetries of spin-orbit torques in spin-source/ferromagnet bilayer devices by using a spin-source material with low crystalline symmetry. We use WTe2, a transition-metal dichalcogenide whose surface crystal structure has only one mirror plane and no two-fold rotational invariance. Consistent with these symmetries, we generate an out-of-plane antidamping torque when current is applied along a low-symmetry axis of WTe2/Permalloy bilayers, but not when current is applied along a high-symmetry axis. Controlling spin-orbit torques by crystal symmetries in multilayer samples provides a new strategy for optimizing future magnetic technologies.

  14. Orthorhombic Ti2O3: A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide

    KAUST Repository

    Li, Yangyang

    2017-12-16

    Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long-wavelength regimes. In this work, the discovery of orthorhombic-structured Ti2O3 films is reported as a unique narrow-bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well-known corundum-structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n-type with a very high electron concentration, while the bulk-type trigonal-structured Ti2O3 is p-type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X-ray magnetic circular dichroism measurements. Using first-principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room-temperature ferromagnetism observed in orthorhombic-structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.

  15. Orthorhombic Ti2O3: A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide

    KAUST Repository

    Li, Yangyang; Weng, Yakui; Yin, Xinmao; Yu, Xiaojiang; Sarath Kumar, S. R.; Wehbe, Nimer; Wu, Haijun; Alshareef, Husam N.; Pennycook, Stephen J.; Breese, Mark B. H.; Chen, Jingsheng; Dong, Shuai; Wu, Tao

    2017-01-01

    Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long-wavelength regimes. In this work, the discovery of orthorhombic-structured Ti2O3 films is reported as a unique narrow-bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well-known corundum-structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n-type with a very high electron concentration, while the bulk-type trigonal-structured Ti2O3 is p-type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X-ray magnetic circular dichroism measurements. Using first-principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room-temperature ferromagnetism observed in orthorhombic-structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.

  16. Novel superconducting state in ferromagnetic superconductor UCoGe. Microscopic coexistence of ferromagnetism and superconductivity probed by 59Co-NQR measurements

    International Nuclear Information System (INIS)

    Ishida, Kenji; Hattori, Taisuke; Ihara, Yoshihiko; Nakai, Yusuke; Sato, Noriaki K.; Deguchi, Kazuhiko; Tamura, Nobuyuki; Satoh, Isamu

    2010-01-01

    We have investigated the relationship between ferromagnetism and superconductivity in ferromagnetic superconductor UCoGe from 59 Co nuclear quadrupole resonance (NQR) measurements. Our experimental results indicate the microscopic coexistence of ferromagnetism and superconductivity in UCoGe, and suggest a 'self-induced vortex state' in its superconducting state. We also review NQR experiments, which play an important role in this study. (author)

  17. Academic coordination at university: Strategies for high quality education

    Directory of Open Access Journals (Sweden)

    Maria del Mar Durán Bellonch

    2009-08-01

    Full Text Available Most lecturers and professors involved in teaching School Management and Education Management courses have been engaged in developing some innovative actions to improve the training quality that we offer to students in the Pedagogy degree at the Autonomous University of Barcelona. These actions are aimed at increasing co-ordination among the teaching staff when designing and implementing the course curricula. Co-ordination meetings, exchanges of teaching experiences, discussions about what, how and when to teach the different contents, in which courses and at what level, methodological issues pointed out through technical description cards or the elaboration of study cases to be solved have become the basis of relevant actions during the last academic years. This paper explains each one of them, and provides useful information about the theoretical background, the process carried out, some of the results obtained, the output and the tools created.

  18. Possibilities of obtaining and controlling high-quality pressure castings

    Directory of Open Access Journals (Sweden)

    S. Pietrowski

    2011-07-01

    Full Text Available The paper presents the influence of the type of furnace charging melting, refining and modification silumins 226 and 231 on the porosity and microstructure of castings. It was shown that in order to reduce or eliminate the porosity of the castings is necessary to the refining ECOSAL-AL113 of liquid silumin both in the melting furnace, and in the ladle and an additional nitrogen, in the heat furnace modified and refining with nitrogen. To control the effects of refining and modifying the TDA method was used. It was found that based on crystal- lization curve can be qualitatively assess the gas porosity of the castings. In order to control and quality control silumins author developed a computer program using the method of TDA, which sets out: Rm, A5, HB and casting porosity P and the concentration of hydrogen in them. The program also informs the technological procedures to be performed for liquid silumin improper preparation.

  19. TWO FERROMAGNETIC SPHERES IN HOMOGENEOUS MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    Yury A. Krasnitsky

    2018-01-01

    Full Text Available The problem of two spherical conductors is studied quite in detail with bispherical coordinates usage and has numerous appendices in an electrostatics. The boundary-value problem about two ferromagnetic spheres enclosed on homogeneous and infinite environment in which the lack of spheres exists like homogeneous magnetic field is considered. The solution of Laplace's equation in the bispherical system of coordinates allows us to find the potential and field distribution in all spaces, including area between spheres. The boundary conditions in potential continuity and in ordinary density constituent of spheres surfaces induction flux are used. It is supposed that spheres are identical, and magnetic permeability of their material is expressed in  >> 0. The problem about falling of electromagnetic plane wave on the system of two spheres, which possesses electrically small sizes, can be considered as quasistationary. The scalar potentials received as a result of Laplace's equation solution are represented by the series containing Legendre polynomials. The concept of two spheres system effective permeability is introduced. It is equal to the advantage in magnitude of magnetic induction flux vector through a certain system’s section arising due to its magnetic properties. Necessary ratios for the effective permeability referred to the central system’s section are obtained. Particularly, the results can be used during the analysis of ferroxcube core clearance, which influences on the magnetic antenna properties. 

  20. Vortex precession in thin elliptical ferromagnetic nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Zaspel, C.E., E-mail: craig.zaspel@umwestern.edu

    2017-07-01

    Highlights: • A general form for the magnetostatic energy is calculated for the vortex state in a ferromagnetic ellipse. • The ellipse magnetostatic energy is minimized by conformal mapping the circular disk onto the ellipse. • The gyrotropic precession frequency is obtained in general for a range of ellipticities. - Abstract: The magnetostatic energy is calculated for a magnetic vortex in a noncircular elliptical nanodisk. It is well-known that the energy of a vortex in the circular disk is minimized though an ansatz that eliminates the magnetostatic charge at the disk edge. Beginning with this ansatz for the circular disk, a conformal mapping of a circle interior onto the interior of an ellipse results in the magnetization of the elliptical disk. This magnetization in the interior of an ellipse also has no magnetostatic charge at the disk edge also minimizing the magnetostatic energy. As expected the energy has a quadratic dependence on the displacement of the vortex core from the ellipse center, but reflecting the lower symmetry of the ellipse. Through numerical integration of the magnetostatic integral a general expression for the energy is obtained for ellipticity values from 1.0 to about 0.3. Finally a general expression for the gyrotropic frequency as described by the Thiele equation is obtained.

  1. Ferromagnetic resonance studies of lunar core stratigraphy

    Science.gov (United States)

    Housley, R. M.; Cirlin, E. H.; Goldberg, I. B.; Crowe, H.

    1976-01-01

    We first review the evidence which links the characteristic ferromagnetic resonance observed in lunar fines samples with agglutinatic glass produced primarily by micrometeorite impacts and present new results on Apollo 15, 16, and 17 breccias which support this link by showing that only regolith breccias contribute significantly to the characteristic FMR intensity. We then provide a calibration of the amount of Fe metal in the form of uniformly magnetized spheres required to give our observed FMR intensities and discuss the theoretical magnetic behavior to be expected of Fe spheres as a function of size. Finally, we present FMR results on samples from every 5 mm interval in the core segments 60003, 60009, and 70009. These results lead us to suggest: (1) that secondary mixing may generally be extensive during regolith deposition so that buried regolith surfaces are hard to recognize or define; and (2) that local grinding of rocks and pebbles during deposition may lead to short scale fluctuations in grain size, composition, and apparent exposure age of samples.

  2. Ferromagnetic characteristics of HfFe2

    International Nuclear Information System (INIS)

    Novakovic, N.; Belosevic-Cavor, J.; Cekic, B.; Manasijevic, M.; Milosevic, Z. . E-mail address of correspoding author: novnik@rt270.vin.bg.ac.yu; Novakovic, N.)

    2003-01-01

    The magnetic hyperfine fields at 181 Ta ion-probe sites in the HfFe 2 polycrystalline binary compound were measured using the time-differential perturbed angular correlation (TDPAC) method. Measurements were performed in the absence of polarizing external magnetic field, at room temperature. The existence of two different structures, dominant cubic MgCu 2 -type and hexagonal MgZn 2 -type in our HfFe 2 sample was refined. Both structures are ferromagnetic with Curie temperatures, which differ significantly (588 K for MgCu 2 and 427 K for MgZn 2 ). The corresponding values of hyperfine fields are H hf 13.8±0.1 T for MgCu 2 -type structure and H hf = 8.0±0.2 T for MgZn 2 -type structure. Calculations using LAPW-Wien 97 program package are in progress and preliminary results are in good agreement with experiment. The analysis includes qualitative explanation of the exchange interactions mechanism between magnetic dipole moment of the observed 181 Ta ion-probe and magnetic dipole moments of the nearest neighbours on the corresponding coordination polyhedra. All these results will be published recently. (author)

  3. Nuclear magnetic resonance in ferromagnetic terbium metal

    International Nuclear Information System (INIS)

    Cha, C.L.T.

    1974-01-01

    The magnetic properties of terbium were studied by the method of zero field nuclear magnetic resonance at 1.5 to 4 and 85 to 160 0 K. Two unconventional experimental techniques have been employed: the swept frequency and the swept temperature technique. Near 4 0 K, triplet resonance line structures were found and interpreted in terms of the magnetic domain and wall structures of ferromagnetic terbium. In the higher temperature range, temperature dependence of the resonance frequency and the quadrupole splitting were measured. The former provides a measurement of the temperature dependence of the magnetization M, and it agrees with bulk M measurements as well as the latest spin wave theory of M(T) (Brooks 1968). The latter agrees well with a calculation using a very general single ion density matrix for collective excitations (Callen and Shtrikman 1965). In addition, the small temperature-independent contribution to the electric field gradient at the nucleus due to the lattice and conduction electrons was untangled from the P(T) data. Also an anomalous and unexplained relaxation phenomenon was also observed

  4. Room temperature ferromagnetic gadolinium silicide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

    2018-03-06

    A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.

  5. Controlled synthesis of high-quality nickel sulfide chain-like tubes and echinus-like nanostructures by a solution chemical route

    International Nuclear Information System (INIS)

    Zhang Yahui; Guo Lin; He Lin; Liu, Kang; Chen Chinping; Zhang Qi; Wu Ziyu

    2007-01-01

    Chain-like NiS tubes and echinus-like nickel sulfide (Ni 3 S 2 ) nanostructures were synthesized successfully by a solution chemical route. The growth models of these two materials and the most possible mutation process between these two different morphologies are discussed. The temperature and field dependent magnetizations, M(T) and M(H), show that both the samples have a very weak ferromagnetism and exhibit a strong paramagnetic response in a high applied field

  6. prediction of bread-making quality using size exclusion high

    African Journals Online (AJOL)

    ACSS

    Variation in the distribution of protein molecular weight in wheat (Triticum aestivum), influences ... with high G/G ratios in SDS-insoluble protein fraction were Sceptre x Nata and Kariega x Sceptre. ...... Molecular characterisation and dynamic.

  7. High-quality single crystals for neutron experiments

    Indian Academy of Sciences (India)

    studies and our collaborative research projects with other UK and international groups will be discussed. Keywords. Crystal growth; floating zone method; neutron scattering. ... of single crystals of new materials is a highly competitive business.

  8. In vitro utilization of ferromagnetic nanoparticles in hemodialysis therapy

    International Nuclear Information System (INIS)

    Stamopoulos, D; Benaki, D; Bouziotis, P; Zirogiannis, P N

    2007-01-01

    The in vitro utilization of biocompatible ferromagnetic nanoparticles (BFNs) in hemodialysis (HD), routinely used today for the treatment of end stage renal disease (ESRD), is introduced in this work. The proposed strategy is termed magnetically assisted hemodialysis (MAHD) and it aims to become a more efficient development of conventional HD. The method is based on the production of biocompatible ferromagnetic nanoparticles-targeted binding substances conjugates (BFNs-TBSs Cs) constructed of BFNs and specifically designed TBSs that should have high affinity and binding capacity for target toxic substances (TTSs) which must be removed from the ESRD patient subjected to HD. Antibodies or even specific proteins could serve as the TBS of the desired BFNs-TBSs Cs. The BFNs-TBSs Cs should be administered to the patient timely prior to the MAHD session so as to bind with the desired TTSs during their free circulation in the vascular network. Eventually, the complete BFNs-TBSs-TTSs structure can be selectively removed during the MAHD session by means of an external inhomogeneous magnetic field that is applied either at the dialyzer or at other collection point(s) along the blood circulation line of the dialysis machine. The advantages of MAHD over conventional HD regarding the patient's comfort and overall health status are discussed in detail among practical issues. To examine this proposition we employed Fe 3 O 4 and bovine serum albumin (BSA) as the BFN and the TBS constituents respectively, since they are both highly biocompatible. By means of x-ray diffraction, atomic force microscopy, circular dichroism spectropolarimetry, UV-vis spectrophotometry, SQUID magnetometry, and nuclear magnetic resonance we evaluated (i) the structural/morphological characteristics, (ii) the magnetic retraction efficiency, and most importantly (iii) the toxin binding affinity and capacity of both bare Fe 3 O 4 BFNs and Fe 3 O 4 -BSA Cs by performing in vitro experiments on specific TTSs

  9. In vitro utilization of ferromagnetic nanoparticles in hemodialysis therapy

    Energy Technology Data Exchange (ETDEWEB)

    Stamopoulos, D [Institute of Materials Science, NCSR ' Demokritos' , 153-10, Aghia Paraskevi, Athens (Greece); Benaki, D [Institute of Biology, NCSR ' Demokritos' , 153-10, Aghia Paraskevi, Athens (Greece); Bouziotis, P [Institute of Radioisotopes-Radiodiagnostic Products, NCSR ' Demokritos' , 153-10, Aghia Paraskevi, Athens (Greece); Zirogiannis, P N [Department of Nephrology, General Hospital ' G Gennimatas' , National Health System, 115-27, Athens (Greece)

    2007-12-12

    The in vitro utilization of biocompatible ferromagnetic nanoparticles (BFNs) in hemodialysis (HD), routinely used today for the treatment of end stage renal disease (ESRD), is introduced in this work. The proposed strategy is termed magnetically assisted hemodialysis (MAHD) and it aims to become a more efficient development of conventional HD. The method is based on the production of biocompatible ferromagnetic nanoparticles-targeted binding substances conjugates (BFNs-TBSs Cs) constructed of BFNs and specifically designed TBSs that should have high affinity and binding capacity for target toxic substances (TTSs) which must be removed from the ESRD patient subjected to HD. Antibodies or even specific proteins could serve as the TBS of the desired BFNs-TBSs Cs. The BFNs-TBSs Cs should be administered to the patient timely prior to the MAHD session so as to bind with the desired TTSs during their free circulation in the vascular network. Eventually, the complete BFNs-TBSs-TTSs structure can be selectively removed during the MAHD session by means of an external inhomogeneous magnetic field that is applied either at the dialyzer or at other collection point(s) along the blood circulation line of the dialysis machine. The advantages of MAHD over conventional HD regarding the patient's comfort and overall health status are discussed in detail among practical issues. To examine this proposition we employed Fe{sub 3}O{sub 4} and bovine serum albumin (BSA) as the BFN and the TBS constituents respectively, since they are both highly biocompatible. By means of x-ray diffraction, atomic force microscopy, circular dichroism spectropolarimetry, UV-vis spectrophotometry, SQUID magnetometry, and nuclear magnetic resonance we evaluated (i) the structural/morphological characteristics, (ii) the magnetic retraction efficiency, and most importantly (iii) the toxin binding affinity and capacity of both bare Fe{sub 3}O{sub 4} BFNs and Fe{sub 3}O{sub 4}-BSA Cs by performing in vitro

  10. Quality

    International Nuclear Information System (INIS)

    Burnett, N.; Jeffries, J.; Mach, J.; Robson, M.; Pajot, D.; Harrigan, J.; Lebsack, T.; Mullen, D.; Rat, F.; Theys, P.

    1993-01-01

    What is quality? How do you achieve it? How do you keep it once you have got it. The answer for industry at large is the three-step hierarchy of quality control, quality assurance and Total quality Management. An overview is given of the history of quality movement, illustrated with examples from Schlumberger operations, as well as the oil industry's approach to quality. An introduction of the Schlumberger's quality-associated ClientLink program is presented. 15 figs., 4 ills., 16 refs

  11. High quality actively cooled plasma-facing components for fusion

    International Nuclear Information System (INIS)

    Nygren, R.E.

    1995-01-01

    This paper interweaves some suggestions for developing actively cooled plasma-facing components (PFCs) for future fusion devices, with supporting examples taken from the design, fabrication and operation of Tore Supra's Phase III outboard pump limiter (OPL). This actively cooled midplane limiter, designed for heat and particle removal during long-pulse operation, has been operated under essentially thermally steady state conditions. Testing to identify braze flaws, analysis of the impact of joining flaws on the thermal-hydraulic performance of the OPL, and the extensive calorimetry and IR thermography used to confirm and update safe operating limits for power handling of the OPL are reviewed. This experience suggests that, for PFCs in future fusion devices, flaw-tolerant designs are possible; analyses of the impacts of flaws on performance can provide criteria for quality assurance; and validating appropriate methods of inspection for such flaws early in the design development of PFCs is prudent. The need for in-service monitoring is also discussed. (orig.)

  12. Health care in small prisons: incorporating high-quality standards.

    Science.gov (United States)

    Rieder, Jean-Pierre; Casillas, Alejandra; Mary, Gérard; Secretan, Anne-Dominique; Gaspoz, Jean-Michel; Wolff, Hans

    2013-01-01

    In the past, health management in Geneva's six post-trial prisons had been variable and inconsistent. In 2008, the unit of penitentiary medicine of the Geneva University Hospitals was mandated to re-organize and provide health care at all six prison facilities. The specific aim of this paper is to outline the example as a practical solution to some of the common challenges in unifying the structure and process of health services across multiple small facilities, while meeting European prison health and local quality standards. Geneva's post-trial prisons are small and close to one another in geographical proximity - ideal conditions for the construction of a health mobile team (HMT). This multidisciplinary mobile team operated like a community ambulatory care model; it was progressively launched in all prison facilities in Geneva. The authors incorporated an implementation strategy where health providers partnered with prison and community stakeholders in the health delivery model's development and adaption process. The model's strategic initiatives are described along the following areas, in light of other international prison health activity and prior care models: access to a health care professional, equivalence of care, patient consent, confidentiality, humanitarian interventions, and professional competence and independence. From the perspective of the HMT members, the authors provide the "lessons learned" through this experience, especially to providers who are working on prison health services reform and coordination improvement. The paper particularly stresses the importance of partnering with community health stakeholders and prison staff, a key component to the approach.

  13. Electrical detection of ferromagnetic resonance in ferromagnet/n-GaAs heterostructures by tunneling anisotropic magnetoresistance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Boyko, Y.; Geppert, C. C.; Christie, K. D.; Stecklein, G.; Crowell, P. A., E-mail: crowell@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Patel, S. J. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Palmstrøm, C. J. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2014-11-24

    We observe a dc voltage peak at ferromagnetic resonance (FMR) in samples consisting of a single ferromagnetic (FM) layer grown epitaxially on the n-GaAs (001) surface. The FMR peak is detected as an interfacial voltage with a symmetric line shape and is present in samples based on various FM/n-GaAs heterostructures, including Co{sub 2}MnSi/n-GaAs, Co{sub 2}FeSi/n-GaAs, and Fe/n-GaAs. We show that the interface bias voltage dependence of the FMR signal is identical to that of the tunneling anisotropic magnetoresistance (TAMR) over most of the bias range. Furthermore, we show how the precessing magnetization yields a dc FMR signal through the TAMR effect and how the TAMR phenomenon can be used to predict the angular dependence of the FMR signal. This TAMR-induced FMR peak can be observed under conditions where no spin accumulation is present and no spin-polarized current flows in the semiconductor.

  14. A high-quality catalog of the Drosophila melanogaster proteome

    DEFF Research Database (Denmark)

    Brunner, Erich; Ahrens, Christian H.; Mohanty, Sonaly

    2007-01-01

    % of the predicted Drosophila melanogaster proteome by detecting 9,124 proteins from 498,000 redundant and 72,281 distinct peptide identifications. This unprecedented high proteome coverage for a complex eukaryote was achieved by combining sample diversity, multidimensional biochemical fractionation and analysis...

  15. Bust economics: foragers choose high quality habitats in lean times

    Directory of Open Access Journals (Sweden)

    Sonny S. Bleicher

    2016-01-01

    Full Text Available In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high.

  16. Whole high-quality light environment for humans and plants

    Science.gov (United States)

    Sharakshane, Anton

    2017-11-01

    Plants sharing a single light environment on a spaceship with a human being and bearing a decorative function should look as natural and attractive as possible. And consequently they can be illuminated only with white light with a high color rendering index. Can lighting optimized for a human eye be effective and appropriate for plants? Spectrum-based effects have been compared under artificial lighting of plants by high-pressure sodium lamps and general-purpose white LEDs. It has been shown that for the survey sample phytochrome photo-equilibria does not depend significantly on the parameters of white LED light, while the share of phytoactive blue light grows significantly as the color temperature increases. It has been revealed that yield photon flux is proportional to luminous efficacy and increases as the color temperature decreases, general color rendering index Ra and the special color rendering index R14 (green leaf) increase. General-purpose white LED lamps with a color temperature of 2700 K, Ra > 90 and luminous efficacy of 100 lm/W are as efficient as the best high-pressure sodium lamps, and at a higher luminous efficacy their yield photon flux per joule is even bigger in proportion. Here we show that demand for high color rendering white LED light is not contradictory to the agro-technical objectives.

  17. Electronic Structure Evolution across the Peierls Metal-Insulator Transition in a Correlated Ferromagnet

    Directory of Open Access Journals (Sweden)

    P. A. Bhobe

    2015-10-01

    Full Text Available Transition metal compounds often undergo spin-charge-orbital ordering due to strong electron-electron correlations. In contrast, low-dimensional materials can exhibit a Peierls transition arising from low-energy electron-phonon-coupling-induced structural instabilities. We study the electronic structure of the tunnel framework compound K_{2}Cr_{8}O_{16}, which exhibits a temperature-dependent (T-dependent paramagnetic-to-ferromagnetic-metal transition at T_{C}=180  K and transforms into a ferromagnetic insulator below T_{MI}=95  K. We observe clear T-dependent dynamic valence (charge fluctuations from above T_{C} to T_{MI}, which effectively get pinned to an average nominal valence of Cr^{+3.75} (Cr^{4+}∶Cr^{3+} states in a 3∶1 ratio in the ferromagnetic-insulating phase. High-resolution laser photoemission shows a T-dependent BCS-type energy gap, with 2G(0∼3.5(k_{B}T_{MI}∼35  meV. First-principles band-structure calculations, using the experimentally estimated on-site Coulomb energy of U∼4  eV, establish the necessity of strong correlations and finite structural distortions for driving the metal-insulator transition. In spite of the strong correlations, the nonintegral occupancy (2.25 d-electrons/Cr and the half-metallic ferromagnetism in the t_{2g} up-spin band favor a low-energy Peierls metal-insulator transition.

  18. Room temperature ferromagnetism in Mn-doped NiO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Layek, Samar, E-mail: samarlayek@gmail.com; Verma, H.C.

    2016-01-01

    Mn-doped NiO nanoparticles of the series Ni{sub 1−x}Mn{sub x}O (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum. - Highlights: • Mn-doped NiO nanoparticles are prepared by a simple hydrothermal method. • Unit cell volume decreases with increasing doping concentration. • Mn-doping leads to room temperature ferromagnetism in NiO nanoparticles. • Magnetization is highest for 2% Mn-doping. • Above 2%, magnetization decreases with increasing doping.

  19. Room temperature ferromagnetism in Mn-doped NiO nanoparticles

    International Nuclear Information System (INIS)

    Layek, Samar; Verma, H.C.

    2016-01-01

    Mn-doped NiO nanoparticles of the series Ni_1_−_xMn_xO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum. - Highlights: • Mn-doped NiO nanoparticles are prepared by a simple hydrothermal method. • Unit cell volume decreases with increasing doping concentration. • Mn-doping leads to room temperature ferromagnetism in NiO nanoparticles. • Magnetization is highest for 2% Mn-doping. • Above 2%, magnetization decreases with increasing doping.

  20. Magnetic enhancement of ferroelectric polarization in a self-grown ferroelectric-ferromagnetic composite

    Science.gov (United States)

    Kumar, Amit; Narayan, Bastola; Pachat, Rohit; Ranjan, Rajeev

    2018-02-01

    Ferroelectric-ferromagnetic multiferroic composites are of great interest both from the scientific and technological standpoints. The extent of coupling between polarization and magnetization in such two-phase systems depends on how efficiently the magnetostrictive and electrostrictive/piezoelectric strain gets transferred from one phase to the other. This challenge is most profound in the easy to make 0-3 ferroelectric-ferromagnetic particulate composites. Here we report a self-grown ferroelectric-ferromagnetic 0-3 particulate composite through controlled spontaneous precipitation of ferrimagnetic barium hexaferrite phase (BaF e12O19 ) amid ferroelectric grains in the multiferroic alloy system BiFe O3-BaTi O3 . We demonstrate that a composite specimen exhibiting merely ˜1% hexaferrite phase exhibits ˜34% increase in saturation polarization in a dc magnetic field of ˜10 kOe. Using modified Rayleigh analysis of the polarization field loop in the subcoercive field region we argue that the substantial enhancement in the ferroelectric switching is associated with the reduction in the barrier heights of the pinning centers of the ferroelectric-ferroelastic domain walls in the stress field generated by magnetostriction in the hexaferrite grains when the magnetic field is turned on. Our study proves that controlled precipitation of the magnetic phase is a good strategy for synthesis of 0-3 ferroelectric-ferromagnetic particulate multiferroic composite as it not only helps in ensuring a good electrical insulating character of the composite, enabling it to sustain high enough electric field for ferroelectric switching, but also the factors associated with the spontaneity of the precipitation process ensure efficient transfer of the magnetostrictive strain/stress to the surrounding ferroelectric matrix making domain wall motion easy.