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Sample records for underwent structural magnetic

  1. Magnetic multilayer structure

    Science.gov (United States)

    Herget, Philipp; O'Sullivan, Eugene J.; Romankiw, Lubomyr T.; Wang, Naigang; Webb, Bucknell C.

    2016-07-05

    A mechanism is provided for an integrated laminated magnetic device. A substrate and a multilayer stack structure form the device. The multilayer stack structure includes alternating magnetic layers and diode structures formed on the substrate. Each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by a diode structure.

  2. Magnetic Structure of Erbium

    DEFF Research Database (Denmark)

    Gibbs, D.; Bohr, Jakob; Axe, J. D.

    1986-01-01

    We present a synchrotron x-ray scattering study of the magnetic phases of erbium. In addition to the magnetic scattering located at the fundamental wave vector τm we also observe scattering from magnetoelastically induced charge modulations at the fundamental wave vector, at twice the fundamental......, and at positions split symmetrically about the fundamental. As the temperature is lowered below 52 K the charge and magnetic scattering display a sequence of lock-in transitions to rational wave vectors. A spin-slip description of the magnetic structure is presented which explains the wave vectors...

  3. SMARTer for magnetic structure studies

    Indian Academy of Sciences (India)

    Small angle neutron scattering; magnetic structure; Cu(NiFe); CuCo; ... micromagnetism, magnetic clusters embedded in a solid nonmagnetic matrix, mag- .... project. E G R Putra acknowledges the support from IAEA through the ISNS2008.

  4. Optimally segmented magnetic structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bahl, Christian; Bjørk, Rasmus

    We present a semi-analytical algorithm for magnet design problems, which calculates the optimal way to subdivide a given design region into uniformly magnetized segments.The availability of powerful rare-earth magnetic materials such as Nd-Fe-B has broadened the range of applications of permanent...... is not available.We will illustrate the results for magnet design problems from different areas, such as electric motors/generators (as the example in the picture), beam focusing for particle accelerators and magnetic refrigeration devices.......We present a semi-analytical algorithm for magnet design problems, which calculates the optimal way to subdivide a given design region into uniformly magnetized segments.The availability of powerful rare-earth magnetic materials such as Nd-Fe-B has broadened the range of applications of permanent...... magnets[1][2]. However, the powerful rare-earth magnets are generally expensive, so both the scientific and industrial communities have devoted a lot of effort into developing suitable design methods. Even so, many magnet optimization algorithms either are based on heuristic approaches[3...

  5. Spin Structures in Magnetic Nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Brok, Erik; Frandsen, Cathrine

    2013-01-01

    Spin structures in nanoparticles of ferrimagnetic materials may deviate locally in a nontrivial way from ideal collinear spin structures. For instance, magnetic frustration due to the reduced numbers of magnetic neighbors at the particle surface or around defects in the interior can lead to spin...... canting and hence a reduced magnetization. Moreover, relaxation between almost degenerate canted spin states can lead to anomalous temperature dependences of the magnetization at low temperatures. In ensembles of nanoparticles, interparticle exchange interactions can also result in spin reorientation....... Here, we give a short review of anomalous spin structures in nanoparticles....

  6. Magnetic structures: neutron diffraction studies

    International Nuclear Information System (INIS)

    Bouree-Vigneron, F.

    1990-01-01

    Neutron diffraction is often an unequivocal method for determining magnetic structures. Here we present some typical examples, stressing the sequence through experiments, data analysis, interpretation and modelisation. Two series of compounds are chosen: Tb Ni 2 Ge 2 and RBe 13 (R = Gd, Tb, Dy, Ho, Er). Depending on the nature of the elements, the magnetic structures produced can be commensurate, incommensurate or even show a transition between two such phases as a function of temperature. A model, taking magnetic exchange and anisotropy into account, will be presented in the case of commensurate-incommensurate magnetic transitions in RBe 13

  7. Internal structure of magnetic endosomes

    Science.gov (United States)

    Rivière, C.; Wilhelm, C.; Cousin, F.; Dupuis, V.; Gazeau, F.; Perzynski, R.

    2007-01-01

    The internal structure of biological vesicles filled with magnetic nanoparticles is investigated using the following complementary analyses: electronic transmission microscopy, dynamic probing by magneto-optical birefringence and structural probing by Small Angle Neutron Scattering (SANS). These magnetic vesicles are magnetic endosomes obtained via a non-specific interaction between cells and anionic magnetic iron oxide nanoparticles. Thanks to a magnetic purification process, they are probed at two different stages of their formation within HeLa cells: (i) adsorption of nanoparticles onto the cellular membrane and (ii) their subsequent internalisation within endosomes. Differences in the microenvironment of the magnetic nanoparticles at those two different stages are highlighted here. The dynamics of magnetic nanoparticles adsorbed onto cellular membranes and confined within endosomes is respectively 3 and 5 orders of magnitude slower than for isolated magnetic nanoparticles in aqueous media. Interestingly, SANS experiments show that magnetic endosomes have an internal structure close to decorated vesicles, with magnetic nanoparticles locally decorating the endosome membrane, inside their inner-sphere. These results, important for future biomedical applications, suggest that multiple fusions of decorated vesicles are the biological processes underlying the endocytosis of that kind of nanometric materials.

  8. Plated lamination structures for integrated magnetic devices

    Science.gov (United States)

    Webb, Bucknell C.

    2014-06-17

    Semiconductor integrated magnetic devices such as inductors, transformers, etc., having laminated magnetic-insulator stack structures are provided, wherein the laminated magnetic-insulator stack structures are formed using electroplating techniques. For example, an integrated laminated magnetic device includes a multilayer stack structure having alternating magnetic and insulating layers formed on a substrate, wherein each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by an insulating layer, and a local shorting structure to electrically connect each magnetic layer in the multilayer stack structure to an underlying magnetic layer in the multilayer stack structure to facilitate electroplating of the magnetic layers using an underlying conductive layer (magnetic or seed layer) in the stack as an electrical cathode/anode for each electroplated magnetic layer in the stack structure.

  9. Structural design of DEALS magnet

    International Nuclear Information System (INIS)

    Bezler, P.; Hsieh, S.Y.; Balderes, T.; Brown, T.; Bundy, J.

    1979-01-01

    A design for the extraneous magnet structure to support all the magnet loads was developed. The structure consists of two demountable structural systems designed to support the in-plane and out-of-plane loads, respectively. The in-plane loads are resisted by a cold central bucking cylinder and pin connected, plate-beam structural members following the outer periphery of each coil. The out-of-plane, torsional loads are resisted by the concerted action of the central bucking column and a continuous plate structure interconnecting all the coils. The adequacy of the structures were assessed by application of finite element analysis methods. The design study proved the feasibility of resisting the magnetic loadings with a demountable support structure extraneous to the superconducting coil. The resulting magnet system, although estimated to be higher in cost than a continuous coil, incorporates a means for complete coil replacement in a time scale commensurate with conventional nuclear power plant repairs and without the dismantling of the toroidal blanket and plasma shell systems

  10. Surface magnetic structures in amorphous ferromagnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    Usov, N.A., E-mail: usov@obninsk.ru [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Serebryakova, O.N.; Gudoshnikov, S.A. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, IZMIRAN, 108840 Troitsk, Moscow (Russian Federation); Tarasov, V.P. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation)

    2017-05-01

    The spatial period of magnetization perturbations that occur near the surface of magnetic nanotube or nanowire under the influence of surface magnetic anisotropy is determined by means of numerical simulation as a function of the sample geometry and material parameters. The surface magnetization distribution obtained is then used to estimate the period of the surface magnetic texture in amorphous microwire of several micrometers in diameter by means of appropriate variational procedure. The period of the surface magnetic texture in amorphous microwire is found to be significantly smaller than the wire diameter. - Highlights: • Magnetic structure may arise near the magnetic nanotube surface under the influence of surface magnetic anisotropy. • The period of the surface magnetization pattern is calculated as a function of the sample geometry. • Similar magnetic structure may exist in amorphous microwire of several micrometers in diameter. • The period of the surface magnetic structure in amorphous wire is found to be significantly smaller than the wire diameter.

  11. Anisotropic magnetism in field-structured composites

    International Nuclear Information System (INIS)

    Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.

    2000-01-01

    Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society

  12. Magnetic structure of molecular magnet Fe[Fe(CN) 6

    Indian Academy of Sciences (India)

    We have studied the magnetic structure of Fe[Fe(CN)6]·4H2O, prepared by precipitation method, using neutron diffraction technique. Temperature dependent DC magnetization study down to 4.2 K shows that the compound undergoes from a high temperature disordered (paramagnetic) to an ordered magnetic phase ...

  13. Structure and magnetic field of periodic permanent magnetic focusing system with open magnetic rings

    International Nuclear Information System (INIS)

    Peng Long; Li Lezhong; Yang Dingyu; Zhu Xinghua; Li Yuanxun

    2011-01-01

    The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120 mT for a traveling wave tube system. - Research highlights: → For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. → A new structure of periodic permanent magnet (PPM) focusing system with open magnetic rings is proposed. → The new PPM focusing system with open magnetic rings meets the requirements for TWT system.

  14. Optimally segmented permanent magnet structures

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Bjørk, Rasmus; Smith, Anders

    2016-01-01

    We present an optimization approach which can be employed to calculate the globally optimal segmentation of a two-dimensional magnetic system into uniformly magnetized pieces. For each segment the algorithm calculates the optimal shape and the optimal direction of the remanent flux density vector......, with respect to a linear objective functional. We illustrate the approach with results for magnet design problems from different areas, such as a permanent magnet electric motor, a beam focusing quadrupole magnet for particle accelerators and a rotary device for magnetic refrigeration....

  15. Structural safety features for superconducting magnets

    International Nuclear Information System (INIS)

    Lehner, J.; Reich, M.; Powell, J.; Bezler, P.; Gardner, D.; Yu, W.; Chang, T.Y.

    1975-01-01

    A survey has been carried out for various potential structural safety problems of superconducting fusion magnets. These areas include: (1) Stresses due to inhomogeneous temperature distributions in magnets where normal regions have been initiated. (2) Stress distributions and yield forces due to cracks and failed regions. (3) Superconducting magnet response due to seismic excitation. These analyses have been carried out using a variety of large capacity finite element computer codes that allow for the evaluation of stresses in elastic or elastic-plastic zones and around singularities in the magnet structure. Thus far, these analyses have been carried out on UWMAK-I type magnet systems

  16. Powder Neutron Diffraction and Magnetic structures

    International Nuclear Information System (INIS)

    Vigneron, F.

    1986-01-01

    The determination of the magnetic structures of materials (ferromagnetic, antiferromagnetic, helimagnetic, .) can be achieved only by neutron diffraction. A general survey of the powder technique is given: 2-axis spectrometer and analysis of the magnetic data. For the REBe/sb13/ intermetallic compounds (RE = Rare Earth), commensurate and/or incommensurate magnetic structures are observed and discussed as a function of RE (Gd, Tb, Dy, Ho, Er)

  17. Structural peculiarities in magnetic small particles

    International Nuclear Information System (INIS)

    Haneda, K.; Morrish, A.H.

    1993-01-01

    Nanostructured magnetic materials, consisting of nanometer-sized crystallites, are currently a developing subject. Evidence has been accumulating that they possess properties that can differ substantially from those of bulk materials. This paper illustrates how Moessbauer spectroscopy can yield useful information on the structural peculiarities associated with these small particles. As illustrations, metallic iron and iron-oxide systems are considered in detail. The subjects discussed include: (1) Phase stabilities in small particles, (2) deformed or nonsymmetric atomic arrangements in small particles, and (3) peculiar magnetic structures or non-collinear spin arrangements in small magnetic oxide particles that are correlated with lower specific magnetizations as compared to the bulk values. (orig.)

  18. High-field permanent-magnet structures

    International Nuclear Information System (INIS)

    Leupoid, H.A.

    1989-01-01

    This patent describes a permanent magnet structure. It comprises an azimuthally circumscribed section of a hollow hemispherical magnetic flux source, the magnetic orientation in the section with respect to the polar axis being substantially equal to twice the polar angle, a superconducting planar sheet abutting one flat face of the section along a longitudinal meridian, and at least one other planar sheet of selected material abutting another flat face of the section and perpendicular to the first-mentioned sheet

  19. Magnetism and Structure in Functional Materials

    CERN Document Server

    Planes, Antoni; Saxena, Avadh

    2005-01-01

    Magnetism and Structure in Functional Materials addresses three distinct but related topics: (i) magnetoelastic materials such as magnetic martensites and magnetic shape memory alloys, (ii) the magnetocaloric effect related to magnetostructural transitions, and (iii) colossal magnetoresistance (CMR) and related magnanites. The goal is to identify common underlying principles in these classes of materials that are relevant for optimizing various functionalities. The emergence of apparently different magnetic/structural phenomena in disparate classes of materials clearly points to a need for common concepts in order to achieve a broader understanding of the interplay between magnetism and structure in this general class of new functional materials exhibiting ever more complex microstructure and function. The topic is interdisciplinary in nature and the contributors correspondingly include physicists, materials scientists and engineers. Likewise the book will appeal to scientists from all these areas.

  20. Structure and dynamics of magnetic nanoparticles

    DEFF Research Database (Denmark)

    Clausen, K.N.; Bødker, F.; Hansen, M.F.

    2000-01-01

    In this paper we present X-ray and neutron diffraction data illustrating aspects of crystal and magnetic structures of ferromagnetic alpha-Fe and antiferromagnetic NiO nanoparticles, as well as inelastic neutron scattering studies of the magnetic fluctuations in NiO and in canted antiferromagnetic...

  1. Magnetic structures of erbium under high pressure

    DEFF Research Database (Denmark)

    Kawano, S.; Lebech, B.; Achiwa, N.

    1993-01-01

    Neutron diffraction studies of the magnetic structures of erbium metal at 4.5 K and 11.5 kbar hydrostatic pressure have revealed that the transition to a conical structure at low temperatures is suppressed and that the cycloidal structure, with modulation vector Q congruent-to (2/7 2pi/c)c persists...

  2. The spin structure of magnetic nanoparticles and in magnetic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Disch, Sabrina

    2011-09-26

    The present thesis provides an extensive and original contribution to the investigation of magnetic nanoparticles regarding synthesis and structural characterization using advanced scattering methods in all length scales between the atomic and mesoscopic size range. Particular emphasis is on determination of the magnetic structure of single nanoparticles as well as preparation and characterization of higher dimensional assemblies thereof. The unique physical properties arising from the finite size of magnetic nanoparticles are pronounced for very small particle sizes. With the aim of preparing magnetic nanoparticles suitable for investigation of such properties, a micellar synthesis route for very small cobalt nanoparticles is explored. Cobalt nanoparticles with diameters of less than 3 nm are prepared and characterized, and routes for variation of the particle size are developed. The needs and limitations of primary characterization and handling of such small and oxidation-sensitive nanoparticles are highlighted and discussed in detail. Comprehensive structural and magnetic characterization is performed on iron oxide nanoparticles of {proportional_to} 10 nm in diameter. Particle size and narrow size distribution are determined with high precision. Investigation of the long range and local atomic structure reveals a particle size dependent magnetite - maghemite structure type with lattice distortions induced at the particle surface. The spatial magnetization distribution within these nanoparticles is determined to be constant in the particle core with a decrease towards the particle surface, thus indicating a magnetic dead layer or spin canting close to the surface. Magnetically induced arrangements of such nanoparticles into higher dimensional assemblies are investigated in solution and by deposition of long range ordered mesocrystals. Both cases reveal a strong dependence of the found structures on the nanoparticle shape (spheres, cubes, and heavily truncated

  3. Ultrathin magnetic structures IV applications of nanomagnetism

    CERN Document Server

    Heinrich, Bretislav

    2004-01-01

    The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism which already has a profound impact in technology and is providing the basis for a revolution in electronics. The last decade has seen dramatic progress in the development of magnetic devices for information technology but also in the basic understanding of the physics of magnetic nanostructures. Volume III describes thin film magnetic properties and methods for characterising thin film structure topics that underpin the present 'spintronics' revolution in which devices are based on combined magnetic materials and semiconductors. The present volume (IV) deals with the fundamentals of spintronics: magnetoelectronic materials, spin injection and detection, micromagnetics and the development of magnetic random access memory based on GMR and tunnel junction devices. Together these books provide readers with a comprehensive account of an exciting and rapidly developing field. The treatment is de...

  4. Ultrathin magnetic structures III fundamentals of nanomagnetism

    CERN Document Server

    Bland, JAC

    2004-01-01

    The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism which already has a profound impact in technology and is providing the basis for a revolution in electronics. The last decade has seen dramatic progress in the development of magnetic devices for information technology but also in the basic understanding of the physics of magnetic nanostructures. This volume describes thin film magnetic properties and methods for characterising thin film structure topics that underpin the present 'spintronics' revolution in which devices are based on combined magnetic materials and semiconductors. Volume IV deals with the fundamentals of spintronics: magnetoelectronic materials, spin injection and detection, micromagnetics and the development of magnetic random access memory based on GMR and tunnel junction devices. Together these books provide readers with a comprehensive account of an exciting and rapidly developing field. The treatment is designed to be ...

  5. Structural alloys for high field superconducting magnets

    International Nuclear Information System (INIS)

    Morris, J.W. Jr.

    1985-08-01

    Research toward structural alloys for use in high field superconducting magnets is international in scope, and has three principal objectives: the selection or development of suitable structural alloys for the magnet support structure, the identification of mechanical phenomena and failure modes that may influence service behavior, and the design of suitable testing procedures to provide engineering design data. This paper reviews recent progress toward the first two of these objectives. The structural alloy needs depend on the magnet design and superconductor type and differ between magnets that use monolithic and those that employ force-cooled or ICCS conductors. In the former case the central requirement is for high strength, high toughness, weldable alloys that are used in thick sections for the magnet case. In the latter case the need is for high strength, high toughness alloys that are used in thin welded sections for the conductor conduit. There is productive current research on both alloy types. The service behavior of these alloys is influenced by mechanical phenomena that are peculiar to the magnet environment, including cryogenic fatigue, magnetic effects, and cryogenic creep. The design of appropriate mechanical tests is complicated by the need for testing at 4 0 K and by rate effects associated with adiabatic heating during the tests. 46 refs

  6. Magnetic structure of holmium-yttrium superlattices

    DEFF Research Database (Denmark)

    Jehan, D.A.; McMorrow, D.F.; Cowley, R.A.

    1993-01-01

    We present the results of a study of the chemical and magnetic structures of a series of holmium-yttrium superlattices and a 5000 angstrom film of holmium, all grown by molecular-beam epitaxy. By combining the results of high-resolution x-ray diffraction with detailed modeling, we show...... that the superlattices have high crystallographic integrity: the structural coherence length parallel to the growth direction is typically almost-equal-to 2000 angstrom, while the interfaces between the two elements are well defined and extend over approximately four lattice planes. The magnetic structures were...... determined using neutron-scattering techniques. The moments on the Ho3+ ions in the superlattices form a basal-plane helix. From an analysis of the superlattice structure factors of the primary magnetic satellites, we are able to determine separately the contributions made by the holmium and yttrium...

  7. The internal structure of magnetic nanoparticles determines the magnetic response

    Czech Academy of Sciences Publication Activity Database

    Pacáková, Barbara; Kubíčková, Simona; Salas, G.; Mantlíková, Alice; Marciello, M.; Morales, M.P.; Nižňanský, D.; Vejpravová, Jana

    2017-01-01

    Roč. 9, č. 16 (2017), s. 5129-5140 ISSN 2040-3364 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : nanoparticles * single-domain * internal structure Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 7.367, year: 2016

  8. MULTISCALE DYNAMICS OF SOLAR MAGNETIC STRUCTURES

    International Nuclear Information System (INIS)

    Uritsky, Vadim M.; Davila, Joseph M.

    2012-01-01

    Multiscale topological complexity of the solar magnetic field is among the primary factors controlling energy release in the corona, including associated processes in the photospheric and chromospheric boundaries. We present a new approach for analyzing multiscale behavior of the photospheric magnetic flux underlying these dynamics as depicted by a sequence of high-resolution solar magnetograms. The approach involves two basic processing steps: (1) identification of timing and location of magnetic flux origin and demise events (as defined by DeForest et al.) by tracking spatiotemporal evolution of unipolar and bipolar photospheric regions, and (2) analysis of collective behavior of the detected magnetic events using a generalized version of the Grassberger-Procaccia correlation integral algorithm. The scale-free nature of the developed algorithms makes it possible to characterize the dynamics of the photospheric network across a wide range of distances and relaxation times. Three types of photospheric conditions are considered to test the method: a quiet photosphere, a solar active region (NOAA 10365) in a quiescent non-flaring state, and the same active region during a period of M-class flares. The results obtained show (1) the presence of a topologically complex asymmetrically fragmented magnetic network in the quiet photosphere driven by meso- and supergranulation, (2) the formation of non-potential magnetic structures with complex polarity separation lines inside the active region, and (3) statistical signatures of canceling bipolar magnetic structures coinciding with flaring activity in the active region. Each of these effects can represent an unstable magnetic configuration acting as an energy source for coronal dissipation and heating.

  9. Structure and Evolution of Magnetic Cataclysmic Variables

    Science.gov (United States)

    Andronov, I. L.

    2007-06-01

    Theoretical models and observational results are reviewed. The general picture of the structure and evolution of cataclysmic variables (CV) is presented, together with a brief discussion of additional mechanisms of intrinsic variability of the components and magnetic activity of secondaries. Special attention is paid to the accretion structures - flow, disk, column - which are affected by the magnetic field of the white dwarf. The mass and angular momentum transfer in asynchronous MCVs leads to a "propeller" stage of rapid synchronization, after which the "idlings" of the white dwarf are altered to "swingings" with a characteristic time of century(ies). The disk- magnetic field interaction leads to precession of the white dwarf, which causes quasi-periodic changes of the equilibrium rotational period. "Shot noise" in cataclysmic variables is discussed based on one-bandpass and multi-color observations.

  10. Dipolar vortex structures in magnetized rotating plasma

    International Nuclear Information System (INIS)

    Liu Jixing

    1990-01-01

    Dipolar solitary vortices of both electrostatic and electromagnetic character in low-β, in homogeneous rotating plasma confined in a constant external magnetic field were systematically presented. The main stimulus to this investigation is the expectation to apply this coherent structure as a candidate constituent of plasma turbulance to understand the anomalous transport phenomena in confined plasma. The electrostatic vortices have similar structure and properties as the Rossby vortices in rotating fluids, the electromagnetic vortices obtained here have no analogy in hydrodynamics and hence are intrinsic to magnetized plasma. It is valuably remarked that the intrinsic electromagnetic vortices presented here have no discontinuity of perturbed magnetic field δB and parallel current j(parallel) on the border of vortex core. The existence region of the new type of vortex is found much narrower than the Rossby type one. (M.T.)

  11. Structure requirements for magnetic energy storage devices

    International Nuclear Information System (INIS)

    Eyssa, Y.M.; Huang, X.

    1993-01-01

    Large variety of large and small magnetic energy storage systems have been designed and analyzed in the last 20 years. Cryoresistive and superconductive energy storage (SMES) magnets have been considered for applications such as load leveling for electric utilities, pulsed storage for electromagnetic launchers and accelerator devices, and space borne superconductive energy storage systems. Large SMES are supported by a combination of cold and warm structure while small SMES are supported only by cold structure. In this article we provide analytical and numerical tools to estimate the structure requirements as function of the stored energy and configuration. Large and small solenoidal and toroidal geometries are used. Considerations for both warm and cold structure are discussed. Latest design concepts for both large and small units are included. (orig.)

  12. Highly ordered FEPT and FePd magnetic nano-structures: Correlated structural and magnetic studies

    International Nuclear Information System (INIS)

    Lukaszew, Rosa Alejandra; Cebollada, Alfonso; Clavero, Cesar; Garcia-Martin, Jose Miguel

    2006-01-01

    The micro-structure of epitaxial FePt and FePd films grown on MgO (0 0 1) substrates is correlated to their magnetic behavior. The FePd films exhibit high chemical ordering and perpendicular magnetic anisotropy. On the other hand FePt films exhibit low chemical ordering, with nano-grains oriented in two orthogonal directions, forcing the magnetization to remain in the plane of the films

  13. Structural analysis of suerconducting bending magnets

    International Nuclear Information System (INIS)

    Meuser, R.B.

    1980-05-01

    Mechanical stresses, displacements, and the effects of displacements upon aberrations of the magnetic field in the aperture have been calculated for a class of superconducting bending-magnet configurations. The analytical model employed for the coil is one in which elements are free to slide without restraint upon each other, and upon the surrounding structure. Coil configurations considered range from an idealized one in which the current density varies as cosine theta to more realistic ones consisting of regions of uniform current density. With few exceptions, the results for the more realistic coils closely match those of the cos theta coil

  14. Neutron scattering studies of modulated magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Aagaard Soerensen, Steen

    1999-08-01

    This report describes investigations of the magnetic systems DyFe{sub 4}Al{sub 8} and MnSi by neutron scattering and in the former case also by X-ray magnetic resonant scattering. The report is divided into three parts: An introduction to the technique of neutron scattering with special emphasis on the relation between the scattering cross section and the correlations between the scattering entities of the sample. The theoretical framework of neutron scattering experiments using polarized beam technique is outlined. The second part describes neutron and X-ray scattering investigation of the magnetic structures of DyFe{sub 4}Al{sub 8}. The Fe sublattice of the compound order at 180 K in a cycloidal structure in the basal plane of the bct crystal structure. At 25 K the ordering of the Dy sublattice shows up. By the element specific technique of X-ray resonant magnetic scattering, the basal plane cycloidal structure was also found for the Dy sublattice. The work also includes neutron scattering studies of DyFe{sub 4}Al{sub 8} in magnetic fields up to 5 T applied along a <110> direction. The modulated structure at the Dy sublattice is quenched by a field lower than 1 T, whereas modulation is present at the Fe sublattice even when the 5 T field is applied. In the third part of the report, results from three small angle neutron experiments on MnSi are presented. At ambient pressure, a MnSi is known to form a helical spin density wave at temperature below 29 K. The application of 4.5 kbar pressure intended as hydrostatic decreased the Neel temperature to 25 K and changed the orientation of the modulation vector. To understand this reorientation within the current theoretical framework, anisotropic deformation of the sample crystal must be present. The development of magnetic critical scattering with an isotropic distribution of intensity has been studied at a level of detail higher than that of work found in the literature. Finally the potential of a novel polarization

  15. Method and apparatus for control of a magnetic structure

    Science.gov (United States)

    Challenger, Michael P.; Valla, Arthur S.

    1996-06-18

    A method and apparatus for independently adjusting the spacing between opposing magnet arrays in charged particle based light sources. Adjustment mechanisms between each of the magnet arrays and the supporting structure allow the gap between the two magnet arrays to be independently adjusted. In addition, spherical bearings in the linkages to the magnet arrays permit the transverse angular orientation of the magnet arrays to also be adjusted. The opposing magnet arrays can be supported above the ground by the structural support.

  16. Basic study of magnetic microwires for sensor applications: Variety of magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Chizhik, Alexander, E-mail: oleksandr.chyzhyk@ehu.es [Universidad del Pais Vasco, UPV/EHU, 20080 San Sebastian (Spain); Zhukov, Arcady [Universidad del Pais Vasco, UPV/EHU, 20080 San Sebastian (Spain); IKERBASQUE, 48011 Bilbao (Spain); Gonzalez, Julian [Universidad del Pais Vasco, UPV/EHU, 20080 San Sebastian (Spain); Stupakiewicz, Andrzej [Laboratory of Magnetism, University of Bialystok, 15-245 Bialystok (Poland)

    2017-01-15

    We examine magnetic glass-coated microwires used for magnetic sensors. Images of domain structures and magnetization reversal were obtained with magneto-optical Kerr microscopy. Of particular importance were temperature-induced transformations of surface magnetic structures. Different surface magnetic domains coexist, characterized by various domain periods, magnetization directions, and nobilities of domain walls. - Highlights: • Temperature induced transformation of the domain structure in the microwires. • Co-existence of two magnetic structures differing in period and mobility of domain walls. • Short review of the basic domain structures in microwire.

  17. Open magnetic structures on the sun

    International Nuclear Information System (INIS)

    Levine, R.H.; Altschuler, M.D.; Harvey, J.W.; Jackson, B.V.

    1977-01-01

    High-resolution harmonic analysis of the solar magnetic field has been used successfully to calculate the geometry of open magnetic field lines in the solar corona. Comparison of the loci of open field line footpoints with solar X-ray photographs shows that all of the coronal holes during two solar rotations are successfully represented, including details of their evolution. Some open magnetic configurations derived in the calculations precede by up to one solar rotation the manifestation of coincident dark areas on the X-ray photographs. The only other areas that contribute open field lines to the corona are separations between active-region loop systems. By varying the radius at which field lines are forced to be open in the calculation, it is possible to more closely reproduce the surface configuration of particular coronal holes. Comparison of the size of X-ray holes with the fraction of the solar surface covered by open field lines leads to the conclusion that a significant part of the area of coronal holes must contain closed magnetic fields. Comparison of open field lines which lie in the equatorial plane of the Sun with solar wind data indicates that eventual high-speed solar wind streams are associated with those parts of open magnetic structures that diverge the least. Several important questions raised by this study are under investigation using data for the entire Skylab period

  18. Magnetic Field Structure in Relativistic Jets

    Directory of Open Access Journals (Sweden)

    Jermak Helen

    2013-12-01

    Full Text Available Relativistic jets are ubiquitous when considering an accreting black hole. Two of the most extreme examples of these systems are blazars and gamma-ray bursts (GRBs, the jets of which are thought to be threaded with a magnetic field of unknown structure. The systems are made up of a black hole accreting matter and producing, as a result, relativistic jets of plasma from the poles of the black hole. Both systems are viewed as point sources from Earth, making it impossible to spatially resolve the jet. In order to explore the structure of the magnetic field within the jet we take polarisation measurements with the RINGO polarimeters on the world’s largest fully autonomous, robotic optical telescope: The Liverpool Telescope. Using the polarisation degree and angle measured by the RINGO polarimeters it is possible to distinguish between global magnetic fields created in the central engine and random tangled magnetic fields produced locally in shocks. We also monitor blazar sources regularly during quiescence with periods of flaring monitored more intensively. Reported here are the early polarisation results for GRBs 060418 and 090102, along with future prospects for the Liverpool Telescope and the RINGO polarimeters.

  19. The vector structure of active magnetic fields

    Science.gov (United States)

    Parker, E. N.

    1985-01-01

    Observations are needed to show the form of the strains introduced into the fields above the surface of the Sun. The longitudinal component alone does not provide the basic information, so that it has been necessary in the past to use the filamentary structure observed in H sub alpha to supplement the longitudinal information. Vector measurements provide the additional essential information to determine the strains, with the filamentary structure available as a check for consistency. It is to be expected, then, that vector measurements will permit a direct mapping of the strains imposed on the magnetic fields of active regions. It will be interesting to study the relation of those strains to the emergence of magnetic flux, flares, eruptive prominences, etc. In particular we may hope to study the relaxation of the strains via the dynamical nonequilibrium.

  20. High performance hybrid magnetic structure for biotechnology applications

    Science.gov (United States)

    Humphries, David E [El Cerrito, CA; Pollard, Martin J [El Cerrito, CA; Elkin, Christopher J [San Ramon, CA

    2009-02-03

    The present disclosure provides a high performance hybrid magnetic structure made from a combination of permanent magnets and ferromagnetic pole materials which are assembled in a predetermined array. The hybrid magnetic structure provides means for separation and other biotechnology applications involving holding, manipulation, or separation of magnetic or magnetizable molecular structures and targets. Also disclosed are further improvements to aspects of the hybrid magnetic structure, including additional elements and for adapting the use of the hybrid magnetic structure for use in biotechnology and high throughput processes.

  1. Structural characterization of copolymer embedded magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nedelcu, G.G., E-mail: ggnedelcu@yahoo.com [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania); Nastro, A.; Filippelli, L. [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Cazacu, M.; Iacob, M. [Institute of Macromolecular Chemistry “Petru Poni”, Aleea Grigore Ghica Voda, nr. 41A, 700487 Iasi (Romania); Rossi, C. Oliviero [Department of Chemistry and Chemical Technology, University of Calabria, Via P. Bucci, 87036 Arcavacata di Rende, Cosenza (Italy); Popa, A.; Toloman, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca 5 (Romania); Dobromir, M.; Iacomi, F. [Faculty of Physics, University “Alexandru Ioan Cuza”, Carol I Bulevard, Nr.11, 700506 Iasi (Romania)

    2015-10-15

    Highlights: • The emulsion polymerization method was used to synthesize three samples of poly(methyl methacrylate-co-acrylic acid) coated magnetite obtained before through co-precipitation technique. • Poly(methyl methacrylate-co-acrylic acid) coated magnetite nanoparticles were prepared having spherical shape and dimensions between 13 and 16 nm without agglomerations. • Fourier transform infrared spectra have found that the magnetite was pure and spectral characteristics of PMMA-co-AAc were present. • The electron spin resonance spectra revealed that interactions between nanoparticles are very weak due to the fact that the nanoparticles have been individually embedded in polymer. • The resonance field values as function of temperature demonstrate that the presence of polymer has not modified essentially its magnetic properties, except that at temperatures below 140 K there was a change due to decreasing of the magnetic anisotropy. - Abstract: Small magnetic nanoparticles (Fe{sub 3}O{sub 4}) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  2. Spin-resolved magnetic studies of focused ion beam etched nano-sized magnetic structures

    International Nuclear Information System (INIS)

    Li Jian; Rau, Carl

    2005-01-01

    Scanning ion microscopy with polarization analysis (SIMPA) is used to study the spin-resolved surface magnetic structure of nano-sized magnetic systems. SIMPA is utilized for in situ topographic and spin-resolved magnetic domain imaging as well as for focused ion beam (FIB) etching of desired structures in magnetic or non-magnetic systems. Ultra-thin Co films are deposited on surfaces of Si(1 0 0) substrates, and ultra-thin, tri-layered, bct Fe(1 0 0)/Mn/bct Fe(1 0 0) wedged magnetic structures are deposited on fcc Pd(1 0 0) substrates. SIMPA experiments clearly show that ion-induced electrons emitted from magnetic surfaces exhibit non-zero electron spin polarization (ESP), whereas electrons emitted from non-magnetic surfaces such as Si and Pd exhibit zero ESP, which can be used to calibrate sputtering rates in situ. We report on new, spin-resolved magnetic microstructures, such as magnetic 'C' states and magnetic vortices, found at surfaces of FIB patterned magnetic elements. It is found that FIB milling has a negligible effect on surface magnetic domain and domain wall structures. It is demonstrated that SIMPA can evolve into an important and efficient tool to study magnetic domain, domain wall and other structures as well as to perform magnetic depth profiling of magnetic nano-systems to be used in ultra-high density magnetic recording and in magnetic sensors

  3. The Magnetic Structure of Filament Barbs

    Science.gov (United States)

    Chae, Jongchul; Moon, Yong-Jae; Park, Young-Deuk

    2005-06-01

    There is a controversy about how features protruding laterally from filaments, called barbs, are magnetically structured. On 2004 August 3, we observed a filament that had well-developed barbs. The observations were performed using the 10 inch refractor of the Big Bear Solar Observatory. A fast camera was employed to capture images at five different wavelengths of the Hα line and successively record them on the basis of frame selection. The terminating points of the barbs were clearly discernable in the Hα images without any ambiguity. The comparison of the Hα images with the magnetograms taken by SOHO MDI revealed that the termination occurred above the minor polarity inversion line dividing the magnetic elements of the major polarity and those of the minor polarity. There is also evidence that the flux cancellation proceeded on the polarity inversion line. Our results together with similar other recent observations support the idea that filament barbs are cool matter suspended in local dips of magnetic field lines, formed by magnetic reconnection in the chromosphere.

  4. Iron nanoparticle assemblies: structures and magnetic behavior

    International Nuclear Information System (INIS)

    Farrell, D; Cheng, Y; Kan, S; Sachan, M; Ding, Y; Majetich, S A; Yang, L

    2005-01-01

    Self-assembly of spherical, surfactant-coated nanoparticles is discussed, an examples are presented to demonstrate the variety of structures that can be formed, and the conditions that lead to them. The effect of the concentration on the magnetic properties is then examined for 8.5 nm Fe nanoparticles. Dilute dispersions, arrays formed by evaporation of the dispersions, and nanoparticle crystals grown by slow diffusion of a poorly coordinating solvent were characterized by zero field-cooled magnetization, remanent hysteresis loop, and magnetic relaxation measurements. The average spacing between the particles was determined from a combination of transmission electron microscopy and small angle x-ray scattering. In the arrays the spacing was 2.5 nm between the edges of the particle cores, while in the nanoparticle crystals the particles were more tightly packed, with a separation of 1.1 nm. The reduced separation increased the magnetostatic interaction strength in the nanoparticle crystals, which showed distinctly different behavior in the rate of approach to saturation in the remanent hysteresis loops, and in the faster rate of time-dependent magnetic relaxation

  5. Correlation between physical structure and magnetic anisotropy of a magnetic nanoparticle colloid

    Science.gov (United States)

    Dennis, C. L.; Jackson, A. J.; Borchers, J. A.; Gruettner, C.; Ivkov, R.

    2018-05-01

    We show the effects of a time-invariant magnetic field on the physical structure and magnetic properties of a colloid comprising 44 nm diameter magnetite magnetic nanoparticles, with a 24 nm dextran shell, in water. Structural ordering in this colloid parallel to the magnetic field occurs simultaneously with the onset of a colloidal uniaxial anisotropy. Further increases in the applied magnetic field cause the nanoparticles to order perpendicular to the field, producing unexpected colloidal unidirectional and trigonal anisotropies. This magnetic behavior is distinct from the cubic magnetocrystalline anisotropy of the magnetite and has its origins in the magnetic interactions among the mobile nanoparticles within the colloid. Specifically, these field-induced anisotropies and colloidal rearrangements result from the delicate balance between the magnetostatic and steric forces between magnetic nanoparticles. These magnetic and structural rearrangements are anticipated to influence applications that rely upon time-dependent relaxation of the magnetic colloids and fluid viscosity, such as magnetic hyperthermia and shock absorption.

  6. Method of using triaxial magnetic fields for making particle structures

    Science.gov (United States)

    Martin, James E.; Anderson, Robert A.; Williamson, Rodney L.

    2005-01-18

    A method of producing three-dimensional particle structures with enhanced magnetic susceptibility in three dimensions by applying a triaxial energetic field to a magnetic particle suspension and subsequently stabilizing said particle structure. Combinations of direct current and alternating current fields in three dimensions produce particle gel structures, honeycomb structures, and foam-like structures.

  7. The structure of magnetic materials; La structure des substances magnetiques

    Energy Technology Data Exchange (ETDEWEB)

    Villain, J. [Commissariat a l' energie atomique et aux energies alternatives - CEA, C.E.N. Saclay (France)

    1960-07-01

    The paper deals with the prediction of the structure of magnetic materials below the critical point. The molecular field approximation is used: exchange interactions with unlimited range are assumed; the magnetic ions are supposed to form a Bravais lattice. The critical temperature T{sub c} is first calculated (section 1) without assuming any decomposition of the crystal into sublattices, and the magnetic structure at T{sub c} is given. It is next shown (section 2) that the essential features of this structure persist below T{sub c}, and the various possible cases are considered. It is possible that no decomposition into sublattices takes place, i.e. the magnetic structure and the nuclear structure have incommensurable periods. A detailed treatment is then given for the body-centered quadratic lattice (section 3) with interaction between first, second and third neighbours. Reprint of a paper published in Journal of Physical Chemistry, vol. 11, no. 3/4, p. 303-309, 1959 [French] Ce travail a pour objet la prevision systematique de la structure des substances magnetiques au-dessous du point de transition et l'etude des differents cas qui peuvent se presenter lorsque les ions magnetiques forment un reseau de Bravais. On se place dans une approximation de champ moleculaire, mais on ne fait aucune restriction concernant la portee des interactions d'echange. Apres avoir determine (Section 1) la temperature critique et la structure magnetique a cette temperature sans supposer a priori l'existence d'une decomposition en sous-reseaux, on montre (Section 2) que cette structure reste stable en dessous de la temperature critique, et on etudie les divers cas possibles. Il peut arriver en particulier que la structure magnetique ait une periode incommensurable avec celle du reseau cristallin. L'example du reseau quadratique centre avec couplage entre premiers, seconds et troisiemes voisins (Section 3) fournit une bonne illustration de cette etude. Reproduction d'un article publie

  8. Structural magnetic resonance imaging in epilepsy

    International Nuclear Information System (INIS)

    Deblaere, Karel; Achten, Eric

    2008-01-01

    Because of its sensitivity and high tissue contrast, magnetic resonance imaging (MRI) is the technique of choice for structural imaging in epilepsy. In this review the effect of using optimised scanning protocols and the use of high field MR systems on detection sensitivity is discussed. Also, the clinical relevance of adequate imaging in patients with focal epilepsy is highlighted. The most frequently encountered MRI findings in epilepsy are reported and their imaging characteristics depicted. Imaging focus will be on the diagnosis of hippocampal sclerosis and malformations of cortical development, two major causes of medically intractable focal epilepsy. (orig.)

  9. Structural magnetic resonance imaging in epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Deblaere, Karel [Ghent University Hospital, Department of Neuroradiology, Ghent (Belgium); Ghent University Hospital, MR Department - 1K12, Ghent (Belgium); Achten, Eric [Ghent University Hospital, Department of Neuroradiology, Ghent (Belgium)

    2008-01-15

    Because of its sensitivity and high tissue contrast, magnetic resonance imaging (MRI) is the technique of choice for structural imaging in epilepsy. In this review the effect of using optimised scanning protocols and the use of high field MR systems on detection sensitivity is discussed. Also, the clinical relevance of adequate imaging in patients with focal epilepsy is highlighted. The most frequently encountered MRI findings in epilepsy are reported and their imaging characteristics depicted. Imaging focus will be on the diagnosis of hippocampal sclerosis and malformations of cortical development, two major causes of medically intractable focal epilepsy. (orig.)

  10. 3D Biomimetic Magnetic Structures for Static Magnetic Field Stimulation of Osteogenesis

    OpenAIRE

    Irina Alexandra Paun; Roxana Cristina Popescu; Bogdan Stefanita Calin; Cosmin Catalin Mustaciosu; Maria Dinescu; Catalin Romeo Luculescu

    2018-01-01

    We designed, fabricated and optimized 3D biomimetic magnetic structures that stimulate the osteogenesis in static magnetic fields. The structures were fabricated by direct laser writing via two-photon polymerization of IP-L780 photopolymer and were based on ellipsoidal, hexagonal units organized in a multilayered architecture. The magnetic activity of the structures was assured by coating with a thin layer of collagen-chitosan-hydroxyapatite-magnetic nanoparticles composite. In vitro experime...

  11. Molecular structure and motion in zero field magnetic resonance

    International Nuclear Information System (INIS)

    Jarvie, T.P.

    1989-10-01

    Zero field magnetic resonance is well suited for the determination of molecular structure and the study of motion in disordered materials. Experiments performed in zero applied magnetic field avoid the anisotropic broadening in high field nuclear magnetic resonance (NMR) experiments. As a result, molecular structure and subtle effects of motion are more readily observed

  12. Cryogenic magnet case and distributed structural materials for high-field superconducting magnets

    International Nuclear Information System (INIS)

    Summers, L.T.; Miller, J.R.; Kerns, J.A.; Myall, J.O.

    1987-01-01

    The superconducting magnets of the Tokamak Ignition/Burn Experimental Reactor (TIBER II) will generate high magnetic fields over large bores. The resulting electromagnetic forces require the use of large volumes of distributed steel and thick magnet case for structural support. Here we review the design allowables, calculated loads and forces, and structural materials selection for TIBER II. 7 refs., 2 figs., 3 tabs

  13. Fabrication and properties of submicrometer structures of magnetic materials

    International Nuclear Information System (INIS)

    Martin, J.I.; Velez, M.; Nogues, J.; Schuller, I.K.

    1998-01-01

    The method of electron beam lithography is described. This technique allows to fabricate well defined submicrometer structures of magnetic materials, that are suitable to show and study interesting physical properties by transport measurements either in Superconductivity or in Magnetism. In particular, using these structures, we have analyzed pinning effects of the vortex lattice in superconductors and magnetization reversal processes in magnetic materials. (Author) 15 refs

  14. Structural and magnetic stability of Fe2NiSi

    International Nuclear Information System (INIS)

    Gupta, Dinesh C.; Bhat, Idris Hamid; Chauhan, Mamta

    2014-01-01

    Full-potential ab-initio calculations in the stable F-43m phase have been performed to investigate the structural and magnetic properties of Fe 2 NiSi inverse Heusler alloys. The spin magnetic moment distributions show that present material is ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancy in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. It is found that the main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for present alloy

  15. Transport properties of electrons in fractal magnetic-barrier structures

    Science.gov (United States)

    Sun, Lifeng; Fang, Chao; Guo, Yong

    2010-09-01

    Quantum transport properties in fractal magnetically modulated structures are studied by the transfer-matrix method. It is found that the transmission spectra depend sensitively not only on the incident energy and the direction of the wave vector but also on the stage of the fractal structures. Resonance splitting, enhancement, and position shift of the resonance peaks under different magnetic modulation are observed at four different fractal stages, and the relationship between the conductance in the fractal structure and magnetic modulation is also revealed. The results indicate the spectra of the transmission can be considered as fingerprints for the fractal structures, which show the subtle correspondence between magnetic structures and transport behaviors.

  16. Magnetic structures synthesized by controlled oxidative etching: Structural characterization and magnetic behavior

    Directory of Open Access Journals (Sweden)

    Álvaro de Jesús Ruíz-Baltazar

    Full Text Available A facile strategy for the fabrication Fe3O4 nanostructures at room temperature and with well-defined morphology is proposed. In this methodology, the iron precursors were reduced by sodium borohydride. Subsequently an oxidative etching process promotes the formation of Fe2O3 nanostructures. Magnetic measurements revealed a well-defined superparamagnetic behavior for the material. The Zero-Field-Cooled (ZFC and Field-Cooled (FC magnetization curves reveals that critical and blocking temperature were 24 and 350 °C respectively. The Fe3O4 nanostructures were characterized using aberration-corrected (Cs scanning transmission electron microscopy (STEM and energy dispersive spectroscopy (EDS. Additionally, Raman spectra support the Fe3O4 presence and corroborate the efficiency of the synthesis process to obtain magnetite. Keywords: Chemical synthesis, Fe3O4 nanoparticles, Structural characterization, Magnetic properties

  17. Ultrathin magnetic structures II measurement techniques and novel magnetic properties

    CERN Document Server

    Heinrich, Bretislav

    2006-01-01

    The ability to understand and control the unique properties of interfaces has created an entirely new field of magnetism, with profound impact in technology and serving as the basis for a revolution in electronics. Our understanding of the physics of magnetic nanostructures has also advanced significantly. This rapid development has generated a need for a comprehensive treatment that can serve as an introduction to the field for those entering it from diverse fields, but which will also serve as a timely overview for those already working in this area. The four-volume work Ultra-Thin Magnetic

  18. SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeongwoo; Chae, Jongchul [Department of Physics and Astronomy, Seoul National University, Seoul 08826 (Korea, Republic of); Liu, Chang; Jing, Ju [Space Weather Research Laboratory, New Jersey Institute of Technology, Newark, NJ 07102 (United States)

    2016-09-20

    How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encircling the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.

  19. SOLAR MULTIPLE ERUPTIONS FROM A CONFINED MAGNETIC STRUCTURE

    International Nuclear Information System (INIS)

    Lee, Jeongwoo; Chae, Jongchul; Liu, Chang; Jing, Ju

    2016-01-01

    How eruption can recur from a confined magnetic structure is discussed based on the Solar Dynamics Observatory observations of the NOAA active region 11444, which produced three eruptions within 1.5 hr on 2012 March 27. The active region (AR) had the positive-polarity magnetic fields in the center surrounded by the negative-polarity fields around. Since such a distribution of magnetic polarity tends to form a dome-like magnetic fan structure confined over the AR, the multiple eruptions were puzzling. Our investigation reveals that this event exhibits several properties distinct from other eruptions associated with magnetic fan structures: (i) a long filament encircling the AR was present before the eruptions; (ii) expansion of the open–closed boundary (OCB) of the field lines after each eruption was suggestive of the growing fan-dome structure, and (iii) the ribbons inside the closed magnetic polarity inversion line evolved in response to the expanding OCB. It thus appears that in spite of multiple eruptions the fan-dome structure remained undamaged, and the closing back field lines after each eruption rather reinforced the fan-dome structure. We argue that the multiple eruptions could occur in this AR in spite of its confined magnetic structure because the filament encircling the AR was adequate for slipping through the magnetic separatrix to minimize the damage to its overlying fan-dome structure. The result of this study provides a new insight into the productivity of eruptions from a confined magnetic structure.

  20. Structural aspects of superconducting fusion magnets

    International Nuclear Information System (INIS)

    Reich, M.; Lehner, J.; Powell, J.

    1977-01-01

    Some methods for studying various static, dynamic, elastic-plastic, and fracture mechanics problems of superconducting magnets are described. Sample solutions are given for the UWMAK-I magnet. Finite element calculations were used

  1. Magnetic structure of URhSi single crystal

    Czech Academy of Sciences Publication Activity Database

    Prokeš, K.; Andreev, Alexander V.; Honda, F.; Sechovský, V.

    2003-01-01

    Roč. 261, - (2003), s. 131-138 ISSN 0304-8853 R&D Projects: GA ČR GA202/02/0739 Institutional research plan: CEZ:AV0Z1010914 Keywords : URhSi single crystal * magnetization * neutron diffraction * magnetic structure determination Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.910, year: 2003

  2. Computer modeling of magnetic structure for IC-35 cyclotron

    International Nuclear Information System (INIS)

    Alenitskij, Yu.G.; Morozov, N.A.

    1998-01-01

    An extensive series of calculations has been carried out in order to design the magnetic structure of the IC-35 cyclotron for radioisotope production. The calculations were carried out by 2-D POISCR code. The average magnetic field and its variation were produced with the help of two different calculation models. The parameters of the cyclotron magnetic system are presented

  3. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    International Nuclear Information System (INIS)

    Sun Jinji; Fang Jiancheng

    2011-01-01

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  4. A novel structure of permanent-magnet-biased radial hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Sun Jinji, E-mail: sunjinji@aspe.buaa.edu.c [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China); Fang Jiancheng [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beijing University of Aeronautics and Astronautics, 100191 (China)

    2011-01-15

    The paper proposes a novel structure for a permanent-magnet-biased radial hybrid magnetic bearing. Based on the air gap between the rotor and stator of traditional radial hybrid magnetic bearings, a subsidiary air gap is first constructed between the permanent magnets and the inner magnetic parts. Radial magnetic bearing makes X and Y magnetic fields independent of each other with separate stator poles, and the subsidiary air gap makes control flux to a close loop. As a result, magnetic field coupling of the X and Y channels is decreased significantly by the radial hybrid magnetic bearing and makes it easier to design control systems. Then an external rotor structure is designed into the radial hybrid magnetic bearing. The working principle of the radial hybrid magnetic bearing and its mathematical model is discussed. Finally, a non-linear magnetic network method is proposed to analyze the radial hybrid magnetic bearing. Simulation results indicate that magnetic fields in the two channels of the proposed radial hybrid magnetic bearing decouple well from each other.

  5. Structure of magnetic field in Tokamaks

    International Nuclear Information System (INIS)

    Heller, M.V.A.P.; Caldas, I.L.

    1990-01-01

    Magnetic surfaces, necessary to plasma confinement, can be extinguished by resonant helical perturbations with small intensities due to plasma oscillations or external helical currents. The mapping of magnetic field is obtained intergrating numerically the differential equation of its lines. Criteria which evaluate the chaotic distribution of lines between resonant magnetic islands are presented. (M.C.K.) [pt

  6. Laser direct writing (LDW of magnetic structures

    Directory of Open Access Journals (Sweden)

    Alaa Alasadi

    2018-05-01

    Full Text Available Laser direct writing (LDW has been used to pattern 90nm thick permalloy (Ni81Fe19 into 1-D and 2-D microstructures with strong shape anisotropy. Sub-nanosecond laser pulses were focused with a 0.75 NA lens to a 1.85μm diameter spot, to achieve a fluence of approximately 350 mJ.cm-2 and ablate the permalloy film. Computer-controlled sample scanning then allowed structures to be defined. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 650 nm - 6.75μm and magneto-optical measurements showed coercivity reducing across this width range from 47 Oe to 11 Oe. Attempts to fabricate wires narrower than 650nm resulted in discontinuities in the wires and a marked decrease in coercivity. This approach is extremely rapid and was carried out in air, at room temperature and with no chemical processing. The 6-kHz laser pulse repetition rate allowed wire arrays across an area of 4 mm x 0.18 mm to be patterned in 85 s.

  7. Laser direct writing (LDW) of magnetic structures

    Science.gov (United States)

    Alasadi, Alaa; Claeyssens, F.; Allwood, D. A.

    2018-05-01

    Laser direct writing (LDW) has been used to pattern 90nm thick permalloy (Ni81Fe19) into 1-D and 2-D microstructures with strong shape anisotropy. Sub-nanosecond laser pulses were focused with a 0.75 NA lens to a 1.85μm diameter spot, to achieve a fluence of approximately 350 mJ.cm-2 and ablate the permalloy film. Computer-controlled sample scanning then allowed structures to be defined. Scan speeds were controlled to give 30% overlap between successive laser pulses and reduce the extent of width modulation in the final structures. Continuous magnetic wires that adjoined the rest of the film were fabricated with widths from 650 nm - 6.75μm and magneto-optical measurements showed coercivity reducing across this width range from 47 Oe to 11 Oe. Attempts to fabricate wires narrower than 650nm resulted in discontinuities in the wires and a marked decrease in coercivity. This approach is extremely rapid and was carried out in air, at room temperature and with no chemical processing. The 6-kHz laser pulse repetition rate allowed wire arrays across an area of 4 mm x 0.18 mm to be patterned in 85 s.

  8. Structure and magnetic properties of Alnico ribbons

    Science.gov (United States)

    Zhang, Ce; Li, Ying; Han, Xu-Hao; Du, Shuai-long; Sun, Ji-bing; Zhang, Ying

    2018-04-01

    Al-Ni-Co alloy has been widely applied in various industrial fields due to its excellent thermal and magnetic stability. In this paper, new Al-Ni-Co ribbons are prepared by simple processes combining melt-spinning with annealing, and their phase transition, microstructure and magnetic properties are studied. The results show that after as-spun ribbons are annealed, the grain size of ribbons increases from 1.1 ± 0.3 μm to 4.8 ± 0.8 μm, but still much smaller than that of the bulk Al-Ni-Co alloy manufactured by traditional technologies. In addition, some rod-like Al70Co20Ni10-type, Al9Co2-type and Fe2Nb-type phases are precipitated at grain boundaries; simultaneously, the distinct spinodal decomposition microstructure with periodic ingredient variation is thoroughly formed in all grains by the reaction of α → α1 + α2. Furthermore, the α1 and α2 distribute alternately like a maze, the Fe-Co-rich α1 phase holds 35.9-47.3 vol%, while the Al-Ni-rich α2 phase occupies the rest. Finally, the coercivity of annealed ribbons can reach to 485.3 ± 76.6 Oe. If the annealed ribbons are further aged at 560 °C, their Hc even increases to 738.1 ± 81.0 Oe. The coercivity mechanism is discussed by the combination of microstructure and domain structure.

  9. Control of Spin Wave Dynamics in Spatially Twisted Magnetic Structures

    Science.gov (United States)

    2017-06-27

    control the spin wave dynamics of magnetic structures twisted spatially, we prepared the exchange-coupled films with the hard magnetic L10-FePt and...information writing of magnetic storage and spintronic applications. Introduction and Objective: Recent rapid progress in the research field of nano...scaled bilayer elements is also an important aim of this project. Approach/Method: The exchange-coupled films with the hard magnetic L10-FePt and

  10. Magnetic and thermodynamic properties of Ising model with borophene structure in a longitudinal magnetic field

    Science.gov (United States)

    Shi, Kaile; Jiang, Wei; Guo, Anbang; Wang, Kai; Wu, Chuang

    2018-06-01

    The magnetic and thermodynamic properties of borophene structure have been studied for the first time by Monte Carlo simulation. Two-dimensional borophene structure consisting of seven hexagonal B36 units is described by Ising model. Each B36 basic unit includes three benzene-like with spin-3/2. The general formula for the borophene structure is given. The numerical results of the magnetization, the magnetic susceptibility, the internal energy and the specific heat are studied with various parameters. The possibility to test the predicted magnetism in experiment are illustrated, for instance, the maximum on the magnetization curve. The multiple hysteresis loops and the magnetization plateaus are sensitive to the ferromagnetic or ferrimagnetic exchange coupling in borophene structure. The results show the borophene structure could have applications in spintronics, which deserves further studies in experiments.

  11. Magnetic shielding structure optimization design for wireless power transmission coil

    Science.gov (United States)

    Dai, Zhongyu; Wang, Junhua; Long, Mengjiao; Huang, Hong; Sun, Mingui

    2017-09-01

    In order to improve the performance of the wireless power transmission (WPT) system, a novel design scheme with magnetic shielding structure on the WPT coil is presented in this paper. This new type of shielding structure has great advantages on magnetic flux leakage reduction and magnetic field concentration. On the basis of theoretical calculation of coil magnetic flux linkage and characteristic analysis as well as practical application feasibility consideration, a complete magnetic shielding structure was designed and the whole design procedure was represented in detail. The simulation results show that the coil with the designed shielding structure has the maximum energy transmission efficiency. Compared with the traditional shielding structure, the weight of the new design is significantly decreased by about 41%. Finally, according to the designed shielding structure, the corresponding experiment platform is built to verify the correctness and superiority of the proposed scheme.

  12. Open H-shaped permanent magnet structure for NMR imaging

    International Nuclear Information System (INIS)

    Nguyen, V.; Delamare, J.; Yonnet, J.P.

    1996-01-01

    Since NMR imaging at low field is now technically possible, permanent magnets can replace resistive coils or superconducting magnets. This paper reviews most of NMR structures that provide an uniform field using only permanent magnets. We propose a new open H-shaped structure that is simple to manufacture. This structure has been calculated thanks to an optimization program and a calculation method we presente here. It enables to determine with a good accuracy the field created by passive systems composed by permanent magnets and ferromagnetic materials. (author)

  13. Magnetic structure of two- and three-dimensional supramolecular compounds

    Energy Technology Data Exchange (ETDEWEB)

    Decurtins, S.; Schmalle, H.W.; Pellaux, R. [Zurich Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    Supramolecular chiral networks of oxalato-bridged transition metals show either two- or three-dimensional structural features. The magnetic structures of such compounds have been investigated by means of elastic neutron powder diffraction. (author) 2 figs., 2 refs.

  14. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  15. Symmetry analysis in neutron diffraction studies of magnetic structures. IV

    International Nuclear Information System (INIS)

    Izyumov, Yu.A.; Naish, V.E.; Petrov, S.B.

    1979-01-01

    By analyzing the exchange Hamiltonian, the authors develop the technique of determining the magnetic structures liable to occur in a crystal. The technique rests on Bertaut's idea that the exchange eigenfunction corresponds to some magnetic structure. A technically simple and efficient method of diagonalizing the exchange matrix is worked out using the devices of space group representation theory. A method is presented to find the magnetic structures with equal exchange energy (exchange multiplets). The occcurrence of exchange multiplets results from the additional invariance of the exchange Hamiltonian under rotation of all the spins. The degeneracy within the exchange multiplet may be the reason why some magnetic structures arise not according to one irreducible representation of the space group. The theory is illustrated with reference to an example of the magnetic structure of spinels. (Auth.)

  16. Magnetism in structures with ferromagnetic and superconducting layers

    Energy Technology Data Exchange (ETDEWEB)

    Zhaketov, V. D.; Nikitenko, Yu. V., E-mail: nikiten@nf.jinr.ru [Joint Institute for Nuclear Research (Russian Federation); Radu, F. [Helmholtz-Zentrum Berlin für Materialen un Energie (Germany); Petrenko, A. V. [Joint Institute for Nuclear Research (Russian Federation); Csik, A. [MTA Atomki, Institute for Nuclear Research (Hungary); Borisov, M. M.; Mukhamedzhanov, E. Kh. [Russian Research Centre Kurchatov Institute (Russian Federation); Aksenov, V. L. [Russian Research Centre Kurchatov Institute, Konstantinov St. Petersburg Nuclear Physics Institute (Russian Federation)

    2017-01-15

    The influence of superconductivity on ferromagnetism in the layered Ta/V/Fe{sub 1–x}V{sub x}/V/Fe{sub 1–x}V{sub x}/Nb/Si structures consisting of ferromagnetic and superconducting layers is studied using polarized neutron reflection and scattering. It is experimentally shown that magnetic structures with linear sizes from 5 nm to 30 μm are formed in these layered structures at low temperatures. The magnetization of the magnetic structures is suppressed by superconductivity at temperatures below the superconducting transition temperatures in the V and Nb layers. The magnetic states of the structures are shown to undergo relaxation over a wide magnetic-field range, which is caused by changes in the states of clusters, domains, and Abrikosov vortices.

  17. Magnetic structure of volcanic neck; Kazangankei no jiki kozo

    Energy Technology Data Exchange (ETDEWEB)

    Makino, M; Okuma, S; Morijiri, R; Nakatsuka, T [Geological Survey of Japan, Tsukuba (Japan)

    1997-05-27

    This paper describes the summary and result of magnetic exploration on the Kabutoyama volcano in the city of Nishinomiya, Hyogo Prefecture, Japan. It also states the interpretation and discussion on magnetic anomaly in the volcanic conduit of the mountain by using a three-dimensional magnetic structure model. Terrain surface magnetic exploration for the Kabutoyama volcano was performed by using six traverse lines each in different azimuths with the triangulation point at the summit as the basic point and by using a proton magnetometer. The exploration results of the six traverse lines around the Kabutoyama volcano may be generalized as follows: magnetic anomaly in the vicinity of the summit is moderate with little change, but it increases to 500 nT to 2,500 nT in the vicinity of the distances of 150 m to 200 m; a peak is formed with a width of a few tens of meters; and the magnetic anomaly showed a trend of rapidly decreasing at outer sides of the peak. The results of the magnetic exploration and the magnetization intensity measurement leads to a belief that such a magnetic anomalous band of an annular form would exist corresponding to the boundary or its vicinity of andesite and granite, and the Rokko granite having magnetization intensity as small as can be neglected would be distributed at outer sides of the boundary. The result of the three-dimensional magnetic structure model calculation, which assumes the internal structure of the magnetic structure to be non-uniformly magnetized, reproduced the magnetic anomaly patterns well as compared with the observation results. 1 ref., 5 figs.

  18. Temperature dependence of the magnetization of canted spin structures

    DEFF Research Database (Denmark)

    Jacobsen, Henrik; Lefmann, Kim; Brok, Erik

    2012-01-01

    Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models for the ......Numerous studies of the low-temperature saturation magnetization of ferrimagnetic nanoparticles and diamagnetically substituted ferrites have shown an anomalous temperature dependence. It has been suggested that this is related to freezing of canted magnetic structures. We present models...... for the temperature dependence of the magnetization of a simple canted spin structure in which relaxation can take place at finite temperatures between spin configurations with different canting angles. We show that the saturation magnetization may either decrease or increase with decreasing temperature, depending...

  19. Origin and structures of solar eruptions II: Magnetic modeling

    Science.gov (United States)

    Guo, Yang; Cheng, Xin; Ding, MingDe

    2017-07-01

    The topology and dynamics of the three-dimensional magnetic field in the solar atmosphere govern various solar eruptive phenomena and activities, such as flares, coronal mass ejections, and filaments/prominences. We have to observe and model the vector magnetic field to understand the structures and physical mechanisms of these solar activities. Vector magnetic fields on the photosphere are routinely observed via the polarized light, and inferred with the inversion of Stokes profiles. To analyze these vector magnetic fields, we need first to remove the 180° ambiguity of the transverse components and correct the projection effect. Then, the vector magnetic field can be served as the boundary conditions for a force-free field modeling after a proper preprocessing. The photospheric velocity field can also be derived from a time sequence of vector magnetic fields. Three-dimensional magnetic field could be derived and studied with theoretical force-free field models, numerical nonlinear force-free field models, magnetohydrostatic models, and magnetohydrodynamic models. Magnetic energy can be computed with three-dimensional magnetic field models or a time series of vector magnetic field. The magnetic topology is analyzed by pinpointing the positions of magnetic null points, bald patches, and quasi-separatrix layers. As a well conserved physical quantity, magnetic helicity can be computed with various methods, such as the finite volume method, discrete flux tube method, and helicity flux integration method. This quantity serves as a promising parameter characterizing the activity level of solar active regions.

  20. SOLAR ENERGETIC PARTICLE MODULATIONS ASSOCIATED WITH COHERENT MAGNETIC STRUCTURES

    International Nuclear Information System (INIS)

    Trenchi, L.; Bruno, R.; D'amicis, R.; Marcucci, M. F.; Telloni, D.; Zurbuchen, T. H.; Weberg, M.

    2013-01-01

    In situ observations of solar energetic particles (SEPs) often show rapid variations of their intensity profile, affecting all energies simultaneously, without time dispersion. A previously proposed interpretation suggests that these modulations are directly related to the presence of magnetic structures with a different magnetic topology. However, no compelling evidence of local changes in magnetic field or in plasma parameters during SEP modulations has been reported. In this paper, we performed a detailed analysis of SEP events and we found several signatures in the local magnetic field and/or plasma parameters associated with SEP modulations. The study of magnetic helicity allowed us to identify magnetic boundaries, associated with variations of plasma parameters, which are thought to represent the borders between adjacent magnetic flux tubes. It is found that SEP dispersionless modulations are generally associated with such magnetic boundaries. Consequently, we support the idea that SEP modulations are observed when the spacecraft passes through magnetic flux tubes, filled or devoid of SEPs, which are alternatively connected and not connected with the flare site. In other cases, we found SEP dropouts associated with large-scale magnetic holes. A possible generation mechanism suggests that these holes are formed in the high solar corona as a consequence of magnetic reconnection. This reconnection process modifies the magnetic field topology, and therefore, these holes can be magnetically isolated from the surrounding plasma and could also explain their association with SEP dropouts.

  1. Magnetic coupling at perovskite and rock-salt structured interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Matvejeff, M., E-mail: mikko.matvejeff@picosun.com [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan); Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Ahvenniemi, E. [Department of Chemistry, Aalto University, Kemistintie 1, 02150 Espoo (Finland); Takahashi, R.; Lippmaa, M. [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8581 Chiba (Japan)

    2015-10-05

    We study magnetic coupling between hole-doped manganite layers separated by either a perovskite or a rock-salt barrier of variable thickness. Both the type and the quality of the interface have a strong impact on the minimum critical barrier thickness where the manganite layers become magnetically decoupled. A rock-salt barrier layer only 1 unit cell (0.5 nm) thick remains insulating and is able to magnetically de-couple the electrode layers. The technique can therefore be used for developing high-performance planar oxide electronic devices such as magnetic tunnel junctions and quantum well structures that depend on magnetically and electronically sharp heterointerfaces.

  2. Plane and hemispherical potential structures in magnetically expanding plasmas

    International Nuclear Information System (INIS)

    Takahashi, Kazunori; Igarashi, Yuichi; Fujiwara, Tamiya

    2010-01-01

    Two-dimensional potential structures are measured for different gas pressure in expanding argon plasma using permanent magnets, where the magnetic field is about 100 G in the source and several gauss in the diffusion chamber. The plane potential drop is observed near the source exit for 0.35 mTorr, while the potential structure becomes hemispherical when increasing up to 1 mTorr; the hemispherical structure results in the radial divergence of the ion beam. It is found that the trajectories of the accelerated ions and the electrons overcoming the potential drop are dominated by the potential structure and magnetic-field lines, respectively.

  3. Short Large-Amplitude Magnetic Structures (SLAMS) at Venus

    Science.gov (United States)

    Collinson, G. A.; Wilson, L. B.; Sibeck, D. G.; Shane, N.; Zhang, T. L.; Moore, T. E.; Coates, A. J.; Barabash, S.

    2012-01-01

    We present the first observation of magnetic fluctuations consistent with Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock of the planet Venus. Three monolithic magnetic field spikes were observed by the Venus Express on the 11th of April 2009. The structures were approx.1.5->11s in duration, had magnetic compression ratios between approx.3->6, and exhibited elliptical polarization. These characteristics are consistent with the SLAMS observed at Earth, Jupiter, and Comet Giacobini-Zinner, and thus we hypothesize that it is possible SLAMS may be found at any celestial body with a foreshock.

  4. Structure and phase formation behavior and dielectric and magnetic properties of lead iron tantalate-lead zirconate titanate multiferroic ceramics

    International Nuclear Information System (INIS)

    Wongmaneerung, R.; Tipakontitikul, R.; Jantaratana, P.; Bootchanont, A.; Jutimoosik, J.; Yimnirun, R.; Ananta, S.

    2016-01-01

    Highlights: • The multiferroic ceramics consisted of PFT and PZT. • Crystal structure changed from cubic to mixedcubic and tetragonal with increasing PZT content. • Dielectric showed the samples underwent a typical relaxor ferroelectric behavior. • Magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops. - Abstract: Multiferroic (1 − x)Pb(Fe_0_._5Ta_0_._5)O_3–xPb(Zr_0_._5_3Ti_0_._4_7)O_3 (or PFT–PZT) ceramics were synthesized by solid-state reaction method. The crystal structure and phase formation of the ceramics were examined by X-ray diffraction (XRD). The local structure surrounding Fe and Ti absorbing atoms was investigated by synchrotron X-ray Absorption Near-Edge Structure (XANES) measurement. Dielectric properties were studied as a function of frequency and temperature using a LCR meter. A vibrating sample magnetometer (VSM) was used to determine the magnetic hysteresis loops. XRD study indicated that the crystal structure of the sample changed from pure cubic to mixed cubic and tetragonal with increasing PZT content. XANES measurements showed that the local structure surrounding Fe and Ti ions was similar. Dielectric study showed that the samples underwent a typical relaxor ferroelectric behavior while the magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops.

  5. Structure and phase formation behavior and dielectric and magnetic properties of lead iron tantalate-lead zirconate titanate multiferroic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wongmaneerung, R., E-mail: re_nok@yahoo.com [Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Tipakontitikul, R. [Department of Physics, Ubonratchathani University, Ubonratchathani 31490 (Thailand); Jantaratana, P. [Department of Physics, Kasetsart University, Bangkok 10900 (Thailand); Bootchanont, A.; Jutimoosik, J.; Yimnirun, R. [School of Physics, Institute of Science, and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Ananta, S. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2016-03-15

    Highlights: • The multiferroic ceramics consisted of PFT and PZT. • Crystal structure changed from cubic to mixedcubic and tetragonal with increasing PZT content. • Dielectric showed the samples underwent a typical relaxor ferroelectric behavior. • Magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops. - Abstract: Multiferroic (1 − x)Pb(Fe{sub 0.5}Ta{sub 0.5})O{sub 3}–xPb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} (or PFT–PZT) ceramics were synthesized by solid-state reaction method. The crystal structure and phase formation of the ceramics were examined by X-ray diffraction (XRD). The local structure surrounding Fe and Ti absorbing atoms was investigated by synchrotron X-ray Absorption Near-Edge Structure (XANES) measurement. Dielectric properties were studied as a function of frequency and temperature using a LCR meter. A vibrating sample magnetometer (VSM) was used to determine the magnetic hysteresis loops. XRD study indicated that the crystal structure of the sample changed from pure cubic to mixed cubic and tetragonal with increasing PZT content. XANES measurements showed that the local structure surrounding Fe and Ti ions was similar. Dielectric study showed that the samples underwent a typical relaxor ferroelectric behavior while the magnetic properties showed very interesting behavior with square saturated magnetic hysteresis loops.

  6. The structure of the big magnetic storms

    International Nuclear Information System (INIS)

    Mihajlivich, J. Spomenko; Chop, Rudi; Palangio, Paolo

    2010-01-01

    The records of geomagnetic activity during Solar Cycles 22 and 23 (which occurred from 1986 to 2006) indicate several extremely intensive A-class geomagnetic storms. These were storms classified in the category of the Big Magnetic Storms. In a year of maximum solar activity during Solar Cycle 23, or more precisely, during a phase designated as a post-maximum phase in solar activity (PPM - Phase Post maximum), near the autumn equinox, on 29, October 2003, an extremely strong and intensive magnetic storm was recorded. In the first half of November 2004 (7, November 2004) an intensive magnetic storm was recorded (the Class Big Magnetic Storm). The level of geomagnetic field variations which were recorded for the selected Big Magnetic Storms, was ΔD st=350 nT. For the Big Magnetic Storms the indicated three-hour interval indices geomagnetic activity was Kp = 9. This study presents the spectral composition of the Di - variations which were recorded during magnetic storms in October 2003 and November 2004. (Author)

  7. Structure and magnetization of Co4N thin film

    Science.gov (United States)

    Pandey, Nidhi; Gupta, Mukul; Gupta, Rachana; Rajput, Parasmani; Stahn, Jochen

    2018-02-01

    In this work, we studied the local structure and the magnetization of Co4N thin films deposited by a reactive dc magnetron sputtering process. The interstitial incorporation of N atoms in a fcc Co lattice is expected to expand the structure. This expansion yields interesting magnetic properties e.g. a larger magnetic moment (than Co) and a very high value of spin polarization ratio in Co4N . By optimizing the growth conditions, we prepared Co4N film having lattice parameter close to its theoretically predicted value. The N concentration was measured using secondary ion mass spectroscopy. Detailed magnetization measurements using bulk magnetization method and polarized neutron reflectivity confirm that the magnetic moment of Co in Co4N is higher than that of Co.

  8. Magnetic Properties of Three Impact Structures in Canada

    Science.gov (United States)

    Scott, R. G.; Pilkington, M.; Tanczyk, E. I.; Grieve, R. A. F.

    1995-09-01

    Magnetic anomaly lows associated with the West Hawk Lake (Manitoba), Deep Bay (Saskatchewan) and Clearwater Lakes (Quebec) impact structures, are variable in lateral extent and intensity, a characteristic shared with most impact structures [1]. Drill core from the centres of these structures provides a unique opportunity to ground truth the causes of the reduction in magnetic field intensity in impact structures. Magnetic susceptibility and remanent magnetization levels have been found to be well below regional levels in melt rocks, impact breccias, fractured/shocked basement rocks in the central uplifts, and post-impact sediments. Deep Bay, formed in Pre-Cambrian paragneisses, is a complex crater with a submerged central uplift. It has been extensively infilled with non-magnetic black shales of Cretaceous age [2]. An airborne magnetic low of about 100 nT is associated with the Deep Bay structure. Below the shales and along the rim of the structure are highly brecciated country rocks with variable amounts of very fine rock flour. Susceptibility and remanent magnetization are both weak due to extensive alteration in the brecciated rocks. Alteration of the brecciated rocks, and the effect of several hundred meters of non-magnetic sedimentary infill, both contribute to the magnetic low. West Hawk Lake, a simple crater, was excavated in metavolcanic and metasedimentary rocks of the Superior Province [3], and has a ground magnetic low of about 250 nT. As with Deep Bay, West Hawk Lake has been infilled with dominantly non-magnetic sediments. Brecciation and alteration are extensive, with breccia derived from greenschist-facies meta-andesite displaying slightly higher susceptibilities and remanent magnetizations than breccia derived from the more felsic metasediments. Brecciation has effectively randomized magnetization vectors, and subsequent alteration resulted in the destruction of magnetic phases. These two factors contribute to the magnetic low over this structure

  9. Graphite structure and magnetic parameters of flake graphite cast iron

    Czech Academy of Sciences Publication Activity Database

    Vértesy, G.; Uchimoto, T.; Takagi, T.; Tomáš, Ivan; Kage, H.

    2017-01-01

    Roč. 442, Nov (2017), s. 397-402 ISSN 0304-8853 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:68378271 Keywords : magnetic NDE * magnetic adaptive testing * cast iron * graphite structure * pearlite content Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

  10. Influence of magnetic fields on structural martensitic transitions

    Energy Technology Data Exchange (ETDEWEB)

    Lashley, J C [Los Alamos National Laboratory; Cooley, J C [Los Alamos National Laboratory; Smith, J L [Los Alamos National Laboratory; Fisher, R A [NON LANL; Modic, K A [Los Alamos National Laboratory; Yang, X- D [TEMPLE UNIV; Riseborough, P S [TEMPLE UNIV.; Opeil, C P [BOSTON COLLEGE; Finlayson, T R [UNIV OF MELBOURNE; Goddard, P A [UNIV OF OXFORD; Silhanek, A V [INPAC

    2009-01-01

    We show evidence that a structural martensitic transition is related to significant changes in the electronic structure, as revealed in thermodynamic measurements made in high-magnetic fields. The magnetic field dependence is considered unusual as many influential investigations of martensitic transitions have emphasized that the structural transitions are primarily lattice dynamical and are driven by the entropy due to the phonons. We provide a theoretical framework which can be used to describe the effect of magnetic field on the lattice dynamics in which the field dependence originates from the dielectric constant.

  11. New insight in magnetic saturation behavior of nickel hierarchical structures

    Science.gov (United States)

    Ma, Ji; Zhang, Jianxing; Liu, Chunting; Chen, Kezheng

    2017-09-01

    It is unanimously accepted that non-ferromagnetic inclusions in a ferromagnetic system will lower down total saturation magnetization in unit of emu/g. In this study, ;lattice strain; was found to be another key factor to have critical impact on magnetic saturation behavior of the system. The lattice strain determined assembling patterns of primary nanoparticles in hierarchical structures and was intimately related with the formation process of these architectures. Therefore, flower-necklace-like and cauliflower-like nickel hierarchical structures were used as prototype systems to evidence the relationship between assembling patterns of primary nanoparticles and magnetic saturation behaviors of these architectures. It was found that the influence of lattice strain on saturation magnetization outperformed that of non-ferromagnetic inclusions in these hierarchical structures. This will enable new insights into fundamental understanding of related magnetic effects.

  12. Local magnetic structure determination using polarized neutron holography

    International Nuclear Information System (INIS)

    Szakál, Alex; Markó, Márton; Cser, László

    2015-01-01

    A unique and important property of the neutron is that it possesses magnetic moment. This property is widely used for determination of magnetic structure of crystalline samples observing the magnetic components of the diffraction peaks. Investigations of diffraction patterns give information only about the averaged structure of a crystal but for discovering of local spin arrangement around a specific (e.g., impurity) nucleus remains still a challenging problem. Neutron holography is a useful tool to investigate the local structure around a specific nucleus embedded in a crystal lattice. The method has been successfully applied experimentally in several cases using non-magnetic short range interaction of the neutron and the nucleus. A mathematical model of the hologram using interaction between magnetic moment of the atom and the neutron spin for polarized neutron holography is provided. Validity of a polarized neutron holographic experiment is demonstrated by applying the proposed method on model systems

  13. Effects of the magnetic field on the structure of materials

    International Nuclear Information System (INIS)

    Nakajima, Tetsuo

    1984-02-01

    This is a report of the ''Meeting on the effects of a magnetic field on the structure of materials'' held at KEK, Japan. The purpose of the Meeting was to study the diffraction of SR X-ray in a magnetic field. It was found that the effects of a magnetic field have been seen in various substnaces. The effects are due to the Zeeman effect, the Lamor diamagnetism, the Landau diamagnetism, the Meissner effect and the polarization effect. The topics discussed at the Meeting were the structure study of biological specimens by field orientation, the study of cell structure by field orientation, the phase transition under a strong pulse field, the behavior of high molecular liquid crystal in a magnetic field, the change of the f-electron density of the Tb 3+ ions in Tb IG in a magnetic field at low temperature, an electromagnet loaded on a goniometer and an in-situ observation system for the structure of magnetic domain, the control of structural phase transition by a magnetic field, the use of synchrotron orbit radiation for the structural analysis of random systems, and the field effect on chemical reactions. (Kato, T.)

  14. 3D Biomimetic Magnetic Structures for Static Magnetic Field Stimulation of Osteogenesis

    Directory of Open Access Journals (Sweden)

    Irina Alexandra Paun

    2018-02-01

    Full Text Available We designed, fabricated and optimized 3D biomimetic magnetic structures that stimulate the osteogenesis in static magnetic fields. The structures were fabricated by direct laser writing via two-photon polymerization of IP-L780 photopolymer and were based on ellipsoidal, hexagonal units organized in a multilayered architecture. The magnetic activity of the structures was assured by coating with a thin layer of collagen-chitosan-hydroxyapatite-magnetic nanoparticles composite. In vitro experiments using MG-63 osteoblast-like cells for 3D structures with gradients of pore size helped us to find an optimum pore size between 20–40 µm. Starting from optimized 3D structures, we evaluated both qualitatively and quantitatively the effects of static magnetic fields of up to 250 mT on cell proliferation and differentiation, by ALP (alkaline phosphatase production, Alizarin Red and osteocalcin secretion measurements. We demonstrated that the synergic effect of 3D structure optimization and static magnetic stimulation enhances the bone regeneration by a factor greater than 2 as compared with the same structure in the absence of a magnetic field.

  15. 3D Biomimetic Magnetic Structures for Static Magnetic Field Stimulation of Osteogenesis.

    Science.gov (United States)

    Paun, Irina Alexandra; Popescu, Roxana Cristina; Calin, Bogdan Stefanita; Mustaciosu, Cosmin Catalin; Dinescu, Maria; Luculescu, Catalin Romeo

    2018-02-07

    We designed, fabricated and optimized 3D biomimetic magnetic structures that stimulate the osteogenesis in static magnetic fields. The structures were fabricated by direct laser writing via two-photon polymerization of IP-L780 photopolymer and were based on ellipsoidal, hexagonal units organized in a multilayered architecture. The magnetic activity of the structures was assured by coating with a thin layer of collagen-chitosan-hydroxyapatite-magnetic nanoparticles composite. In vitro experiments using MG-63 osteoblast-like cells for 3D structures with gradients of pore size helped us to find an optimum pore size between 20-40 µm. Starting from optimized 3D structures, we evaluated both qualitatively and quantitatively the effects of static magnetic fields of up to 250 mT on cell proliferation and differentiation, by ALP (alkaline phosphatase) production, Alizarin Red and osteocalcin secretion measurements. We demonstrated that the synergic effect of 3D structure optimization and static magnetic stimulation enhances the bone regeneration by a factor greater than 2 as compared with the same structure in the absence of a magnetic field.

  16. Magnetic domain structure and magnetically-induced reorientation in Ni–Mn–Ga magnetic shape memory alloy

    Czech Academy of Sciences Publication Activity Database

    Heczko, Oleg; Bradshaw, V.

    2017-01-01

    Roč. 131, č. 4 (2017), s. 1063-1065 ISSN 0587-4246 R&D Projects: GA ČR GA15-00262S Institutional support: RVO:68378271 Keywords : magnetic shape memory effect * magnetic domain structure * 3D visualization * domain mirroring Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.469, year: 2016

  17. Giant Magnetic Field Enhancement in Hybridized MIM Structures

    KAUST Repository

    Alrasheed, Salma; Di Fabrizio, Enzo M.

    2017-01-01

    We propose numerically an approach to narrow the plasmon linewidth and enhance the magnetic near field intensity at a magnetic hot spot in a hybridized metal-insulatormetal (MIM) structure. First we insert in part of the dielectric layer of the MIM

  18. Coherent magnetic structures in terbium/holmium superlattices

    DEFF Research Database (Denmark)

    Bryn-Jacobsen, C.; Cowley, R.A.; McMorrow, D.F.

    1997-01-01

    to 230 K, two samples retain this magnetic structure while the third undergoes a transition first to a mixed phase of helically and ferromagnetically ordered Tb moments, then to a phase with only helically ordered To moments. Ln all cases, the magnetic ordering is found to be long ranged, with coherence...

  19. Spontaneous phase transitions in magnetic films with a modulated structure

    International Nuclear Information System (INIS)

    Arzamastseva, G. V.; Evtikhov, M. G.; Lisovskii, F. V.; Mansvetova, E. G.

    2011-01-01

    The influence of monoperiodic and biperiodic bias fields on the nucleation of domain structures in quasi-uniaxial magnetic films near the Curie point has been studied experimentally. The main types of observed nonuniform magnetic moment distributions have been established and chains of a devil’s staircase phase transitions are shown to be realized when the films are slowly cooled.

  20. Generic structural mechanics aspects of fusion magnet systems

    International Nuclear Information System (INIS)

    Reich, M.; Powell, J.R.

    1980-01-01

    Structural mechanic requirements for future large superconducting fusion magnets are assessed. Current structural analysis methods and standards do not yet appear sufficient for a complete evaluation of such systems, under all potential operating and accident conditions. Recommendations are made for development of needed structural methods and specialized standards for fusion magnets. These include, among others, better composite structural methods with various failure criteria for metallic, as well as non-metallic materials, coupled thermal-electrical-structural codes, incorporating winding and fabrication effects, and use of probabilistic methods for life prediction. In order to help meet program goals for fusion commericialization, it is recommended that such work be initiated relatively soon. (orig.)

  1. Core/Shell Structured Magnetic Nanoparticles for Biological Applications

    International Nuclear Information System (INIS)

    Park, Jeong Chan; Jung, Myung Hwan

    2013-01-01

    Magnetic nanoparticles have been widely used for biomedical applications, such as magnetic resonance imaging (MRI), hyperthermia, drug delivery and cell signaling. The surface modification of the nanomaterials is required for biomedical use to give physiogical stability, surface reactivity and targeting properties. Among many approaches for the surface modification with materials, such as polymers, organic ligands and metals, one of the most attractive ways is using metals. The fabrication of metal-based, monolayer-coated magnetic nanoparticles has been intensively studied. However, the synthesis of metal-capped magnetic nanoparticles with monodispersities and controllable sizes is still challenged. Recently, gold-capped magnetic nanoparticles have been reported to increase stability and to provide biocompatibility. Magnetic nanoparticle with gold coating is an attractive system, which can be stabilized in biological conditions and readily functionalized in biological conditions and readily functionalized through well-established surface modification (Au-S) chemistry. The Au coating offers plasmonic properties to magnetic nanoparticles. This makes the magnetic/Au core/shell combinations interesting for magnetic and optical applications. Herein, the synthesis and characterization of gold capped-magnetic core structured nanomaterials with different gold sources, such as gold acetate and chloroauric acid have been reported. The core/shell nanoparticles were transferred from organic to aqueous solutions for biomedical applications. Magnetic core/shell structured nanoparticles have been prepared and transferred from organic phase to aqueous solutions. The resulting Au-coated magnetic core nanoparticles might be an attractive system for biomedical applications, which are needed both magnetic resonance imaging and optical imaging

  2. Structure and Magnetic Properties of Lanthanide Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Dickerson, James Henry [Vanderbilt Univ., Nashville, TN (United States)

    2014-06-01

    We have had considerable success on this project, particularly in the understanding of the relationship between nanostructure and magnetic properties in lanthanide nanocrystals. We also have successfully facilitated the doctoral degrees of Dr. Suseela Somarajan, in the Department of Physics and Astronomy, and Dr. Melissa Harrison, in the Materials Science Program. The following passages summarize the various accomplishments that were featured in 9 publications that were generated based on support from this grant. We thank the Department of Energy for their generous support of our research efforts in this area of materials science, magnetism, and electron microscopy.

  3. MAGNETIC FIELD STRUCTURES TRIGGERING SOLAR FLARES AND CORONAL MASS EJECTIONS

    International Nuclear Information System (INIS)

    Kusano, K.; Bamba, Y.; Yamamoto, T. T.; Iida, Y.; Toriumi, S.; Asai, A.

    2012-01-01

    Solar flares and coronal mass ejections, the most catastrophic eruptions in our solar system, have been known to affect terrestrial environments and infrastructure. However, because their triggering mechanism is still not sufficiently understood, our capacity to predict the occurrence of solar eruptions and to forecast space weather is substantially hindered. Even though various models have been proposed to determine the onset of solar eruptions, the types of magnetic structures capable of triggering these eruptions are still unclear. In this study, we solved this problem by systematically surveying the nonlinear dynamics caused by a wide variety of magnetic structures in terms of three-dimensional magnetohydrodynamic simulations. As a result, we determined that two different types of small magnetic structures favor the onset of solar eruptions. These structures, which should appear near the magnetic polarity inversion line (PIL), include magnetic fluxes reversed to the potential component or the nonpotential component of major field on the PIL. In addition, we analyzed two large flares, the X-class flare on 2006 December 13 and the M-class flare on 2011 February 13, using imaging data provided by the Hinode satellite, and we demonstrated that they conform to the simulation predictions. These results suggest that forecasting of solar eruptions is possible with sophisticated observation of a solar magnetic field, although the lead time must be limited by the timescale of changes in the small magnetic structures.

  4. Structural and magnetic studies on copper succinate dihydrate ...

    Indian Academy of Sciences (India)

    M P BINITHA

    2017-08-21

    Aug 21, 2017 ... rials chemistry, heterogeneous catalysis, gas storage, polymer magnets, etc. ... super exchange interactions among copper atoms through bridging .... Thus, these two water molecules in the structure of copper succinate are.

  5. Electronic band structure of magnetic bilayer graphene superlattices

    International Nuclear Information System (INIS)

    Pham, C. Huy; Nguyen, T. Thuong; Nguyen, V. Lien

    2014-01-01

    Electronic band structure of the bilayer graphene superlattices with δ-function magnetic barriers and zero average magnetic flux is studied within the four-band continuum model, using the transfer matrix method. The periodic magnetic potential effects on the zero-energy touching point between the lowest conduction and the highest valence minibands of pristine bilayer graphene are exactly analyzed. Magnetic potential is shown also to generate the finite-energy touching points between higher minibands at the edges of Brillouin zone. The positions of these points and the related dispersions are determined in the case of symmetric potentials.

  6. Influence of different rotor magnetic circuit structure on the performance of permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Qiu Hongbo

    2017-09-01

    Full Text Available In order to compare the performance difference of the permanent magnet synchronous motors (PMSM with different rotor structure, two kinds of rotor magnetic circuit structure with surface-mounted radial excitation and tangential excitation are designed respectively. By comparing and analyzing the results, the difference of the motor performance was determined. Firstly, based on the finite element method (FEM, the motor electromagnetic field performance was studied, and the magnetic field distribution of the different magnetic circuit structure was obtained. The influence mechanism of the different magnetic circuit structure on the air gap flux density was obtained by using the Fourier theory. Secondly, the cogging torque, output torque and overload capacity of the PMSM with different rotor structure were studied. The effect mechanism of the different rotor structure on the motor output property difference was obtained. The motor prototype with two kinds of rotor structure was manufactured, and the experimental study was carried out. By comparing the experimental data and simulation data, the correctness of the research is verified. This paper lays a foundation for the research on the performance of the PMSM with different magnetic circuit structure.

  7. Magnetic structure in the entrance region of spheromaks sustained by a magnetized coaxial plasma gun under long pulse operation

    International Nuclear Information System (INIS)

    Amemiya, Naoyuki; Takaichi, Kazuaki; Katsurai, Makoto

    1989-01-01

    The magnetic structure in coaxial-gun-sustained spheromaks has been investigated. The plasma gun has been operated with a small axial/radial bias magnetic flux as compared to the azimuthal magnetic flux produced by the discharge current. Stronger magnetic field is observed in the entrance region (ER) than in the flux conserver (FC). In both ER and FC, the magnetic structure is nearly axisymmetric. The axial magnetic field in ER is amplified up to about sixteen times as large as the bias magnetic field. This amplification is limited by the drastic change in the magnetic structure, which occurs when the discharge current becomes very large. The magnetic structure before the drastic change is interpreted with the Bessel function model. The μ estimation shows that the magnetic structure is mainly determined by the boundary geometry, not by the external magnetic flux and current. (author)

  8. The symmetries of magnetic structures in rare earth tetraborides

    International Nuclear Information System (INIS)

    Schaefer, W.; Will, G.; Buschow, K.H.J.

    1975-01-01

    The collinear antiferromagnetic spin configurations, which are possible in the rare earth tetraboride structure (space group P 4/mbm) and their distinction by neutron diffraction are discussed. The symmetries of the different antiferromagnetic structures are described by the corrosponding magnetic space groups. Neutron diffraction data collected from ErB 4 are integrated in the structure discussion. (orig.) [de

  9. Tripolar electric field Structure in guide field magnetic reconnection

    OpenAIRE

    S. Fu; S. Huang; M. Zhou; B. Ni; X. Deng

    2018-01-01

    It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplit...

  10. Structural materials for large superconducting magnets for tokamaks

    International Nuclear Information System (INIS)

    Long, C.J.

    1976-12-01

    The selection of structural materials for large superconducting magnets for tokamak-type fusion reactors is considered. The important criteria are working stress, radiation resistance, electromagnetic interaction, and general feasibility. The most advantageous materials appear to be face-centered-cubic alloys in the Fe-Ni-Cr system, but high-modulus composites may be necessary where severe pulsed magnetic fields are present. Special-purpose structural materials are considered briefly

  11. The dynamics of coronal magnetic structures

    International Nuclear Information System (INIS)

    Weber, W.

    1978-01-01

    An analysis is made of the evolution of coronal magnetic fields due to the interaction with the solar wind. An analysis of the formation of coronal streamers, arising as a result of the stretching of bipolar fields, is given. Numerical simulations of the formation of coronal streamers are presented. Fast-mode shocks as triggers of microturbulence in the solar corona are discussed

  12. Self-Organized Structures in Magnetic Liquids

    DEFF Research Database (Denmark)

    Oddershede, Lene; Bohr, Jakob

    1996-01-01

    , but the bigger ones grow on the expense of the smaller. From the center of mass of the columns a 2D-Veronoi pattern is constructed in the plane of the cell, and the edge statistics are found as a function of the fraction of magnetic liquid in the Hele-Shaw cell. The average number of edges in the Veronoi cells...

  13. New helical-shape magnetic pole design for Magnetic Lead Screw enabling structure simplification

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Xia, Yongming; Wu, Weimin

    2015-01-01

    Magnetic lead screw (MLS) is a new type of high performance linear actuator that is attractive for many potential applications. The main difficulty of the MLS technology lies in the manufacturing of its complicated helical-shape magnetic poles. Structure simplification is, therefore, quite...

  14. Structural investigation of chemically synthesized ferrite magnetic nanomaterials

    Science.gov (United States)

    Uyanga, E.; Sangaa, D.; Hirazawa, H.; Tsogbadrakh, N.; Jargalan, N.; Bobrikov, I. A.; Balagurov, A. M.

    2018-05-01

    In recent times, interest in ferrite magnetic nanomaterials has considerably grown, mainly due to their highly promising medical and biological applications. Spinel ferrite powder samples, with high heat generation abilities in AC magnetic fields, were studied for their application to the hyperthermia treatment of cancer tumors. These properties of ferrites strongly depend on their chemical composition, ion distribution between crystallographic positions, magnetic structure and method of preparation. In this study, crystal and magnetic structures of several magnetic spinels were investigated by neutron diffraction. The explanation of the mechanism triggering the heat generation ability in the magnetic materials, and the electronic and magnetic states of ferrite-spinel type structures, were theoretically defined by a first-principles method. Ferrites with the composition of CuxMg1-xFe2O4 have been investigated as a heat generating magnetic nanomaterial. Atomic fraction of copper in ferrite was varied between 0 and 100% (that is, x between 0 and 1.0 with 0.2 steps), with the copper dope limit corresponding to appear a tetragonal phase.

  15. Vibrating wire apparatus for periodic magnetic structure measurement

    International Nuclear Information System (INIS)

    Temnykh, A.B.

    2003-01-01

    Devices with periodic magnetic structures such as wigglers and undulators are often key elements in synchrotron radiation sources. In applications where the coherence of the emitted radiation is important, magnetic field errors distorting the periodicity of the field can significantly reduce the performance of the devices. Thus, the measurement, localization, and correction of the field errors can be a critical issue. This article presents a new method for magnetic field measurements in periodic magnetic structures. The method uses a vibrating taut wire passing through the magnetic structure, and it involves measurements of the amplitudes and phases of the standing waves excited on the wire by the Lorentz force between an AC current in the wire and the surrounding magnetic field. For certain arrangements of the wire, vibrations in the wire will be excited by only non-periodic magnetic field component, i.e., by the error field. By measuring the phase and amplitude of these waves, one can reconstruct the error field distribution and then correct it. The method was tested on a permanent magnet wiggler with 19.8 cm period and a peak field of ∼7000G. It demonstrated ∼0.6G RMS sensitivity, δB rms /B rms ∼1.2x10 -4 and spatial resolution sufficient to identify poles generating the field error. Good agreement was found between field error measurements obtained with the vibrating wire method and with traditional Hall probe field mapping

  16. Magnetic structures in ultra-thin Holmium films: Influence of external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, L.J. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Mello, V.D. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, Mossoró 59625-620, RN (Brazil); Anselmo, D.H.A.L. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, Natal 59600-900, RN (Brazil); Vasconcelos, M.S., E-mail: mvasconcelos@ect.ufrn.br [Escola de Ciência e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil)

    2015-03-01

    We address the magnetic phases in very thin Ho films at the temperature interval between 20 K and 132 K. We show that slab size, surface effects and magnetic field due to spin ordering impact significantly the magnetic phase diagram. Also we report that there is a relevant reduction of the external field strength required to saturate the magnetization and for ultra-thin films the helical state does not form. We explore the specific heat and the susceptibility as auxiliary tools to discuss the nature of the phase transitions, when in the presence of an external magnetic field and temperature effects. The presence of an external field gives rise to the magnetic phase Fan and the spin-slip structures. - Highlights: • We analyze the magnetic phases of very thin Ho films in the temperature interval 20–132 K. • We show that slab size, etc. due to spin ordering may impact the magnetic phase diagram. • All magnetic phase transitions, for strong magnetic fields, are marked by the specific heat. • The presence of an external field gives rise to the magnetic phase Fan and the spin-slip one.

  17. Synergistic structures from magnetic freeze casting with surface magnetized alumina particles and platelets.

    Science.gov (United States)

    Frank, Michael B; Hei Siu, Sze; Karandikar, Keyur; Liu, Chin-Hung; Naleway, Steven E; Porter, Michael M; Graeve, Olivia A; McKittrick, Joanna

    2017-12-01

    Magnetic freeze casting utilizes the freezing of water, a low magnetic field and surface magnetized materials to make multi-axis strengthened porous scaffolds. A much greater magnetic moment was measured for larger magnetized alumina platelets compared with smaller particles, which indicated that more platelet aggregation occurred within slurries. This led to more lamellar wall alignment along the magnetic field direction during magnetic freeze casting at 75 mT. Slurries with varying ratios of magnetized particles to platelets (0:1, 1:3, 1:1, 3:1, 7:1, 1:0) produced porous scaffolds with different structural features and degrees of lamellar wall alignment. The greatest mechanical enhancement in the magnetic field direction was identified in the synergistic condition with the highest particle to platelet ratio (7:1). Magnetic freeze casting with varying ratios of magnetized anisotropic and isotropic alumina provided insights about how heterogeneous morphologies aggregate within lamellar walls that impact mechanical properties. Fabrication of strengthened scaffolds with multi-axis aligned porosity was achieved without introducing different solid materials, freezing agents or additives. Resemblance of 7:1 particle to platelet scaffold microstructure to wood light-frame house construction is framed in the context of assembly inspiration being derived from both natural and synthetic sources. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Two-dimensional chiral asymmetry in unidirectional magnetic anisotropy structures

    Directory of Open Access Journals (Sweden)

    P. Perna

    2016-05-01

    Full Text Available We investigate the symmetry-breaking effects of magnetic nanostructures that present unidirectional (one-fold magnetic anisotropy. Angular and field dependent transport and magnetic properties have been studied in two different exchange-biased systems, i.e. ferromagnetic (FM/ antiferromagnetic (AFM bilayer and spin-valve structures. We experimentally show the direct relationships between the magnetoresistance (MR response and the magnetization reversal pathways for any field value and direction. We demonstrate that even though the MR signals are related to different transport phenomena, namely anisotropic magnetoresistance (AMR and giant magnetoresistance (GMR, chiral asymmetries are found around the magnetization hard-axis direction, in both cases originated from the one-fold symmetry of the interfacial exchange coupling. Our results indicate that the chiral asymmetry of transport and magnetic behaviors are intrinsic of systems with an unidirectional contribution.

  19. Two-dimensional chiral asymmetry in unidirectional magnetic anisotropy structures

    Energy Technology Data Exchange (ETDEWEB)

    Perna, P., E-mail: paolo.perna@imdea.org; Guerrero, R.; Niño, M. A. [IMDEA-Nanoscience, c/ Faraday, 9 Campus de Cantoblanco, 28049 Madrid (Spain); Ajejas, F.; Maccariello, D.; Cuñado, J. L. [IMDEA-Nanoscience, c/ Faraday, 9 Campus de Cantoblanco, 28049 Madrid (Spain); DFMC and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Muñoz, M. [IMM-CSIC, Isaac Newton 8, PTM, 28760 Tres Cantos, Madrid (Spain); ISOM, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Prieto, J. L. [ISOM, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Miranda, R.; Camarero, J. [IMDEA-Nanoscience, c/ Faraday, 9 Campus de Cantoblanco, 28049 Madrid (Spain); DFMC and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, 28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid (Spain)

    2016-05-15

    We investigate the symmetry-breaking effects of magnetic nanostructures that present unidirectional (one-fold) magnetic anisotropy. Angular and field dependent transport and magnetic properties have been studied in two different exchange-biased systems, i.e. ferromagnetic (FM)/ antiferromagnetic (AFM) bilayer and spin-valve structures. We experimentally show the direct relationships between the magnetoresistance (MR) response and the magnetization reversal pathways for any field value and direction. We demonstrate that even though the MR signals are related to different transport phenomena, namely anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR), chiral asymmetries are found around the magnetization hard-axis direction, in both cases originated from the one-fold symmetry of the interfacial exchange coupling. Our results indicate that the chiral asymmetry of transport and magnetic behaviors are intrinsic of systems with an unidirectional contribution.

  20. Periodical plasma structures controlled by external magnetic field

    Science.gov (United States)

    Schweigert, I. V.; Keidar, M.

    2017-06-01

    The characteristics of two-dimensional periodical structures in a magnetized plasma are studied using kinetic simulations. Ridges (i.e. spikes in electron and ion density) are formed and became more pronounced with an increase of magnetic field incidence angle in the plasma volume in the cylindrical chamber. These ridges are shifted relative to each other, which results in the formation of a two-dimensional double-layer structure. Depending on Larmor radius and Debye length up to 19 potential steps appear across the oblique magnetic field. The electrical current gathered into the channels is associated with the electron and ion density ridges.

  1. Vortex magnetic structure in circularly magnetized microwires as deduced from magneto-optical Kerr measurements

    KAUST Repository

    Ivanov, Yurii P.

    2014-02-14

    The magneto-optic Kerr effect has been employed to determine the magnetization process and estimate the domain structure of microwires with circular magnetic anisotropy. The diameter of microwires was 8 μm, and pieces 2 cm long were selected for measurements. The analysis of the local surface longitudinal and transverse hysteresis loops has allowed us to deduce a vortex magnetic structure with axial core and circular external shell. Moreover, a bamboo-like surface domain structure is confirmed with wave length of around 10 to 15 μm and alternating chirality in adjacent circular domains. The width of the domain wall is estimated to be less than 3 μm. Finally, closure domain structures with significant helical magnetization component are observed extending up to around 1000 μm from the end of the microwire.

  2. Vortex magnetic structure in circularly magnetized microwires as deduced from magneto-optical Kerr measurements

    KAUST Repository

    Ivanov, Yurii P.; del Real, R. P.; Chubykalo-Fesenko, O.; Vá zquez, M.

    2014-01-01

    The magneto-optic Kerr effect has been employed to determine the magnetization process and estimate the domain structure of microwires with circular magnetic anisotropy. The diameter of microwires was 8 μm, and pieces 2 cm long were selected for measurements. The analysis of the local surface longitudinal and transverse hysteresis loops has allowed us to deduce a vortex magnetic structure with axial core and circular external shell. Moreover, a bamboo-like surface domain structure is confirmed with wave length of around 10 to 15 μm and alternating chirality in adjacent circular domains. The width of the domain wall is estimated to be less than 3 μm. Finally, closure domain structures with significant helical magnetization component are observed extending up to around 1000 μm from the end of the microwire.

  3. Structural and Magnetic Behavioral Improvisation of Nanocalcium Hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Sable, Sharad N., E-mail: sharadtz@hotmail.co [Department of Applied Physics, Priyadarshini College of Engineering, Nagpur (India); Rewatkar, Kishor G. [Department of Physics, Dr. Ambedkar College, Dikshabhumi, Nagpur (India); Nanoti, Vivek M. [Priyadarshini College of Engineering, Nagpur (India)

    2010-04-15

    In modern technoscientific era, the industrial application of nanomaterials has grabbed a paramount importance owing to their improved characteristics. Hexagonal ferrites especially M-type ferrites have been proved to be the promising candidates for nanomaterials by virtue of their ease of applicability in high density recording media, microwave absorption devices, magneto-optic recording media, etc. Keeping a bird's view over, the samples of varied combinations of M-type substituted hexaferrites are synthesized using sol-gel combustion route by blending nitrates and chlorides as oxidants accompanied with fuels like urea, glycine, citric acid, etc. as reducing agents. The substitution of Co{sup 2+} and Sn{sup 4+} ions lie essentially in the octahedral and tetrahedral sites. As the Fe{sup 3+} ions are being replaced by Co{sup 2+} and Sn{sup 4+} ions, the probability of having oxygen vacancies in the structure was found to be greatly reduced. The magnetic particles produced by conventional solid state reactions are often larger than those produced by sol-gel combustion route. Larger particles of magnetic oxides generally exhibit multidomain magnetic structure whereas nanosized particles generally exhibit single domain magnetic structure. The simultaneous or coupled divalent and tetravalent substitution of Co{sup 2+} and Sn{sup 4+} for Fe{sup 3+} ions greatly helps to improvise the magnetic parameters such as Curie temperature, coercivity, remanent magnetization, saturation magnetization, etc. The structural comparison is being analyzed through the XRD, TEM. The samples so synthesized are found to be reseasonably homogeneous and the average particle size of the sample synthesized is found to be in the nanorange. The structural and magnetic properties are observed be improved upon those of the samples reported earlier. This confirms the more viability of such samples in the various applications of digital data devices. Further attempts could possibly lead to

  4. The micro-magnetic structures of Mn sup + ion-implanted GaSb

    CERN Document Server

    Zhang Fu Qiang; Liu Zhi Kai

    2003-01-01

    The micro-magnetic structures of Mn sup + ion-implanted GaSb are studied using a magnetic force microscope (MFM). MFM images reveal that there are many magnetic domains with different magnetization directions in our samples. The magnetic domain structures and the magnetization direction of typical MFM patterns are analyzed by numeric simulation. (author)

  5. Structure and magnetism in novel group IV element-based magnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Tsui, Frank [Univ. of North Carolina, Chapel Hill, NC (United States)

    2013-08-14

    The project is to investigate structure, magnetism and spin dependent states of novel group IV element-based magnetic thin films and heterostructures as a function of composition and epitaxial constraints. The materials systems of interest are Si-compatible epitaxial films and heterostructures of Si/Ge-based magnetic ternary alloys grown by non-equilibrium molecular beam epitaxy (MBE) techniques, specifically doped magnetic semiconductors (DMS) and half-metallic Heusler alloys. Systematic structural, chemical, magnetic, and electrical measurements are carried out, using x-ray microbeam techniques, magnetotunneling spectroscopy and microscopy, and magnetotransport. The work is aimed at elucidating the nature and interplay between structure, chemical order, magnetism, and spin-dependent states in these novel materials, at developing materials and techniques to realize and control fully spin polarized states, and at exploring fundamental processes that stabilize the epitaxial magnetic nanostructures and control the electronic and magnetic states in these complex materials. Combinatorial approach provides the means for the systematic studies, and the complex nature of the work necessitates this approach.

  6. Structural and magnetic domains characterization of magnetite nanoparticles

    International Nuclear Information System (INIS)

    Santoyo-Salazar, J.; Castellanos-Roman, M.A.; Beatriz Gomez, L.

    2007-01-01

    Recently, important advances have been achieved in application, reproducibility and response ability of magnetic materials due to the relationships among processing, structure and nanometric size particle. Features like homogeneity of compounds and nanoparticle-sizing have improved some magnetic properties of materials and their field application. Of particular interest is the study of magnetic materials at the atomic and microstuctural level because the orientation and magnetic domains (large numbers of atoms moments coupled together in a preferential direction) can be observed. In this work, magnetite (Fe 3 O 4 ) powders which were obtained by precipitation route in alkaline medium are analyzed to identify the structure and mechanism formation of domains over the core and border of nanoparticles. Results obtained by XRD, atomic force microscopy (AFM) and magnetic force microscopy (MFM) showed a structural phase corresponding to Fe 3 O 4 and nanoparticles in a range of 20-40 nm. Samples scanned by MFM in nanometric resolution and profile images showed orientation of magnetic domains in the border and cores of the material. Finally, an analysis of repulsion and attraction in magnetic field and direction changes of domains formed by magnetite (Fe 3 O 4 ) powders were done

  7. Summary of the workshop on structural analysis needs for magnetic fusion energy superconducting magnets

    International Nuclear Information System (INIS)

    Reich, M.; Lehner, J.; Powell, J.

    1976-09-01

    The technical portions of the meeting were divided into three major sessions as follows: (1) Review of methods being presently used by the MFE community for structural evaluation of current designs. (2) Future structural analysis needs. (3) Open discussions dealing with adequacy of present methods, the improvements needed for MFE magnet structural analysis, and the establishment of an MFE magnet structural advisory group. Summaries of the individual talks presented on Wednesday and Thursday (i.e., items 1 and 2 above) are included following the workshop schedule given later in this synopsis

  8. Symmetry, structure, and dynamics of monoaxial chiral magnets

    International Nuclear Information System (INIS)

    Togawa, Yoshihiko; Kousaka, Yusuke; Inoue, Katsuya; Kishine, Jun-ichiro

    2016-01-01

    Nontrivial spin orders with magnetic chirality emerge in a particular class of magnetic materials with structural chirality, which are frequently referred to as chiral magnets. Various interesting physical properties are expected to be induced in chiral magnets through the coupling of chiral magnetic orders with conduction electrons and electromagnetic fields. One promising candidate for achieving these couplings is a chiral spin soliton lattice. Here, we review recent experimental observations mainly carried out on the monoaxial chiral magnetic crystal CrNb_3S_6 via magnetic imaging using electron, neutron, and X-ray beams and magnetoresistance measurements, together with the strategy for synthesizing chiral magnetic materials and underlying theoretical backgrounds. The chiral soliton lattice appears under a magnetic field perpendicular to the chiral helical axis and is very robust and stable with phase coherence on a macroscopic length scale. The tunable and topological nature of the chiral soliton lattice gives rise to nontrivial physical properties. Indeed, it is demonstrated that the interlayer magnetoresistance scales to the soliton density, which plays an essential role as an order parameter in chiral soliton lattice formation, and becomes quantized with the reduction of the system size. These interesting features arising from macroscopic phase coherence unique to the chiral soliton lattice will lead to the exploration of routes to a new paradigm for applications in spin electronics using spin phase coherence. (author)

  9. Excitation of magnetic inhomogeneities in three-layer ferromagnetic structure with different parameters of the magnetic anisotropy and exchange

    Energy Technology Data Exchange (ETDEWEB)

    Ekomasov, E.G., E-mail: EkomasovEG@gmail.com [Bashkir State University, 32, Validy Str., Ufa, 450076 (Russian Federation); Murtazin, R.R. [Bashkir State University, 32, Validy Str., Ufa, 450076 (Russian Federation); Nazarov, V.N. [Institute of Molecule and Crystal Physics Ufa Research Centre of Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa, 450075 (Russian Federation)

    2015-07-01

    The generation and evolution of magnetic inhomogeneities, emerging in a thin flat layer with the parameters of the magnetic anisotropy and exchange interaction, with the parameters different from other two thick layers of the three-layer ferromagnetic structure, were investigated. The parameters ranges that determine the possibility of their existence were found. The possibility of the external magnetic field influence on the structure and dynamic properties of localized magnetic inhomogeneities was shown. - Highlights: • The generation of magnetic inhomogeneities in the three-layer ferromagnetic. • The influence of an external field on the parameters of magnetic inhomogeneities. • Numerical study of the structure and dynamics of magnetic inhomogeneities.

  10. Tunable dynamic response of magnetic gels: Impact of structural properties and magnetic fields

    Science.gov (United States)

    Tarama, Mitsusuke; Cremer, Peet; Borin, Dmitry Y.; Odenbach, Stefan; Löwen, Hartmut; Menzel, Andreas M.

    2014-10-01

    Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question of how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.

  11. Magnetic susceptibility, specific heat and magnetic structure of CuNi2(PO4)2

    International Nuclear Information System (INIS)

    Escobal, Jaione; Pizarro, Jose L.; Mesa, Jose L.; Larranaga, Aitor; Fernandez, Jesus Rodriguez; Arriortua, Maria I.; Rojo, Teofilo

    2006-01-01

    The CuNi 2 (PO 4 ) 2 phosphate has been synthesized by the ceramic method at 800 deg. C in air. The crystal structure consists of a three-dimensional skeleton constructed from MO 4 (M II =Cu and Ni) planar squares and M 2 O 8 dimers with square pyramidal geometry, which are interconnected by (PO 4 ) 3- oxoanions with tetrahedral geometry. The magnetic behavior has been studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The bimetallic copper(II)-nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at, approximately, 29.8 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements exhibit a three-dimensional magnetic ordering (λ-type) peak at 29.5 K. The magnetic structure of this phosphate shows ferromagnetic interactions inside the Ni 2 O 8 dimers, whereas the sublattice of Cu(II) ions presents antiferromagnetic couplings along the y-axis. The change of the sign in the magnetic unit-cell, due to the [1/2, 0, 1/2] propagation vector determines a purely antiferromagnetic structure. - Graphical abstract: Magnetic structure of CuNi2(PO4)2

  12. Structural and Magnetic Properties of Sm Implanted GaN

    International Nuclear Information System (INIS)

    Li-Juan, Jiang; Xiao-Liang, Wang; Hong-Ling, Xiao; Zhan-Guo, Wang; Chun, Feng; Ming-Lan, Zhang; Jian, Tang

    2009-01-01

    The structural and magnetic properties of Sm ion-implanted GaN with different Sm concentrations are investigated. XRD results do not show any peaks associated with second phase formation. Magnetic investigations performed by superconducting quantum interference device reveal ferromagnetic behavior with an ordering temperature above room temperature in all the implanted samples, while the effective magnetic moment per Sm obtained from saturation magnetization gives a much higher value than the atomic moment of Sm. These results could be explained by the phenomenological model proposed by Dhar et al. [Phys. Rev. Lett. 94(2005)037205, Phys. Rev. B 72(2005)245203] in terms of a long-range spin polarization of the GaN matrix by the Sm atoms. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  13. Giant Magnetic Field Enhancement in Hybridized MIM Structures

    KAUST Repository

    Alrasheed, Salma

    2017-10-23

    We propose numerically an approach to narrow the plasmon linewidth and enhance the magnetic near field intensity at a magnetic hot spot in a hybridized metal-insulatormetal (MIM) structure. First we insert in part of the dielectric layer of the MIM, at its center, another dielectric material of a high refractive index (HRI). This results in an increase in the magnetic near field enhancement of the magnetic plasmon (MP) resonance by 82% compared with the MIM without the HRI material. We then couple this enhanced MP resonance to a propagating surface plasmon polariton (SPP) to achieve a further enhancement of 438%. The strong coupling between the MP and the SPP is demonstrated by the large anti-crossing in the reflection spectra. The resulting maximum magnetic field enhancement at the gap is ~ |H / Hi|² = 3555.

  14. Collapsing cycloidal structures in the magnetic phase diagram of erbium

    DEFF Research Database (Denmark)

    Jehan, D.A.; McMorrow, D.F.; Simpson, J.A.

    1994-01-01

    The magnetic structure of Er with a magnetic field applied in the hexagonal basal plane has been studied using a combination of experimental techniques and mean-field modeling. From neutron-scattering and magnetization measurements, phase diagrams are constructed. At temperatures above...... approximately 20 K, the application of a field is found to favor cycloidal structures with modulation wave vectors of q(c) = (6/23)c*, (4/15)c*, and (2/7)c*. For fields above almost-equal-to 40 kOe, the (2/7) structure dominates the phase diagram. From a detailed study of this most stable cycloid, we determine...... how it distorts as the field is increased. In low fields, there is a spin reorientation, so that the plane of the cycloid becomes perpendicular to the applied field, while in larger fields, the cycloid collapses through a series of fanlike structures. At lower temperatures, as the field is increased...

  15. Three-Dimensional Magnetic Resonance Imaging of Velopharyngeal Structures

    Science.gov (United States)

    Bae, Youkyung; Kuehn, David P.; Sutton, Bradley P.; Conway, Charles A.; Perry, Jamie L.

    2011-01-01

    Purpose: To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations. Method: Ten Caucasian…

  16. Effect of annealing time on structural and magnetic properties of ...

    Indian Academy of Sciences (India)

    We studied the effects on the structural and magnetic properties of Fe3O4 thin films. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). XRD studies showed pure single phase spinel cubic structure of Fe3O4 with a preferential [111] ...

  17. Periodical plasma structures controlled by external magnetic field

    Science.gov (United States)

    Schweigert, I. V.; Keidar, M.

    2017-11-01

    The plasma of Hall thruster type in external magnetic field is studied in 2D3V kinetic simulations using PIC MCC method. The periodical structure with maxima of electron and ion densities is formed and becomes more pronounced with increase of magnetic field incidence angle in the plasma. These ridges of electron and ion densities are aligned with the magnetic field vector and shifted relative each other. This leads to formation of two-dimensional double-layers structure in cylindrical plasma chamber. Depending on Larmor radius and Debye length up to nineteen potential steps appear across the oblique magnetic field. The electrical current gathered on the wall is associated with the electron and ion density ridges.

  18. Repetitive formation and decay of current sheets in magnetic loops: An origin of diverse magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Dinesh; Bhattacharyya, R. [Udaipur Solar Observatory, Physical Research Laboratory, Dewali, Bari Road, Udaipur 313001 (India); Smolarkiewicz, P. K. [European Centre for Medium-Range Weather Forecasts, Reading RG2 9AX (United Kingdom)

    2015-01-15

    In this work, evolution of an incompressible, thermally homogeneous, infinitely conducting, viscous magnetofluid is numerically explored as the fluid undergoes repeated events of magnetic reconnection. The initial magnetic field is constructed by a superposition of two linear force-free fields and has similar morphology as the magnetic loops observed in the solar corona. The results are presented for computations with three distinct sets of footpoint geometries. To onset reconnection, we rely on numerical model magnetic diffusivity, in the spirit of implicit large eddy simulation. It is generally expected that in a high Lundquist number fluid, repeated magnetic reconnections are ubiquitous and hence can lead to a host of magnetic structures with considerable observational importance. In particular, the simulations presented here illustrate formations of magnetic islands, rotating magnetic helices and rising flux ropes—depending on the initial footpoint geometry but through the common process of repeated magnetic reconnections. Further, we observe the development of extended current sheets in two case studies, where the footpoint reconnections generate favorable dynamics.

  19. Repetitive formation and decay of current sheets in magnetic loops: An origin of diverse magnetic structures

    International Nuclear Information System (INIS)

    Kumar, Dinesh; Bhattacharyya, R.; Smolarkiewicz, P. K.

    2015-01-01

    In this work, evolution of an incompressible, thermally homogeneous, infinitely conducting, viscous magnetofluid is numerically explored as the fluid undergoes repeated events of magnetic reconnection. The initial magnetic field is constructed by a superposition of two linear force-free fields and has similar morphology as the magnetic loops observed in the solar corona. The results are presented for computations with three distinct sets of footpoint geometries. To onset reconnection, we rely on numerical model magnetic diffusivity, in the spirit of implicit large eddy simulation. It is generally expected that in a high Lundquist number fluid, repeated magnetic reconnections are ubiquitous and hence can lead to a host of magnetic structures with considerable observational importance. In particular, the simulations presented here illustrate formations of magnetic islands, rotating magnetic helices and rising flux ropes—depending on the initial footpoint geometry but through the common process of repeated magnetic reconnections. Further, we observe the development of extended current sheets in two case studies, where the footpoint reconnections generate favorable dynamics

  20. The new magnetic structure of LaMnO3

    International Nuclear Information System (INIS)

    Gontchar, L.E.; Nikiforov, A.E.

    1999-01-01

    Complete text of publication follows. The LaMnO 3 is known to be a parent compound for materials having colossal magnetoresistance. The magnetic and structural properties of LaMnO 3 are of the great interest now. In the present work, the new four-sublattices magnetic structure - (A x , F y , G z ) + (G x , C y , A z ) - is proposed. The Spin-Hamiltonian used in this model is based on calculated crystal structure and includes isotropic exchange interaction, the single-ion anisotropy and the antisymmetric exchange and Zeeman interactions. All of these components depend upon JT distortion. The spin-wave approximation is used and the dispersion dependencies of the spin waves are calculated. Our previous consideration of KCuF 3 shows that spin-wave method is not sensitive to small antisymmetric exchange interaction and inequivalency of the g tensors, but these small effects could not be neglected in calculations of magnetic structure. The dependence of antiferromagnetic resonance field upon angle is predicted. It could clarify the real magnetic structure. In spite of the sufficient energy gap in the Γ-point of magnetic Brillouin zone (ΔE = 2.7 meV) the measurements of this dependence could be carried out. (author)

  1. Magnetic assembly of nonmagnetic particles into photonic crystal structures.

    Science.gov (United States)

    He, Le; Hu, Yongxing; Kim, Hyoki; Ge, Jianping; Kwon, Sunghoon; Yin, Yadong

    2010-11-10

    We report the rapid formation of photonic crystal structures by assembly of uniform nonmagnetic colloidal particles in ferrofluids using external magnetic fields. Magnetic manipulation of nonmagnetic particles with size down to a few hundred nanometers, suitable building blocks for producing photonic crystals with band gaps located in the visible regime, has been difficult due to their weak magnetic dipole moment. Increasing the dipole moment of magnetic holes has been limited by the instability of ferrofluids toward aggregation at high concentration or under strong magnetic field. By taking advantage of the superior stability of highly surface-charged magnetite nanocrystal-based ferrofluids, in this paper we have been able to successfully assemble 185 nm nonmagnetic polymer beads into photonic crystal structures, from 1D chains to 3D assemblies as determined by the interplay of magnetic dipole force and packing force. In a strong magnetic field with large field gradient, 3D photonic crystals with high reflectance (83%) in the visible range can be rapidly produced within several minutes, making this general strategy promising for fast creation of large-area photonic crystals using nonmagnetic particles as building blocks.

  2. Defect-induced magnetic structure of CuMnSb

    Czech Academy of Sciences Publication Activity Database

    Máca, František; Kudrnovský, Josef; Drchal, Václav; Turek, I.; Stelmakhovych, O.; Beran, Přemysl; Llobet, A.; Martí, Xavier

    2016-01-01

    Roč. 94, č. 9 (2016), 1-9, č. článku 094407. ISSN 2469-9950 R&D Projects: GA ČR GB14-37427G Institutional support: RVO:68378271 ; RVO:61389005 Keywords : CuMnSb * electronic structure * defects * magnetic order * ab initio calculations * neutron diffraction analysis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.836, year: 2016

  3. Activation of structural alloys in fusion reactor magnets

    International Nuclear Information System (INIS)

    Mann, F.M.; Doran, D.G.

    1986-01-01

    Using the REAC2 code system, both short-term and long-term activation were calculated for possible structural and magnet materials at the shield-magnet interface. The flux was taken from the STARFIRE conceptual design and a 30-year lifetime was assumed. Short-term activation does not seem to be a problem. Only materials with large amounts of niobium appear to be a potential problem for long-term activation. 2 tabs

  4. Dual-function magnetic structure for toroidal plasma devices

    International Nuclear Information System (INIS)

    Brown, R.L.

    1978-01-01

    This invention relates to a support system wherein the iron core and yoke of the plasma current system of a tokamak plasma containment device is redesigned to support the forces of the magnet coils. The containment rings, which occupy very valuable space around the magnet coils, are utilized to serve as yokes for the core such that the conventional yoke is eliminated. The overall result is an improved aspect ratio, reduction in structure, smaller overall size, and improved access to the plasma ring

  5. The effect of internal magnetic structure on the fishbone instability

    International Nuclear Information System (INIS)

    Roberts, D.W.; Powell, E.; Kaita, R.; Bell, R.; Chance, M.; Hatcher, R.; Holland, A.; Kaye, S.; Kessel, C.; Kugel, H.; LeBlanc, B.; Manickam, J.; Okabayashi, M.; Paul, S.; Pomphrey, N.; Sauthoff, N.; Sesnic, S.; Takahashi, H.; White, R.; Asakura, N.; Duperrex, P.; Gammel, G.

    1992-01-01

    Plasmas exhibiting the ''fishbone'' instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations

  6. Magnetic structure and lattice deformation in UO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Aksenov, V L; Frauenheim, T; Sikora, V [Joint Inst. for Nuclear Research, Dubna (USSR)

    1981-12-21

    The magnetic phase transition in UO/sub 2/ is studied by means of a group theoretical analysis and the admitted symmetry groups in the low temperature phase are determined. With the help of the neutron diffraction data of Faber and Lander a three-arm magnetic and crystallographic structure with two types of translational domains is found and a new interpretation of the experiment of Faber and Lander is given.

  7. Oscillations in magnetoresistance and interlayer coupling in magnetic sandwich structures

    International Nuclear Information System (INIS)

    Barnas, J.; Bulka, B.

    1997-01-01

    Kubo formalism is used to calculate the magnetoresistance due to magnetization rotation in a structure consisting two magnetic films separated by nonmagnetic layer. In the approximation of an uniform relaxation time of each layer, the oscillatory term in magnetoresistance corresponds to the oscillation period which depends on the potential barriers at the interfaces. This period is longer than the oscillation period observed in the coupling parameter. (author)

  8. Liquid metal MHD studies with non-magnetic and ferro-magnetic structural material

    Energy Technology Data Exchange (ETDEWEB)

    Patel, A., E-mail: anipatel2009@gmail.com [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Bhattacharyay, R. [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Swain, P.K.; Satyamurthy, P. [Bhabha Atomic Research Center, Mumbai 400085, Maharashtra (India); Sahu, S.; Rajendrakumar, E. [Institute of Plasma Research, Gandhinagar 382428, Gujarat (India); Ivanov, S.; Shishko, A.; Platacis, E.; Ziks, A. [Institute of Physics, University of Latvia, Salaspils 2169 (Latvia)

    2014-10-15

    Highlights: • Effect of structural material on liquid metal MHD phenomena is studied. • Two identical test sections, one made of SS316L (non-magnetic) and other made of SS430 (ferromagnetic) structural material, are considered. • Wall electric potential and liquid metal pressure drop are compared under various experimental conditions. • Experimental results suggest screening of external magnetic field for SS430 material below the saturation magnetic field. - Abstract: In most of the liquid metal MHD experiments reported in the literature to study liquid breeder blanket performance, SS316/SS304 grade steels are used as the structural material which is non-magnetic. On the other hand, the structural material for fusion blanket systems has been proposed to be ferritic martensitic grade steel (FMS) which is ferromagnetic in nature. In the recent experimental campaign, liquid metal MHD experiments have been carried out with two identical test sections: one made of SS316L (non-magnetic) and another with SS430 (ferromagnetic), to compare the effect of structural materials on MHD phenomena for various magnetic fields (up to 4 T). The maximum Hartmann number and interaction number are 1047 and 300, respectively. Each test section consists of square channel (25 mm × 25 mm) cross-section with two U bends, with inlet and outlet at the middle portion of two horizontal legs, respectively. Pb–Li enters into the test section through a square duct and distributed into two parallel paths through a partition plate. In each parallel path, it travels ∼0.28 m length in plane perpendicular to the magnetic field and faces two 90° bends before coming out of the test section through a single square duct. The wall electrical potential and MHD pressure drop across the test sections are compared under identical experimental conditions. Similar MHD behavior is observed with both the test section at higher value of the magnetic field (>2 T)

  9. Structure and evolution of magnetic fields associated with solar eruptions

    International Nuclear Information System (INIS)

    Wang Haimin; Liu Chang

    2015-01-01

    This paper reviews the studies of solar photospheric magnetic field evolution in active regions and its relationship to solar flares. It is divided into two topics, the magnetic structure and evolution leading to solar eruptions and rapid changes in the photospheric magnetic field associated with eruptions. For the first topic, we describe the magnetic complexity, new flux emergence, flux cancelation, shear motions, sunspot rotation and magnetic helicity injection, which may all contribute to the storage and buildup of energy that trigger solar eruptions. For the second topic, we concentrate on the observations of rapid and irreversible changes of the photospheric magnetic field associated with flares, and the implication on the restructuring of the three-dimensional magnetic field. In particular, we emphasize the recent advances in observations of the photospheric magnetic field, as state-of-the-art observing facilities (such as Hinode and Solar Dynamics Observatory) have become available. The linkages between observations, theories and future prospectives in this research area are also discussed. (invited reviews)

  10. The structure of magnetic field in the TEXTOR-DED

    International Nuclear Information System (INIS)

    Finken, K.H.; Abdullaev, S.S.; Jakubowski, M.; Lehnen, M.; Nicolai, A.; Spatschek, K.H.

    2005-01-01

    The main component of the Dynamic Ergodic Divertor (DED) consists of a set of coils installed in the TEXTOR tokamak which creates resonant magnetic perturbations, preferentially at the plasma edge. The main purpose of the DED is to study the effect of the magnetic perturbations on the tokamak plasma. In particular, on the transport of the heat and particles to wall, the plasma confinement and rotation. This report is devoted to the systematic theoretical study of magnetic field and its structure in the TEXTOR-DED. It contains the description of the DED coil system in different operational regimes, the magnetic field created by this coil system, the study of formation of chaotic magnetic field lines and the structure of stochastic (ergodic) zone of field lines at the plasma edge and on the divertor plates, determination of field line diffusion coefficients and the Kolmogorov lengths. The modern mapping method for integration of Hamiltonian field line equations is employed for these studies. A description of the numerical Gourdon code to study the ergodic zone of the DED is also given. The experimental observations of the structure magnetic field lines performed recently in the TEXTOR-DED and their comparison with the modelling are also briefly discussed. (orig.)

  11. Generation of magnetic structures on the solar photosphere

    Energy Technology Data Exchange (ETDEWEB)

    Gangadhara, R. T.; Krishan, V. [Indian Institute of Astrophysics, Bangalore-560034 (India); Bhowmick, A. K.; Chitre, S. M., E-mail: ganga@iiap.res.in [Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai-400098 (India)

    2014-06-20

    The lower solar atmosphere is a partially ionized plasma consisting of electrons, ions, and neutral atoms. In this, which is essentially a three-fluid system, the Hall effect arises from the treatment of the electrons and ions as two separate fluids and the ambipolar diffusion arises from the inclusion of neutrals as the third fluid. The Hall effect and ambipolar diffusion have been shown to be operational in a region beginning from near the photosphere up to the chromosphere. In a partially ionized plasma, the magnetic induction is subjected to ambipolar diffusion and the Hall drift in addition to the usual resistive dissipation. These nonlinear effects create sharp magnetic structures which then submit themselves to various relaxation mechanisms. A first-principles derivation of these effects in a three-fluid system and an analytic solution to the magnetic induction equation in a stationary state are presented, which in the general case includes the Hall effect, ambipolar diffusion, and ohmic dissipation. The temporal evolution of the magnetic field is then investigated under the combined as well as the individual effects of the Hall drift and ambipolar diffusion to demonstrate the formation of steep magnetic structures and the resultant current sheet formation. These structures have just the right features for the release of magnetic energy into the solar atmosphere.

  12. Structure and Magnetic Properties of Rare Earth Doped Transparent Alumina

    Science.gov (United States)

    Limmer, Krista; Neupane, Mahesh; Chantawansri, Tanya

    Recent experimental studies of rare earth (RE) doped alumina suggest that the RE induced novel phase-dependent structural and magnetic properties. Motivated by these efforts, the effects of RE doping of alpha and theta alumina on the local structure, magnetic properties, and phase stability have been examined in this first principles study. Although a direct correlation between the magnetic field dependent materials properties observed experimentally and calculated from first principles is not feasible because of the applied field and the scale, the internal magnetic properties and other properties of the doped materials are evaluated. The RE dopants are shown to increase the substitutional site volume as well as increasingly distort the site structure as a function of ionic radii. Doping both the alpha (stable) and theta (metastable) phases enhanced the relative stability of the theta phase. The energetic doping cost and internal magnetic moment were shown to be a function of the electronic configuration of the RE-dopant, with magnetic moment directly proportional to the number of unpaired electrons and doping cost being inversely related.

  13. A new support structure for high field magnets

    International Nuclear Information System (INIS)

    Bish, P.S.; Caspi, S.; Dietderich, D.R.; Gourlay, S.A.; Hafalia, R.R.; Hannaford, R.; Lietzke, A.F.; Liggins, N.; McInturff, A.D.; Sabbi, G.L.; Scanlan, R.M.; O'Neill, J.; Swanson, J.H

    2001-01-01

    Pre-stress of superconducting magnets can be applied directly through the magnet yoke structure. We have replaced the collar functionality in our 14 Tesla R and D Nb 3 Sn dipole magnets with an assembly procedure based on an aluminum shell and bladders. Bladders, placed between the coil pack and surrounding yoke inside the shell, are pressurized up to 10 ksi [70 MPa] to create an interference gap. Keys placed into the interference gap replace the bladder functionality. Following the assembly, the bladders are deflated and removed. Strain gauges mounted directly on the shell are used to monitor the stress of the entire magnet structure, thereby providing a high degree of pre-stress control without the need for high tolerances. During assembly, a force of 8.2 x 10 5 lbs/ft [12 MN/m] is generated by the bladders and the stress in the 1.57 inch [40mm] aluminum shell reaches 20.3 ksi [140 MPa]. During cool-down the thermal expansion difference between shell and yoke generates an additional compressive force of 6.85 x 10 5 lbs/ft [10 MN/m], corresponding to a final stress in the shell of 39.2 ksi [270 MPa]. Pre-stress conditions are sufficient for 16 T before the coils separate at the bore. Bladders have now been used in the assembly and disassembly of two 14 T magnets. This paper describes the magnet structure, assembly procedure and test results

  14. Magnetic tunnel structures: Transport properties controlled by bias, magnetic field, and microwave and optical radiation

    International Nuclear Information System (INIS)

    Volkov, N.V.; Eremin, E.V.; Tarasov, A.S.; Rautskii, M.V.; Varnakov, S.N.; Ovchinnikov, S.G.; Patrin, G.S.

    2012-01-01

    Different phenomena that give rise to a spin-polarized current in some systems with magnetic tunnel junctions are considered. In a manganite-based magnetic tunnel structure in CIP geometry, the effect of current-channel switching was observed, which causes bias-driven magnetoresistance, rf rectification, and the photoelectric effect. The second system under study, ferromagnetic/insulator/semiconductor, exhibits the features of the transport properties in CIP geometry that are also related to the current-channel switching effect. The described properties can be controlled by a bias, a magnetic field, and optical radiation. At last, the third system under consideration is a cooperative assembly of magnetic tunnel junctions. This system exhibits tunnel magnetoresistance and the magnetic-field-driven microwave detection effect.

  15. Assessment of Alphamagnetic Spectrometer (AMS) Upper Experiment Structural Configuration Shielding Effectiveness Associated with Change from Cryo-Cooled Magnet to Permanent Magnet

    Science.gov (United States)

    Scully, Robert

    2012-01-01

    In the spring of 2010, the Alpha Magnetic Spectrometer 2 (AMS-02) underwent a series of system level electromagnetic interference control measurements, followed by thermal vacuum testing. Shortly after completion of the thermal vacuum testing, the project decided to remove the cryogenically cooled superconducting magnet, and replace it with the original permanent magnet design employed in the earlier AMS- 01 assembly. Doing so necessitated several structural changes, as well as removal or modification of numerous electronic and thermal control devices and systems. At this stage, the project was rapidly approaching key milestone dates for hardware completion and delivery for launch, and had little time for additional testing or assessment of any impact to the electromagnetic signature of the AMS-02. Therefore, an analytical assessment of the radiated emissions behavioural changes associated with the system changes was requested.

  16. Neutron scattering on magnetic nano-structures

    International Nuclear Information System (INIS)

    Ott, F.

    2009-03-01

    The thesis describes measurements of the scrape-off layer (SOL) ion temperature T i with a retarding field analyzer (RFA) in the limiter tokamak Tore Supra. In the first chapter, some well known facts about nuclear fusion, limiter SOL, Langmuir probes, etc. are briefly recalled. Various diagnostics for SOL T i measurements developed in the past are addressed as well. The second chapter is dedicated to the RFA. The principle of the RFA, technical details and operation of the Tore Supra RFA, and the influence of instrumental effects on RFA measurements are addressed. In the third chapter, the experimental results are presented in the form of papers published (or submitted for publication) during the thesis. Some research that was not completed at the time of writing is summarized in the last chapter. Considerable emphasis is placed on study of the instrumental effects of RFAs and their influence on T i measurements. In general, the influence of instrumental effects on T i measurements is found to be relatively small. Selective ion transmission through the RFA slit is found to be responsible for an overestimation of T i by less than 14% even for relatively thick slit plates. The effect of positive space charge inside the analyzer, the influence of the electron repelling grid, the misalignment of the probe head with respect to the magnetic field, and the attenuation of the incident ion current by some of the probe components on T i measurements is negligible. The instrumental study is followed by systematic measurements of T i (as well as other parameters) in the Tore Supra SOL. This includes the scaling of SOL temperatures and electron density with the main plasma parameters (such as the plasma density, toroidal magnetic field, working gas, and the radiated power fraction). Except at very high densities or in detached plasmas, SOL T i is found to be higher than T e by up to a factor of 7. While SOL T i is found to vary by almost two orders of magnitude, following the

  17. Electron vortex magnetic holes: A nonlinear coherent plasma structure

    Energy Technology Data Exchange (ETDEWEB)

    Haynes, Christopher T., E-mail: c.t.haynes@qmul.ac.uk; Burgess, David; Sundberg, Torbjorn [School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Camporeale, Enrico [Multiscale Dynamics, Centrum Wiskunde and Informatica (CWI), Amsterdam (Netherlands)

    2015-01-15

    We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas.

  18. Structure organization and magnetic properties of microscale ferrogels: The effect of particle magnetic anisotropy

    Science.gov (United States)

    Ryzhkov, Aleksandr V.; Melenev, Petr V.; Balasoiu, Maria; Raikher, Yuriy L.

    2016-08-01

    The equilibrium structure and magnetic properties of a ferrogel object of small size (microferrogel(MFG)) are investigated by coarse-grained molecular dynamics. As a generic model of a microferrogel (MFG), a sample with a lattice-like mesh is taken. The solid phase of the MFG consists of magnetic (e.g., ferrite) nanoparticles which are mechanically linked to the mesh making some part of its nodes. Unlike previous models, the finite uniaxial magnetic anisotropy of the particles, as it is the case for real ferrogels, is taken into account. For comparison, two types of MFGs are considered: MFG-1, which dwells in virtually non-aggregated state independently of the presence of an external magnetic field, and MFG-2, which displays aggregation yet under zero field. The structure states of the samples are analyzed with the aid of angle-resolved radial distribution functions and cluster counts. The results reveal the crucial role of the matrix elasticity on the structure organization as well as on magnetization of both MFGs. The particle anisotropy, which plays insignificant role in MFG-1 (moderate interparticle magnetodipole interaction), becomes an important factor in MFG-2 (strong interaction). There, the restrictions imposed on the particle angular freedom by the elastic matrix result in notable diminution of the particle chain lengths as well as the magnetization of the sample. The approach proposed enables one to investigate a large variety of MFGs, including those of capsule type and to purposefully choose the combination of their magnetoelastic parameters.

  19. Atomic and magnetic structure of MnF3

    International Nuclear Information System (INIS)

    Hunter, B.A.; Kennedy, B.J.; Vogt, T.

    2003-01-01

    Full text: The magnetic and atomic structure of MnF 3 has been determined from 4K to 300K using neutron powder diffraction. The MnF 3 compound is the archetypical Mn-based colossal magnetoresistive compound. A Neel temperature of approximately 40K was observed from the temperature variation of the magnetic moment. Below the Neel temperature a large negative thermal expansion was observed, in striking similarity to other Mn-based colossal magnetoresistive compounds. The variation in structure is discussed in relation to other Mn-based compounds, particularly as this compound cannot support charge ordering

  20. Wave propagation in a magnetically structured atmosphere. Pt. 2

    International Nuclear Information System (INIS)

    Roberts, B.

    1981-01-01

    Magnetic fields may introduce structure (inhomogeneity) into an otherwise uniform medium and thus change the nature of wave propagation in that medium. As an example of such structuring, wave propagation in an isolated magnetic slab is considered. It is supposed that disturbances outside the slab are laterally non-propagating. The effect of gravity is ignored. The field can support the propagation of both body and surface waves. The existence and nature of these waves depends upon the relative magnitudes of the sound speed c 0 and Alfven speed upsilonsub(A) inside the slab, and the sound speed csub(e) in the field-free environment. (orig./WL)

  1. Crystal structure and magnetic susceptibility of UOSe single crystals

    International Nuclear Information System (INIS)

    Kaczorowski, D.; Muenster Univ.; Poettgen, R.; Jeitschko, W.; Gajek, Z.; Zygmunt, A.

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T N =100±2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author)

  2. Crystal structure and magnetic susceptibility of UOSe single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kaczorowski, D. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Poettgen, R.; Jeitschko, W. (Muenster Univ. (Germany). Anorganisch-Chemisches Inst.); Gajek, Z.; Zygmunt, A. (Polish Academy of Sciences, Wroclaw (Poland). Inst. for Low Temperature and Structure Research)

    1993-01-01

    The crystal structure and magnetic susceptibility behaviour of UOSe single crystals have been studied. UOSe crystalizes in the tetragonal PbFC1-type structure (space group P4/nmm) with the lattice parameters: a = 390.38(5) pm and c = 698.05(9) pm. It orders antiferromagnetically at T[sub N]=100[+-]2 K and exhibits a very strong anisotropy in the susceptibility vs temperature variation. The magnetic and thermodynamic properties of UOSe are successfully interpreted in the framework of a perturbative ab initio crystal field approach. (Author).

  3. Adiabatic cooling processes in frustrated magnetic systems with pyrochlore structure

    Science.gov (United States)

    Jurčišinová, E.; Jurčišin, M.

    2017-11-01

    We investigate in detail the process of adiabatic cooling in the framework of the exactly solvable antiferromagnetic spin-1/2 Ising model in the presence of the external magnetic field on an approximate lattice with pyrochlore structure. The behavior of the entropy of the model is studied and exact values of the residual entropies of all ground states are found. The temperature variation of the system under adiabatic (de)magnetization is investigated and the central role of the macroscopically degenerated ground states in cooling processes is explicitly demonstrated. It is shown that the model parameter space of the studied geometrically frustrated system is divided into five disjunct regions with qualitatively different processes of the adiabatic cooling. The effectiveness of the adiabatic (de)magnetization cooling in the studied model is compared to the corresponding processes in paramagnetic salts. It is shown that the processes of the adiabatic cooling in the antiferromagnetic frustrated systems are much more effective especially in nonzero external magnetic fields. It means that the frustrated magnetic materials with pyrochlore structure can be considered as very promising refrigerants mainly in the situations with nonzero final values of the magnetic field.

  4. FINEMET type alloy without Si: Structural and magnetic properties

    International Nuclear Information System (INIS)

    Muraca, D.; Cremaschi, V.; Moya, J.; Sirkin, H.

    2008-01-01

    Magnetic and structural properties of a Finemet type alloy (Fe 73.5 Ge 15.5 Nb 3 B 7 Cu 1 ) without Si and high Ge content were studied. Amorphous material was obtained by the melt spinning technique and was heat treated at different temperatures for 1 h under high vacuum to induce the nanocrystallization of the sample. The softest magnetic properties were obtained between 673 and 873 K. The role of Ge on the ferromagnetic paramagnetic transition of the as-quenched alloys and its influence on the crystallization process were studied using a calorimetric technique. Moessbauer spectroscopy was employed in the nanocrystallized alloy annealed at 823 K to obtain the composition of the nanocrystals and the amorphous phase fraction. Using this data and magnetic measurements of the as-quenched alloy, the magnetic contribution of nanocrystals to the alloy annealed at 823 K was estimated via a linear model

  5. Microstructure characterization and magnetic properties of nano structured materials

    International Nuclear Information System (INIS)

    Sun, X.C.

    2000-01-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe 78 Si 9 B 13 ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy (Eds.); selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  6. Structural support system for a superconducting magnet coil

    International Nuclear Information System (INIS)

    Meuser, R.B.

    1977-01-01

    The purpose of the ESCAR (Experimental Superconducting Accelerator Ring) project, now under way at the Lawrence Berkeley Laboratory, is to gather data and experience in the design and operation of a relatively small synchrotron employing superconducting magnets. Such data are essential to ensure that the design of future large accelerators may proceed in a knowledgeable and responsible manner. One of the many engineering problems associated with a superconducting magnet is the design of the coil suspension system. The coil, maintained at the temperature of liquid helium, must be held rigidly by a structure that does not conduct too much heat into the liquid helium system. The suspension system used on the ESCAR magnets is described. Topics covered include the coil support system requirements, ESCAR magnet support system, and operating experience

  7. Microstructure characterization and magnetic properties of nano structured materials

    Energy Technology Data Exchange (ETDEWEB)

    Sun, X.C

    2000-07-01

    The present thesis deals with the unique microstructural properties and their novel magnetic properties of core-shell Ni-Ce nano composite particles, carbon encapsulated Fe, Co, and Ni nanoparticles and the nano crystallization behavior of typical ferromagnetic Fe{sub 78}Si{sub 9}B{sub 13} ribbons. These properties have intensively been investigated by high resolution transmission electron microscopy (HREM), X-ray diffraction (XRD), scanning electron microscopy (Sem), X-ray energy dispersive spectroscopy [eds.]; selected area electron diffraction pattern (SAED), Ft-IR, differential scanning calorimeter (DSC). In addition, magnetic moments measurements at different temperatures and applied fields have been performed by transmission Moessbauer spectroscopy, superconducting quantum interference device magnetometer (SQUID), and vibrating sample magnetometer (VSM). The present studies may provide the insights for the better understanding of the correlation between the unique microstructure and novel magnetic properties for several magnetic nano structured materials. (Author)

  8. High temperature structural and magnetic properties of cobalt nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Ait Atmane, Kahina [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Zighem, Fatih [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Soumare, Yaghoub [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Ibrahim, Mona; Boubekri, Rym [Universite de Toulouse, LPCNO, INSA CNRS UMR 5215, 135 av. de Rangueil, 31077 Toulouse Cedex 4 (France); Maurer, Thomas [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Margueritat, Jeremie [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Piquemal, Jean-Yves, E-mail: jean-yves.piquemal@univ-paris-diderot.fr [Univ. Paris Diderot, Sorbonne Paris Cite, ITODYS, UMR CNRS 7086, 15 rue J.-A. de Baief, 75205 Paris Cedex 13 (France); Ott, Frederic; Chaboussant, Gregory [Laboratoire Leon Brillouin, CEA CNRS UMR 12, IRAMIS, CEA-Saclay, 91191 Gif sur Yvette (France); Schoenstein, Frederic; Jouini, Noureddine [LSPM, CNRS UPR 9001, Universite Paris XIII, Institut Galilee, 99 av. J.-B. Clement, 93430 Villetaneuse (France); Viau, Guillaume, E-mail: gviau@insa-toulouse.fr [Universite de Toulouse, LPCNO, INSA CNRS UMR 5215, 135 av. de Rangueil, 31077 Toulouse Cedex 4 (France)

    2013-01-15

    We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles ({approx}10) at high temperatures (up to 623 K) using in-situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by {mu}{sub 0}H{sub C}=2(K{sub MC}+K{sub shape})/M{sub S} with K{sub MC} the magnetocrystalline anisotropy constant, K{sub shape} the shape anisotropy constant and M{sub S} the saturation magnetization. H{sub C} decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500 K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300-500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. - Graphical abstract: We present in this paper the structural and magnetic properties of high aspect ratio Co nanorods ({approx}10) at high temperatures (up to 623 K) using in-situ X-ray diffraction and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation. Highlights: Black-Right-Pointing-Pointer Ferromagnetic Co nanorods are prepared using the polyol process. Black-Right-Pointing-Pointer The structural and texture properties of the Co nanorods are preserved up to 500 K. Black-Right-Pointing-Pointer The magnetic properties of the Co nanorods are irreversibly altered above 525 K.

  9. Magnetic and Crystal Structure of α-RuCl3

    Science.gov (United States)

    Sears, Jennifer

    The layered honeycomb material α-RuCl3 has been proposed as a candidate material to show significant bond-dependent Kitaev type interactions. This has prompted several recent studies of magnetism in this material that have found evidence for multiple magnetic transitions in the temperature range of 8-14 K. We will present elastic neutron scattering measurements collected using a co-aligned array of α-RuCl3 crystals, identifying zigzag magnetic order within the honeycomb planes with an ordering temperature of ~8 K. It has been reported that the ordering temperature depends on the c axis periodicity of the layered structure, with ordering temperatures of 8 and 14 K for three and two-layer periodicity respectively. While the in-plane magnetic order has been identified, it is clear that a complete understanding of magnetic ordering and interactions will depend on the three dimensional structure of the crystal. Evidence of a structural transition at ~150 K has been reported and questions remain about the structural details, in particular the stacking of the honeycomb layers. We will present x-ray diffraction measurements investigating the low and high temperature structures and stacking disorder in α-RuCl3. Finally, we will present inelastic neutron scattering measurements of magnetic excitations in this material. Work done in collaboration with K. W. Plumb (Johns Hopkins University), J. P. Clancy, Young-June Kim (University of Toronto), J. Britten (McMaster University), Yu-Sheng Chen (Argonne National Laboratory), Y. Qiu, Y. Zhao, D. Parshall, and J. W. Lynn (NCNR).

  10. Structural characterization and magnetic properties of steels subjected to fatigue

    International Nuclear Information System (INIS)

    Lo, C.C.H.; Tang, F.; Biner, S.B.; Jiles, D.C.

    2000-01-01

    Studies have been made on the effects of residual stress and microstructure on the variations of magnetic properties of steels during fatigue. Strain-controlled fatigue tests have been conducted on 0.2wt% C steel samples which were (1) cold-worked (2) cold-worked and annealed at 500 deg. C to relieve residual stress, and (3) annealed at 905 deg. C to produce a ferrite/pearlite structure. The changes of surface microstructure were studied by SEM replica technique. The dislocation structures of samples fatigued for different numbers of cycle were studied by TEM. In the initial stage of fatigue coercivity was found to behave differently for samples which have different residual stress levels. In the intermediate stage the magnetic hysteresis parameters became stable as the dislocation cell structure developed in the samples. In the final stage the magnetic parameters decreased dramatically. The decrease rate is related to the propagation rate of fatigue cracks observed in the SEM study, which was found to be dependent on the sample microstructure. The present results indicate that the magnetic inspection technique is able to differentiate the residual stress effects from the fatigue damage induced by cyclic loading, and therefore it is possible to detect the onset of fatigue failure in steel components via measurements of the changes in magnetic properties.--This work was sponsored by the National Science Foundation, under grant number CMS-9532056

  11. Structure and Magnetism of Mn5Ge3 Nanoparticles

    Directory of Open Access Journals (Sweden)

    Onur Tosun

    2018-04-01

    Full Text Available In this work, we investigated the magnetic and structural properties of isolated Mn5Ge3 nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster gun. X-ray diffraction (XRDand selected area diffraction (SAD measurements show that the nanoparticles crystallize in the hexagonal Mn5Si3-type crystal structure, which is also the structure of bulk Mn5Ge3. The temperature dependence of the magnetization shows that the as-made particles are ferromagnetic at room temperature and have slightly different Curie temperatures. Hysteresis-loop measurements show that the saturation magnetization of the nanoparticles increases significantly with particle size, varying from 31 kA/m to 172 kA/m when the particle size increases from 7.2 to 12.6 nm. The magnetocrystalline anisotropy constant K at 50 K, determined by fitting the high-field magnetization data to the law of approach to saturation, also increases with particle size, from 0.4 × 105 J/m3 to 2.9 × 105 J/m3 for the respective sizes. This trend is mirrored by the coercivity at 50 K, which increases from 0.04 T to 0.13 T. A possible explanation for the magnetization trend is a radial Ge concentration gradient.

  12. Magnetic structure of the spin valve interface

    International Nuclear Information System (INIS)

    Nicholson, D.M.C.; Butler, W.H.; Zhang, X.; MacLaren, J.M.; Gurney, B.A.; Speriosu, V.S.

    1994-01-01

    Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR

  13. Magnetic structure of Tb-Fe films with an artificially layered structure

    International Nuclear Information System (INIS)

    Yamauchi, K.; Habu, K.; Sato, N.

    1988-01-01

    The magnetic structure of Tb-Fe films with an artificially layered structure has been investigated by measuring the temperature dependence of the magnetization of the films. Ferrimagnetic coupling between Tb and Fe through the interface was explicitly observed up to about 9-A Tb and 10-A Fe layers. Films with thinner Tb and Fe layers than these thicknesses are composed of only ferrimagnetically coupled Tb-Fe regions. Films with thicker layers of Tb and Fe are composed of ferrimagnetically coupled Tb-Fe, ferromagnetic Fe, ferromagnetic Tb, and/or magnetically compensated Tb regions. The Tb-Fe films exhibit various temperature dependencies of the magnetization corresponding to these magnetic structures

  14. MAGNETIC FIELD IN ATYPICAL PROMINENCE STRUCTURES: BUBBLE, TORNADO, AND ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Levens, P. J.; Labrosse, N. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Schmieder, B. [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France); López Ariste, A. [IRAP—CNRS UMR 5277, 14, Av. E. Belin, F-31400 Toulouse (France); Dalmasse, K. [CISL/HAO, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Gelly, B., E-mail: p.levens.1@research.gla.ac.uk, E-mail: brigitte.schmieder@obspm.fr [CNRS UMR 3718 THEMIS, La Laguna, Tenerife (Spain)

    2016-08-01

    Spectropolarimetric observations of prominences have been obtained with the THEMIS telescope during four years of coordinated campaigns. Our aim is now to understand the conditions of the cool plasma and magnetism in “atypical” prominences, namely when the measured inclination of the magnetic field departs, to some extent, from the predominantly horizontal field found in “typical” prominences. What is the role of the magnetic field in these prominence types? Are plasma dynamics more important in these cases than the magnetic support? We focus our study on three types of “atypical” prominences (tornadoes, bubbles, and jet-like prominence eruptions) that have all been observed by THEMIS in the He i D{sub 3} line, from which the Stokes parameters can be derived. The magnetic field strength, inclination, and azimuth in each pixel are obtained by using the inversion method of principal component analysis on a model of single scattering in the presence of the Hanle effect. The magnetic field in tornadoes is found to be more or less horizontal, whereas for the eruptive prominence it is mostly vertical. We estimate a tendency toward higher values of magnetic field strength inside the bubbles than outside in the surrounding prominence. In all of the models in our database, only one magnetic field orientation is considered for each pixel. While sufficient for most of the main prominence body, this assumption appears to be oversimplified in atypical prominence structures. We should consider these observations as the result of superposition of multiple magnetic fields, possibly even with a turbulent field component.

  15. Pulsating jet-like structures in magnetized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, V. P. [A. M. Obukhov Institute of Atmospheric Physics RAS, 109017 Moscow (Russian Federation); Pavlov, V. I. [UFR des Mathématiques Pures et Appliquées, Univ. Lille, CNRS FRE 3723 - LML, F-59000 Lille (France)

    2016-08-15

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as “radio pulsars.” The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  16. Superconducting magnetic energy storage apparatus structural support system

    Science.gov (United States)

    Withers, Gregory J.; Meier, Stephen W.; Walter, Robert J.; Child, Michael D.; DeGraaf, Douglas W.

    1992-01-01

    A superconducting magnetic energy storage apparatus comprising a cylindrical superconducting coil; a cylindrical coil containment vessel enclosing the coil and adapted to hold a liquid, such as liquefied helium; and a cylindrical vacuum vessel enclosing the coil containment vessel and located in a restraining structure having inner and outer circumferential walls and a floor; the apparatus being provided with horizontal compression members between (1) the coil and the coil containment vessel and (2) between the coil containment vessel and the vacuum vessel, compression bearing members between the vacuum vessel and the restraining structure inner and outer walls, vertical support members (1) between the coil bottom and the coil containment vessel bottom and (2) between the coil containment vessel bottom and the vacuum vessel bottom, and external supports between the vacuum vessel bottom and the restraining structure floor, whereby the loads developed by thermal and magnetic energy changes in the apparatus can be accommodated and the structural integrity of the apparatus be maintained.

  17. Temperature dependency of silicon structures for magnetic field gradient sensing

    Science.gov (United States)

    Dabsch, Alexander; Rosenberg, Christoph; Stifter, Michael; Keplinger, Franz

    2018-02-01

    This work describes the temperature dependence of two sensors for magnetic field gradient sensors and demonstrates a structure to compensate for the drift of resonance frequency over a wide temperature range. The temperature effect of the sensing element is based on internal stresses induced by the thermal expansion of material, therefore FEM is used to determine the change of the eigenvalues of the sensing structure. The experimental setup utilizes a Helmholtz coil system to generate the magnetic field and to excite the MEMS structure with Lorentz forces. The MEMS structure is placed on a plate heated with resistors and cooled by a Peltier element to control the plate temperature. In the second part, we describe how one can exploit temperature sensitivity for temperature measurements and we show the opportunity to include the temperature effect to increase the sensitivity of single-crystal silicon made flux density gradient sensors.

  18. Crystal structure, characterization and magnetic properties of a 1D ...

    Indian Academy of Sciences (India)

    Crystal structure, characterization and magnetic properties of a 1D copper(II) polymer incorporating a Schiff base with carboxylate side arm. SHYAMAPADA SHIT MADHUSUDAN NANDY CORRADO RIZZOLI CÉDRIC DESPLANCHES SAMIRAN MITRA. Regular Article Volume 128 Issue 6 June 2016 pp 913-920 ...

  19. Structural and magnetic characterization of YIG particles prepared using microemulsions

    International Nuclear Information System (INIS)

    Teijeiro, A.G.; Baldomir, D.; Rivas, J.; Paz, S.; Vaqueiro, P.; Lopez Quintela, A.

    1995-01-01

    Yttrium-iron-garnet (YIG) particles have been synthesized using the microemulsion technique. A comparison of ferrite powders obtained by this method and those prepared by sol-gel and solid state reactions is reported. We have studied both the magnetic and structural properties and have found a dependence on annealing temperatures. ((orig.))

  20. Influence of preparation method on structural and magnetic ...

    Indian Academy of Sciences (India)

    Administrator

    Influence of preparation method on structural and magnetic properties of nickel ferrite nanoparticles. BINU P JACOB, ASHOK KUMAR†, R P PANT†, SUKHVIR SINGH† and. E M MOHAMMED*. Department of Physics, Maharaja's College, Ernakulam 681 011, India. †National Physical Laboratory, New Delhi 110 012, India.

  1. Low temperature magnetic structure of MnSe

    Indian Academy of Sciences (India)

    Abstract. In this paper we report low temperature neutron diffraction studies on MnSe in order to understand the anomalous behaviour of their magnetic and transport prop- erties. Our study indicates that at low temperatures MnSe has two coexisting crystal structures, high temperature NaCl and hexagonal NiAs. NiAs phase ...

  2. Structural, morphological and magnetic properties of La1 ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Home; Journals; Bulletin of Materials Science; Volume 38; Issue 7. Structural, morphological and magnetic properties of La1−NaMnO3 ( ≤ ) nanoparticles produced by the solution combustion method. C O Ehi-Eromosele B I Ita K O Ajanaku A Edobor-Osoh O Aladesuyi S A Adalikwu F E Ehi- ...

  3. Size Induced Structural and Magnetic Properties of Nanostructured ...

    African Journals Online (AJOL)

    Their structural and magnetic properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) measurements. The average crystallite size of CoFe2O4was observed to increase from 23 to 65 nm as the annealing temperature was increased from ...

  4. Synthesis, structure, thermal, transport and magnetic properties of VN ceramics

    Czech Academy of Sciences Publication Activity Database

    Huber, Š.; Jankovský, O.; Sedmidubský, D.; Luxa, J.; Klimová, K.; Hejtmánek, Jiří; Sofer, Z.

    2016-01-01

    Roč. 42, č. 16 (2016), s. 18779-18784 ISSN 0272-8842 R&D Projects: GA ČR GA13-20507S Institutional support: RVO:68378271 Keywords : vanadium mononitride * phase transition * electronic structure * heat capacity * transport properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.986, year: 2016

  5. Patterned Electroplating of Micrometer Scale Magnetic Structures on Glass Substrates

    NARCIS (Netherlands)

    de Vries, A.H.B.; Kanger, Johannes S.; Krenn, Bea E.; van Driel, Roel

    2004-01-01

    This paper has developed a new method of micro patterned electroplating that enables the fabrication of micrometer scale magnetic structures on glass substrates. In contrast to other methods, the process as developed here leaves the surrounding substrate area untouched: that is there is no seed

  6. Patterned electroplating of micrometer scale magnetic structures on glass substrates.

    NARCIS (Netherlands)

    de Vries, A.H.B.; Kanger, S.J.; Krenn, G.E.; van Driel, R.

    2004-01-01

    This paper has developed a new method of micro patterned electroplating that enables the fabrication of micrometer scale magnetic structures on glass substrates. In contrast to other methods, the process as developed here leaves the surrounding substrate area untouched: that is there is no seed

  7. The Catalog: A Flexible Data Structure for Magnetic Tape.

    Science.gov (United States)

    Kay, Martin; Ziehe, Theodore

    This report outlines a generalized storage scheme for large files of highly structured data, or catalogs, and describes their realization on magnetic tape. Each datum, large or small, is assigned to one of a number of data classes of which a user may define any number. The over-all organization of a catalog is given by a map that imposes a tree…

  8. Effect of heat treatment on structure and magnetic properties

    Indian Academy of Sciences (India)

    Fe46Co35Ni19/CNTs nanocomposites have been prepared by an easy two-step route including adsorption and heat treatment processes. We investigated the effect of heat treatment conditions on structure, morphology, nanoparticle sizes and magnetic properties of the Fe46Co35Ni19 alloy nanoparticles attached on the ...

  9. Structural, morphological and magnetic properties of La1 ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 7. Structural, morphological and magnetic properties of La1−NaMnO3 ( ≤ ) nanoparticles produced by the solution combustion method. C O Ehi-Eromosele B I Ita K O Ajanaku A Edobor-Osoh O Aladesuyi S A Adalikwu F E Ehi-Eromosele. Volume 38 ...

  10. Magnetic properties of 2D nickel nanostrips: structure dependent magnetism and Stoner criterion

    International Nuclear Information System (INIS)

    Kashid, Vikas; Shah, Vaishali; Salunke, H G; Mokrousov, Yuriy; Blügel, Stefan

    2015-01-01

    We have investigated different geometries of two-dimensional (2D) infinite length Ni nanowires of increasing width using spin density functional theory calculations. Our simulations demonstrate that the parallelogram motif is the most stable and structures that incorporate the parallelogram motif are more stable as compared to rectangular structures. The wires are conducting and the conductance channels increase with increasing width. The wires have a non-linear behavior in the ballistic anisotropic magnetoresistance ratios (BAMR) with respect to the magnetization directions. All 2D nanowires as well as Ni (1 1 1) and Ni (1 0 0) monolayer investigated are ferromagnetic under the Stoner criterion and exhibit enhanced magnetic moments as compared to bulk Ni and the respective Ni monolayers. The easy axis for all nickel nanowires under investigation is observed to be along the wire axis. The double rectangular nanowire exhibits a magnetic anomaly with a smaller magnetic moment when compared to Ni (1 0 0) monolayer and is the only structure with an easy axis perpendicular to the wire axis. The Stoner parameter which has been known to be structure independent in bulk and surfaces is found to vary with the structure and the width of the nanowires. The less stable rectangular and rhombus shaped nanowires have a higher ferromagnetic strength than parallelogram shaped nanowires. (paper)

  11. Structural design of superconducting magnets for the large coil program

    International Nuclear Information System (INIS)

    Gray, W.H.; Long, C.J.; Stoddart, W.C.T.

    1979-09-01

    The Large Coil Program (LCP) is a research, development, and demonstration effort specifically for the advancement of the technologies involved in the production of large superconducting magnets. This paper presents a review of the status of the structural designs, analysis methods, and verification tests being performed by the participating LCP design teams in the USA, Switzerland, Japan, and the Federal Republic of Germany. The significant structural mechanics concerns that are being investigated with the LCP are presented

  12. COMPASS magnetic field coils and structure systems

    International Nuclear Information System (INIS)

    Crossland, R.T.; Booth, J.A.; Hayward, R.J.; Keogh, P.; Pratt, A.P.

    1987-01-01

    COMPASS is a new experimental toroidal assembly of compact design and with a wide range of physics objectives. It is required to operate either as a Tokamak or as a Reversed Field Pinch with interchangeable circular and dee-section vacuum vessels. The Toroidal field is produced by 16 rectangular coils of 4 turns with tapered conductors on the inside which nest together to form a vault to resist the centering forces. The coils are designed to produce a maximum field on axis of 2.1T which requires a current of 91 kA per turn. Two central solenoids and five pairs of coils symmetrically positioned above and below the machine equator provide the poloidal field. Both coil systems are supported form a mechanical support structure which surrounds the machine. This is primarily designed to resist out-of-plane forces on the TF coils but also acts as the base support for the PF coils and vacuum vessels. An illustration of the COMPASS Load Assembly is given and shows the D-shaped vacuum vessel, the major components and the various field windings

  13. Hybrid Spintronic Structures With Magnetic Oxides and Heusler Alloys

    DEFF Research Database (Denmark)

    Xu, Y. B.; Hassan, S. S. A.; Wong, P. K. J.

    2008-01-01

    Hybrid spintronic structures, integrating half-metallic magnetic oxides and Heusler alloys with their predicted high spin polarization, are important for the development of second-generation spintronics with high-efficient spin injection. We have synthesized epitaxial magnetic oxide Fe3O4 on Ga......As(100) and the unit cell of the Fe3O4 was found to be rotated by 45 degrees to match the gallium arsenide GaAs. The films were found to have a bulk-like moment down to 3-4 nm and a low coercivity indicating a high-quality magnetic interface. The magnetization hysteresis loops of the ultrathin films...... are controlled by uniaxial magnetic anisotropy. The dynamic response of the sample shows a heavily damped precessional response to the applied field pulses. In the Heusler alloy system of Co-2 MnGa on GaAs, we found that the magnetic moment was reduced for thicknesses down to 10 nm, which may account...

  14. Structural and magnetic properties of ball milled copper ferrite

    DEFF Research Database (Denmark)

    Goya, G.F.; Rechenberg, H.R.; Jiang, Jianzhong

    1998-01-01

    The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces....... The canted spin configuration is also suggested by the observed reduction in magnetization of particles in the blocked state. Upon increasing the milling time, nanometer-sized CuFe2O4 particles decompose, forming alpha-Fe2O3 and other phases, causing a further decrease of magnetization. After a milling time...... of 98 h, alpha-Fe2O3 is reduced to Fe3O4, and magnetization increases accordingly to the higher saturation magnetization value of magnetite. Three sequential processes during high-energy ball milling are established: (a) the synthesis of partially inverted CuFe2O4 particles with a noncollinear spin...

  15. Magnetic field effects on the crust structure of neutron stars

    Science.gov (United States)

    Franzon, B.; Negreiros, R.; Schramm, S.

    2017-12-01

    We study the effects of high magnetic fields on the structure and on the geometry of the crust in neutron stars. We find that the crust geometry is substantially modified by the magnetic field inside the star. We build stationary and axis-symmetric magnetized stellar models by using well-known equations of state to describe the neutron star crust, namely, the Skyrme model for the inner crust and the Baym-Pethick-Sutherland equation of state for the outer crust. We show that the magnetic field has a dual role, contributing to the crust deformation via the electromagnetic interaction (manifested in this case as the Lorentz force) and by contributing to curvature due to the energy stored in it. We also study a direct consequence of the crust deformation due to the magnetic field: the thermal relaxation time. This quantity, which is of great importance to the thermal evolution of neutron stars, is sensitive to the crust properties, and, as such, we show that it may be strongly affected by the magnetic field.

  16. Magnetic and Structural Investigations of Nanocrystalline Cobalt-Ferrite

    Directory of Open Access Journals (Sweden)

    I. Sharifi

    2012-10-01

    Full Text Available Cobalt ferrite is an important magnetic material due to their large magneto-crystalline anisotropy, high cohercivity, moderate saturation magnetization and chemical stability.In this study, cobalt ferrites Nanoparticles have been synthesized by the co-precipitation method and a new microemulsion route. We examined the cation occupancy in the spinel structure based on the “Rietveld with energies” method. The Xray measurements revealed the production of a broad single ferrite cubic phase with the average particle sizes of about 12 nm and 7nm, for co-precipitation and micro-emulsion methods, respectively. The FTIR measurements between 400 and 4000 cm-1 confirmed the intrinsic cation vibrations of the spinelstructure for the two methods. Furthermore, the Vibrating Sample Magnetometer (VSM was carried out at room temperature to study the structural and magnetic properties. The results revealed that by changing the method from co-precipitation to the reverse micelle the material exhibits a softer magnetic behavior in such a way that both saturation magnetization and coercivity decrease from 58 to 29 emu/g and from 286 to 25 Oe, respectively.

  17. Structural and magnetic properties of hcp and fcc Ni nanoparticles

    International Nuclear Information System (INIS)

    Gong, J.; Wang, L.L.; Liu, Y.; Yang, J.H.; Zong, Z.G.

    2008-01-01

    The face-centered-cubic (fcc) and hexagonal-close-packed (hcp) Ni nanoparticles were synthesized with citrate by sol-gel method and heat-treating technique. The structure, morphology and magnetic properties of the samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM). Our XRD and TEM results suggested that hcp Ni nanoparticles were successfully synthesized when the heating temperature reaches 300 deg. C. With a further increase in temperature to 400 deg. C, a temperature-induced phase transformation of hcp to fcc was observed. Moreover, the VSM results demonstrated the existence of ferromagnetic behavior in the synthesized fcc and hcp Ni nanoparticles. Nevertheless, the magnetic measurement suggested that the magnetic properties in hcp nanoparticles is probably the sum of two contributions: superparamagnetic and ferromagnetic one. The unsaturated magnetization is much smaller than 47.6 emu/g for the fcc nanoparticles obtained at 400 deg. C and 55 emu/g for the bulk material. It was also found that changes of the stress, grain size and crystal structure during heat-treating have significant influences on the magnetic properties of the Ni nanoparticles

  18. Growth-related magnetic and physical structures in CMR films

    Energy Technology Data Exchange (ETDEWEB)

    Hawley, M.E.; Brown, G.W.; Hundley, M.F. [and others

    1997-09-01

    Scanning tunneling microscopy (STM), atomic force microscopy (AFM), and magnetic force microscopy (MFM) have proven to be powerful tools for revealing property-sensitive structures in magnetic materials. With the renewed interest in perovskite films as materials for read-heads in high density magnetic data storage, the same challenges faced by high temperature superconductor (HTS) film fabrication are repeated for these materials. To begin addressing these challenges, we used vapor phase epitaxy to fabricate La (Sr, Ca,) based manganate films on single crystal perovskite substrates under different conditions and characterized them with scanning probe microscopies, x-ray diffraction, and temperature-dependent magnetization and resistivity measurements (M(T) and {rho}(T)). The as-grown films were polygranular with grain sizes increasing with increasing temperature (T). The post-deposition annealed films consisted of coalesced layers with improved transport properties. The room temperature magnetic structure of the Sr-based films appeared to be related to defects and/or strain.

  19. Structural analysis of Wendelstein 7-X magnet weight supports

    International Nuclear Information System (INIS)

    Egorov, Konstantin; Bykov, Victor; Schauer, Felix; van Eeten, Paul

    2009-01-01

    The Wendelstein 7-X (W7-X) optimized stellarator is presently under construction at the Max-Planck-Institut fuer Plasmaphysik in Greifswald. The goal of W7-X is to verify that the advanced stellarator magnetic confinement concept is a viable option for a fusion reactor. The W7-X coil system consisting of 70 superconducting coils of seven different types is supported by a massive central support structure (CSS), and thermally protected by the cryostat. The magnet system's weight is borne by supports (cryo-legs) which are bolted to the cold CSS. They reach down through the cryostat wall to the warm machine base which means that a small thermal conductivity is important to keep thermal losses at an acceptable level. Therefore, the design of the cryo-legs incorporates glass-reinforced plastic (GRP) tubes which are shrink-fitted into stainless steel flanges at the ends. In order to ensure free thermal shrinkage of the magnet system and to reduce stresses in the cryo-legs, sliding and rotating bearings are used as interfaces to the machine base. Tie rods between the machine base and the warm ends of the cryo-legs prevent toroidal movements of the magnet system with respect to the torus axis. Nevertheless, significant deformation of the CSS during operation results in tilting of the cryo-legs in such a way that toroidal movements of the whole magnet system take place. The number of cryo-legs and their stiffness are chosen such that the toroidal movement is kept within an acceptable range. All these restrictions, as well as requirements concerning simplicity and ease of assembly, make the cryo-leg design and structural analysis quite a complex and challenging task. The paper presents an overview of structural analyses of the W7-X magnet system with cryo-legs, local analyses of a cryo-leg under design loads, and FE simulation of the cryo-leg mechanical test.

  20. Ulysses Data Analysis: Magnetic Topology of Heliospheric Structures

    Science.gov (United States)

    Crooker, Nancy

    2001-01-01

    In this final technical report on research funded by a NASA grant, a project overview is given by way of summaries on nine published papers. Research has included: 1) Using suprathermal electron data to study heliospheric magnetic structures; 2) Analysis of magnetic clouds, coronal mass ejections (CME), and the heliospheric current sheet (HCS); 3) Analysis of the corotating interaction region (CIR) which develop from interactions between solar wind streams of different velocities; 4) Use of Ulysses data in the interpretation of heliospheric events and phenomena.

  1. Strange magnetism and the anapole structure of the proton

    International Nuclear Information System (INIS)

    Hasty, R.; Beck, D.H.; Danagoulian, A.; Blake, A.; Carr, R.; Covrig, S.; Filipoone, B.W.; Ito, T.M.; Gao, J.; Jones, C.E.; Lee, P.; McKeown, R.D.; Savu, V.; Beise, E.J.; Breuer, H.; Spayde, D.T.; Tieulent, R.; Herda, M.C.; Barkhuff, D.; Dodson, G.; Dow, K.; Farkhondeh, M.; Kowalski, S.; Tsentalovich, E.; Yang, B.; Zwart, T.; Hawthorne-Allen, A.M.; Pitt, M.; Ritter, J.; Korsch, W.; Mueller, B.; Wells, S.P.; Averett, T.; Roche, J.; Kramer, K.

    2000-01-01

    The violation of mirror symmetry in the weak force provides a powerful tool to study the internal structure of the proton. Experimental results have been obtained that address the role of strange quarks in generating nuclear magnetism. The measurement reported here provides an unambiguous constraint on strange quark contributions to the proton's magnetic moment through the electron-proton weak interaction. We also report evidence for the existence of a parity-violating electromagnetic effect known as the anapole moment of the proton. The proton's anapole moment is not yet well understood theoretically, but it could have important implications for precision weak interaction studies in atomic systems such as cesium.

  2. Mossbauer analysis of the atomic and magnetic structure of alloys

    CERN Document Server

    Ovchinnikov, VV

    2007-01-01

    The monograph indicates the key problems that have to be solved for the further development of the Mössbauer methods for analysis of the nuclear and magnetic structure of alloys, and offer solution variants for some of these problems based on the generalised results of a wide range of theoretical and experimental investigations,including original work by the author of the book and his colleagues. Contents 1. Description of the nature of the Mössbauer effect 2. Interpretation of the ossbauer spectra of alloys 3.Electrical and magnetics hyperfine interactions of resonant nuclei in metals and

  3. Time domain structures in a colliding magnetic flux rope experiment

    Science.gov (United States)

    Tang, Shawn Wenjie; Gekelman, Walter; Dehaas, Timothy; Vincena, Steve; Pribyl, Patrick

    2017-10-01

    Electron phase-space holes, regions of positive potential on the scale of the Debye length, have been observed in auroras as well as in laboratory experiments. These potential structures, also known as Time Domain Structures (TDS), are packets of intense electric field spikes that have significant components parallel to the local magnetic field. In an ongoing investigation at UCLA, TDS were observed on the surface of two magnetized flux ropes produced within the Large Plasma Device (LAPD). A barium oxide (BaO) cathode was used to produce an 18 m long magnetized plasma column and a lanthanum hexaboride (LaB6) source was used to create 11 m long kink unstable flux ropes. Using two probes capable of measuring the local electric and magnetic fields, correlation analysis was performed on tens of thousands of these structures and their propagation velocities, probability distribution function and spatial distribution were determined. The TDS became abundant as the flux ropes collided and appear to emanate from the reconnection region in between them. In addition, a preliminary analysis of the permutation entropy and statistical complexity of the data suggests that the TDS signals may be chaotic in nature. Work done at the Basic Plasma Science Facility (BaPSF) at UCLA which is supported by DOE and NSF.

  4. Crystal structure and magnetism of UOsAl

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, A.V., E-mail: andreev@fzu.cz [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Daniš, S. [Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic); Šebek, J.; Henriques, M.S.; Vejpravová, J. [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Gorbunov, D.I. [Institute of Physics, Academy of Sciences, Na Slovance 2, 182 21 Prague (Czech Republic); Dresden High Magnetic Field Laboratory (HLD-EMFL), Helmholtz-Zentrum, Dresden-Rossendorf, D-01314 Dresden (Germany); Havela, L. [Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 121 16 Prague (Czech Republic)

    2017-04-15

    Crystal structure, magnetization, and specific heat were studied on single crystal of uranium intermetallic compound UOsAl. It is a hexagonal Laves phase of MgZn{sub 2} type, space group P6{sub 3}/mmc, with lattice parameters a=536.4 pm, c=845.3 pm. Shortest inter-uranium distance 313 pm (along the c-axis) is considerably smaller than the Hill limit (340 pm). The compound is a weakly temperature-dependent paramagnet with magnetic susceptibility of ≈1.5*10{sup −8} m{sup 3} mol{sup −1} (at T=2 K), which is slightly higher with magnetic field along the a-axis compared to the c-axis. The Sommerfeld coefficient of electronic specific heat has moderate value of γ=36 mJ mol{sup −1} K{sup −2}. - Highlights: • Crystal structure and magnetic properties were studied on single crystal of UOsAl with hexagonal structure of MgZn{sub 2} type. • Shortest inter-uranium distance 313 pm (along the c-axis) is considerably smaller than the Hill limit (340 pm). • UOsAl has paramagnetic ground state as the compounds with T=Fe and Ru, i.e. 3d and 4d analogues of Os.

  5. Electronic structure and magnetic properties of zigzag blue phosphorene nanoribbons

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Tao; Hong, Jisang, E-mail: hongj@pknu.ac.kr [Department of Physics, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-08-07

    We investigated the electronic structure and magnetism of zigzag blue phosphorene nanoribbons (ZBPNRs) using first principles density functional theory calculations by changing the widths of ZBPNRs from 1.5 to 5 nm. In addition, the effect of H and O passivation was explored as well. The ZBPNRs displayed intra-edge antiferromagnetic ground state with a semiconducting band gap of ∼0.35 eV; and this was insensitive to the edge structure relaxation effect. However, the edge magnetism of ZBPNRs disappeared with H-passivation. Moreover, the band gap of H-passivated ZBPNRs was greatly enhanced because the calculated band gap was ∼1.77 eV, and this was almost the same as that of two-dimensional blue phosphorene layer. For O-passivated ZBPNRs, we also found an intra-edge antiferromagnetic state. Besides, both unpassivated and O-passivated ZBPNRs preserved almost the same band gap. We predict that the electronic band structure and magnetic properties can be controlled by means of passivation. Moreover, the edge magnetism can be also modulated by the strain. Nonetheless, the intrinsic physical properties are size independent. This feature can be an advantage for device applications because it may not be necessary to precisely control the width of the nanoribbon.

  6. Structure and magnetic exchange coupling of iron based trilayers

    International Nuclear Information System (INIS)

    Mendus, T.

    1998-12-01

    A study of the structural and magnetic properties of Fe based magnetic trilayers is presented. Sample preparation conditions were altered to achieve the best growth conditions and their effect on the magnetic properties determined. Structural information was obtained from RHEED, AES, STM and MEIS; this is believed to be the first time that MEIS has been used to look at this sort of sample. Magnetic characterisation was determined by MOKE with particular interest paid to the biquadratic coupling. The determination of magnetic coupling as a function of sample morphology was studied oil a series of Fe/Cr/Fe samples. Fe/Au/Fe samples oil MgO substrates were also prepared to facilitate MEIS studies. Results indicate that tile fluctuation model best describes tile observed biquadratic coupling in Fe/Cr/Fe trilayers and that the presence of clean, sharp interfaces is required. Annealing and growth at elevated temperature cause interdiffusion at the interfaces, weakening the biquadratic coupling. MEIS structural data from MgO/Fe/Au/Fe samples shows that tile layer structure is dependent oil thickness. There is an apparent reorganisation of tile Au interlayer between a 'bcc'-Iike phase towards tile bulk fcc phase as the layer thickness increases. MEIS is shown to be a very sensitive probe of the crystalline quality and is a powerful probe for the determination of postdeposition sample morphology. Results from an EC collaboration investigating Co/Cr/Co trilayers are also presented. They showed that interlayer coupling and anisotropy of the samples were very sensitive to the preparation conditions. A decrease in the coupling strength is found for sample growth under non-ideal conditions (growth in an applied field, growth at an angle and delays between layer growth). (author)

  7. TWO DIMENTIONAL STATIC MAGNETIC ANALYSIS OF RADIAL MAGNETIC BEARING SYSTEMS WITH DIFFERENT STRUCTURES

    Directory of Open Access Journals (Sweden)

    Yusuf ÖNER

    2005-03-01

    Full Text Available The friction loss of electrical machines is an important problem as like in other rotary machines. In addition, the bearings, where the friction losses occur, also require lubrication at periodic intervals and need to be maintained. In this study, to minimize the friction loss of electrical motor, two dimentional static magnetic analysis of radial magnetic bearing systems with different structures are performed and compared with each other; also, magnetic bearing system with four-pole is realized and applied to an induction motor. In simulation, the forces applied to the rotor of induction motor from designed magnetic bearing system are calculated in a computer by using FEMM software package. In application, when comparing designed magnetic bearing system with mechanical bearings up to the revolution of 350 rpm, it was observed that the loss of no-load operating condition of induction motor is decreased about 15 % with magnetic bearing system. In addition to this, mechanical noisy of the motor is also decreased considerably.

  8. Phase domain structures in cylindrical magnets under conditions of a first-order magnetic phase transition

    International Nuclear Information System (INIS)

    Dzhezherya, Yu.I.; Klymuk, O.S.

    2011-01-01

    The magnetic and resonance properties of cylindrical magnets at first-order phase transition from paramagnetic to ferromagnetic state were theoretically studied. It has been shown that in the external magnetic field directed perpendicularly to the rotation axis, formation of a specific domain structure of paramagnetic and ferromagnetic layers can be energetically favorable. The parameters of cylindrical phase domains as well as their dependences on temperature, magnetic field and material characteristics have been calculated. Peculiarities of the magnetic resonance spectra appearing as a result of the phase domain formation have been considered. Dependence of the resonance field of the system of ferromagnetic domains on magnetization and temperature has been obtained. - Highlights: → Parameters of the equilibrium system of cylindrical phase domains are calculated. → The range of fields for PM and FM phases coexistence is found. → FMR field of the disk domains is found to be lower than that of the PMR field.→ The resonance field increases with the decrease of temperature lower than T || .

  9. Theoretical study of ferromagnetic resonance in exchange - coupled magnetic / nonmagnetic / magnetic multilayer structure

    International Nuclear Information System (INIS)

    Oezdogan, K.; Oezdemir, M.; Yalcin, O.; Aktas, B.

    2002-01-01

    The dispersion relation on ferromagnetic films was calculation by using torque equation of motion with a damping term. The total energy including zeeman, demagnetizing and anisotropy energy terms was used to get ferromagnetic resonance frequency for both uniform and higher order spin wave modes. In antiferromagnetic films, the torque equation of motion for each sub-lattice were written to derive an expression for the dispersion relation. The magnetic trilayer system under investigation consist of two ferromagnetic layers separated by a nonmagnetic layer. The dispersion relation of magnetic/nonmagnetic/magnetic three layers is calculated by using Landau-Lifshitz dynamic equation of motion for the magnetization with interlayer exchange energy. As for the exchange-coupled resonance of ferromagnetic resonance (FMR), the theoretical study has been calculated for both symmetrical and asymmetrical structures. In this systems, the exchange-coupling parameter A 12 between neighboring layers was used to get resonance fields as a function of the angle between the magnetization vectors of each magnetic layers

  10. A Study on Magnetic Decoupling of Compound-Structure Permanent-Magnet Motor for HEVs Application

    Directory of Open Access Journals (Sweden)

    Qiwei Xu

    2016-10-01

    Full Text Available The compound-structure permanent-magnet (CSPM motor is used for an electrical continuously-variable transmission (E-CVT in a hybrid electric vehicle (HEV. It can make the internal combustion engine (ICE independent of the road loads and run in the high efficiency area to improve the fuel economy and reduce the emissions. This paper studies the magnetic coupling of a new type of CSPM motor used in HEVs. Firstly, through the analysis of the parameter matching with CSPM in the HEV, we receive the same dynamic properties’ design parameters between the CSPM motor and the THS (Toyota Hybrid System of the Toyota Prius. Next, we establish the equivalent magnetic circuit model of the overall and the secondary model considering the tangential and radial flux distribution in the outer rotor of the CSPM motor. Based on these two models, we explore the internal magnetic coupling rule of the CSPM motor. Finally, finite element method analysis in 2D-ansoft is used to analyze the magnetic field distribution of the CSPM motor in different operation modes. By the result of the finite element method analysis, the internal magnetic decoupling scheme is put forward, laying the theoretical foundation for the further application of the CSPM motor in HEVs.

  11. Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

    Energy Technology Data Exchange (ETDEWEB)

    Toparli, Cigdem [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Ebin, Burçak [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Nuclear Chemistry and Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey)

    2017-02-01

    The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size. - Highlights: • Ternary FeNiCo alloy nanocrystalline particles were synthesized in a single step. • Cubic crystalline structure and spherical morphology was observed by XRD, SEM and TEM investigations. • The analysis of magnetic properties indicates the soft magnetic features of particles.

  12. Magnetic field structures in active compact radio sources

    International Nuclear Information System (INIS)

    Jones, T.W.; Rudnick, L.; Fiedler, R.L.; Aller, H.D.; Aller, M.F.; Hodge, P.E.

    1985-01-01

    The analysis of simultaneous multifrequency linear polarimetry data between 1.4 GHz and 90 GHz for about 20 active, compact radio sources at six epochs from 1977 December 10 1980 July is presented. In addition, monthly 8 Ghz polarization data on the same sources were examined. The general polarization characteristics of these sources can be well described in terms of magnetic fields which are largely turbulent and slightly anisotropic. The magnetic field symmetry axes are generally aligned with the source structural axes on the milli-arcsecond scale (OJ 287 is a notable exception.) Monte Carlo calculations indicate that observed polarization variations and in particular rotator polarization events can be produced in this model as a consequence of random walks generated through evolution of the turbulent magnetic field. 43 references

  13. Magnetic apatite for structural insights on the plasma membrane

    International Nuclear Information System (INIS)

    Stanca, Sarmiza E; Müller, Robert; Dellith, Jan; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph

    2015-01-01

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications. (paper)

  14. Magnetic apatite for structural insights on the plasma membrane

    Science.gov (United States)

    Stanca, Sarmiza E.; Müller, Robert; Dellith, Jan; Nietzsche, Sandor; Stöckel, Stephan; Biskup, Christoph; Deckert, Volker; Krafft, Christoph; Popp, Jürgen; Fritzsche, Wolfgang

    2015-01-01

    The iron oxide-hydroxyapatite (FeOxHA) nanoparticles reported here differ from those reported before by their advantage of homogeneity and simple preparation; moreover, the presence of carboxymethyldextran (CMD), together with hydroxyapatite (HA), allows access to the cellular membrane, which makes our magnetic apatite unique. These nanoparticles combine magnetic behavior, Raman label ability and the property of interaction with the cellular membrane; they therefore represent an interesting material for structural differentiation of the cell membrane. It was observed by Raman spectroscopy, scanning electron microscopy (SEM) and fluorescence microscopy that FeOxHA adheres to the plasma membrane and does not penetrate the membrane. These insights make the nanoparticles a promising material for magnetic cell sorting, e.g. in microfluidic device applications.

  15. New trend for synthesizing of magnetic nanorods with titanomaghemite structure

    Energy Technology Data Exchange (ETDEWEB)

    Saber, Osama, E-mail: osmohamed@kfu.edu.sa [Faculty of Science, King Faisal University, P.O. Box 400, Al-Hassa 31982 (Saudi Arabia); Egyptian Petroleum Research Institute, Nasr City, P.O. Box 11727, Cairo (Egypt)

    2016-07-15

    This research aims at developing magnetic and optical materials through fabrication of uniform nanorods by facile and novel technique. In this trend, titanium and iron were successfully combined together forming nanorods without template or high temperature by urea hydrolysis. TEM images showed uniform and homogeneous nanorods with dimensions; 10 nm in width and 50 nm in length. In the same time, fine nanoparticles were observed around the nanorods. With further treatment for the nanorods at high temperature and pressure, FESEM images revealed that the dimensions of the rods slightly increased to be 70 nm in length and 12 nm in width with a complete disappearance of the nanoparticles. Using X-ray diffraction, thermal analyses and infrared spectra in addition to the results of the electron microscopy, the oriented attachment mechanism was suggested for the formation of titanium iron oxides nanorods. The magnetic measurements revealed that the prepared nanorods possess ferromagnetic behavior and exhibit high saturation magnetization. Also, the optical properties showed that the nanorods have high absorption in the visible region and possess low band gap energy. Finally, we concluded that it is probably the first time to prepare nanorods by urea hydrolysis. The advanced optical and magnetic properties give the prepared nanorods relevance to use as building blocks in functional nanoscale devices. - Graphical abstract: The present study has a dual aim for developing new and facile method for fabrication of nanorods containing titanomaghemite structure and improving their optical and magnetic properties - Highlights: • Synthesis of titanium iron oxides nanorods with titanomaghemite structure. • Using urea hydrolysis for preparation of nanorods. • Studying of the effect of pressure and temperature on the nanorods. • Enhancement of the magnetic properties of the nanorods in comparison with the nanoparticles. • Improvement of the optical properties of the nanorods

  16. Structural and magnetic properties of nickel antimony ferrospinels

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, S. A.; Tellgren, R.; Porcher, F.; Andre, G.; Ericsson, T.; Nordblad, P; Sadovskaya, N.; Kaleva, G.; Politova, E.; Baldini, M.; Sun, C.; Arvanitis, D.; Kumar, P. Anil; Mathieu, R.

    2015-05-05

    Spinel-type compounds of Fe–Ni–Sb–O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mössbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd – 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mössbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe0.8Ni1.8Sb0.4O4 was determined, with Sb5+ cations occupying octahedral sites, and Fe3+ and Ni2+ occupying both tetrahedral and octahedral sites. Fe3+ mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni2+ mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point.

  17. Magnetic field structure of experimental high beta tokamak equilibria

    International Nuclear Information System (INIS)

    Deniz, A.V.

    1986-01-01

    The magnetic field structure of several low and high β tokamaks in the Columbia High Beta Tokamak (HBT) was determined by high-impedance internal magnetic probes. From the measurement of the magnetic field, the poloidal flux, toroidal flux, toroidal current, and safety factor are calculated. In addition, the plasma position and cross-sectional shape are determined. The extent of the perturbation of the plasma by the probe was investigated and was found to be acceptably small. The tokamaks have major radii of approx.0.24 m, minor radii of approx.0.05 m, toroidal plasma current densities of approx.10 6 A/m 2 , and line-integrated electron densities of approx.10 20 m -2 . The major difference between the low and high β tokamaks is that the high β tokamak was observed to have an outward shift in major radius of both the magnetic center and peak of the toroidal current density. The magnetic center moves inward in major radius after 20 to 30 μsec, presumably because the plasma maintains major radial equilibrium as its pressure decreases from radiation due to impurity atoms. Both the equilibrium and the production of these tokamaks from a toroidal field stabilized z-pinch are modeled computationally. One tokamak evolves from a state with low β features, through a possibly unstable state, to a state with high β features

  18. Magnetic monopole interactions: shell structure of meson and baryon states

    International Nuclear Information System (INIS)

    Akers, D.

    1986-01-01

    It is suggested that a low-mass magnetic monopole of Dirac charge g = (137/2)e may be interacting with a c-quark's magnetic dipole moment to produce Zeeman splitting of meson states. The mass M 0 = 2397 MeV of the monopole is in contrast to the 10 16 -GeV monopoles of grand unification theories (GUT). It is shown that shell structure of energy E/sub n/ = M 0 + 1/4nM 0 ... exists for meson states. The presence of symmetric meson states leads to the identification of the shell structure. The possible existence of the 2397-MeV magnetic monopole is shown to quantize quark masses in agreement with calculations of quantum chromodynamics (QCD). From the shell structure of meson states, the existence of two new mesons is predicted: eta(1814 +/- 50 MeV) with I/sup G/(J/sup PC/) = 0 + (0 -+ ) and eta/sub c/ (3907 +/- 100 MeV) with J/sup PC/ = 0 -+ . The presence of shell structure for baryon states is shown

  19. Tripolar electric field Structure in guide field magnetic reconnection

    Science.gov (United States)

    Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua

    2018-03-01

    It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

  20. Tripolar electric field Structure in guide field magnetic reconnection

    Directory of Open Access Journals (Sweden)

    S. Fu

    2018-03-01

    Full Text Available It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection. In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg. Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

  1. Effect of structural transition on magnetic susceptibility of tantalum carbide

    International Nuclear Information System (INIS)

    Lipatnikov, V.N.; Gusev, A.I.; Rempel', A.A.; Shvejkin, G.P.

    1987-01-01

    Ordering of carbon atoms and vacancies in nonmetal sublattice of TaC y is investigated for the first time by methods of magnetic susceptibility and structural neutron diffraction analysis. Measurements of magnetic susceptibility were conducted on high-sensitive magnetic scales in temperature interval of 300 - 1300 K with holding at each temperature up to the establishment of constant, nonchanging in the course of time value of susceptibility x. When investigating x-hardened tantalum carbide within the interval of TaC 0.82 - TaC 0.85 compositions under the conditions of slow heating, it was observed nonrecorded earlier irreversible decrease of susceptibility at temperature of 960 - 1000 K. With further temperature increase T>T tr it was observed at first even and than uneven increase of x value at a temperature of T tr equal to 1090, 1130 and 1150 K for TaC 0.82 , TaC 0.83 and TaC 0.85 respectively. The measuring of magnetic susceptibility of the same samples at temperature decrease reveals the presence of susceptibility temperature hysteresis in the interval of 1070 - 1090, 1100 - 1130 and 1120 - 1150 for TaC 0.82 , TaC 0.83 and TaC 0.85 . Reversible susceptibility jump corresponding to the temperature hysteresis range at dependences of x(T), is connected with equilibrium structural phase transition of order-disorder

  2. A new support structure for high field magnets

    CERN Document Server

    Hafalia, R R; Caspi, S; Dietderich, D R; Gourlay, S A; Hannaford, R; Lietzke, A F; Liggins, N; McInturff, A D; Sabbi, G L; Scanlan, R M; O'Neill, J; Swanson, J H

    2002-01-01

    Pre-stress of superconducting magnets can be applied directly through the magnet yoke structure. We have replaced the collar functionality in our 14 Tesla R&D Nb//3Sn dipole magnets with an assembly procedure based on an aluminum shell and bladders. Bladders, placed between the coil pack and surrounding yoke inside the shell, are pressurized up to 10 ksi left bracket 70 MPa right bracket to create an interference gap. Keys placed into the interference gap replace the bladder functionality. Following the assembly, the bladders are deflated and removed. Strain gauges mounted directly on the shell are used to monitor the stress of the entire magnet structure, thereby providing a high degree of pre-stress control without the need for high tolerances. During assembly, a force of 8.2 multiplied by 10**5 lbs /ft left bracket 12 MN/m right bracket is generated by the bladders and the stress in the 1.57 double prime left bracket 40 mm right bracket aluminum shell reaches 20.3 ksi left bracket 140 MPa right bracket...

  3. First Cluster results of the magnetic field structure of the mid- and high-altitude cusps

    Directory of Open Access Journals (Sweden)

    P. J. Cargill

    Full Text Available Magnetic field measurements from the four Cluster spacecraft from the mid- and high-altitude cusp are presented. Cluster underwent two encounters with the mid-altitude cusp during its commissioning phase (24 August 2000. Evidence for field-aligned currents (FACs was seen in the data from all three operating spacecraft from northern and southern cusps. The extent of the FACs was of the order of 1 RE in the X-direction, and at least 300 km in the Y-direction. However, fine-scale field structures with scales of the order of the spacecraft separation (300 km were observed within the FACs. In the northern crossing, two of the spacecraft appeared to lie along the same magnetic field line, and observed very well matched signals. However, the third spacecraft showed evidence for structuring transverse to the field on scales of a few hundred km. A crossing of the high-altitude cusp from 13 February 2001 is presented. It is revealed to be a highly dynamic structure with the boundaries moving with velocities ranging from a few km/s to tens of km/s, and having structure on timescales ranging from less than one minute up to several minutes. The cusp proper is associated with the presence of a very disordered magnetic field, which is entirely different from the magnetosheath turbulence.

    Key words. Magnetospheric physics (current systems; magnetopause, cusp, and boundary layers – Space plasma physics (discontinuities

  4. Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

    International Nuclear Information System (INIS)

    Mallick, Sougata; Mallik, Srijani; Bedanta, Subhankar

    2015-01-01

    Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field

  5. Structural and magnetic properties of Mn-implanted Si

    International Nuclear Information System (INIS)

    Zhou Shengqiang; Potzger, K.; Zhang Gufei; Muecklich, A.; Eichhorn, F.; Schell, N.; Groetzschel, R.; Schmidt, B.; Skorupa, W.; Helm, M.; Fassbender, J.; Geiger, D.

    2007-01-01

    Structural and magnetic properties in Mn-implanted, p-type Si were investigated. High resolution structural analysis techniques such as synchrotron x-ray diffraction revealed the formation of MnSi 1.7 nanoparticles already in the as-implanted samples. Depending on the Mn fluence, the size increases from 5 nm to 20 nm upon rapid thermal annealing. No significant evidence is found for Mn substituting Si sites either in the as-implanted or annealed samples. The observed ferromagnetism yields a saturation moment of 0.21μ B per implanted Mn at 10 K, which could be assigned to MnSi 1.7 nanoparticles as revealed by a temperature-dependent magnetization measurement

  6. Local Structure and Magnetism of (Ga,Mn)As

    CERN Document Server

    AUTHOR|(CDS)2093111; Temst, Kristiaan

    Throughout the years, dilute magnetic semiconductors (DMS) have emerged as promising materials for semiconductor-based spintronics. In particular, (Ga,Mn)As has become the model system in which to explore the physics of carrier-mediated ferromagnetism in semiconductors and the associated spintronic phenomena, with a number of interesting functionalities and demonstrated proof-of-concept devices. It constitutes the perfect example of how the magnetic behavior of DMS materials is strongly influenced by local structure. In this thesis, we address key aspects of the interplay between local structure and ferromagnetism of (Ga,Mn)As. We unambiguously identify the lattice site occupied by interstitial Mn as the tetrahedral interstitial site with As nearest neighbors T(As). We show, furthermore, that the T(As) is the most energetically favorable site regardless of the interstitial atom forming or not complexes with substitutional Mn. We also evaluate the thermal stability of both interstitial and substitutional Mn si...

  7. Double-flat-spiral magnetic structures: Theory and application to the RMn6X6 compounds

    International Nuclear Information System (INIS)

    Rosenfeld, E.V.; Mushnikov, N.V.

    2008-01-01

    We studied magnetic structure of a layered magnetic material, the lattice of which consists of magnetic layers separated by alternating non-magnetic layers (slabs) of two different types. For such structure, the exchange integrals between the nearest magnetic layers separated by different slabs may have different values, while the next-nearest neighbor exchange integral is the same for all magnetic layers. We developed a model based on three different interlayer exchange integrals. In the framework of this model we analyzed conditions of the appearance of a magnetic structure of the double-flat-spiral type and its distortion in external magnetic field. The results are most obtained in the analytical form. The model was applied to analyze the magnetic structure and magnetization process of the RMn 6 X 6 (R=Y, Sc, Lu; X=Sn, Ge) compounds with the layered crystal structure

  8. Probing defect and magnetic structures on the nanoscale

    OpenAIRE

    Kallis, Alexis

    2010-01-01

    This thesis reports on experimental research on structural defects and magnetic species on the nanoscale. The latter project involved considerable development work on the production of a spin-polarised mono-energetic positron beam. The construction of the system is described through various trial steps with emphasis on the methods of maximum practical polarization of the positron beam and of electrons in the sample with the smallest possible loss of beam intensity. A new sodium-22 source caps...

  9. Modification of electronic structure, magnetic structure, and topological phase of bismuthene by point defects

    Science.gov (United States)

    Kadioglu, Yelda; Kilic, Sevket Berkay; Demirci, Salih; Aktürk, O. Üzengi; Aktürk, Ethem; Ciraci, Salim

    2017-12-01

    This paper reveals how the electronic structure, magnetic structure, and topological phase of two-dimensional (2D), single-layer structures of bismuth are modified by point defects. We first showed that a free-standing, single-layer, hexagonal structure of bismuth, named h-bismuthene, exhibits nontrivial band topology. We then investigated interactions between single foreign adatoms and bismuthene structures, which comprise stability, bonding, electronic structure, and magnetic structures. Localized states in diverse locations of the band gap and resonant states in band continua of bismuthene are induced upon the adsorption of different adatoms, which modify electronic and magnetic properties. Specific adatoms result in reconstruction around the adsorption site. Single vacancies and divacancies can form readily in bismuthene structures and remain stable at high temperatures. Through rebondings, Stone-Whales-type defects are constructed by divacancies, which transform into a large hole at high temperature. Like adsorbed adatoms, vacancies induce also localized gap states, which can be eliminated through rebondings in divacancies. We also showed that not only the optical and magnetic properties, but also the topological features of pristine h-bismuthene can be modified by point defects. The modification of the topological features depends on the energies of localized states and also on the strength of coupling between point defects.

  10. Higher order magnetic modulation structures in rare earth metal, alloys and compounds under extreme conditions

    International Nuclear Information System (INIS)

    Kawano, S.

    2003-01-01

    Magnetic materials consisting of rare earth ions form modulation structures such as a helical or sinusoidal structure caused by the oscillating magnetic interaction between rare earth ions due to RKKY magnetic interaction. These modulation structures, in some cases, develop further to higher order modulation structures by additional modulations caused by higher order crystalline electric field, magnetic interactions such as spin-lattice interaction, external magnetic field and pressure. The higher order modulation structures are observed in a spin-slip structure or a helifan structure in Ho, and a tilt helix structure in a TbEr alloy. Paramagnetic ions originated from frustration generate many magnetic phases under applied external magnetic field. KUR neutron diffraction groups have performed the development and adjustment of high-pressure instruments and external magnetic fields for neutron diffraction spectrometers. The studies of 'neutron diffraction under extreme conditions' by the seven groups are described in this report. (Y. Kazumata)

  11. Structure and magnetism in Cr-embedded Co nanoparticles.

    Science.gov (United States)

    Baker, S H; Kurt, M S; Roy, M; Lees, M R; Binns, C

    2016-02-03

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core.

  12. Magnetic activity at infrared frequencies in structured metallic photonic crystals

    International Nuclear Information System (INIS)

    O'Brien, S.; Pendry, J.P.

    2002-01-01

    We derive the effective permeability and permittivity of a nanostructured metallic photonic crystal by analysing the complex reflection and transmission coefficients for slabs of various thicknesses. These quantities were calculated using the transfer matrix method. Our results indicate that these structures could be used to realize a negative effective permeability, at least up to infrared frequencies. The origin of the negative permeability is a resonance due to the internal inductance and capacitance of the structure. We also present an analytic model for the effective permeability of the crystal. The model reveals the importance of the inertial inductance due to the finite mass of the electrons in the metal. We find that this contribution to the inductance has implications for the design of metallic magnetic structures in the optical region of the spectrum. We show that the magnetic activity in the structure is accompanied by the concentration of the incident field energy into very small volumes within the structure. This property will allow us to considerably enhance non-linear effects with minute quantities of material. (author)

  13. Progressive Transformation between Two Magnetic Ground States for One Crystal Structure of a Chiral Molecular Magnet.

    Science.gov (United States)

    Li, Li; Nishihara, Sadafumi; Inoue, Katsuya; Kurmoo, Mohamedally

    2016-03-21

    We report the exceptional observation of two different magnetic ground states (MGS), spin glass (SG, T(B) = 7 K) and ferrimagnet (FI, T(C) = 18 K), for one crystal structure of [{Mn(II)(D/L-NH2ala)}3{Mn(III)(CN)6}]·3H2O obtained from [Mn(CN)6](3-) and D/L-aminoalanine, in contrast to one MGS for [{Mn(II)(L-NH2ala)}3{Cr(III)(CN)6}]·3H2O. They consist of three Mn(NH2ala) helical chains bridged by M(III)(CN)6 to give the framework with disordered water molecules in channels and between the M(III)(CN)6. Both MGS are characterized by a negative Weiss constant, bifurcation in ZFC-FC magnetizations, blocking of the moments, both components of the ac susceptibilities, and hysteresis. They differ in the critical temperatures, absolute magnetization for 5 Oe FC (lack of spontaneous magnetization for the SG), and the shapes of the hysteresis and coercive fields. While isotropic pressure increases both T(crit) and the magnetizations linearly and reversibly in each case, dehydration progressively transforms the FI into the SG as followed by concerted in situ magnetic measurements and single-crystal diffraction. The relative strengths of the two moderate Mn(III)-CN-Mn(II) antiferromagnetic (J1 and J2), the weak Mn(II)-OCO-Mn(II) (J3), and Dzyaloshinkii-Moriya antisymmetric (DM) interactions generate the two sets of characters. Examination of the bond lengths and angles for several crystals and their corresponding magnetic properties reveals a correlation between the distortion of Mn(III)(CN)6 and the MGS. SG is favored by higher magnetic anisotropy by less distorted Mn(III)(CN)6 in good accordance with the Mn-Cr system. This conclusion is also born out of the magnetization measurements on orientated single crystals with fields parallel and perpendicular to the unique c axis of the hexagonal space group.

  14. STRUCTURE OF PROMINENCE LEGS: PLASMA AND MAGNETIC FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Levens, P. J.; Labrosse, N. [SUPA School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Schmieder, B. [Observatoire de Paris, Meudon, F-92195 (France); Ariste, A. López, E-mail: p.levens.1@research.gla.ac.uk [Institut de Recherche en Astrophysique et Planétologie, Toulouse (France)

    2016-02-10

    We investigate the properties of a “solar tornado” observed on 2014 July 15, and aim to link the behavior of the plasma to the internal magnetic field structure of the associated prominence. We made multi-wavelength observations with high spatial resolution and high cadence using SDO/AIA, the Interface Region Imaging Spectrograph (IRIS) spectrograph, and the Hinode/Solar Optical Telescope (SOT) instrument. Along with spectropolarimetry provided by the Télescope Héliographique pour l’Etude du Magnétisme et des Instabilités Solaires telescope we have coverage of both optically thick emission lines and magnetic field information. AIA reveals that the two legs of the prominence are strongly absorbing structures which look like they are rotating, or oscillating in the plane of the sky. The two prominence legs, which are both very bright in Ca ii (SOT), are not visible in the IRIS Mg ii slit-jaw images. This is explained by the large optical thickness of the structures in Mg ii, which leads to reversed profiles, and hence to lower integrated intensities at these locations than in the surroundings. Using lines formed at temperatures lower than 1 MK, we measure relatively low Doppler shifts on the order of ±10 km s{sup −1} in the tornado-like structure. Between the two legs we see loops in Mg ii, with material flowing from one leg to the other, as well as counterstreaming. It is difficult to interpret our data as showing two rotating, vertical structures that are unrelated to the loops. This kind of “tornado” scenario does not fit with our observations. The magnetic field in the two legs of the prominence is found to be preferentially horizontal.

  15. Interplay between structural symmetry and magnetism in Ag–Cu

    Energy Technology Data Exchange (ETDEWEB)

    Yen, Tsung-Wen; Lai, S.K., E-mail: sklai@coll.phy.ncu.edu.tw

    2016-01-01

    We present first-principles theoretical calculations of the magnetic properties of bimetallic clusters Ag–Cu. The calculations proceeded by combining a previously developed state-of-the-art optimization algorithm (P.J. Hsu, S.K. Lai, J. Chem. Phys. 124 (2006) 0447110) with an empirical potential and applied this numerical scheme to determine first the lowest energy structures of pure clusters Ag{sub 38} and Cu{sub 38}, and also their different atomic compositions Ag{sub n}Cu{sub 38−n} for n=1,2,…,37. Then, we carried out the Kohn–Sham spin unrestricted density functional theory calculations on the optimized atomic structures obtained in the preceding step. Given the minimized structures from the first step as input configurations, the results of these re-optimized structures by full density functional theory calculations yield more refined electronic and atomic structures. A thorough comparison of the structural differences between these two sets of atomic geometries, one from using an empirical potential in which the electronic degrees of freedom were included approximately and another from subsequent minimization using the spin unrestricted density functional theory, sheds light on how the electronic charges disperse near atoms in clusters Ag{sub n}Cu{sub 38−n}, and hence the distributions of electronic spin and charge densities at re-optimized sites of the cluster. These data of the electronic dispersion and the ionic configuration give clue to the mystery of the unexpected net magnetic moments which were found in some of the clusters Ag{sub n}Cu{sub 38−n} at n=1–4, 24 as well as the two pure clusters. Possible origins for this unanticipated magnetism were explained in the context of the point group theory in much the same idea as the Clemenger–Nilsson model applied to simple metal clusters except that we draw particular attention to the atomic topologies and stress the bearing that they have on valence electrons in inducing them to disperse and

  16. Non-superconducting magnet structures for near-term, large fusion experimental devices

    International Nuclear Information System (INIS)

    File, J.; Knutson, D.S.; Marino, R.E.; Rappe, G.H.

    1980-10-01

    This paper describes the magnet and structural design in the following American tokamak devices: the Princeton Large Torus (PLT), the Princeton Divertor Experiment (PDX), and the Tokamak Fusion Test Reactor (TFTR). The Joint European Torus (JET), also presented herein, has a magnet structure evolved from several European programs and, like TFTR, represents state of the art magnet and structure design

  17. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    International Nuclear Information System (INIS)

    Masrour, R.; Jabar, A.

    2016-01-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established. - Highlights: • The dendrimer structure is investigated using Monte Carlo simulations. • The transition temperatures are obtained for different coordination numbers and generations. • The magnetic hysteresis cycle has been established. • The dendrimer structure exhibit the superparamagnetic behavior.

  18. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R., E-mail: rachidmasrour@hotmail.com; Jabar, A.

    2016-11-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established. - Highlights: • The dendrimer structure is investigated using Monte Carlo simulations. • The transition temperatures are obtained for different coordination numbers and generations. • The magnetic hysteresis cycle has been established. • The dendrimer structure exhibit the superparamagnetic behavior.

  19. Ultrahigh energy nuclei propagation in a structured, magnetized universe

    International Nuclear Information System (INIS)

    Armengaud, Eric; Sigl, Guenter; Miniati, Francesco

    2005-01-01

    We compare the propagation of iron and proton nuclei above 10 19 eV in a structured Universe with source and magnetic field distributions obtained from a large-scale structure simulation and source densities ∼10 -5 Mpc -3 . All relevant cosmic ray interactions are taken into account, including photo-disintegration and propagation of secondary products. Iron injection predicts spectral shapes different from proton injection which disagree with existing data below ≅30 EeV. Injection of light nuclei or protons must therefore contribute at these energies. However, at higher energies, existing data are consistent with injection of pure iron with spectral indices between ∼2 and ∼2.4. This allows a significant recovery of the spectrum above ≅100 EeV, especially in the case of large deflections. Significant autocorrelation and anisotropy, and considerable cosmic variance are also predicted in this energy range. The mean atomic mass fluctuates considerably between different scenarios. At energies below 60 EeV, if the observed A > or approx. 35, magnetic fields must have a negligible effect on propagation. At the highest energies the observed flux will be dominated by only a few sources whose location may be determined by next generation experiments to within 10-20 deg. even if extra-galactic magnetic fields are important

  20. Magnetic properties of dendrimer structures with different coordination numbers: A Monte Carlo study

    Science.gov (United States)

    Masrour, R.; Jabar, A.

    2016-11-01

    We investigate the magnetic properties of Cayley trees of large molecules with dendrimer structure using Monte Carlo simulations. The thermal magnetization and magnetic susceptibility of a dendrimer structure are given with different coordination numbers, Z=3, 4, 5 and different generations g=3 and 2. The variation of magnetizations with the exchange interactions and crystal fields have been given of this system. The magnetic hysteresis cycles have been established.

  1. Magnetic structure of RPdSn (R=Tb, Ho) single crystal compounds under strong magnetic field

    International Nuclear Information System (INIS)

    Andoh, Y.; Kurisu, M.; Nakamoto, G.; Tsutaoka, T.; Kawano, S.

    2003-01-01

    Rare earth compounds RTX, where R stands for rare earth elements, T for Ni, Pd or Rh, and X for Sn or Ge, crystallize to a rhombic ε-TiNiSi structure. Only rare earth elements R contribute to magnetic properties since T and X atoms are nonmagnetic. The competition between RKKY indirect interaction and large magnetic anisotropy generates many complicated magnetic phases. At a low temperature phase, complicated magnetisms such as meta-magnetism were observed in magnetization curves with many steps. In previous experiments dealing with RPdSn where R means Tb or Ho, some characteristics of magnetic properties of these compounds were deduced from magnetization measurements and neutron diffraction without external magnetic field. In this report, the change of magnetic scattering of neutron diffraction was studied under external magnetic fields in order to reveal the mechanism of the phase transformations of the compounds. The difference between TbPdSn and HoPdSn compounds was observed in magnetic field dependence of the wave vectors of the magnetic scattering. Two independent wave vectors in magnetic scattering existed in HoPdSn compound. (Y. Kazumata)

  2. Magnetic properties of rare earth oxides with perovskite structure

    International Nuclear Information System (INIS)

    Hinatsu, Yukio

    2008-01-01

    A perovskite composite oxide is represented by the general formula of ABO 3 . Cations at the B site characterize magnetic properties of the oxide. Many studies have been accumulated for transition metal elements at the B sites. In this report the studies of rare earth elements at the B sites are reviewed. In rare elements, tetravalent ions such as Ce 4+ , Pr 4+ and Tb 4+ can occupy the B sites with Ba and Sr ions at the A sites. Both the SrTbO 3 and BaTbO 3 have an orthorhombic structure and show the antiferromagnetic transition at about 33 K, which is originated from terbium ions coupled antiferromagnetically with the six neighboring terbium ions. A tetravalent praseodymium perovskite SrPrO 3 shows no existence of the magnetic ordering down to 2.0 K. This is in contrast to the result of isomorphous BaPrO 3 , which shows an antiferromagnetic transition at 11.5 K. A double perovskite structure is represented by the formula A 2 LnMO 6 (A=Ba, Sr, Ca; M=Ru, Ir). In a double perovskite compound Ba 2 PrRuO 6 , the Pr 3+ and Ru 5+ ions are arranged with regularity over the six-coordinate B sites. This compound transforms to an antiferromagnetic state below 117 K. Antiferromagnetic transition temperatures T N for isomorphous Sr and Ca show a clear tendency, T N (A=Ba)>T N (Sr)>T N (Ca), in the compounds with the same rare earth elements (Ln). The 6H-perovskite structure Ba 3 LnRu 2 O 9 consists of linkages between LnO 6 octahedra and Ru 2 O 9 dimers made from face-shared RuO 6 octahedra. The 6H-perovskite structure Ba 3 MRu 2 O 9 (M=Sc, Y, La, Nd-Gd, Dy-Lu) have the valence state of Ba 3 M 3+ Ru 2 4.5+ O 9 . The magnetic susceptibilities show a broad maximum at 135-370 K. This magnetic behavior is ascribed to the antiferromagnetic coupling between two Ru ions in a Ru 2 O 9 dimer and to the magnetic interaction between the Ru 2 O 9 dimers. (author)

  3. Proceedings of the workshop on structural analysis needs for magnetic fusion energy superconducting magnets: a technical assessment

    International Nuclear Information System (INIS)

    Reich, M.; Lehner, J.; Powell, J.; Bezler, P.

    1976-01-01

    The technical portions of the meeting were divided into three major sessions as follows: (1) Review of methods being presently used by the MFE community for structural evaluation of current designs. (2) Future structural analysis needs. (3) Open discussions dealing with adequacy of present methods, the improvements needed for MFE magnet structural analysis, and the establishment of an MFE magnet structural advisory group. Summaries of the individual talks are presented

  4. Proceedings of the workshop on structural analysis needs for magnetic fusion energy superconducting magnets: a technical assessment

    Energy Technology Data Exchange (ETDEWEB)

    Reich, M.; Lehner, J.; Powell, J.; Bezler, P.

    1976-01-01

    The technical portions of the meeting were divided into three major sessions as follows: (1) Review of methods being presently used by the MFE community for structural evaluation of current designs. (2) Future structural analysis needs. (3) Open discussions dealing with adequacy of present methods, the improvements needed for MFE magnet structural analysis, and the establishment of an MFE magnet structural advisory group. Summaries of the individual talks are presented.

  5. Structural and magnetic properties of nickel antimony ferrospinels

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, S.A. [Center of Materials Science, Karpov’ Institute of Physical Chemistry, Moscow, 105064 (Russian Federation); Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Tellgren, R. [Department of Chemistry, Uppsala University, Box 538, 751 21 Uppsala (Sweden); Porcher, F.; André, G. [Laboratoire Leon Brillouin, Saclay (France); Ericsson, T. [Department of Chemistry, Uppsala University, Box 538, 751 21 Uppsala (Sweden); Nordblad, P. [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Sadovskaya, N.; Kaleva, G.; Politova, E. [Center of Materials Science, Karpov’ Institute of Physical Chemistry, Moscow, 105064 (Russian Federation); Baldini, M. [HPSynC, Carnegie Institution of Washington, Argonne, IL 60439 (United States); Sun, C. [X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Arvanitis, D. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Anil Kumar, P. [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Mathieu, R., E-mail: roland.mathieu@angstrom.uu.se [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden)

    2015-05-05

    Spinel-type compounds of Fe–Ni–Sb–O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mössbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd – 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mössbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe{sub 0.8}Ni{sub 1.8}Sb{sub 0.4}O{sub 4} was determined, with Sb{sup 5+} cations occupying octahedral sites, and Fe{sup 3+} and Ni{sup 2+} occupying both tetrahedral and octahedral sites. Fe{sup 3+} mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni{sup 2+} mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point. - Highlights: • Polycrystalline spinel-type compounds of (Fe,Ni)[Fe,Ni,Sb]2O4 were synthesized. • Fe (3+) and Ni (2+) cations occupy mainly tetrahedral (resp. octahedral) sites. • The ferrimagnetic behavior observed below 650 K is investigated in detail. • Squid magnetometry and neutron powder diffraction data are compared.

  6. Structural and magnetic properties of nickel antimony ferrospinels

    International Nuclear Information System (INIS)

    Ivanov, S.A.; Tellgren, R.; Porcher, F.; André, G.; Ericsson, T.; Nordblad, P.; Sadovskaya, N.; Kaleva, G.; Politova, E.; Baldini, M.; Sun, C.; Arvanitis, D.; Anil Kumar, P.; Mathieu, R.

    2015-01-01

    Spinel-type compounds of Fe–Ni–Sb–O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mössbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd – 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mössbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe 0.8 Ni 1.8 Sb 0.4 O 4 was determined, with Sb 5+ cations occupying octahedral sites, and Fe 3+ and Ni 2+ occupying both tetrahedral and octahedral sites. Fe 3+ mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni 2+ mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point. - Highlights: • Polycrystalline spinel-type compounds of (Fe,Ni)[Fe,Ni,Sb]2O4 were synthesized. • Fe (3+) and Ni (2+) cations occupy mainly tetrahedral (resp. octahedral) sites. • The ferrimagnetic behavior observed below 650 K is investigated in detail. • Squid magnetometry and neutron powder diffraction data are compared

  7. Electronic structure and magnetic properties of Pd sub(3)Fe

    International Nuclear Information System (INIS)

    Kuhnen, C.A.

    1988-01-01

    In this work we study the electronic and magnetic properties of the Pd sub(3)Fe alloy. For the ordered phase of Pd sub(3)Fe we employed the Linear Muffin-Tin Orbitals Method, with the atomic sphere approximation, which is a first principles method and includes spin polarization. The theoretical results for the thermal and magnetic properties show good agreement with experience. Here we explain the formation of the localized magnetic moments from completely itinerant electrons. We investigate the influence of the hydrogen in the physical properties of the compound Pd sub(3)Fe, where we obtain a drastic reduction in the magnetic moments at the Pd and Fe sites. This reduction is confirmed by experience. The self consistent potentials of the Pd sub(3)Fe compound were used for an analysis of the influence of the disorder in the electronic structure of Pd sub(3)Fe alloy. To this end, we employ a spin polarized version of the Green's Function Method with the Coherent Potential Approximation (or KKR-CPA). The results obtained show that in random ferromagnetic alloys different degrees of disorder occurs for the different spin directions. The formation of the magnetic moments in these alloys were explained from the existence of 'virtual crystal' states for spin up electrons and 'split band' states for spin down electrons. Finally we employ the muffin-tin orbitals to calculate the X-ray photoemission spectra of the Pd sub(3)Fe and Pd sub(3)FeH compounds, which allows us a direct comparison between theory and experiment. (author)

  8. Magnetic field adjustment structure and method for a tapered wiggler

    Science.gov (United States)

    Halbach, Klaus

    1988-01-01

    An improved method and structure is disclosed for adjusting the magnetic field generated by a group of electromagnet poles spaced along the path of a charged particle beam to compensate for energy losses in the charged particles which comprises providing more than one winding on at least some of the electromagnet poles; connecting one respective winding on each of several consecutive adjacent electromagnet poles to a first power supply, and the other respective winding on the electromagnet pole to a different power supply in staggered order; and independently adjusting one power supply to independently vary the current in one winding on each electromagnet pole in a group whereby the magnetic field strength of each of a group of electromagnet poles may be changed in smaller increments.

  9. Growth and structure of Co/Au magnetic thin films

    International Nuclear Information System (INIS)

    Marsot, N.

    1999-01-01

    We have studied the growth and the crystallographic structure of magnetic ultra thin cobalt/gold films (Co/Au), in order to investigate the correlations between their magnetic and structural properties. Room temperature (R.T.) Co growth on Au (111) proceeds in three stages. Up to 2 Co monolayers (ML), a bilayer island growth mode is observed. Between 2 and 5 ML, coalescence of the islands occurs, covering the substrate surface and a Co/Au mixing is observed resulting from the de-construction of the Herringbone reconstruction. Finally, beyond 5 ML, the CoAu mixing is buried and the Co growth continues in a 3-D growth. Annealing studies at 600 K on this system show a smoothing effect of the Co film, and at the same time, segregation of Au atoms. The quality of the Co/Au interface (sharpness) is not enhanced by the annealing. The local order was studied by SEXAFS and the long range order by GIXRD showing that the Co film has a hexagonal close packed structure, with an easy magnetization axis perpendicular to the surface. From a local order point of view, the Co grows with an incoherent epitaxy and keeps its own bulk parameters. The GIXRD analysis shows a residual strain in the Co film of 4%. The difference observed between the local order analysis and the long range order results is explained in terms of the low dimensions of the diffracting domains. The evolution of film strains, as a function of the Co coverage, shows a marked deviation from the elastic strain theory. Modification of the strain field in the Co film as a function of the Au coverage is studied by GIXRD analysis. The Au growth study, at R.T., shows no evidence of a Au/Co mixing in the case of the Au/Co interface. The Au overlayer adopts a twinned face centred cubic structure on the rough Co film surface. (author)

  10. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    Science.gov (United States)

    Zhukova, V.; Korchuganova, O. A.; Aleev, A. A.; Tcherdyntsev, V. V.; Churyukanova, M.; Medvedeva, E. V.; Seils, S.; Wagner, J.; Ipatov, M.; Blanco, J. M.; Kaloshkin, S. D.; Aronin, A.; Abrosimova, G.; Orlova, N.; Zhukov, A.

    2017-07-01

    We studied the magnetic properties and domain wall (DW) dynamics of Fe47.4Ni26.6Si11B13C2 and Fe77.5Si7.5B15 microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe77.5Si7.5B15, while DW velocity of samples Fe47.4Ni26.6Si11B13C2 is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe47.4Ni26.6Si11B13C2 sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe47.4Ni26.6Si11B13C2. Consequently we studied the structure of Fe47.4Ni26.6Si11B13C2 sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  11. Varieties of Dioptase: Their Magnetic Structure and Collective Excitations

    Science.gov (United States)

    Prisk, T.; Hoffmann, C.; Kolesnikov, A.; Anovitz, L. M.; Matsuda, M.; Podlesnyak, A.; Yan, J.

    2017-12-01

    Diopase [Cu6Si6O18 * 6 H2O] is a copper cyclosilicate mineral that exists within three different polymorphic forms. In the naturally occurring green phase, micropore channels are formed by corrugated rings of Si6O18 connected by Cu2+ ions. These channels contain rings of water molecules H2O which are co-ordinated to the Cu2+ ions, forming Jahn-Teller distorted octahedra. This results in the polymorph's green color. When the mineral is annealed at 400 C, it transforms into a blue polymorph where the positions of the the water molecules H2O become disordered within the channels. If annealed at 600 C, the water molecules are expelled from crystal structure altogether, leaving intact a framework where where the copper atom has quasi-planar co-ordination with neighboring oxygen atoms. The Cu2+ ions are responsible for the appearance of long-range antiferromagnetic order in green dioptase at 14 K. Comparative magnetic susceptibility measurements of these polymorphs demonstrate that altering the hydration state of the mineral leads to profound changes in its magnetic properties. This is presumably due to the fact that the local environment of the Cu2+ ions is modified by changes in the Cu atom's co-ordination with the water oxygen. Green, blue, and black dioptase together provide a case study in the coupling of a mineral's hydration state to its magnetic properties. In this presentation, we report upon a comparative study of dioptase polymorphs. We have applied heat capacity, magnetic susceptibility, single-crystal diffraction, and inelastic neutron scattering techniques. Magnetic diffraction patterns were obtained using the Polarized Triple Axis Spectrometer at the High Flux Isotope Reactor, while measurements of the spin wave dispersion were performed using the Cold Neutron Chopper Spectrometer at the Spallation Neutron Source. We find that, in green dioptase, the Cu2+ ions form spiral antiferromagnetic chains parallel to the micropore channels. However, in blue

  12. Magnetic interactions and electronic structure of Ni–Mn–In

    Energy Technology Data Exchange (ETDEWEB)

    D' Souza, Sunil Wilfred [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, Madhya Pradesh (India); Chakrabarti, Aparna [Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Barman, Sudipta Roy, E-mail: barmansr@gmail.com [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, Madhya Pradesh (India)

    2016-04-15

    Highlights: • The ground state of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} is ferromagnetic. • The magnetic moments of Ni–Mn–In are in good agreement with the magnetization measurements. • Exchange coupling parameters exhibit a strong competition between ferromagnetic and antiferromagnetic configurations. • Jahn–Teller splitting of the Ni 3d e{sub g} states drives the martensite transformation. - Abstract: The electronic structure and magnetic properties of a magnetic shape memory alloy Ni–Mn–In have been studied using spin polarized fully relativistic Korringa–Kohn–Rostoker (SPRKKR) method. The total energy calculations with different starting magnetic spin configurations show that the ground state of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} is ferromagnetic. The spin and orbital magnetic moments of Ni{sub 2}Mn{sub 1.4}In{sub 0.6} and Ni{sub 2}MnIn are in good agreement with the magnetization measurements. The exchange coupling parameters of the different sublattice interactions exhibit a strong competition between ferromagnetic and antiferromagnetic configurations, due to the substitution of excess Mn atoms at the In site in Ni{sub 2}Mn{sub 1.4}In{sub 0.6}. The Curie temperature of Ni{sub 2}MnIn, calculated under a mean field approximation, is found to be in relatively good agreement with the experimental values. While Ni{sub 2}MnIn does not undergo martensite transition, it is shown that a Jahn–Teller splitting of the Ni 3d e{sub g} states plays an important role in driving the martensite transformation in Ni{sub 2}Mn{sub 1.4}In{sub 0.6}. We find that both the calculated ultra-violet photoemission spectra and the inverse photoemission spectra are in good agreement with the existing experimental data.

  13. Structural and functional cardiac changes in myotonic dystrophy type 1: a cardiovascular magnetic resonance study

    Directory of Open Access Journals (Sweden)

    Hermans Mieke CE

    2012-07-01

    Full Text Available Abstract Background Myotonic dystrophy type 1 (MD1 is a neuromuscular disorder with potential involvement of the heart and increased risk of sudden death. Considering the importance of cardiomyopathy as a predictor of prognosis, we aimed to systematically evaluate and describe structural and functional cardiac alterations in patients with MD1. Methods Eighty MD1 patients underwent physical examination, electrocardiography (ECG, echocardiography and cardiovascular magnetic resonance (CMR. Blood samples were taken for determination of NT-proBNP plasma levels and CTG repeat length. Results Functional and structural abnormalities were detected in 35 patients (44%. Left ventricular systolic dysfunction was found in 20 cases, left ventricular dilatation in 7 patients, and left ventricular hypertrophy in 6 patients. Myocardial fibrosis was seen in 10 patients (12.5%. In general, patients had low left ventricular mass indexes. Right ventricular involvement was uncommon and only seen together with left ventricular abnormalities. Functional or structural cardiac involvement was associated with age (p = 0.04, male gender (p Conclusions CMR can be useful to detect early structural and functional myocardial abnormalities in patients with MD1. Myocardial involvement is strongly associated with conduction abnormalities, but a normal ECG does not exclude myocardial alterations. These findings lend support to the hypothesis that MD1 patients have a complex cardiac phenotype, including both myocardial and conduction system alteration.

  14. Structure of transformer oil-based magnetic fluids studied using acoustic spectroscopy

    International Nuclear Information System (INIS)

    Kúdelčík, Jozef; Bury, Peter; Drga, Jozef; Kopčanský, Peter; Závišová, Vlasta; Timko, Milan

    2013-01-01

    The structural changes in transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature were studied by acoustic spectroscopy. The attenuation of acoustic wave was measured as a function of the magnetic field in the range of 0–300 mT and in the temperature range of 15–35 °C for various magnetic nanoparticles concentrations. The effect of anisotropy of the acoustic attenuation was determined, too. The both strong influence of the magnetic field on the acoustic attenuation and its hysteresis were observed. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs, leading to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids also has very important influence on the structural changes because of the mechanism of thermal motion that acts against the cluster creation. The observed influences of both magnetic field and temperature on the investigated magnetic fluid structure are discussed. - Highlights: ► Structural changes in transformer oil-based magnetic fluids were investigated. ► The acoustic spectroscopy as the method of investigation was used. ► The influence of magnetic field on the structural was studied. ► The influence of temperatures on the structures was investigated, too. ► The influence of external conditions on the structure of MF is interpreted.

  15. Structure of transformer oil-based magnetic fluids studied using acoustic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kudelcik, Jozef, E-mail: kudelcik@fyzika.uniza.sk [Department of Physics, University of Zilina, Univerzitna 1, 010 01 Zilina (Slovakia); Bury, Peter; Drga, Jozef [Department of Physics, University of Zilina, Univerzitna 1, 010 01 Zilina (Slovakia); Kopcansky, Peter; Zavisova, Vlasta; Timko, Milan [Department of Magnetism, IEP SAS, Watsonova 47, 040 01 Kosice (Slovakia)

    2013-01-15

    The structural changes in transformer oil-based magnetic fluids upon the effect of an external magnetic field and temperature were studied by acoustic spectroscopy. The attenuation of acoustic wave was measured as a function of the magnetic field in the range of 0-300 mT and in the temperature range of 15-35 Degree-Sign C for various magnetic nanoparticles concentrations. The effect of anisotropy of the acoustic attenuation was determined, too. The both strong influence of the magnetic field on the acoustic attenuation and its hysteresis were observed. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles occurs, leading to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids also has very important influence on the structural changes because of the mechanism of thermal motion that acts against the cluster creation. The observed influences of both magnetic field and temperature on the investigated magnetic fluid structure are discussed. - Highlights: Black-Right-Pointing-Pointer Structural changes in transformer oil-based magnetic fluids were investigated. Black-Right-Pointing-Pointer The acoustic spectroscopy as the method of investigation was used. Black-Right-Pointing-Pointer The influence of magnetic field on the structural was studied. Black-Right-Pointing-Pointer The influence of temperatures on the structures was investigated, too. Black-Right-Pointing-Pointer The influence of external conditions on the structure of MF is interpreted.

  16. Cryogenic expansion joint for large superconducting magnet structures

    Science.gov (United States)

    Brown, Robert L.

    1978-01-01

    An expansion joint is provided that accommodates dimensional changes occurring during the cooldown and warm-up of large cryogenic devices such as superconducting magnet coils. Flattened tubes containing a refrigerant such as gaseous nitrogen (N.sub.2) are inserted into expansion spaces in the structure. The gaseous N.sub.2 is circulated under pressure and aids in the cooldown process while providing its primary function of accommodating differential thermal contraction and expansion in the structure. After lower temperatures are reached and the greater part of the contraction has occured, the N.sub.2 liquefies then solidifies to provide a completely rigid structure at the cryogenic operating temperatures of the device.

  17. Structural, morphological and magnetic analysis of Cd–Co–S dilute magnetic semiconductor nanofilms

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Suresh [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India); Negi, N.S. [Department of Physics, Himachal Pradesh University, Summer Hill, Shimla, Himachal Pradesh 171005 (India); Katyal, S.C. [Department of Physics, Jaypee Institute of Information Technology, Sec-128, Noida, Uttar Pradesh 201301 (India); Sharma, Pankaj, E-mail: pankaj.sharma@juit.ac.in [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India); Sharma, Vineet [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan, Himachal Pradesh 173234 (India)

    2014-10-01

    Cd{sub 1−x}Co{sub x}S dilute magnetic semiconductor nanofilms (0≤x≤0.08 at%) deposited by chemical bath deposition have been investigated using grazing angle x-ray diffraction, atomic force microscopy and vibrating sample magnetometer. The introduction of Co{sup 2+} ions in CdS structure induces structural disorders and hence, results in degradation of crystallinity. The crystallite size, interplanar spacing and lattice parameter ratio decrease with increasing Co{sup 2+} concentration in CdS. The diamagnetic state of CdS disappears with increase in Co concentration and films with x>0.02 exhibit ferromagnetism. This may be explained in terms of the spin–orbit interactions and Co{sup 2+} ion induced the lattice defects and phase separation. - Highlights: • Cd{sub 1−x}Co{sub x}S dilute magnetic semiconductor nanofilms (0≤x≤0.08 at%) deposited by CBD. • The diamagnetic state of CdS vanishes for x=0.02. • For x>0.02, dilute magnetic semiconductor nanofilms shows a ferromagnetic state.

  18. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    International Nuclear Information System (INIS)

    Sreelekha, N.; Subramanyam, K.; Amaranatha Reddy, D.; Murali, G.; Ramu, S.; Rahul Varma, K.; Vijayalakshmi, R.P.

    2016-01-01

    Highlights: • Cu_1_−_xCo_xS nanoparticles were synthesized via chemical co-precipitation method. • Structural, band gap, magnetization and photocatalysis studies were carried out. • All the doped samples exhibited intrinsic room temperature ferromagnetism. • Effect of magnetic properties on photocatalytic activity was analyzed. • CuS:Co nanoparticles may find applications in photocatalytic and spintronic devices. - Abstract: Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  19. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sreelekha, N.; Subramanyam, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Physics, Raghu Engineering College, Visakhapatnam, Andrapradesh 531162 (India); Amaranatha Reddy, D. [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609735 (Korea, Republic of); Murali, G. [Department of BIN Fusion Technology & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Ramu, S. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Rahul Varma, K. [Department of Mechanical Engineering, University of California, Berkeley (United States); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2016-08-15

    Highlights: • Cu{sub 1−x}Co{sub x}S nanoparticles were synthesized via chemical co-precipitation method. • Structural, band gap, magnetization and photocatalysis studies were carried out. • All the doped samples exhibited intrinsic room temperature ferromagnetism. • Effect of magnetic properties on photocatalytic activity was analyzed. • CuS:Co nanoparticles may find applications in photocatalytic and spintronic devices. - Abstract: Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  20. Structural and magnetic properties of nanocrystalline stannic substituted cobalt ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Y.M., E-mail: ymabbas@live.com [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Mansour, S.A. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Physics Department, Faculty of Science, King AbdulAziz University, Rabegh (Saudi Arabia); Ibrahim, M.H. [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt); Physics Department, Faculty of Science, King AbdulAziz University (Saudi Arabia); Ali, Shehab. E., E-mail: shehab_ali@science.suez.edu.eg [Physics Department, Faculty of Science, Suez Canal University, Ismailia (Egypt)

    2012-09-15

    The structural and magnetic properties of the spinel ferrite system Co{sub 1+x}Fe{sub 2-2x}Sn{sub x}O{sub 4} (x=0.0-1.0) have been studied. Samples in the series were prepared by the ceramic technique. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. Far infrared absorption spectra show two significant absorption bands, around 600 cm{sup -1} and 425 cm{sup -1}, which are respectively attributed to tetrahedral (A) and octahedral [B] vibrations of the spinel. Scanning Electron Microscopy (SEM) was used to study surface morphology. SEM images reveal particles in the nanosize range. The transmission electronic microscope (TEM) reveals that the grains are spherical in shape. TEM analysis confirmed the X-ray results. The magnetic properties of the prepared samples were characterized by using a vibrating sample magnetometer. - Highlights: Black-Right-Pointing-Pointer The spinel ferrite system has been formed at 1000 Degree-Sign C by using ceramic techniques. Black-Right-Pointing-Pointer Structural and microstructural evolutions have been studied using XRD and the Rietveld method. Black-Right-Pointing-Pointer The refinement result showed cationic distribution in the lattice is partially an inverse spinel. Black-Right-Pointing-Pointer The transmission electronic microscope analysis confirmed the X-ray results. Black-Right-Pointing-Pointer Magnetic properties of the samples were characterized by using a vibrating sample magnetometer.

  1. Structural and magnetic properties of nanocrystalline stannic substituted cobalt ferrite

    International Nuclear Information System (INIS)

    Abbas, Y.M.; Mansour, S.A.; Ibrahim, M.H.; Ali, Shehab. E.

    2012-01-01

    The structural and magnetic properties of the spinel ferrite system Co 1+x Fe 2−2x Sn x O 4 (x=0.0–1.0) have been studied. Samples in the series were prepared by the ceramic technique. The structural and microstructural evolutions of the nanophase have been studied using X-ray powder diffraction and the Rietveld method. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is partially an inverse spinel. Far infrared absorption spectra show two significant absorption bands, around 600 cm −1 and 425 cm −1 , which are respectively attributed to tetrahedral (A) and octahedral [B] vibrations of the spinel. Scanning Electron Microscopy (SEM) was used to study surface morphology. SEM images reveal particles in the nanosize range. The transmission electronic microscope (TEM) reveals that the grains are spherical in shape. TEM analysis confirmed the X-ray results. The magnetic properties of the prepared samples were characterized by using a vibrating sample magnetometer. - Highlights: ► The spinel ferrite system has been formed at 1000 °C by using ceramic techniques. ► Structural and microstructural evolutions have been studied using XRD and the Rietveld method. ► The refinement result showed cationic distribution in the lattice is partially an inverse spinel. ► The transmission electronic microscope analysis confirmed the X-ray results. ► Magnetic properties of the samples were characterized by using a vibrating sample magnetometer.

  2. Moessbauer spectroscopic studies of the magnetic and structural properties of novel nanophase magnetic materials

    International Nuclear Information System (INIS)

    Milford, G.H.

    2000-08-01

    identify the position of the Fe 3+ component within the particle. As Conversion Electron Moessbauer Spectroscopy is a surface sensitive technique with over 90% of the signal produced in the first 100nm of the particles different spectra should result for different structures. Unfortunately as the particles were orientated at an angle to the gamma-ray direction this investigation was inconclusive. Ferrofluid samples have provided a model system to investigate the superparamagnetic relaxation phenomena of different sized spherical particles of iron oxide with diameters of 5-7 nm. Moessbauer Spectroscopy in conjunction with Thermal Decay of Remanence has identified τ 0 to be approximately 1 x 10 -10 s for all the different particle sizes. This work provides evidence for the hypothesis that τ 0 is related to the material and it is not a function of the particle size. In addition to this the ferrofluid samples have been studied using high field Moessbauer Spectroscopy in order to characterise the structure of the spherical particles. This has resulted in a model for the physical and chemical structure of the particles. The particles consist of an internal ferrimagnetic core of γ-Fe 2 O 3 surrounded by a γ-Fe 2 O 3 canted ferrimagnetic surface layer. The depth of the surface layer remains constant with varying particle size. Ferritin extracted from Listeria innocua bacterium has been studied to provide information about the physical and magnetic structure of the iron containing core. Variable temperature Moessbauer Spectroscopy has shown that Listeria innocua ferritin behaves in a different manner to all ferritins studied previously. The iron core undergoes a magnetic collapse with no evidence of superparamagnetism at 20K resulting in a magnetically split sextet with narrow linewidths at 4.2K corresponding to an Fe 3+ compound. Listeria innocua ferritin has therefore been identified as having a new form of iron containing core. (author)

  3. A Novel Integrated Structure with a Radial Displacement Sensor and a Permanent Magnet Biased Radial Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2014-01-01

    Full Text Available In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

  4. On boundaries among magnetic structures at the sun

    Science.gov (United States)

    Ishkov, V. N.; Linke, J.

    1990-10-01

    Results of an analysis of published observational data on large complex active regions (CARs) on the sun are briefly discussed. Boundaries detected in the lower region of the solar atmosphere are shown to reveal the separation of independently developing magnetic structures, which may interact to produce eruption effects such as flares, reconnection, and flux-tube cancelling, as proposed by Linke and Bachmann (1989). The characteristics of these boundaries are illustrated with diagrams based on CAR data for June-July 1982, July-August 1983, and October 1979.

  5. Reactor structure and superconducting magnet system of ITER

    International Nuclear Information System (INIS)

    Tada, Eisuke; Yoshida, Kiyoshi; Shibanuma, Kiyoshi; Okuno, Kiyoshi; Tsuji, Hiroshi; Shimamoto, Susumu

    1993-01-01

    Fusion Experimental Reactors are one of the major steps toward realization of the fusion energy and the key objective are to demonstrate the scientific and technological feasibility prior to the Demo Fusion Reactor. ITER (International Thermonuclear Experimental Reactor) is one of experimental reactors and the conceptual design has been completed by the united efforts of USA, USSR, EC and Japan. In parallel with the conceptual design, key technology development in various areas has being conducted. This paper describes the overall design concepts and the latest technological achievements of the ITER reactor structure and superconducting magnet system. (author)

  6. Filament shape versus coronal potential magnetic field structure

    Science.gov (United States)

    Filippov, B.

    2016-01-01

    Solar filament shape in projection on disc depends on the structure of the coronal magnetic field. We calculate the position of polarity inversion lines (PILs) of coronal potential magnetic field at different heights above the photosphere, which compose the magnetic neutral surface, and compare with them the distribution of the filament material in Hα chromospheric images. We found that the most of the filament material is enclosed between two PILs, one at a lower height close to the chromosphere and one at a higher level, which can be considered as a height of the filament spine. Observations of the same filament on the limb by the Solar Terrestrial Relations Observatory spacecraft confirm that the height of the spine is really very close to the value obtained from the PIL and filament border matching. Such matching can be used for filament height estimations in on-disc observations. Filament barbs are housed within protruding sections of the low-level PIL. On the base of simple model, we show that the similarity of the neutral surfaces in potential and non-potential fields with the same sub-photospheric sources is the reason for the found tendency for the filament material to gather near the potential-field neutral surface.

  7. Restoration the domain structure from magnetic force microscopy image

    Science.gov (United States)

    Wu, Dongping; Lou, Yuanfu; Wei, Fulin; Wei, Dan

    2012-04-01

    This contribution gives an approximation method to calculate the stray field of the scanning plane from the magnetic force microscopy (MFM) force gradient image. Before calculation, a Butterworth low-pass filter has been used to remove a part of the noise of the image. The discrete Fourier transform (DFT) method has been used to calculate the magnetic potential of the film surface. It shows that the potential is not correct because the low-frequency noise has been enlarged. The approximation method gives a better result of the potential and proves that the MFM force gradient of the perpendicular component image also gives the perpendicular component of the stray field. Supposing that the distance between the tip and the sample is as small as near zero, the force gradient image also gives the magnetic charge distribution of the film surface. So if the orientation of the film from hysteresis loop is known, then the domain structure of the film can be determined. For perpendicular orientation, the absolution value of the perpendicular component of stray field gives the domain and domain wall position. For in-plane orientation, the absolution value of in-plane component of stray field gives the domain and domain wall position.

  8. Advanced welding for closed structure. Pt. 1 The magnetic approach

    Energy Technology Data Exchange (ETDEWEB)

    Sacripanti, A.; Paoloni, M.; Sagratella, G. [ENEA Centro Ricerche Casaccia, Rome (Italy). Dipt. Innovazione

    1999-07-01

    This report describes the activities developed for the European Contract BRITE AWCS III to study the use of magnetic sensing techniques to obtain an accurate detection of the internal reinforcement of the closed steel structures employed in the shipbuilding industry. After a description of the methods, techniques and problems for the magnetic testing of materials in the conventional approach, a new method was tried to obtain the wanted results. The obtained conclusion shows that the magnetic non destructive testing approach produce very small effects to measure, are too much sensible to the anisotropy of the magnetic properties of the steel plates and to the quality of the contact with the reinforcement. This system is not flexible enough to assemble a sensing for the goal of the BRITE AWCS III. [Italian] Questo rapporto descrive le attivita' sperimentali sviluppate nell'ambito del contratto europeo BRITE AWCS III, in cui si sono utilizzate tecniche magnetiche per ottenere un preciso rilevamento dei rinforzi interni di strutture metalliche chiuse utilizzate nell'industria delle costruzioni navali. Dopo la descrizione dei metodi, delle tecniche e dei problemi riguardanti il testing magnetico dei materiali, e' stato introdotto un approccio innovativo basato su elettromagneti costruiti ad hoc. Le conclusioni ottenute mostrano che nel nuovo approccio, il testing magnetico non distruttivo produce perturbazioni troppo piccole per essere correttamente apprezzate, risulta inoltre troppo legato alle anisotropie ed alla qualita' del contatto tra piatto e web ed infine esso appare poco flessibile per soddisfare le richieste tecniche del BRITE AWCS III.

  9. Collision-Free Structure Using Thin-Film Magnet For Electrostatic Energy Harvester

    International Nuclear Information System (INIS)

    Yoshii, S; Yamaguchi, K; Fujita, T; Kanda, K; Maenaka, K

    2016-01-01

    This paper proposes collision-free structure using NdFeB thin-film magnet for vibration energy harvesters. By using stripe shaped NdFeB magnet array on the Si MEMS structure, we finally obtained 3 mN of magnetic repulsive force on 8 × 8 mm 2 specimen with 40 μm air-gap. (paper)

  10. Collision-Free Structure Using Thin-Film Magnet For Electrostatic Energy Harvester

    Science.gov (United States)

    Yoshii, S.; Yamaguchi, K.; Fujita, T.; Kanda, K.; Maenaka, K.

    2016-11-01

    This paper proposes collision-free structure using NdFeB thin-film magnet for vibration energy harvesters. By using stripe shaped NdFeB magnet array on the Si MEMS structure, we finally obtained 3 mN of magnetic repulsive force on 8 × 8 mm2 specimen with 40 μm air-gap.

  11. Asymmetric bistable reflection and polarization switching in a magnetic nonlinear multilayer structure

    DEFF Research Database (Denmark)

    Tuz, Vladimir R.; Novitsky, Denis V.; Prosvirnin, Sergey L.

    2014-01-01

    Optical properties of one-dimensional photonic structures consisting of Kerr-type nonlinear and magnetic layers under the action of an external static magnetic field in the Faraday geometry are investigated. The structure is a periodic arrangement of alternating nonlinear and magnetic layers (a o...

  12. Octupolar out-of-plane magnetic field structure generation during collisionless magnetic reconnection in a stressed X-point collapse

    Energy Technology Data Exchange (ETDEWEB)

    Graf von der Pahlen, J.; Tsiklauri, D. [School of Physics and Astronomy, Queen Mary University of London, London E1 4NS (United Kingdom)

    2014-06-15

    The out-of-plane magnetic field, generated by fast magnetic reconnection, during collisionless, stressed X-point collapse, was studied with a kinetic, 2.5D, fully electromagnetic, relativistic particle-in-cell numerical code, using both closed (flux conserving) and open boundary conditions on a square grid. It was discovered that the well known quadrupolar structure in the out-of-plane magnetic field gains four additional regions of opposite magnetic polarity, emerging near the corners of the simulation box, moving towards the X-point. The emerging, outer, magnetic field structure has opposite polarity to the inner quadrupolar structure, leading to an overall octupolar structure. Using Ampere's law and integrating electron and ion currents, defined at grid cells, over the simulation domain, contributions to the out-of-plane magnetic field from electron and ion currents were determined. The emerging regions of opposite magnetic polarity were shown to be the result of ion currents. Magnetic octupolar structure is found to be a signature of X-point collapse, rather than tearing mode, and factors relating to potential discoveries in experimental scenarios or space-craft observations are discussed.

  13. Magnetic domain structure of MnAs thin films as a function of temperature

    International Nuclear Information System (INIS)

    Mizuguchi, Masaki; Manago, Takashi; Akinaga, Hiroyuki; Kuramochi, Hiromi; Okabayashi, Jun

    2003-01-01

    We have investigate magnetic domain structures of MnAs thin films grown on GaAs substrates by a magnetic force microscope. We observed, by an atomic force microscope, rectangular defects along GaAs [110] direction which disperse randomly on the surface of MnAs/GaAs(001). The Curie temperature of MnAs is 45degC, and it is successfully confirmed directly by the variable temperature magnetic force microscope observation. We also investigated magnetic domain structures of MnAs/GaAs(111)B, and no apparent relation was observed between the topographic structure and the magnetic domain structure. (author)

  14. Structural and conformational study of polysaccharides by nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Bossennec, Veronique

    1989-01-01

    As some natural polysaccharides are involved in important biological processes, the use of nuclear magnetic resonance appears to be an adapted mean to determine their structure-activity relationship and is therefore the object of this research thesis. By using bi-dimensional proton-based NMR techniques, it is possible to identify minority saccharide units, to determine their conformation, and to identify units which they are bound to. The author reports the application of these methods to swine mucosa heparin, and to heparins displaying a high and low anticoagulant activity. The dermatan sulphate has also been studied, and the NMR analysis allowed some polymer structure irregularities to be identified. A molecular modelling of dermatan sulphate has been performed [fr

  15. Structural looseness investigation in slow rotating permanent magnet generators

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Mijatovic, Nenad; Sweeney, Christian Walsted

    2016-01-01

    Structural looseness in electric machines is a condition influencing the alignment of the machine and thus the overall bearing health. In this work, assessment of the above mentioned failure mode is tested on a slow rotating (running speed equal to 0.7Hz) permanent magnet generator (PMG), while...... collecting vibration and current data in order to cross-reference the indications from the two monitoring techniques. It is found that electric signature analysis shows no response even when two hold down bolts are untightened, whereas the analysis results from the vibration data exhibit superior performance....... The vibration-based condition indicators with the best response are the stator slot pass frequency, which can be directly related to the cogging torque in PMGs, and the 4th electric frequency harmonic, whose amplitudes increase due to the overall lower structure damping coefficient under looseness...

  16. Structural modeling of the Vichada impact structure from interpreted ground gravity and magnetic anomalies

    International Nuclear Information System (INIS)

    Hernandez, Orlando; Khurama, Sait; Alexander, Gretta C

    2011-01-01

    A prominent positive free-air gravity anomaly mapped over a roughly 50-km diameter basin is consistent with a mascon centered on (4 degrades 30 minutes N, 69 degrades 15 minutes W) in the Vichada Department, Colombia, South America. Ground follow up gravity and magnetic anomalies were modeled confirming the regional free air gravity anomalies. These potential field anomalies infer a hidden complex impact basin structure filled with tertiary sedimentary rocks and recent quaternary deposits. Negative Bouguer anomalies of 8 mgals to 15 mgals amplitude are associated with a concentric sedimentary basin with a varying thickness from 100 m to 500 m in the outer rings to 700 m to 1000 m at the center of the impact crater basin. Strong positive magnetic anomalies of 100 nt to 300 nt amplitude infer the presence of a local Precambrian crystalline basement that was affected by intensive faulting producing tectonic blocks dipping to the center of the structure, showing a typical domino structure of impact craters such as that of Sudbury, Ontario, Canada. Basic to intermediate mineralized veins and dikes with contrasting density and magnetic susceptibility properties could be emplaced along these faulting zones, as inferred from local gravity and magnetic highs. The geologic mapping of the area is limited by the flat topography and absence of outcrops/ geomorphologic units. Nevertheless, local normal faults along the inner ring together with radially sparse irregular blocks over flat terrains can be associated with terraced rims or collapse of the inner crater structure and eject blanket, respectively. A detailed airborne electromagnetic survey is recommended to confirm the gravity and magnetic anomalies together with a seismic program to evaluate the economic implications for energy and mineral exploration of the Vichada impact structure.

  17. Stacked nickelocenes: synthesis, structural characterization, and magnetic properties.

    Science.gov (United States)

    Trtica, Sabrina; Prosenc, Marc Heinrich; Schmidt, Michael; Heck, Jürgen; Albrecht, Ole; Görlitz, Detlef; Reuter, Frank; Rentschler, Eva

    2010-02-15

    The disubstitution of 1,8-diiodonaphthalene (1) with cyclopentadienyl nucleophiles reveals 1,8-(dicyclopentadienyl)-naphthalene, which rapidly undergoes Diels-Alder reaction forming 1,8-(3a',4',7',7a'-tetrahydro-4',7'-methanoindene-7a',8'-diyl)-naphthalene (2). A subsequent retro-Diels-Alder reaction in the presence of sodium hydride yields the disodium salt of 1,8-(dicyclopentadiendiyl)-naphthalene 3. The disodium salt 3 was the starting material to obtain the paramagnetic bisnickelocene derivative 4, which structure was obtained by X-ray structure analysis, revealing two nickelocenes kept together in a stacked fashion by a 1,8-naphthalene clamp. An electronic interaction between the two nickel atoms is found as a result of cyclic voltammetry, indicating five different oxidation states +4, +3, +2, +1, and 0. The magnetic properties of 4 in solution were studied by variable temperature paramagnetic (1)H NMR spectroscopy and Evans method and revealed Curie behavior between 213 and 293 K. The magnetic susceptibility of a powdered sample of 4 was measured, and an antiferromagnetic interaction with an exchange coupling of J(12) = -31.49 cm(-1) is found. In accord with experimental data, broken symmetry density functional theory (DFT) calculations revealed four antiferromagnetically coupled electrons resulting in an open shell singlet ground state.

  18. Shell structure of potassium isotopes deduced from their magnetic moments

    CERN Document Server

    Papuga, J.; Kreim, K; Barbieri, C; Blaum, K; De Rydt, M; Duguet, T; Garcia Ruiz, R F; Heylen, H; Kowalska, M; Neugart, R; Neyens, G; Nortershauser, W; Rajabali, M M; Sanchez, R; Smirnova, N; Soma, V; Yordanov, D T

    2014-09-29

    $\\textbf{Background:}$ Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. \\\\ \\\\ $\\textbf{Purpose:}$ Extend our knowledge about the evolution of the $1/2^+$ and $3/2^+$ states for K isotopes beyond the $N = 28$ shell gap. \\\\ \\\\ $\\textbf{Method:}$ High-resolution collinear laser spectroscopy on bunched atomic beams. \\\\ \\\\ $\\textbf{Results:}$ From measured hyperfine structure spectra of K isotopes, nuclear spins and magnetic moments of the ground states were obtained for isotopes from $N = 19$ up to $N = 32$. In order to draw conclusions about the composition of the wave functions and the occupation of the levels, the experimental data were compared to shell-model calculations using SDPF-NR and SDPF-U effective interactions. In addition, a detailed discussion about the evolution of the gap between proton $1d_{3/2}$ and $2s_{1/2}$ in the shell model and $\\textit{ab initio}$ framework is al...

  19. Size and thickness effect on magnetic structures of maghemite hollow magnetic nanoparticles

    International Nuclear Information System (INIS)

    Sayed, Fatima; Labaye, Yvan; Sayed Hassan, Rodaina; El Haj Hassan, Fouad; Yaacoub, Nader; Greneche, Jean-Marc

    2016-01-01

    The effect of surface anisotropy on the magnetic ground state of hollow maghemite nanoparticles is investigated using atomistic Monte Carlo simulation. The computer modeling is carried on hollow nanostructures as a function of size and shell thickness. It is found that the large contribution of the surface anisotropy imposes a “throttled” spin structure where the moments located at the outer surface tend to orient normal to the surface while those located at the inner surface appear to be more aligned. For increasing values of surface anisotropy in the frame of a radial model, the magnetic moments become radially oriented either inward or outward giving rise to a “hedgehog” configuration with nearly zero net magnetization. We also show the effect of the size of hollow nanoparticle on the spin behavior where the spin non-collinearity increases (for fixed value of surface anisotropy) as the diameter of the hollow nanoparticle increases due to the significant increase in surface-to-volume ratio, the thickness being constant. Moreover, the thickness of the hollow nanoparticle shell influences the spin configuration and thus the relation between surface anisotropy and the size or the thickness of the hollow nanoparticle is established.

  20. Size and thickness effect on magnetic structures of maghemite hollow magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sayed, Fatima; Labaye, Yvan, E-mail: yvan.labaye@univ-lemans.fr [Université du Maine, Institut des Molécules et Matériaux du Mans CNRS UMR-6283 (France); Sayed Hassan, Rodaina; El Haj Hassan, Fouad [Université Libanaise, Faculté des Sciences Section I, MPLAB (Lebanon); Yaacoub, Nader, E-mail: nader.yaacoub@univ-lemans.fr; Greneche, Jean-Marc [Université du Maine, Institut des Molécules et Matériaux du Mans CNRS UMR-6283 (France)

    2016-09-15

    The effect of surface anisotropy on the magnetic ground state of hollow maghemite nanoparticles is investigated using atomistic Monte Carlo simulation. The computer modeling is carried on hollow nanostructures as a function of size and shell thickness. It is found that the large contribution of the surface anisotropy imposes a “throttled” spin structure where the moments located at the outer surface tend to orient normal to the surface while those located at the inner surface appear to be more aligned. For increasing values of surface anisotropy in the frame of a radial model, the magnetic moments become radially oriented either inward or outward giving rise to a “hedgehog” configuration with nearly zero net magnetization. We also show the effect of the size of hollow nanoparticle on the spin behavior where the spin non-collinearity increases (for fixed value of surface anisotropy) as the diameter of the hollow nanoparticle increases due to the significant increase in surface-to-volume ratio, the thickness being constant. Moreover, the thickness of the hollow nanoparticle shell influences the spin configuration and thus the relation between surface anisotropy and the size or the thickness of the hollow nanoparticle is established.

  1. Interplay between structure and magnetism in HoxPr1-x alloys. 2. Resonant x-ray magnetic scattering

    DEFF Research Database (Denmark)

    Vigliante, A.; Christensen, M.J.; Hill, J.P.

    1998-01-01

    X-ray-scattering techniques have been used to study the crystal and magnetic structures of HoxPr1-x alloys in the form of thin films. Three distinct crystal structures are found as a function of concentration x, each of which has a characteristic magnetic structure. For x greater than or equal to 0.......6 a hexagonal-close-packed phase is found with the magnetic moments ordered in a basal-plane helix, whereas for 0.4 less than or equal to x... hexagonal-close-packed and remain nonmagnetic down to the lowest temperatures studied. Using x-ray magnetic resonance scattering techniques, we demonstrate that a small, static spin-density wave is induced within the alloy 5d band at both the Pr and Ho sites in both of the magnetically ordered phases...

  2. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    International Nuclear Information System (INIS)

    Zhukova, V.; Korchuganova, O.A.; Aleev, A.A.; Tcherdyntsev, V.V.; Churyukanova, M.; Medvedeva, E.V.; Seils, S.; Wagner, J.; Ipatov, M.; Blanco, J.M.; Kaloshkin, S.D.; Aronin, A.; Abrosimova, G.; Orlova, N.

    2017-01-01

    Highlights: • High domain wall mobility of Fe-Ni-based microwires. • Enhancement of domain wall velocity and mobility in Fe-rich microwires after annealing. • Observation of areas enriched by Si and depleted by B after annealing. • Phase separation in annealed Fe-Ni based microwires in metallic nucleus and near the interface layer. - Abstract: We studied the magnetic properties and domain wall (DW) dynamics of Fe 47.4 Ni 26.6 Si 11 B 13 C 2 and Fe 77.5 Si 7.5 B 15 microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe 77.5 Si 7.5 B 15 , while DW velocity of samples Fe 47.4 Ni 26.6 Si 11 B 13 C 2 is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe 47.4 Ni 26.6 Si 11 B 13 C 2 sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe 47.4 Ni 26.6 Si 11 B 13 C 2 . Consequently we studied the structure of Fe 47.4 Ni 26.6 Si 11 B 13 C 2 sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  3. Electronic structure, magnetic and structural properties of Ni doped ZnO nanoparticles

    International Nuclear Information System (INIS)

    Kumar, Shalendra; Vats, Prashant; Gautam, S.; Gupta, V.P.; Verma, K.D.; Chae, K.H.; Hashim, Mohd; Choi, H.K.

    2014-01-01

    Highlights: • XRD, and HR-TEM results show the single phase nature of Ni doped ZnO nanoparticles. • dc magnetization results indicate the RT-FM in Ni doped ZnO nanoparticles. • Ni L 3,2 edge NEXAFS spectra infer that Ni ions are in +2 valence state. • O K edge NEXAFS spectra show that O vacancy increases with Ni doping in ZnO. - Abstract: We report structural, magnetic and electronic structural properties of Ni doped ZnO nanoparticles prepared by auto-combustion method. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and dc magnetization measurements. The XRD and HR-TEM results indicate that Ni doped ZnO nanoparticles have single phase nature with wurtzite lattice and exclude the presence of secondary phase. NEXAFS measurements performed at Ni L 3,2 -edges indicates that Ni ions are in +2 valence state and exclude the presence of Ni metal clusters. O K-edge NEXAFS spectra indicate an increase in oxygen vacancies with Ni-doping, while Zn L 3,2 -edge show the absence of Zn-vacancies. The magnetization measurements performed at room temperature shows that pure and Ni doped ZnO exhibits ferromagnetic behavior

  4. Uranium hetero-bimetallic complexes: synthesis, structure and magnetic properties

    International Nuclear Information System (INIS)

    Le Borgne, Th.

    2000-01-01

    The aim of this thesis is to synthesize molecular complexes with uranium and transition metal ions in close proximity, to determine the nature of the magnetic interaction between them. We decided to use Schiff bases as assembling ligands, which are unusual for uranium (IV). Although the simplest Schiff bases, such as H 2 Salen, lead to ligand exchange reactions, the bi-compartmental Schiff base H 4 L 6 (bis(3-hydroxy-salicylidene) - 2,2-dimethyl-propylene) allows the crystal structure determination of the complex [L 6 Cu(pyr)]U[L 6 Cu].2pyr, obtained by reaction of the metallo-ligand H 2 L 6 Cu with U(acac) 4 . In this manner, the complexes [L 6 Co(pyr)] 2 U and [L 6 Ni(pyr)] 2 U.pyr were also isolated, as well as the compounds in which the paramagnetic ions have been exchanged by the diamagnetic ions Zn II , Zr IV and Th IV ': [L 6 Zn(pyr)] 2 U, [L 6 Cu] 2 Zr and [L 6 Cu(pyr)]Th[L 6 Cu].2pyr. These complexes are the first which involve three metallic centres assembling by the means of a hexa-dentate Schiff base. The crystalline structures show, for all these complexes, the outstanding orthogonal arrangement of the two fragments L 6 M around the central atom which is in a dodecahedral environment of eight oxygen atoms of two Schiff bases. The syntheses of the isostructural complexes Cu2 II and Zn 2 U in which the uranium (IV) ion is close, in the first one, to the paramagnetic ion Cu II and, in the second one, to the diamagnetic ion Zn II , has allowed the use of the empiric method to determine the nature of the magnetic interaction between an f element and a transition metal. The comparison of the magnetic behaviour of two complexes Cu 2 U and Zn 2 U, expressed by the variation of χT vs T, reveals the ferromagnetic interaction in the heart of the triad Cu-U-Cu. The magnetic behaviour of the complexes Cu 2 Th et Cu 2 Zr which does not show any coupling between the two copper (II) ions and the weak antiferromagnetic interaction in the Ni 2 U compound, favour the

  5. Local structure and magnetization of ferromagnetic Cu-doped ZnO films: no magnetism at the dopant?

    Czech Academy of Sciences Publication Activity Database

    Vachhani, P.S.; Šipr, Ondřej; Bhatnagar, A.K.; Ramamoorthy, R.K.; Choudhary, R.J.; Phase, D.M.; Dalba, G.; Kuzmin, A.; Rocca, F.

    2016-01-01

    Roč. 678, Sep (2016), s. 304-311 ISSN 0925-8388 R&D Projects: GA ČR(CZ) GAP108/11/0853 Institutional support: RVO:68378271 Keywords : EXAFS * NEXAFS * magnetization * crystal structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.133, year: 2016

  6. Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

    International Nuclear Information System (INIS)

    Kumar, Shalendra; Song, T.K.; Gautam, Sanjeev; Chae, K.H.; Kim, S.S.; Jang, K.W.

    2015-01-01

    Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L 3,2 NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L 3,2 edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles

  7. Structural and magnetic stability of Fe{sub 2}NiSi

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dinesh C., E-mail: idu.idris@gmail.com; Bhat, Idris Hamid, E-mail: idu.idris@gmail.com; Chauhan, Mamta, E-mail: idu.idris@gmail.com [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior - 474011 (India)

    2014-04-24

    Full-potential ab-initio calculations in the stable F-43m phase have been performed to investigate the structural and magnetic properties of Fe{sub 2}NiSi inverse Heusler alloys. The spin magnetic moment distributions show that present material is ferromagnetic in stable F-43m phase. Further, spin resolved electronic structure calculations show that the discrepancy in magnetic moments of Fe-I and Fe-II depend upon the hybridization of Fe with the main group element. It is found that the main group electron concentration is predominantly responsible in establishing the magnetic properties, formation of magnetic moments and the magnetic order for present alloy.

  8. A comparative study of magnetoresistance and magnetic structure in recycled vs. virgin NdFeB-type sintered magnets

    Science.gov (United States)

    Shen, Shida; Tsoi, Maxim; Prosperi, Davide; Tudor, Catalina O.; Dove, Stephen K.; Bevan, Alex I.; Furlan, Gojmir; Zakotnik, Miha

    2017-11-01

    Recycled NdFeB magnets are emerging as a viable alternative to virgin NdFeB, because of lower production costs and environmental impacts. Recycled NdFeB magnets produced via the recently reported magnet-to-magnet (m2 m™) recycling process display unanticipated enhancements of magnetic and physical properties that may arise because of their unique microstructure. In the present study, we compare electrical transport and magnetic properties of these recycled magnets (Grade: N42SH, Br = 1289 mT, Hcj = 1876 kA/m, BHmax = 323.4 kJ/m3, Dy content = 4.0 wt%) with an equivalent grade of commercial NdFeB magnet produced from virgin material by conventional techniques (Grade: N42SH, Br = 1215 mT, Hcj = 1943 kA/m, BHmax = 285.0 kJ/m3, with Dy content = 4.6 wt%). Atomic force microscopy (AFM) and magnetic force microscopy (MFM) analyses revealed very similar surface morphology and magnetic structure for the virgin and recycled samples. However, bulk electrical transport measurements demonstrated a 27% enhancement in the resistivity of the recycled magnets. This suggests that the electrical properties of NdFeB alloys are enhanced during Grain Boundary Engineering™ (GBE™). Moreover, point-contact measurements, used to probe the electrical transport properties on the microscopic scale, found similar results to those of the bulk measurements.

  9. Magnetically addressable fluorescent Fe3O4/ZnO nanocomposites: Structural, optical and magnetization studies

    Science.gov (United States)

    Roychowdhury, A.; Pati, S. P.; Mishra, A. K.; Kumar, S.; Das, D.

    2013-06-01

    Fe3O4/ZnO nanocomposites (NCs) are prepared by a wet chemical route. X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy studies confirm the coexistence of Fe3O4 and ZnO phases in the NCs. The UV-vis absorption spectra show a red shift of the absorption peak with increase in Fe3O4 content indicating a modification of the band structure of ZnO in the NCs. Photoluminescence emission spectra of the NCs display strong excitonic emission in the UV region along with weak emission bands in the visible range caused by electronic transitions involving defect-related energy levels in the band gap of ZnO. Positron annihilation lifetimes indicate that cation vacancies in the ZnO structure are the strong traps for positrons and the overall defect concentration in the NCs decreases with increase in Fe3O4 content. Dc magnetization measurements reveal an anomalous temperature dependence of the coercivity of the NCs that is argued to be due to the anomalous variation of magnetocrystalline anisotropy at lower temperature. The irreversibility observed in the temperature dependent ZFC-FC magnetization points to the presence of a spin-glass phase in the NCs.

  10. Nanocrystalline Fe-Pt alloys. Phase transformations, structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Lyubina, J.V.

    2006-12-21

    This work has been devoted to the study of phase transformations involving chemical ordering and magnetic properties evolution in bulk Fe-Pt alloys composed of nanometersized grains. Nanocrystalline Fe{sub 100-x}Pt{sub x} (x=40-60) alloys have been prepared by mechanical ball milling of elemental Fe and Pt powders at liquid nitrogen temperature. The as-milled Fe-Pt alloys consist of {proportional_to} 100 {mu}m sized particles constituted by randomly oriented grains having an average size in the range of 10-40 nm. Depending on the milling time, three major microstructure types have been obtained: samples with a multilayer-type structure of Fe and Pt with a thickness of 20-300 nm and a very thin (several nanometers) A1 layer at their interfaces (2 h milled), an intermediate structure, consisting of finer lamellae of Fe and Pt (below approximately 100 nm) with the A1 layer thickness reaching several tens of nanometers (4 h milled) and alloys containing a homogeneous A1 phase (7 h milled). Subsequent heat treatment at elevated temperatures is required for the formation of the L1{sub 0} FePt phase. The ordering develops via so-called combined solid state reactions. It is accompanied by grain growth and thermally assisted removal of defects introduced by milling and proceeds rapidly at moderate temperatures by nucleation and growth of the ordered phases with a high degree of the long-range order. In a two-particle interaction model elaborated in the present work, the existence of hysteresis in recoil loops has been shown to arise from insufficient coupling between the low- and the high-anisotropy particles. The model reveals the main features of magnetisation reversal processes observed experimentally in exchange-coupled systems. Neutron diffraction has been used for the investigation of the magnetic structure of ordered and partially ordered nanocrystalline Fe-Pt alloys. (orig.)

  11. Magnetic and magnetoresistance studies of nanometric electrodeposited Co films and Co/Cu layered structures: Influence of magnetic layer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Zsurzsa, S., E-mail: zsurzsa.sandor@wigner.mta.hu; Péter, L.; Kiss, L.F.; Bakonyi, I.

    2017-01-01

    The magnetic properties and the magnetoresistance behavior were investigated for electrodeposited nanoscale Co films, Co/Cu/Co sandwiches and Co/Cu multilayers with individual Co layer thicknesses ranging from 1 nm to 20 nm. The measured saturation magnetization values confirmed that the nominal and actual layer thicknesses are in fairly good agreement. All three types of layered structure exhibited anisotropic magnetoresistance for thick magnetic layers whereas the Co/Cu/Co sandwiches and Co/Cu multilayers with thinner magnetic layers exhibited giant magnetoresistance (GMR), the GMR magnitude being the largest for the thinnest Co layers. The decreasing values of the relative remanence and the coercive field when reducing the Co layer thickness down to below about 3 nm indicated the presence of superparamagnetic (SPM) regions in the magnetic layers which could be more firmly evidenced for these samples by a decomposition of the magnetoresistance vs. field curves into a ferromagnetic and an SPM contribution. For thicker magnetic layers, the dependence of the coercivity (H{sub c}) on magnetic layer thickness (d) could be described for each of the layered structure types by the usual equation H{sub c}=H{sub co}+a/d{sup n} with an exponent around n=1. The common value of n suggests a similar mechanism for the magnetization reversal by domain wall motion in all three structure types and hints also at the absence of coupling between magnetic layers in the Co/Cu/Co sandwiches and Co/Cu multilayers. - Highlights: • Electrodeposited nanoscale Co films and Co/Cu layered structures. • Co layer thickness (d) dependence of coercivity (H{sub c}) and magnetoresistance. • H{sub c} depends on Co layer thickness according to H{sub c}=H{sub co}+a/d{sup n} with n around 1. • The common n value suggests a similar mechanism of magnetization reversal. • The common n value suggests the absence of coupling between magnetic layers.

  12. Modulated (Ga,TM)N structures: optics and magnetism

    International Nuclear Information System (INIS)

    Grois, A.

    2015-01-01

    Gallium nitride and related compounds are not only the building blocks of many state of the art devices (e.g. blue and white LEDs, high electron mobility transistors), but once combined with magnetic dopants (i.e. transition metals and rare earths), further functionalities (e.g. spintronics - the simultaneous utilisation of the electrons electric charge and magnetic moment) are enabled. The incorporation of the magnetic dopants depends on the growth conditions and the type of dopant. As a function of these parameters various phases with quite different properties can be produced. In this work the optical and magnetic properties of three of these phases which are interesting from a technological and fundamental point of view and can be produced by metalorganic vapour phase epitaxy are studied by advanced structural, chemical, spectroscopic and magnetometric techniques as a function of the transition metal concentration, growth temperature and codopant concentration. These phases are dilute (Ga,Mn)N and (Ga,Fe)N, iron nitride and galfenol nanocrystals embedded in (Ga,Fe)N, and Mn-Mgx [Mg tief x] complexes in (Ga,Mn)N:Mg. Dilute (Ga,Mn)N is found to be a superexchange ferromagnet with Mn3+ [Mn hoch 3+] concentration dependent Curie temperature, which is of the order of 1 K for the highest studied Mn concentration of approximately 3 %. The lack of carrier mediated ferromagnetism is explained by confirming the presence of strong coupling between the Mn 3d electrons and valence band holes via giant Zeeman effect measurements. Upon Si donor codoping the charge state of Mn is reduced to 2+, and hints towards superexchange antiferromagnetism between the Mn2+ [Mn hoch 2+] ions are observed. The magnetic properties of a single planar array of [gamma]'-Gax [Ga tief x]Fe4-x [Fe tief 4-x]N nanocrystals embedded in GaN are analysed and a clear uniaxial shape anisotropy is revealed. The puzzling finding of a six-fold in-plane anisotropy is discussed and various possible

  13. Magnetic and structural properties of ferrihydrite/hematite nanocomposites

    International Nuclear Information System (INIS)

    Pariona, N.; Camacho-Aguilar, K.I.; Ramos-González, R.; Martinez, Arturo I.; Herrera-Trejo, M.; Baggio-Saitovitch, E.

    2016-01-01

    A rich variety of ferrihydrite/hematite nanocomposites (NCs) with specific size, composition and properties were obtained in transformation reactions of 2-line ferrihydrite. Transmission electron microscopy (TEM) observations showed that the NCs consist of clusters of strongly aggregated nanoparticles (NPs) similarly to a “plum pudding”, where hematite NPs “raisins” are surrounded by ferrihydrite “pudding”. Magnetic measurements of the NCs correlate very well with TEM results; i.e., higher coercive fields correspond to greater hematite crystallite size. First order reversal curve (FORC) measurements were used for the characterization of the magnetic components of the NCs. FORC diagrams revealed that the NCs prepared at short times are composed by single domains with low coercivity, and NCs prepared at times larger than 60 min exhibited elongated distribution along the Hc axis. It suggested that these samples consist of mixtures of different kinds of hematite particles, ones with low coercivity and others with coercivity greater than 600 Oe. For NCs prepared at times larger than 60 min, Mossbauer spectroscopy revealed the presence of two sextets, which one was assigned to fine hematite particles and other to hematite particles with hyperfine parameters near to bulk hematite. The correlation of the structural and magnetic properties of the ferrihydrite/hematite NCs revealed important characteristics of these materials which have not been reported elsewhere. - Highlights: • Ferrihydrite/hematite nanocomposites were prepared. • The “plum pudding” morphology of the ferrihydrite/hematite nanocomposites was found. • The FORC diagrams of ferrihydrite/hematite nanocomposites have been measured.

  14. Magnetic and structural properties of ferrihydrite/hematite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pariona, N.; Camacho-Aguilar, K.I.; Ramos-González, R. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Martinez, Arturo I., E-mail: mtz.art@gmail.com [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Herrera-Trejo, M. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Río de Janeiro 22290-180 (Brazil)

    2016-05-15

    A rich variety of ferrihydrite/hematite nanocomposites (NCs) with specific size, composition and properties were obtained in transformation reactions of 2-line ferrihydrite. Transmission electron microscopy (TEM) observations showed that the NCs consist of clusters of strongly aggregated nanoparticles (NPs) similarly to a “plum pudding”, where hematite NPs “raisins” are surrounded by ferrihydrite “pudding”. Magnetic measurements of the NCs correlate very well with TEM results; i.e., higher coercive fields correspond to greater hematite crystallite size. First order reversal curve (FORC) measurements were used for the characterization of the magnetic components of the NCs. FORC diagrams revealed that the NCs prepared at short times are composed by single domains with low coercivity, and NCs prepared at times larger than 60 min exhibited elongated distribution along the Hc axis. It suggested that these samples consist of mixtures of different kinds of hematite particles, ones with low coercivity and others with coercivity greater than 600 Oe. For NCs prepared at times larger than 60 min, Mossbauer spectroscopy revealed the presence of two sextets, which one was assigned to fine hematite particles and other to hematite particles with hyperfine parameters near to bulk hematite. The correlation of the structural and magnetic properties of the ferrihydrite/hematite NCs revealed important characteristics of these materials which have not been reported elsewhere. - Highlights: • Ferrihydrite/hematite nanocomposites were prepared. • The “plum pudding” morphology of the ferrihydrite/hematite nanocomposites was found. • The FORC diagrams of ferrihydrite/hematite nanocomposites have been measured.

  15. Investigation of turbulent structures in the edge of magnetized plasmas

    International Nuclear Information System (INIS)

    Nold, Bernhard

    2012-01-01

    Rising energy cost and progressing climate change will exacerbate existing and give birth to new conflicts. Energy savings and the development of new technologies can counteract the reasons for these conflicts. Beside renewable energy sources, nuclear fusion can help to meet this challenge. To build future fusion power plants smaller and more efficient, the magnetic confinement must be improved and the load on plasma facing components reduced. To this end, better understanding is required of turbulent transport processes in magnetized plasmas. Within the frame of the present work, the properties and dynamics of turbulent density structures (''blobs'') have been investigated, as well as their interaction with shear flows. Langmuir-probe measurements have been conducted in the tokamak ASDEX Upgrade and in the stellarator TJ-K, and compared with GEMR plasma turbulence simulations. It has been shown, that blobs are generated at the last closed flux surface (LCFS) of ASDEX Upgrade. They propagate perpendicular to the magnetic field lines in the radial and poloidal directions. The poloidal E x B-drift depends on the radial variation of the plasma potential. The latter is given by the electron temperature profile in front of the electrically conducting wall. Experimental results show, that this can lead to a shear layer inside the scrape-off layer (SOL) of a divertor tokamak due to inhomogeneous connection lengths to the wall. Blobs can hardly cross such a shear layer unchanged. This investigation shows how blobs can exchange particles and energy across a shear layer without changing their shapes and velocities substantially. However, the dynamics of the structures are different between both sides of the shear layer. Parallel drift-wave dynamics are dominant on the plasma core side, i.e. density and potential of the blobs are in phase. Outside of the shear layer, the interchange mechanism dominates due to shorter parallel connection lengths to the wall. The poloidal

  16. Filamentary structure and magnetic field orientation in Musca

    Science.gov (United States)

    Cox, N. L. J.; Arzoumanian, D.; André, Ph.; Rygl, K. L. J.; Prusti, T.; Men'shchikov, A.; Royer, P.; Kóspál, Á.; Palmeirim, P.; Ribas, A.; Könyves, V.; Bernard, J.-Ph.; Schneider, N.; Bontemps, S.; Merin, B.; Vavrek, R.; Alves de Oliveira, C.; Didelon, P.; Pilbratt, G. L.; Waelkens, C.

    2016-05-01

    Herschel has shown that filamentary structures are ubiquitous in star-forming regions, in particular in nearby molecular clouds associated with Gould's Belt. High dynamic range far-infrared imaging of the Musca cloud with SPIRE and PACS reveals at least two types of filamentary structures: (1) the main ~10-pc scale high column-density linear filament; and (2) low column-density striations in close proximity to the main filament. In addition, we find features with intermediate column densities (hair-like strands) that appear physically connected to the main filament. We present an analysis of this filamentary network traced by Herschel and explore its connection with the local magnetic field. We find that both the faint dust emission striations and the plane-of-the-sky (POS) magnetic field are locally oriented close to perpendicular to the high-density main filament (position angle ~25-35°). The low-density striations and strands are oriented parallel to the POS magnetic field lines, which are derived previously from optical polarization measurements of background stars and more recently from Planck observations of dust polarized emission. The position angles are 97 ± 25°, 105 ± 7°, and 105 ± 5°. From these observations, we propose a scenario in which local interstellar material in this cloud has condensed into a gravitationally-unstable filament (with "supercritical" mass per unit length) that is accreting background matter along field lines through the striations. We also compare the filamentary structure in Musca with what is seen in similar Herschel observations of the Taurus B211/3 filament system and find that there is significantly less substructure in the Musca main filament than in the B211/3 filament. We suggest that the Musca cloud may represent an earlier evolutionary stage in which the main filament has not yet accreted sufficient mass and energy to develop a multiple system of intertwined filamentary components. Herschel is an ESA space

  17. Temperature- and field-induced structural transitions in magnetic colloidal clusters

    Science.gov (United States)

    Hernández-Rojas, J.; Calvo, F.

    2018-02-01

    Magnetic colloidal clusters can form chain, ring, and more compact structures depending on their size. In the present investigation we examine the combined effects of temperature and external magnetic field on these configurations by means of extensive Monte Carlo simulations and a dedicated analysis based on inherent structures. Various thermodynamical, geometric, and magnetic properties are calculated and altogether provide evidence for possibly multiple structural transitions at low external magnetic field. Temperature effects are found to overcome the ordering effect of the external field, the melted stated being associated with low magnetization and a greater compactness. Tentative phase diagrams are proposed for selected sizes.

  18. Periodic vortex pinning by regular structures in Nb thin films: magnetic vs. structural effects

    Science.gov (United States)

    Montero, Maria Isabel; Jonsson-Akerman, B. Johan; Schuller, Ivan K.

    2001-03-01

    The defects present in a superconducting material can lead to a great variety of static and dynamic vortex phases. In particular, the interaction of the vortex lattice with regular arrays of pinning centers such as holes or magnetic dots gives rise to commensurability effects. These commensurability effects can be observed in the magnetoresistance and in the critical current dependence with the applied field. In recent years, experimental results have shown that there is a dependence of the periodic pinning effect on the properties of the vortex lattice (i.e. vortex-vortex interactions, elastic energy and vortex velocity) and also on the dots characteristics (i.e. dot size, distance between dots, magnetic character of the dot material, etc). However, there is not still a good understanding of the nature of the main pinning mechanisms by the magnetic dots. To clarify this important issue, we have studied and compared the periodic pinning effects in Nb films with rectangular arrays of Ni, Co and Fe dots, as well as the pinning effects in a Nb film deposited on a hole patterned substrate without any magnetic material. We will discuss the differences on pinning energies arising from magnetic effects as compared to structural effects of the superconducting film. This work was supported by NSF and DOE. M.I. Montero acknowledges postdoctoral fellowship by the Secretaria de Estado de Educacion y Universidades (Spain).

  19. Coherent drift wave structures in sheared magnetic fields

    International Nuclear Information System (INIS)

    Morrison, P.J.; Horton, W.

    1993-01-01

    For the problem of calculating the coherent drift wave structures in sheared magnetic fields, the authors have found it useful to derive the governing nonlinear pde from a variational principle. The variational principle is based on the free energy functional F[var-phi] = ∫ V F(var-phi, ∇ var-phi, x)dx dy. The method is applied to the vortex with speed u derived in Su et al., given by ∇ 2 var-phi = (1 - v d /u) var-phi - S m 2 /u 2 (x - var-phi/u) (x - var-phi/2u) var-phi where space is measured in units of ρ s , var-phi = (eΦ/T e )(L n /ρ s ) and the magnetic shear parameter is S m . While the linearized problem (var-phi much-lt ux) describes the usual shear induced damping, nonlinear solutions with trapped flow (var-phi > ur 0 ) form nonlinear self-bound states, which are maxima of the free energy F. The authors discuss the analytic properties and the numerical procedures for solving these types of nonlinear pde's

  20. Nonlinear dynamics of drift structures in a magnetized dissipative plasma

    International Nuclear Information System (INIS)

    Aburjania, G. D.; Rogava, D. L.; Kharshiladze, O. A.

    2011-01-01

    A study is made of the nonlinear dynamics of solitary vortex structures in an inhomogeneous magnetized dissipative plasma. A nonlinear transport equation for long-wavelength drift wave structures is derived with allowance for the nonuniformity of the plasma density and temperature equilibria, as well as the magnetic and collisional viscosity of the medium and its friction. The dynamic equation describes two types of nonlinearity: scalar (due to the temperature inhomogeneity) and vector (due to the convectively polarized motion of the particles of the medium). The equation is fourth order in the spatial derivatives, in contrast to the second-order Hasegawa-Mima equations. An analytic steady solution to the nonlinear equation is obtained that describes a new type of solitary dipole vortex. The nonlinear dynamic equation is integrated numerically. A new algorithm and a new finite difference scheme for solving the equation are proposed, and it is proved that the solution so obtained is unique. The equation is used to investigate how the initially steady dipole vortex constructed here behaves unsteadily under the action of the factors just mentioned. Numerical simulations revealed that the role of the vector nonlinearity is twofold: it helps the dispersion or the scalar nonlinearity (depending on their magnitude) to ensure the mutual equilibrium and, thereby, promote self-organization of the vortical structures. It is shown that dispersion breaks the initial dipole vortex into a set of tightly packed, smaller scale, less intense monopole vortices-alternating cyclones and anticyclones. When the dispersion of the evolving initial dipole vortex is weak, the scalar nonlinearity symmetrically breaks a cyclone-anticyclone pair into a cyclone and an anticyclone, which are independent of one another and have essentially the same intensity, shape, and size. The stronger the dispersion, the more anisotropic the process whereby the structures break: the anticyclone is more intense

  1. Acoustic investigation of structure of magnetic fluids based on transformer oil mogul

    International Nuclear Information System (INIS)

    Kudelcik, J.; Bury, P.; Kopcansky, P.; Timko, M.

    2013-01-01

    In this paper the authors study the influence of temperature on the changes of the acoustic attenuation in magnetic fluids based on transformer oil MOGUL caused by an external magnetic field measured. The influences of both magnetic field and temperature on the structures of investigated magnetic fluids based on the transformer oil MOGUL were observed using acoustic spectroscopy. The effect of external magnetic field on the creation of clusters of nanoparticles in magnetic fluids was confirmed and their influence on the development of attenuation was described. In this type of magnetic fluid complicated structures of clusters at magnetic field over 100 mT are created. These structures are than at higher magnetic field almost stable. This state of equilibrium is not function of time. Measurements also confirmed that the lifetime of these structures or clusters is very short. The further investigation of the time and temperature dependences of the acoustic attenuation on the magnetic field at different concentrations of magnetic nanoparticles and various direction of magnetic field are necessary to understand all processes in this magnetic fluid. (authors)

  2. The relationship between microstructure and magnetic properties in high-energy permanent magnets characterized by polytwinned structures

    Science.gov (United States)

    This report summarizes the results of a study of the relationship between microstructure and magnetic properties in a unique genre of ferromagnetic material characterized by a polysynthetically twinned structure which arises during solid state transformation. These results stem from the work over a period of approximately 27 months of a nominal 3 year grant period. The report also contains a proposal to extend the research project for an additional 3 years. The polytwinned structures produce an inhomogeneous magnetic medium in which the easy axis of magnetization varies quasi-periodically giving rise to special domain configurations which are expected to markedly influence the mechanism of magnetization reversal and hysteresis behavior of these materials in bulk or thin films. The extraordinary permanent magnet properties exhibited by the well-known Co-Pt alloys as well as the Fe-Pt and Fe-Pd systems near the equiatomic composition derive from the formation of a polytwinned microstructure.

  3. Magnetic structures of holmium-lutetium alloys and superlattices

    DEFF Research Database (Denmark)

    Swaddling, P.P.; Cowley, R.A.; Ward, R.C.C.

    1996-01-01

    Alloys and superlattices of Ho and Lu have been grown using molecular beam epitaxy and their magnetic structures determined using neutron-scattering techniques. The 4f moments in the alloys form a helix at all compositions with the moments aligned in the basal plane perpendicular to the wave vector...... of the helix remaining coherent through the nonmagnetic Lu blocks. The neutron scattering from the superlattices is consistent with a model in which there are different phase advances of the helix turn angle through the Ho and Lu blocks, but with a localized moment on the Ho sites only. A comparison...... of Ho and Lu. At low temperatures, for superlattices with fewer than approximately twenty atomic planes of Ho, the Ho moments within a block undergo a phase transition from helical to ferromagnetic order, with the coupling between successive blocks dependent on the thickness of the Lu spacer....

  4. Mechanosynthesis, crystal structure and magnetic characterization of neodymium orthoferrite

    Energy Technology Data Exchange (ETDEWEB)

    Serna, Pedro Vera; Campos, Cecilio Garcia [Division de Ingenierias, Universidad Politecnica de Tecamac (UPTECAMAC), Tecamac de Felipe Villanueva, Estado de Mexico (Mexico); De Jesus, Felix Sanchez; Miro, Ana Maria Bolarin [Area Academica de Ciencias de la Tierra y Materiales, Universidad Autonoma del Estado de Hidalgo (UAEH), Mineral de la Reforma, Hidalgo (Mexico); Loran, Jose Antonio Juanico [Division de Ingenieria Industrial Nanotecnologia, Universidad Politecnica del Valle de Mexico (UPVM), Tultitlan, Estado de Mexico (Mexico); Longwell, Jeffrey, E-mail: pedrovera.upt@gmail.com [Department of Languages and Linguistics, New Mexico State University (NMSU), Las Cruces, NM (United States)

    2016-03-15

    Neodymium orthoferrite NdFeO{sub 3} was obtained at room temperature by mechanosynthesis with a stoichiometric ratio of Nd2O{sub 3} and Fe{sub 2}O{sub 3} powders, whereas the traditional synthesis requires a temperature of approximately 1000 °C. The crystal structure was analyzed by X-ray diffraction analysis using Cu radiation and a LynxEye XE detector, whose strong fluorescence filtering enabled a high signal intensity. The analysis indicated that the obtained crystallites were nano-sized. The particle morphology was observed by scanning electron microscopy, and the magnetic saturation was tested by vibrating sample magnetometry. The synthesis of NdFeO{sub 3} was detected after a few hours of milling, indicating that the milling imparted mechanical energy to the system. (author)

  5. Structural and magnetic properties of barium-gadolinium hexaferrites

    Science.gov (United States)

    Litsardakis, G.; Manolakis, I.; Serletis, C.; Efthimiadis, K. G.

    A series of Gd-substituted M-type barium hexaferrites has been prepared by the ceramic route, according to the formula (Ba 1-xGd x)O·5.25Fe 2O 3 ( x=0-0.30). XRD analysis revealed that all the samples present primarily an M-type structure. Samples x=0 and x=0.05 are single-phase. Hematite (Fe 2O 3) and GdFeO 3 were detected in the remaining samples. Coercivity ( Hc) shows remarkably high values, ˜293 kA/m for x=0.20 and 0.30 with a maximum of 322 kA/m for x=0.25. Specific saturation magnetization ( σsat) of the samples presents a small increase up to x=0.10. The microstructure examination indicates that Gd may act as a grain growth inhibitor.

  6. Magnetic susceptibility of transition metal alloys with a hcp structure

    International Nuclear Information System (INIS)

    Volkenshtejn, N.V.; Galoshina, Eh.V.; Gorina, N.B.; Korenovskij, N.L.; Polyakova, V.P.; Savitskij, E.M.

    1978-01-01

    The angular dependence of the magnetic susceptibility of single crystals of Ru-Nb, Re-W and Os-Re alloys is investigated in the region of the hexagonal closely packed structure. The spin susceptibility is estimated on the basis of available data on the electron specific heat. The principal values of the orbital component of the susceptibility are determined under the assumption of isotopy of the spin contribution to the susceptibility. In Ru-Nb alloys the magnitudes of the orbital contributions and the susceptibility anisotropy are found to increase; in Re-W the spin contribution is noticeably greater whereas the orbital susceptibility is smaller, as is the anistropy. In the Os-Re alloy the orbital contributions increase and the susceptibility anisotropy is constant. It is suggested that the addition of the second component changes the overlapping of the d-electron wave functions

  7. The Effect of a Guide Field on the Structures of Magnetic Islands: 2D PIC Simulations

    Science.gov (United States)

    Huang, C.; Lu, Q.; Lu, S.; Wang, P.; Wang, S.

    2014-12-01

    Magnetic island plays an important role in magnetic reconnection. Using a series of 2D PIC simulations, we investigate the magnetic structures of a magnetic island formed during multiple X-line magnetic reconnection, considering the effects of the guide field in symmetric and asymmetric current sheets. In a symmetric current sheet, the current in the direction forms a tripolar structure inside a magnetic island during anti-parallel reconnection, which results in a quadrupole structure of the out-of-plane magnetic field. With the increase of the guide field, the symmetry of both the current system and out-of-plane magnetic field inside the magnetic island is distorted. When the guide field is sufficiently strong, the current forms a ring along the magnetic field lines inside magnetic island. At the same time, the current carried by the energetic electrons accelerated in the vicinity of the X lines forms another ring at the edge of the magnetic island. Such a dual-ring current system enhance the out-of-plane magnetic field inside the magnetic island with a dip in the center of the magnetic island. In an asymmetric current sheet, when there is no guide field, electrons flows toward the X lines along the separatrices from the side with a higher density, and are then directed away from the X lines along the separatrices to the side with a lower density. The formed current results in the enhancement of the out-of-plane magnetic field at one end of the magnetic island, and the attenuation at the other end. With the increase of the guide field, the structures of both the current system and the out-of-plane magnetic field are distorted.

  8. Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

    International Nuclear Information System (INIS)

    Kúdelčík, Jozef; Bury, Peter; Kopčanský, Peter; Timko, Milan

    2015-01-01

    The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined

  9. Structure of nanoparticles in transformer oil-based magnetic fluids, anisotropy of acoustic attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Kúdelčík, Jozef, E-mail: kudelcik@fyzika.uniza.sk [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Bury, Peter [Department of Physics, University of Žilina, Univerzitná 1, 010 01 Žilina (Slovakia); Kopčanský, Peter; Timko, Milan [Department of Magnetism, IEP SAS, Watsonova 47, 040 01 Košice (Slovakia)

    2015-08-15

    The anisotropy of acoustic attenuation in transformer oil-based magnetic fluids upon the external magnetic field was studied to discover the structure of nanoparticles. When a magnetic field is increased, the interaction between the external magnetic field and the magnetic moments of the nanoparticles leads to the aggregation of magnetic nanoparticles and following clusters formation. However, the temperature of magnetic fluids and the concentration of nanoparticles also have very important influence on the structural changes. The measurement of the dependence of the acoustic attenuation on the angle between the magnetic field direction and acoustic wave vector (anisotropy) can give the useful information about the structure of magnetic nanoparticles formations. In the present, the results of anisotropy measurements of the transformer oil-based magnetic fluids are described and using appropriate theory the basic parameters of clusters are calculated. On the basis of the performed calculations, the proportion of the acoustic wave energy used for excitation of the translational and rotational degrees of freedom was also established. - Highlights: • Nanoparticles formation in transformer oil-based magnetic fluids was investigated. • The anisotropy acoustic spectroscopy as the method of investigation was used. • The external conditions on the structure of magnetic fluids were studied. • The structure parameters using suitable theoretical model were determined.

  10. Electronic structure and magnetic properties of Dy adatom on Ir surface

    Science.gov (United States)

    Shick, A. B.; Lichtenstein, A. I.

    2018-05-01

    The electronic structure and magnetism of individual Dy atom adsorbed on the (1 1 1) surface of Ir is investigated using the combination of the density functional theory with the Hubbard-I approximation to the Anderson impurity model (DFT + HIA). The Dy3+ adatom is found magnetic with the magnetic moment of 9.35μB in the external magnetic field. The spin and orbital magnetic moments, and their ratio are evaluated, and compared with the X-ray magnetic circular dichroism data. The positive magnetic anisotropy energy of ≈ 1.3 meV determines the out-of-plane orientation of the Dy adatom magnetic moment. The role of 5d-4f interorbital exchange polarization in modification of the 4f shell energy spectrum is emphasized. We predict the Dy magnetization to drop by the factor of three with switching off the external magnetic field.

  11. Analysis and Comparison of Magnetic Structures in a Tapped Boost Converter for LED Applications

    DEFF Research Database (Denmark)

    Mira Albert, Maria del Carmen; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    This paper presents an an alysis and comparison of magnetics structures in a tapped boost converter for LED applications. The magnetic structure is a coupled inductor which is analyzed in a conventional wire-wound core as well as in a planar structure for different interleaving winding arrangements...

  12. Triple-q, Modulated Magnetic Structure and Critical Behaviour of Neodymium

    DEFF Research Database (Denmark)

    Lebech, Bente; Bak, Poul Erik

    1978-01-01

    In order to study the magnetic structure of neodymium, the authors have performed neutron scattering measurements on single crystals. The results of these measurements are combined with the results of renormalisation-group theory and Landau symmetry arguments. Below the Neel temperature......, the magnetic structure was found to be a unique two-dimensional ordered structure, accompanied by a similarly patterned lattice distortion...

  13. Investigation of the field dependent spin structure of exchange coupled magnetic heterostructures

    International Nuclear Information System (INIS)

    Gurieva, Tatiana

    2016-05-01

    This thesis describes the investigation of the field dependent magnetic spin structure of an antiferromagnetically (AF) coupled Fe/Cr heterostructure sandwiched between a hardmagnetic FePt buffer layer and a softmagnetic Fe top layer. The depth-resolved experimental studies of this system were performed via Magneto-optical Kerr effect (MOKE), Vibrating Sample Magnetometry (VSM) and various measuring methods based on nuclear resonant scattering (NRS) technique. Nucleation and evolution of the magnetic spiral structure in the AF coupled Fe/Cr multilayer structure in an azimuthally rotating external magnetic field were observed using NRS. During the experiment a number of time-dependent magnetic side effects (magnetic after-effect, domain-wall creep effect) caused by the non-ideal structure of a real sample were observed and later explained. Creation of the magnetic spiral structure in rotating external magnetic field was simulated using a one-dimensional micromagnetic model.The cross-sectional magnetic X-ray diffraction technique was conceived and is theoretically described in the present work. This method allows to determine the magnetization state of an individual layer in the magnetic heterostructure. It is also applicable in studies of the magnetic structure of tiny samples where conventional x-ray reflectometry fails.

  14. Developments of the neutron scattering analysis method for the determination of magnetic structures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Je-Geun; Chung, Jae Gwan; Park, Jung Hwan; Kong, Ung Girl [Inha Univ., Incheon (Korea); So, Ji Yong [Seoul National University, Seoul(Korea)

    2001-04-01

    Neutron diffraction is up to now almost the only and very important experimental method of determining the magnetic structure of materials. Unlike the studies of crystallographic structure, however to use neutron diffraction for magnetic structure determination is not easily accessible to non-experts because of the complexity of magnetic group theory: which is very important in the magnetic structure analysis. With the recent development of computer code for magnetic group, it is now time to rethink of these difficulties. In this work, we have used the computer code of the magnetic group (Mody-2) and Fullprof refinement program in order to study the magnetic structure of YMnO{sub 3} and other interesting materials. YMnO{sub 3} forms in the hexagonal structure and show both ferroelectric and antiferromagnetic phase transitions. Since it was recently found that YMnO{sub 3} can be used as a nonvolatile memory device, there has been many numbers of applied research on this material. We used neutron diffraction to determine the magnetic structure, and, in particular, to investigate the correlation between the order parameters of the ferroelectric and antiferromagnetic phase transitions. From this study, we have demonstrated that with a proper use of the computer code of the magnetic group one can overcome most of difficulties arising from the magnetic group theory. 4 refs., 8 figs., 5 tabs. (Author)

  15. Variations of structure and magnetic properties in UTGe hydrides (T=late transition metal)

    Czech Academy of Sciences Publication Activity Database

    Adamska, A.M.; Havela, L.; Skourski, Y.; Andreev, Alexander V.

    2012-01-01

    Roč. 515, FEB (2012), s. 171-179 ISSN 0925-8388 Institutional research plan: CEZ:AV0Z10100520 Keywords : actinide allos and compounds * metal hydrides * crystal structure * magnetic meaurements * high magnetic fields Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.390, year: 2012

  16. Magnetic structure of Fe-based amorphous and thermal annealed microwires

    International Nuclear Information System (INIS)

    Olivera, J.; Provencio, M.; Prida, V.M.; Hernando, B.; Santos, J.D.; Perez, M.J.; Gorria, P.; Sanchez, M.L.; Belzunce, F.J.

    2005-01-01

    The magnetic structure of amorphous and thermal annealed glass coated microwires is studied by thermomagnetic, DSC, and Bitter domain pattern techniques. The long-range dipolar interaction between parallel aligned microwires and the appearance of large Barkhausen jumps steps in the axially magnetized loops are discussed in terms of reversal magnetization process

  17. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    Zhukova, V. [Dpto. de Física de Materiales, Fac. Químicas, UPV/EHU, 20018 San Sebastian (Spain); Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Korchuganova, O.A.; Aleev, A.A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow (Russian Federation); Tcherdyntsev, V.V.; Churyukanova, M. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Medvedeva, E.V. [Institute of Electrophysics, Ural Branch, Russian Academy of Sciences 620016 Yekaterinburg (Russian Federation); Seils, S.; Wagner, J. [Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Ipatov, M. [Dpto. de Física de Materiales, Fac. Químicas, UPV/EHU, 20018 San Sebastian (Spain); Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Blanco, J.M. [Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Kaloshkin, S.D. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Aronin, A. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Insitute of Solid State Physics, Moscow Region, 142432 Chernogolovka (Russian Federation); Abrosimova, G.; Orlova, N. [Insitute of Solid State Physics, Moscow Region, 142432 Chernogolovka (Russian Federation); and others

    2017-07-01

    Highlights: • High domain wall mobility of Fe-Ni-based microwires. • Enhancement of domain wall velocity and mobility in Fe-rich microwires after annealing. • Observation of areas enriched by Si and depleted by B after annealing. • Phase separation in annealed Fe-Ni based microwires in metallic nucleus and near the interface layer. - Abstract: We studied the magnetic properties and domain wall (DW) dynamics of Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} and Fe{sub 77.5}Si{sub 7.5}B{sub 15} microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe{sub 77.5}Si{sub 7.5}B{sub 15}, while DW velocity of samples Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2}. Consequently we studied the structure of Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  18. Megarectumsigma underwent surgery for chronic faecal impact action

    International Nuclear Information System (INIS)

    Canessa, C.; Gomez del Valle, M.; Caraballo, M.

    2002-01-01

    Seven patients with megarectumsigma underwent surgery for chronic faecal impaction,reviewing clinical diagnosis, aetiology and medical and surgical management.It is suggested medical management of chronic faecal impaction trying to achieve elective surgery.The curative surgery should include the resection of all pathologic bowel, but in Duhamel procedure and its modifications distal rectal tran section should be at the peritoneal reflection.Habr-Gama modification has shown to be technically easier and it has been communicated good functional results.Local unfavourable conditions may be resolve by staged surgery,which allows outline definitive bowel reconstruction after functional assessment

  19. Magnetic properties of novel dynamic self-assembled structures generated on the liquid/air interface

    International Nuclear Information System (INIS)

    Snezhko, A.; Aranson, I.S.

    2007-01-01

    We report on experimental and theoretical studies of magnetic properties of recently discovered dynamic multi-segment self-organized structures ('magnetic snakes'). Magnetic order and response of such snakes are determined by a novel unconventional mechanism provided by a self-induced surface wave. It gives rise to a nontrivial magnetic order: the segments of the snake exhibit long-range antiferromagnetic order mediated by the surface waves, while each segment is composed of ferromagnetically aligned chains of microparticles. Magnetic properties of the snakes are probed by in-plane magnetic field. A phenomenological model is proposed to explain the experimental observations

  20. 1. The determination of crystal and magnetic structures

    International Nuclear Information System (INIS)

    Elemans, J.B.A.A.

    1975-01-01

    A theoretical foundation of the technique of thermal neutron scattering by powders is outlined. A description of the experimental set-up is given. A beam of themalized neutrons emerges from the reactor (HFR at Petten) through a slit system. It is diffracted by a manochromator crystal with a finite mosaic structure, a Cu (111) crystal being used. After passing through 10 cm pyrolytic graphite with a ''window'' from 0.23 to 0.29 nm as a lambda/2 filter, resulting in a wave length of 0.257 nm, the neutrons are taken off at a predetermined angle defined by a second slit system, resulting in a beam in which the sample is bathed. The neutrons scattered by the sample are detected by a counter moving in an arc with the position of the sample as center. The standard measurement time for a 10 cm 3 sample was two days. A discussion of the mathematical procedures for deriving the magnetic structure from the observed counts is given

  1. New hybrid magnet system for structure research at highest magnetic fields and temperatures in the millikelvin region

    International Nuclear Information System (INIS)

    Smeibidl, Peter; Ehmler, Hartmut; Tennant, Alan; Bird, Mark

    2012-01-01

    The Helmholtz Centre Berlin (HZB) is a user facility for the study of structure and dynamics with neutrons and synchrotron radiation with special emphasis on experiments under extreme conditions. Neutron scattering is uniquely suited to study magnetic properties on a microscopic length scale, because neutrons have comparable wavelengths and, due to their magnetic moment, they interact with the atomic magnetic moments. At HZB a dedicated instrument for neutron scattering at extreme magnetic fields and low temperatures is under construction, the Extreme Environment Diffractometer ExED. It is projected according to the time-of-flight principle for elastic and inelastic neutron scattering and for the special geometric constraints of analysing samples in a high field magnet. The new hybrid magnet will not only allow for novel experiments, it will be at the forefront of development in magnet technology itself. With a set of superconducting and resistive coils a maximum field above 30 T will be possible. To compromise between the needs of the magnet design for highest fields and the concept of the neutron instrument, the magnetic field will be generated by means of a coned, resistive inner solenoid and a superconducting outer solenoid with horizontal field orientation. To allow for experiments down to Millikelvin Temperatures the installation of a 3 He or a dilution cryostat with a closed cycle precooling stage is foreseen.

  2. Radio polarization and magnetic field structure in M 101

    Science.gov (United States)

    Berkhuijsen, E. M.; Urbanik, M.; Beck, R.; Han, J. L.

    2016-04-01

    We observed total and polarized radio continuum emission from the spiral galaxy M 101 at λλ 6.2 cm and 11.1 cm with the Effelsberg telescope. The angular resolutions are 2.´ 5 (=5.4 kpc) and 4.´ 4 (=9.5 kpc), respectively. We use these data to study various emission components in M 101 and properties of the magnetic field. Separation of thermal and non-thermal emission shows that the thermal emission is closely correlated with the spiral arms, while the non-thermal emission is more smoothly distributed indicating diffusion of cosmic ray electrons away from their places of origin. The radial distribution of both emissions has a break near R = 16 kpc (=7.´ 4), where it steepens to an exponential scale length of L ≃ 5 kpc, which is about 2.5 times smaller than at Rchange in the structure of M 101 takes place, which also affects the distributions of the strength of the random and ordered magnetic field. Beyond R = 16 kpc the radial scale length of both fields is about 20 kpc, which implies that they decrease to about 0.3 μG at R = 70 kpc, which is the largest optical extent. The equipartition strength of the total field ranges from nearly 10 μG at Rmechanism. We show that energetic events causing H I shells of mean diameter pitch angles that are about 8° larger than those of H I filaments. Based on observations with the 100 m telescope of the MPIfR at Effelsberg.FITS files of the images are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A114

  3. Determination of localized magnetic moments in Fe-Cr-Al alloys and the electron structure

    International Nuclear Information System (INIS)

    Blau, W.

    1977-01-01

    The localized magnetic moments of Fe and Cr are determined by combination of saturation magnetization measurements and magnetic diffuse scattering. Power series characterizing the interactions between the different kinds of atoms in the alloys are chosen to describe the concentration dependence of the magnetic moments. The different terms are discussed on the basis of band structure models valid for dilute alloys taking into account their modification by impurity interactions. (author)

  4. Structural and magnetic properties of granular CoPd multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Vivas, L.G.; Figueroa, A.I.; Bartolomé, F. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain); Rubín, J. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Ciencia y Tecnología de Materiales y Fluidos, E-50018 Zaragoza (Spain); García, L.M. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain); Deranlot, C.; Petroff, F. [Unité Mixte de Physique CNRS/Thales, F-91767 Palaiseau Cedex, France and Université Paris-Sud, F-191405 Orsay Cedex (France); Ruiz, L.; González-Calbet, J.M [Dept. de Química Inorgánica, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Brookes, N.B.; Wilhelm, F.; Rogalev, A. [European Synchrotron Radiation Facility (ESRF), CS40220, F-38043 Grenoble Cedex 9 (France); Bartolomé, J. [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Dept. de Física de la Materia Condensada, E-50009 Zaragoza (Spain)

    2016-02-15

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk. - Highlights: • CoPd granular nanolayers show perpendicular magnetic anisotropy. • Three magnetic phases are detected: hard-ferro, soft-ferro and superparamagnetism. • The nanoparticles have Co-core and CoPd alloy shell morphology.

  5. Structural and magnetic properties of granular CoPd multilayers

    International Nuclear Information System (INIS)

    Vivas, L.G.; Figueroa, A.I.; Bartolomé, F.; Rubín, J.; García, L.M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J.M; Brookes, N.B.; Wilhelm, F.; Rogalev, A.; Bartolomé, J.

    2016-01-01

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk. - Highlights: • CoPd granular nanolayers show perpendicular magnetic anisotropy. • Three magnetic phases are detected: hard-ferro, soft-ferro and superparamagnetism. • The nanoparticles have Co-core and CoPd alloy shell morphology.

  6. Structural, magnetic and electronic structural properties of Mn doped CeO2 nanoparticles

    Science.gov (United States)

    Kumari, Kavita; Vij, Ankush; Hashim, Mohd.; Chae, K. H.; Kumar, Shalendra

    2018-05-01

    Nanoparticles of Ce1-xMnxO2, (x=0.0, 0.01, and 0.05) have been synthesized by using co-precipitation method, and then characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), near edge x-ray absorption fine structure (NEXAFS) spectroscopy and dc magnetization measurements. XRD results clearly showed that the all the samples have single phase nature and exclude the presence of any secondary phase. The average particle size calculated using XRD TEM measurements found to decrease with increase in Mn doping in the range of 4.0 - 9.0 nm. The structural parameters such as strain, interplaner distance and lattice parameter is observed to decrease with increase in doping. The morphology of Ce1-xMnxO2 nanoparticles measured using TEM micrographs indicate that nanoparticle have spherical shape morphology. Magnetic hysteresis curve for Ce1-xMnxO2, (x = 0.0, 0.01, and 0.05) confirms the ferromagnetic ordering room temperature. The value of saturation magnetization is observed to decrease with increase in temperature from 10 K to 300 K. The NEXAFS spectra measured at Ce M4,5 edge reveals that Ce-ions are in +4 valance state.

  7. Magnetic structure of the magnetocaloric compound AlFe{sub 2}B{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Cedervall, Johan, E-mail: johan.cedervall@kemi.uu.se [Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala (Sweden); Andersson, Mikael Svante; Sarkar, Tapati [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Delczeg-Czirjak, Erna K. [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Bergqvist, Lars [Department of Materials and Nano Physics and Swedish e-Science Research Centre (SeRC), Royal Institute of Technology (KTH), Electrum 229, SE-164 40 Kista (Sweden); Hansen, Thomas C. [Institut Laue-Langevin, B.P. 156, Grenoble Cedex 9, 38042 France (France); Beran, Premysl [Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez, 25068 Czech Republic (Czech Republic); Nordblad, Per [Department of Engineering Sciences, Uppsala University, Box 534, 751 21 Uppsala (Sweden); Sahlberg, Martin [Department of Chemistry – Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala (Sweden)

    2016-04-15

    The crystal and magnetic structures of AlFe{sub 2}B{sub 2} have been studied with a combination of X-ray and neutron diffraction and electronic structure calculations. The magnetic and magnetocaloric properties have been investigated by magnetisation measurements. The samples have been produced using high temperature synthesis and subsequent heat treatments. The compound crystallises in the orthorhombic crystal system Cmmm and it orders ferromagnetically at 285 K through a second order phase transition. At temperatures below the magnetic transition the magnetic moments align along the crystallographic a-axis. The magnetic entropy change from 0 to 800 kA/m was found to be −1.3 J/K kg at the magnetic transition temperature. - Graphical abstract: The magnetic structure of AlFe{sub 2}B{sub 2} has been investigated using neutron diffraction and the magnetic spins have been found to align ferromagnetically along the crystallographic a-axis. - Highlights: • The crystal and magnetic structures of AlFe{sub 2}B{sub 2} have been studied. • Orders ferromagnetically at 285 K via a second order phase transition. • The magnetic moments are found to be aligned along the crystallographic a-axis. • The magnetic entropy change from 0 to 800 kA/m was found to be −1.3 J/K kg.

  8. Experimental analysis of clustering structures in magnetic and MR fluids using ultrasound

    International Nuclear Information System (INIS)

    Bramantya, M A; Takuma, H; Faiz, M; Sawada, T; Motozawa, M

    2009-01-01

    The formation of clustering structures in magnetic and MR fluids has an influence on ultrasonic propagation. We propose a qualitative analysis of these structures by measuring properties of ultrasonic propagation. Since magnetic and MR fluids are opaque, the non-contact inspection using this ultrasonic technique can be very useful for analyzing the inner structures of magnetic and MR fluids. We measured ultrasonic propagation velocity in a hydrocarbon-based magnetic fluid and MR fluid precisely. Based on these results, the clustering structures of these fluids were analyzed experimentally in terms of elapsed time dependence, effect of external magnetic field strength and angle, and hysteresis phenomena. A comparison of ultrasonic velocity propagation between magnetic and MR fluid was discussed.

  9. Magnetic structure of Akita-Yakeyama volcano; Akita Yakeyama chiiki no jikiteki kozo

    Energy Technology Data Exchange (ETDEWEB)

    Okuma, S [Geological Survey of Japan, Tsukuba (Japan)

    1996-10-01

    Akita-Yakeyama is a Quaternary volcano located in the north-western part of the Sengan geothermal area. Geothermal resource surveys have been performed from the middle of the 1970s in the Sengan geothermal area, and the Sumikawa geothermal power plant started its operation in 1995. By the analysis, the magnetic basement depth became lower in the north of Yakeyama body. However, the distribution including low magnetic anomaly in the south of Yakeyama body could not be explained only by a simple magnetic structure model. In this study, the magnetic anomaly in this area was analyzed in detail, and a construction of the magnetic structure model was intended by taking borehole data into account. The low magnetic intensity zone with low amplitude agreed well with the geothermal alteration zone. The high magnetic intensity zone and the low magnetic intensity zone corresponded with the distributions of volcanic rocks magnetized normally and reversely, respectively. Kakkonda and Matsukawa geothermal power plants were located in the distinct low magnetic intensity zones. There was a low magnetic intensity zone with long wave length over the whole Sengan geothermal area. A high magnetic intensity zone was observed in the northern foot of this area. From the magnetic measurements of borehole sample rocks, this was found to correspond with the newly formed granite body. 9 refs., 4 figs.

  10. Magnetic structure analyses of multiferroics RMnO3 and RMn2O5

    International Nuclear Information System (INIS)

    Arima, Taka-hisa; Kimura, Hiroyuki

    2010-01-01

    Magnetic structure of typical multiferroic materials RMnO 3 and RMn 2 O 5 (R:rare earth) has been investigated by neutron diffraction. Magnetic structure analysis using single crystal revealed that both the materials have a cycloidal magnetic structure, where ferroelectricity arises. Polarized neutron diffraction under electric field found the one-to-one correspondence between the direction of cycloidal rotation (spin chirality) and the direction of the electric polarization, evincing that the electric polarization is directly induced by the cycloidal magnetic order. (author)

  11. Structural and magnetic properties of Fe60Al40 alloys prepared by means of a magnetic mill

    International Nuclear Information System (INIS)

    Bernal-Correa, R.; Rosales-Rivera, A.; Pineda-Gomez, P.; Salazar, N.A.

    2010-01-01

    A study on synthesis, structural and magnetic characterization of Fe 60 Al 40 (at.%) alloys prepared by means of mechanical alloying process is presented. The mechanical alloying was performed using a milling device with magnetically controlled ball movement (Uni-Ball-Mill 5 equipment) at several milling times. The characterization was carried out via X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The effects of milling time on the structural state, morphological evolution and magnetic behaviour of the Fe 60 Al 40 (at.%) alloys are discussed. Besides, in this current study we emphasize the result that indicating a ferro-para-ferromagnetic transition from a correlation between X-ray diffraction and magnetization data.

  12. Effect of defects, magnetocrystalline anisotropy, and shape anisotropy on magnetic structure of iron thin films by magnetic force microscopy

    Directory of Open Access Journals (Sweden)

    Ke Xu

    2017-05-01

    Full Text Available Microstructures of magnetic materials, including defects and crystallographic orientations, are known to strongly influence magnetic domain structures. Measurement techniques such as magnetic force microscopy (MFM thus allow study of correlations between microstructural and magnetic properties. The present work probes effects of anisotropy and artificial defects on the evolution of domain structure with applied field. Single crystal iron thin films on MgO substrates were milled by Focused Ion Beam (FIB to create different magnetically isolated squares and rectangles in [110] crystallographic orientations, having their easy axis 45° from the sample edge. To investigate domain wall response on encountering non-magnetic defects, a 150 nm diameter hole was created in the center of some samples. By simultaneously varying crystal orientation and shape, both magnetocrystalline anisotropy and shape anisotropy, as well as their interaction, could be studied. Shape anisotropy was found to be important primarily for the longer edge of rectangular samples, which exaggerated the FIB edge effects and provided nucleation sites for spike domains in non-easy axis oriented samples. Center holes acted as pinning sites for domain walls until large applied magnetic fields. The present studies are aimed at deepening the understanding of the propagation of different types of domain walls in the presence of defects and different crystal orientations.

  13. ALGORITHM FOR MANAGEMENT OF HYPERTENSIVE PATIENTS UNDERWENT UROLOGY INTERVENTIONS

    Directory of Open Access Journals (Sweden)

    S. S. Davydova

    2013-01-01

    Full Text Available Aim. To study the efficacy of cardiovascular non-invasive complex assessment and pre-operative preparation in hypertensive patients needed in surgical treatment of urology dis- eases.Material and methods. Males (n=883, aged 40 to 80 years were included into the study. The main group consisted of patients that underwent laparotomic nephrectomy (LTN group; n=96 and patients who underwent laparoscopic nephrectomy (LSN group; n=53. Dynamics of ambulatory blood pressure monitoring (ABPM data was analyzed in these groups in the immediate postoperative period. The efficacy of a package of non-invasive methods for cardiovascular system assessment was studied. ABPM was performed after nephrectomy (2-nd and 10-th days after surgery in patients with complaints of vertigo episodes or intense general weakness to correct treatment.Results. In LTN group hypotension episodes or blood pressure (BP elevations were observed in 20 (20.8% and 22 (22.9% patients, respectively, on the 2-nd day after the operation. These complications required antihypertensive treatment correction. Patients with hypotension episodes were significantly older than patients with BP elevation and had significantly lower levels of 24-hour systolic BP, night diastolic BP and minimal night systolic BP. Re-adjustment of antihypertensive treatment on the 10-th postoperative day was required to 2 (10% patients with hypotension episodes and to 1 (4.5% patient with BP elevation. Correction of antihypertensive therapy was required to all patients in LSN group on the day 2, and to 32 (60.4% patients on the 10-th day after the operation. Reduction in the incidence of complications (from 1.2% in 2009 to 0.3% in 2011, p<0.001 was observed during the application of cardiovascular non-invasive complex assessment and preoperative preparation in hypertensive patients.Conclusion. The elaborated management algorithm for patients with concomitant hypertension is recommended to reduce the cardiovascular

  14. ALGORITHM FOR MANAGEMENT OF HYPERTENSIVE PATIENTS UNDERWENT UROLOGY INTERVENTIONS

    Directory of Open Access Journals (Sweden)

    S. S. Davydova

    2015-09-01

    Full Text Available Aim. To study the efficacy of cardiovascular non-invasive complex assessment and pre-operative preparation in hypertensive patients needed in surgical treatment of urology dis- eases.Material and methods. Males (n=883, aged 40 to 80 years were included into the study. The main group consisted of patients that underwent laparotomic nephrectomy (LTN group; n=96 and patients who underwent laparoscopic nephrectomy (LSN group; n=53. Dynamics of ambulatory blood pressure monitoring (ABPM data was analyzed in these groups in the immediate postoperative period. The efficacy of a package of non-invasive methods for cardiovascular system assessment was studied. ABPM was performed after nephrectomy (2-nd and 10-th days after surgery in patients with complaints of vertigo episodes or intense general weakness to correct treatment.Results. In LTN group hypotension episodes or blood pressure (BP elevations were observed in 20 (20.8% and 22 (22.9% patients, respectively, on the 2-nd day after the operation. These complications required antihypertensive treatment correction. Patients with hypotension episodes were significantly older than patients with BP elevation and had significantly lower levels of 24-hour systolic BP, night diastolic BP and minimal night systolic BP. Re-adjustment of antihypertensive treatment on the 10-th postoperative day was required to 2 (10% patients with hypotension episodes and to 1 (4.5% patient with BP elevation. Correction of antihypertensive therapy was required to all patients in LSN group on the day 2, and to 32 (60.4% patients on the 10-th day after the operation. Reduction in the incidence of complications (from 1.2% in 2009 to 0.3% in 2011, p<0.001 was observed during the application of cardiovascular non-invasive complex assessment and preoperative preparation in hypertensive patients.Conclusion. The elaborated management algorithm for patients with concomitant hypertension is recommended to reduce the cardiovascular

  15. Structural and magnetic properties of Gd/Fe multilayers grown by pulsed laser deposition

    DEFF Research Database (Denmark)

    Kant, K. Mohan; Bahl, Christian Robert Haffenden; Pryds, Nini

    2010-01-01

    This work investigates the structural and the magnetic properties of Gd/Fe multilayered thin films grown by pulsed laser deposition onto Si (001) substrates at room temperature. he Fe layer thickness is varied from 70 to 150 nm and its effect on the structural and magnetic properties of Fe/Gd/Fe ...

  16. Rietveld refinement of magnetic structures from pulsed-neutron-source powder-diffraction data

    International Nuclear Information System (INIS)

    Robinson, R.A.; Lawson, A.C.; Larson, A.C.; Von Dreele, R.B.; Goldstone, J.A.

    1994-01-01

    The General Structure Analysis System, GSAS, has recently been modified to include magnetic neutron- scattering cross-sections. Low-temperature diffraction data have been taken on the hexagonal noncollinear antiferromagnet UPdSn on both the HIPD and the NPD powder diffractometers ail LANSCE. The low-resolution data reveal that the magnetic structure has orthorhombic symmetry (magnetic space group P c m'c2 1 ) between 25K and 40K, and monoclinic symmetry (magnetic space group PC 1121 ) below 25K. The high-resolution data reveal that there are structural distortions with corresponding symmetry changes in each of these phases, to give chemical space groups Cmc2 1 and P2 1 , respectively, while the paramagnetic phase above 40K has space group P6 3 mc. Using GSAS, we have refined data sets from both diffractometers simultaneously, including both magnetic and structural cross-sections. Magnetoelastic coefficients for the distortions have been extracted and we have determined the sign of the coupling between the structural monoclinicity and the magnetic monoclinicity. The magnetic results from Rietveld refinement are in good agreement with model fitting to the integrated intensities of seven independent magnetic reflections and these, in turn, agree with measurements made on the same sample using the constant-wavelength reactor technique. Our results therefore validate, to some level, both the technique of using spallation sources for complicated magnetic structures and the specifics of the GSAS Rietveld code

  17. Structural and magnetic properties of barium-gadolinium hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Litsardakis, G. [Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)]. E-mail: Lits@eng.auth.gr; Manolakis, I. [Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Serletis, C. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Efthimiadis, K.G. [Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)

    2007-03-15

    A series of Gd-substituted M-type barium hexaferrites has been prepared by the ceramic route, according to the formula (Ba{sub 1-x}Gd{sub x})O.5.25Fe{sub 2}O{sub 3} (x=0-0.30). XRD analysis revealed that all the samples present primarily an M-type structure. Samples x=0 and x=0.05 are single-phase. Hematite (Fe{sub 2}O{sub 3}) and GdFeO{sub 3} were detected in the remaining samples. Coercivity (H{sub c}) shows remarkably high values, {approx}293kA/m for x=0.20 and 0.30 with a maximum of 322kA/m for x=0.25. Specific saturation magnetization ({sigma}{sub sat}) of the samples presents a small increase up to x=0.10. The microstructure examination indicates that Gd may act as a grain growth inhibitor.

  18. Molecular-Field Calculation of the Magnetic Structure in Erbium

    DEFF Research Database (Denmark)

    Jensen, J.

    1976-01-01

    A molecular-field calculation of the magnetic configurations in Er is found to reproduce the neutron diffraction results of the three different magnetic phases and to give a reasonable fit to the magnetization data at 4.2K. The two-ion coupling is considered to be described by the inter......-planar coupling parameters deduced from the dispersion of the spin waves in the low temperature conical phases. The four (effective) crystal-field parameters are determined by the fit to the experimental data. Projecting the magnetic moments present in the intermediate phase of Er (18-52.4K) to a common origin...

  19. Electric-field effects on electronic tunneling transport in magnetic barrier structures

    International Nuclear Information System (INIS)

    Guo Yong; Wang Hao; Gu Binglin; Kawazoe, Yoshiyuki

    2000-01-01

    Electronic transport properties in magnetic barrier structures under the influence of an electric field have been investigated. The results indicate that the characteristics of transmission resonance are determined not only by the structure and the incident wave vector but also strongly by the electric field. It is shown that the transmission coefficient at resonance in the low-energy range is suppressed by applying the electric field for electron tunneling through the magnetic barrier structure, arranged with identical magnetic barriers and wells. It is also shown that the transmission resonance is first enhanced up to optimal resonance, and then suppressed with further increased electric field for electron tunneling through the magnetic barrier structure, arranged with unidentical building blocks. Strong suppression of the current density is also found in the magnetic barrier structure, arranged with two different building blocks

  20. Soft x-ray resonant diffraction study of magnetic structure in magnetoelectric Y-type hexaferrite

    Science.gov (United States)

    Ueda, H.; Tanaka, Y.; Wakabayashi, Y.; Kimura, T.

    2018-05-01

    The effect of magnetic field on the magnetic structure associated with magnetoelectric properties in a Y-type hexaferrite, Ba1.3Sr0.7CoZnFe11AlO22, was investigated by utilizing the soft x-ray resonant diffraction technique. In this hexaferrite, the so-called alternating longitudinal conical phase is stabilized at room temperature and zero magnetic field. Below room temperature, however, this phase is transformed into the so-called transverse conical phase by applying an in-plane magnetic field (≈ 0.3 T). The transverse conical phase persists even after removing the magnetic field. The magnetoelectricity, which is magnetically-induced electric polarization, observed in the hexaferrite is discussed in terms of the temperature-dependent magnetic structure at zero field.

  1. Two-dimensional Monte Carlo simulations of structures of a suspension comprised of magnetic and nonmagnetic particles in uniform magnetic fields

    International Nuclear Information System (INIS)

    Peng Xiaoling; Min Yong; Ma Tianyu; Luo Wei; Yan Mi

    2009-01-01

    The structures of suspensions comprised of magnetic and nonmagnetic particles in magnetic fields are studied using two-dimensional Monte Carlo simulations. The magnetic interaction among magnetic particles, magnetic field strength, and concentrations of both magnetic and nonmagnetic particles are considered as key influencing factors in the present work. The results show that chain-like clusters of magnetic particles are formed along the field direction. The size of the clusters increases with increasing magnetic interaction between magnetic particles, while it keeps nearly unchanged as the field strength increases. As the concentration of magnetic particles increases, both the number and size of the clusters increase. Moreover, nonmagnetic particles are found to hinder the migration of magnetic ones. As the concentration of nonmagnetic particles increases, the hindrance on migration of magnetic particles is enhanced

  2. Magnetic and structural properties of yellow europium oxide compound and Eu(OH)3

    International Nuclear Information System (INIS)

    Lee, Dongwook; Seo, Jiwon; Valladares, Luis de los Santos; Avalos Quispe, O.; Barnes, Crispin H.W.

    2015-01-01

    A new material based on a yellow europium oxide compound was prepared from europium oxide in a high vacuum environment. The structural and magnetic properties of the material were investigated. Owing to the absence of a crystal structure, the material exhibited a disordered magnetic behavior. In a reaction with deionized (DI) water without applied heat, the compound assumed a white color as soon as the DI water reached the powder, and the structure became polycrystalline Eu(OH) 3 . The magnetic properties, such as the thermal hysteresis, disappeared after the reaction with DI water, and the magnetic susceptibility of the yellow oxide compound weakened. The magnetic properties of Eu(OH) 3 were also examined. Although Eu 3+ is present in Eu(OH) 3 , a high magnetic moment due to the crystal field effect was observed. - Graphical abstract: (top left) Optical image of the yellow europium oxide compound. (top right) Optical image of the product of DI water and yellow europium oxide. (bottom) Magnetization curves as a function of temperature measured in various magnetic field. - Highlights: • We prepared a new material based on a yellow europium oxide compound from europium oxide. • We characterized the magnetic properties of the material which exhibits a disordered magnetic behavior such as thermal hysteresis. • The compound turned white (Eu(OH) 3 ) as soon as the DI water reached the powder. • The thermal hysteresis disappeared after the reaction with DI water and the magnetic susceptibility of the yellow oxide compound weakened

  3. Crystallographic and magnetic structure of the novel compound ErGe 1.83

    Science.gov (United States)

    Oleksyn, O.; Schobinger-Papamantellos, P.; Ritter, C.; de Groot, C. H.; Buschow, K. H. J.

    1997-02-01

    The crystal structure and the magnetic ordering of the novel orthorhombic compound ErGe 2-x has been studied by neutron powder diffraction and magnetic measurements. The crystal structure belongs to the DyGe 1.85-type (space group Cmc2 1)·ErGe 2-x ( x = 0.17 (2)) orders antiferromagnetically below TN = 6 K and displays a metamagnetic behaviour. The magnetic cell has the same size as the chemical unit cell ( q = 0 ). The magnetic space group is Cmc2 1 (Sh 36173). At T = 1.5 K the magnetic moments of the two erbium sites have the same ordered magnetic moment values of 7.63 (6) μB/Er and are antiferromagnetically coupled leading to an uniaxial structure along the a direction.

  4. Modeling of ironless permanent magnet planar motor structures

    NARCIS (Netherlands)

    Boeij, de J.; Lomonova, E.A.; Vandenput, A.J.A.

    2006-01-01

    This paper describes an analytical model that includes end effects for ironless synchronous permanent-magnet planar actuators. Because of its flexibility, the model can be used to predict the performance of various permanent-magnet array and coil array topologies and commutation schemes. Moreover,

  5. Surface structure of quark stars with magnetic fields

    Indian Academy of Sciences (India)

    We investigate the impact of magnetic fields on the electron distribution of the electrosphere of quark stars. For moderately strong magnetic fields of ∼ 1013 G, quantization effects are generally weak due to the large number density of electrons at surface, but can nevertheless affect the photon emission properties of quark ...

  6. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    Science.gov (United States)

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander; Adamski, Paweł; Moszyński, Dariusz

    2016-09-01

    Four nanocomposites containing mixed phases of Co3Mo3N and Co2Mo3N doped with chromium have been prepared. A linear fit is found for relation between Co2Mo3N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2-300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping.

  7. Structural and magnetic properties of granular CoPd multilayers

    Science.gov (United States)

    Vivas, L. G.; Figueroa, A. I.; Bartolomé, F.; Rubín, J.; García, L. M.; Deranlot, C.; Petroff, F.; Ruiz, L.; González-Calbet, J. M.; Brookes, N. B.; Wilhelm, F.; Rogalev, A.; Bartolomé, J.

    2016-02-01

    Multilayers of bimetallic CoPd alloyed and assembled nanoparticles, prepared by room temperature sequential sputtering deposition on amorphous alumina, were studied by means of high-resolution transmission electron microscopy, x-ray diffraction, SQUID-based magnetometry and x-ray magnetic circular dichroism. Alloying between Co and Pd in these nanoparticles gives rise to a high perpendicular magnetic anisotropy. Their magnetic properties are temperature dependent: at low temperature, the multilayers are ferromagnetic with a high coercive field; at intermediate temperature the behavior is of a soft-ferromagnet, and at higher temperature, the perpendicular magnetic anisotropy in the nanoparticles disappears. The magnetic orbital moment to spin moment ratio is enhanced compared with Co bare nanoparticles and Co fcc bulk.

  8. Structural and magnetic study of dysprosium substituted cobalt ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hemaunt, E-mail: hvatsal@gmail.com [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Srivastava, R.C. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Pal Singh, Jitendra [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Negi, P. [Department of Physics, Govind Ballabh Pant University of Agr. & Technology, Pantnagar, Uttarakhand 263145 (India); Agrawal, H.M. [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of); Das, D. [UGC-DAE CSR Kolkata Centre, Kolkata 700098 (India); Hwa Chae, Keun [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul 02792 (Korea, Republic of)

    2016-03-01

    The present work investigates the magnetic behavior of Dy{sup 3+} substituted cobalt ferrite nanoparticles. X-ray diffraction studies reveal presence of cubic spinel phases in these nanoparticles. Raman spectra of these nanoparticles show change in intensity of Raman bands, which reflects cation redistribution in cubic spinel lattice. Saturation magnetization and coercivity decrease with increase of Dy{sup 3+}concentration in these nanoparticles. Room temperature Mössbauer measurements show the cation redistribution in these nanoparticles and corroborates the results obtained from Raman Spectroscopic measurements. Decrease in magnetization of Dy{sup 3+} substituted cobalt ferrite is attributed to the reduction in the magnetic interaction and cation redistribution. - Highlights: • Slight decrease in crystallite size after Dy{sup 3+} doping. • Saturation magnetization and coercivity decrease after Dy{sup 3+} doping. • Mössbauer measurements show the cation redistribution in the samples.

  9. NUMERICAL SIMULATION OF MAGNETIC FIELD STRUCTURE IN CYLINDRICAL FILM SCREEN

    Directory of Open Access Journals (Sweden)

    G. F. Gromyko

    2016-01-01

    Full Text Available A numerical method for solving the boundary value problem for a nonlinear magnetostatic equation describing the external magnetostatic field penetration through the cylindrical film coating is developed. A mathematical model of the shielding problem based on the use of the boundary conditions of the third kind on the film surface is studied. The nonlinear dependence of the film magnetic permeability on magnetic field conforms with experimental data. The distribution of the magnetic field strength in the film layer and the magnetic permeability of the film material depending on the magnitude of the external magnetic field strength are investigated numerically.

  10. Structural, magnetic characterization (dependencies of coercivity and loss with the frequency) of magnetic cores based in Finemet

    Science.gov (United States)

    Osinalde, M.; Infante, P.; Domínguez, L.; Blanco, J. M.; del Val, J. J.; Chizhik, A.; González, J.

    2017-12-01

    We report changes of coercivity, induced magnetic anisotropy, magneto-optical domain structure and frequency dependencies of coercivity and energy loss (up to 10 MHz) associated with the structural modifications produced by thermal treatments under applied magnetic field (field annealing) in toroidal wound cores of Fe73.5Cu1Nb3Si15.5B7 amorphous alloy. The thermal treatment (535 °C, 1 h) leads to the typical nanocrystalline structure of α-Fe(Si) nanograins (60-65% relative volume, 10-20 nm average grain size embedded in a residual amorphous matrix, while the magnetic field with the possibility to be applied in two directions to the toroidal core axis, that is in transverse (which is equivalent to the transverse direction of the ribbon) or longitudinal (equivalent to the longitudinal direction of the ribbon), develops a macroscopic uniaxial magnetic anisotropy in the transverse (around 245 J/m3) or longitudinal (around 85 J/m3) direction of the ribbon, respectively. It is remarkable the quasi-unhysteretic character of the cores with these two kinds of field annealing as comparing with that of the as-quenched one. Magneto-optical study by Kerr-effect of the ribbons provides useful information on the domain structure of the surface in agreement with the direction and intensity of the induced magnetic anisotropy. This induced uniaxial magnetic anisotropy plays a very important role on the Hc(f) and EL(f) curves, (f: frequency), being drastic the presence and direction of the induced magnetic anisotropy. In addition, these frequency dependencies show a significant change at the frequency around 100 Hz.

  11. Intraoperative seizures and seizures outcome in patients underwent awake craniotomy.

    Science.gov (United States)

    Yuan, Yang; Peizhi, Zhou; Xiang, Wang; Yanhui, Liu; Ruofei, Liang; Shu, Jiang; Qing, Mao

    2016-11-25

    Awake craniotomies (AC) could reduce neurological deficits compared with patients under general anesthesia, however, intraoperative seizure is a major reason causing awake surgery failure. The purpose of the study was to give a comprehensive overview the published articles focused on seizure incidence in awake craniotomy. Bibliographic searches of the EMBASE, MEDLINE,were performed to identify articles and conference abstracts that investigated the intraoperative seizure frequency of patients underwent AC. Twenty-five studies were included in this meta-analysis. Among the 25 included studies, one was randomized controlled trials and 5 of them were comparable studies. The pooled data suggested the general intraoperative seizure(IOS) rate for patients with AC was 8%(fixed effect model), sub-group analysis identified IOS rate for glioma patients was 8% and low grade patients was 10%. The pooled data showed early seizure rates of AC patients was 11% and late seizure rates was 35%. This systematic review and meta-analysis shows that awake craniotomy is a safe technique with relatively low intraoperative seizure occurrence. However, few RCTs were available, and the acquisition of further evidence through high-quality RCTs is highly recommended.

  12. Magnetic and structural properties of the magnetic shape memory compound Ni2Mn1.48Sb0.52

    International Nuclear Information System (INIS)

    Brown, P J; Gandy, A P; Neumann, K U; Sheikh, A; Ziebeck, K R A; Ishida, K; Oikawa, K; Ito, W; Kainuma, R; Kanomata, T; Ouladdiaf, B

    2010-01-01

    Magnetization and high resolution neutron powder diffraction measurements on the magnetic shape memory compound Ni 2 Mn 1.48 Sb 0.52 have confirmed that it is ferromagnetic below 350 K and undergoes a structural phase transition at T M ∼310 K. The high temperature phase has the cubic L2 1 structure with a = 5.958 A, with the excess manganese atoms occupying the 4(b) Sb sites. In the cubic phase above ∼310 K the manganese moments are ferromagnetically aligned. The magnetic moment at the 4(a) site is 1.57(12) μ B and it is almost zero (0.15(9) μ B ) at the 4(b) site. The low temperature orthorhombic phase which is only fully established below 50 K has the space group Pmma with a cell related to the cubic one by a Bain transformation a orth = (a cub + b cub )/2; b orth = c cub and c orth = (a cub - b cub ). The change in cell volume is ∼2.5%. The spontaneous magnetization of samples cooled in fields less than 0.5 T decreases at temperatures below T M and at 2 K the magnetic moment per formula unit in fields up to 5.5 T is 2.01(5) μ B . Neutron diffraction patterns obtained below ∼132 K gave evidence for a weak incommensurate magnetic modulation with propagation vector (2/3, 1/3, 0).

  13. Magnetic layering transitions in a polyamidoamine (PAMAM) dendrimer nano-structure: Monte Carlo study

    Science.gov (United States)

    Ziti, S.; Aouini, S.; Labrim, H.; Bahmad, L.

    2017-02-01

    We study the magnetic layering transitions in a polyamidoamine (PAMAM) dendrimer nano-structure, under the effect of an external magnetic field. We examine the magnetic properties, of this model of the spin S=1 Ising ferromagnetic in real nanostructure used in several scientific domains. For T=0, we give and discuss the ground state phase diagrams. At non null temperatures, we applied the Monte Carlo simulations giving important results summarized in the form of the phase diagrams. We also analyzed the effect of varying the external magnetic field, and found the layering transitions in the polyamidoamine (PAMAM) dendrimer nano-structure.

  14. Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale

    Science.gov (United States)

    Hauptmann, Nadine; Dupé, Melanie; Hung, Tzu-Chao; Lemmens, Alexander K.; Wegner, Daniel; Dupé, Bertrand; Khajetoorians, Alexander A.

    2018-03-01

    We image simultaneously the geometric, the electronic, and the magnetic structures of a buckled iron bilayer film that exhibits chiral magnetic order. We achieve this by combining spin-polarized scanning tunneling microscopy and magnetic exchange force microscopy (SPEX) to independently characterize the geometric as well as the electronic and magnetic structures of nonflat surfaces. This new SPEX imaging technique reveals the geometric height corrugation of the reconstruction lines resulting from strong strain relaxation in the bilayer, enabling the decomposition of the real-space from the electronic structure at the atomic level and the correlation with the resultant spin-spiral ground state. By additionally utilizing adatom manipulation, we reveal the chiral magnetic ground state of portions of the unit cell that were not previously imaged with spin-polarized scanning tunneling microscopy alone. Using density functional theory, we investigate the structural and electronic properties of the reconstructed bilayer and identify the favorable stoichiometry regime in agreement with our experimental result.

  15. Description of symmetry of magnetic structures by representations of space groups. [Tables, projecton operator methods

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, W

    1974-10-15

    A description of magnetic structures based on the use of representations of space groups is given. Representations of the space groups were established for each compound on the basis of experimental data by the method of projection operators. The compounds contained in the list are collected according to crystal systems, alphabetically within each system. The description of each compound consists of the four parts. The first part contain the chemical symbol of the compound, the second its space group. The next part contains the chemical symbol of the magnetic atom and its positions in Wychoff notation with the number of equivalent positions in the crystal unit cell. The main description of a compound magnetic structure is given in the fourth part. It contains: K vector defined in the reciprocal space, the representation according to which a magnetic structure is transformed and the axial vector function S which describes the magnetic structure.

  16. Electronic structures and magnetic/optical properties of metal phthalocyanine complexes

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shintaro; Suzuki, Atsushi, E-mail: suzuki@mat.usp.ac.jp; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture. 2500 Hassaka, Hikone, Shiga 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic / optical properties of metal phthalocyanine complexes were studied by quantum calculations using density functional theory. Effects of central metal and expansion of π orbital on aromatic ring as conjugation system on the electronic structures, magnetic, optical properties and vibration modes of infrared and Raman spectra of metal phthalocyanines were investigated. Electron and charge density distribution and energy levels near frontier orbital and excited states were influenced by the deformed structures varied with central metal and charge. The magnetic parameters of chemical shifts in {sup 13}C-nuclear magnetic resonance ({sup 13}C-NMR), principle g-tensor, A-tensor, V-tensor of electric field gradient and asymmetry parameters derived from the deformed structures with magnetic interaction of nuclear quadruple interaction based on electron and charge density distribution with a bias of charge near ligand under crystal field.

  17. The role of the nature of pillars in the structural and magnetic properties of magnetic pillared vlays

    DEFF Research Database (Denmark)

    Bachir, Cherifa; Lan, Yanhua; Mereacre, Valeriu

    2011-01-01

    of pillared clays by examining in detail the influence of the calcination temperature and the nature of different pillared clays on these properties. Magnetic layered systems from different pillared clays were prepared and characterized. Firstly, Ti-, Al-, and Zr-pillared clays (Ti-PILCs, Al-PILCs, and Zr......-PILCs, respectively) were produced at different calcination temperatures and then magnetic pillared clays (Ti-M-PILCs, Al-M-PILCs, and Zr-M-PILCs) were prepared at ambient temperature. The synthesis involves a reduction in aqueous solution of the original Fe-exchanged pillared clay using NaBH4. The structural....... Similar experiments with Al- and Zr-pillars have been discussed. A correlation between the XRF data, porosity, FF calculation, and magnetic properties led to the conclusion that the sample Al-M-PILC previously calcined at 500 degrees C was the most stable material after the magnetization process. The same...

  18. Thermal, magnetic, and structural properties of soft magnetic FeCrNbCuSiB alloy ribbons

    International Nuclear Information System (INIS)

    Rosales-Rivera, A.; Valencia, V.H.; Quintero, D.L.; Pineda-Gomez, P.; Gomez, M.

    2006-01-01

    The thermal, magnetic and structural properties of amorphous magnetic Fe 73.5-x Cr x Nb 3 Cu 1 Si 13.5 B 9 alloy ribbons, with x=0, 2, 4, 6, 8, and 10, were studied by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magneto-impedance measurements and X-ray diffraction (XRD). The ribbons exhibit ultrasoft magnetic behavior, especially giant magneto-impedance effect, GMI. A three-peak behavior was observed in GMI curves. Particular attention has been given to observation of crystallization kinetics via DSC and TGA. The primary crystallization T pcr , and Curie T c , temperatures were determined from DSC and TGA data, respectively. The effect of partial substitution of iron by Cr on the thermal and magnetic properties is discussed

  19. Coercivity enhancement in Ce-Fe-B based magnets by core-shell grain structuring

    Directory of Open Access Journals (Sweden)

    M. Ito

    2016-05-01

    Full Text Available Ce-based R2Fe14B (R= rare-earth nano-structured permanent magnets consisting of (Ce,Nd2Fe14B core-shell grains separated by a non-magnetic grain boundary phase, in which the relative amount of Nd to Ce is higher in the shell of the magnetic grain than in its core, were fabricated by Nd-Cu infiltration into (Ce,Nd2Fe14B hot-deformed magnets. The coercivity values of infiltrated core-shell structured magnets are superior to those of as-hot-deformed magnets with the same overall Nd content. This is attributed to the higher value of magnetocrystalline anisotropy of the shell phase in the core-shell structured infiltrated magnets compared to the homogeneous R2Fe14B grains of the as-hot-deformed magnets, and to magnetic isolation of R2Fe14B grains by the infiltrated grain boundary phase. First order reversal curve (FORC diagrams suggest that the higher anisotropy shell suppresses initial magnetization reversal at the edges and corners of the R2Fe14B grains.

  20. Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field

    International Nuclear Information System (INIS)

    Rezania, H.

    2017-01-01

    We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.

  1. Spin structure factors of Heisenberg spin chain in the presence of anisotropy and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Rezania, H., E-mail: rezania.hamed@gmail.com

    2017-02-01

    We have theoretically studied the spin structure factors of spin chain in the presence of longitudinal field and transverse anisotropy. The possible effects of easy axis magnetization are investigated in terms of anisotropy in the Heisenberg interactions. This anisotropy is considered for exchange coupling constants perpendicular to magnetic field direction. The original spin model hamiltonian is mapped to a bosonic model via a hard core bosonic transformation where an infinite hard core repulsion is imposed to constrain one boson occupation per site. Using Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. The spectrum of the bosonic gas has been implemented in order to obtain two particle propagator which corresponds to spin structure factor of original Heisenberg chain model Hamiltonian. The results show the position of peak in the longitudinal structure factor at fixed value for anisotropy moves to higher frequency with magnetic field. Also the intensity of dynamical structure factor decreases with magnetic field. A small dependence of longitudinal dynamical spin structure factor on the anisotropy is observed for fixed value of magnetic field. Our results show longitudinal static structure factor is found to be monotonically increasing with magnetic field due to increase of spins aligning along magnetic field. Furthermore the dispersion behaviors of static longitudinal and transverse structure factors for different magnetic fields and anisotropy parameters are addressed. - Highlights: • Theoretical calculation of spin structure factors of Heisenberg chain. • The investigation of the effect of anisotropy spin structure factors of Heisenberg chain. • The investigation of the effect of magnetic field on spin structure factors of Heisenberg chain.

  2. Finite element analysis of structural response of superconducting magnet for a fusion reactor

    International Nuclear Information System (INIS)

    Reich, M.; Powell, J.; Bezler, P.; Chang, T.Y.; Prachuktam, S.

    1975-01-01

    In the proposal Tokamak fusion reactor, the superconducting unit consists of an assembly of D-shaped magnets standing vertically and arranged in a toroidal configuration. Each magnet is a composite structure comprised of Nb-22%Ti and Nb-48%Ti, and stabilizing metals such as copper and aluminum or stainless steel held together by reinforced epoxies which also serve as insulators and spacers. The magnets are quite large, typically 15-20 meters in diameter with rectangular cross sections around 0.93x2m. Under static loading condition, the magnet is subjected to dead weight and large magnetic field forces, which may induce high stresses in the structure. Furthermore, additional stresses due to earthquake must also be considered for the design of the component. Both static and dynamic analyses of a typical field magnet have been performed by use of the finite element method. The magnet was assumed to be linearly elastic with equivalent homogeneous material properties. Various finite element models have been considered in order to better represent the structure for a particular loading case. For earthquake analysis, the magnet was assumed to be subjected to 50% of the El Centro 1940 earthquake and the dynamic response was obtained by the displacement spectrum analysis procedure. In the paper, numerical results are presented and the structure behavior of the magnet under static and dynamic loading conditions is discussed

  3. Effect of alloying on the electronic structure and magnetic properties ...

    Indian Academy of Sciences (India)

    Unknown

    We analyse the effect of local environment and the hybridization between the constituent bands on the elec- tronic and magnetic ..... statements made earlier that although the augmented .... ics, Trieste, for the financial help through its Network.

  4. Structure of the magnetic field line diversion in Helias configurations

    International Nuclear Information System (INIS)

    Strumberger, E.

    1991-01-01

    The vacuum magnetic field outside the last closed magnetic surface of Helias configurations is investigated with respect to its field line diversion properties. In a Helias configuration with N periods N half-helix like edges run on the toroidally outward side of the plasma boundary and yield the possibility of separatrix formation due to the coincidence of helical edge and x-points between islands. With the choice N=5, and ι=1 at the plasma boundary, there are five magnetic islands outside the last closed magnetic surface. In the case considered, islands are lying in front of the helical edge at the beginning, in the middle and at the end of this edge, while in positions in between x-points are in front of the helical edge. (author) 3 refs., 5 figs

  5. Evolution of the magnetic field structure of the Crab pulsar.

    Science.gov (United States)

    Lyne, Andrew; Graham-Smith, Francis; Weltevrede, Patrick; Jordan, Christine; Stappers, Ben; Bassa, Cees; Kramer, Michael

    2013-11-01

    Pulsars are highly magnetized rotating neutron stars and are well known for the stability of their signature pulse shapes, allowing high-precision studies of their rotation. However, during the past 22 years, the radio pulse profile of the Crab pulsar has shown a steady increase in the separation of the main pulse and interpulse components at 0.62° ± 0.03° per century. There are also secular changes in the relative strengths of several components of the profile. The changing component separation indicates that the axis of the dipolar magnetic field, embedded in the neutron star, is moving toward the stellar equator. This evolution of the magnetic field could explain why the pulsar does not spin down as expected from simple braking by a rotating dipolar magnetic field.

  6. Influence of Magnetic Topology on Mars' Ionospheric Structure

    Science.gov (United States)

    Adams, D.; Xu, S.; Mitchell, D. L.; Fillingim, M. O.; Lillis, R. J.; Andersson, L.; Fowler, C. M.; Benna, M.; Connerney, J. E. P.; Elrod, M. K.; Girazian, Z.; Vogt, M.

    2017-12-01

    The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission has been in Mars' orbit since September 2014 (>1 Mars year), and has collected particle and field data within the ionosphere over wide ranges of altitudes, latitudes, and local times. This study uses MAVEN data to (1) analyze the influence of magnetic topology on the day-side ionosphere and (2) identify the sources of the night-side ionosphere. On the day side, magnetic strength and elevation angle are commonly used as proxies for magnetic topology. In this study, we use pitch-angle-resolved suprathermal electron measurements by the Solar Wind Electron Analyzer (SWEA) to directly deduce the magnetic topology instead of using a proxy. On the night side, the main sources of ionospheric plasma are bulk transport and plasma pressure gradient flow from the day side, as well as in situ production by electron impact ionization (EII). Plasma transport at Mars is complicated by the presence of intense crustal magnetic fields. Closed crustal magnetic fields form isolated plasma environments ("miniature magnetospheres") that inhibit external sources of cold ionospheric plasma as well as suprathermal (ionizing) electrons. Inside these closed magnetic loops, we study how the plasma evolves with bulk flow transport as the only source. By comparing closed and non-closed magnetic configurations, the effects of pressure gradient flow and EII can be distinguished. Finally, the densities of O2+, O+, and NO+, as measured by the Neutral Gas and Ion Mass Spectrometer (NGIMS), are examined. Inside miniature magnetospheres on the night side, the abundances of these species are found to be primarily controlled by the different recombination rates, as there is little plasma created within these regions by EII or transported from the neighboring regions by plasma pressure gradient flow.

  7. Thermal and structural analysis of a cryogenic conduction cooling system for a HTS NMR magnet

    Energy Technology Data Exchange (ETDEWEB)

    In, Se Hwan; Hong, Yong Jun; Yeom, Han Kil; Ko, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2016-03-15

    The superconducting NMR magnets have used cryogen such as liquid helium for their cooling. The conduction cooling method using cryocoolers, however, makes the cryogenic cooling system for NMR magnets more compact and user-friendly than the cryogen cooling method. This paper describes the thermal and structural analysis of a cryogenic conduction cooling system for a 400 MHz HTS NMR magnet, focusing on the magnet assembly. The highly thermo-conductive cooling plates between HTS double pancake coils are used to transfer the heat generated in coils, namely Joule heating at lap splice joints, to thermal link blocks and finally the cryocooler. The conduction cooling structure of the HTS magnet assembly preliminarily designed is verified by thermal and structural analysis. The orthotropic thermal properties of the HTS coil, thermal contact resistance and radiation heat load are considered in the thermal analysis. The thermal analysis confirms the uniform temperature distribution for the present thermal design of the NMR magnet within 0.2 K. The mechanical stress and the displacement by the electromagnetic force and the thermal contraction are checked to verify structural stability. The structural analysis indicates that the mechanical stress on each component of the magnet is less than its material yield strength and the displacement is acceptable in comparison with the magnet dimension.

  8. Method of magnetic susceptibility mapping of drilled cores. Experimental measurements for geologic structures determination

    International Nuclear Information System (INIS)

    Delrive, C.

    1993-01-01

    The evaluation of the safety of a deep geologic repository for dangerous materials requires the knowledge of the interstitial system of the surrounding host rock. A method is proposed for the determination of geologic structures (in particular fractures) from the magnetic susceptibility mapping of drilled cores. The feasibility of the method has been demonstrated using a SQUID magneto-gradient meter. A measurement tool using a new magnetic susceptibility captor and a testing bench have been developed. This tool allows the measurement of rocks with a magnetic susceptibility greater than 10 -5 SI units and can generate magnetic susceptibility maps with 4 x 4 mm 2 pixels. A magnetic visibility criterion has been defined which allows to foresee if a structure is visible or not. According to the measurements done, it is shown that any centimeter-scale structure with a sufficient magnetic contrast (20%) with respect to the matrix is visible. Therefore, the dip and the orientation of such structure can be determined with a 3 degree and a 5 degree precision, respectively. The position of the structure along the core axis is known with a 4 mm precision. On the other hand, about half of the magnetic contrasts observed do not correspond to the visual analyses and can be explained by very small variations of the mineralogic composition. This last point offers some interesting ways for future research using magnetic susceptibility mapping. (J.S.). 31 refs., 90 figs., 18 tabs., 2 photos., 6 appends

  9. Crystal structure and magnetism of Fe2(OH)[B2O4(OH)

    DEFF Research Database (Denmark)

    Kurayoshi, Yotaro; Hara, Shigeo; Sato, Hirohiko

    2014-01-01

    The structure and magnetism of Fe2(OH)[B2O4(OH)] are reported. Powder x-ray diffraction reveals a characteristic structure containing two crystallographically independent zigzag-ladder chains of magnetic Fe2+ ions. Magnetization measurements reveal a phase transition at 85 K, below which a weak...... spontaneous magnetization (approximate to 0.15 μB/Fe) appears. Below 85 K, magnetization increases with decreasing temperature down to 70 K, below which it decreases and approaches a constant value at low temperature. The Mossbauer spectrum at room temperature is composed of two paramagnetic doublets...... corresponding to the two crystallographic Fe2+ sites. Below 85 K, each doublet undergoes further splitting because of the magnetic hyperfine fields. The temperature dependence of the hyperfine field is qualitatively different for the two distinguishable Fe2+ sites. This is responsible for the anomalous...

  10. New structures of Fe3S for rare-earth-free permanent magnets

    Science.gov (United States)

    Yu, Shu; Zhao, Xin; Wu, Shunqing; Nguyen, Manh Cuong; Zhu, Zi-zhong; Wang, Cai-Zhuang; Ho, Kai-Ming

    2018-02-01

    We applied an adaptive genetic algorithm (AGA) to search for low-energy crystal structures of Fe3S. A number of structures with energies lower than that of the experimentally reported Pnma and I-4 structures have been obtained from our AGA searches. These low-energy structures can be classified as layer-motif and column-motif structures. In the column-motif structures, Fe atoms self-assemble into rods with a bcc type of underlying lattice, which are separated by the holes terminated by S atoms. In the layer-motif structures, the bulk Fe is broken into slabs of several layers passivated by S atoms. Magnetic property calculations showed that the column-motif structures exhibit reasonably high uniaxial magnetic anisotropy. In addition, we examined the effect of Co doping to Fe3S and found that magnetic anisotropy can be enhanced through Co doping.

  11. Structure and magnetic properties of chromium doped cobalt molybdenum nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Guskos, Niko; Żołnierkiewicz, Grzegorz; Typek, Janusz; Guskos, Aleksander [Institute of Physics, Faculty of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, Szczecin, Piastów 48, 70-311 Szczecin (Poland); Adamski, Paweł; Moszyński, Dariusz [Institute of Inorganic Chemical Technology and Environment Engineering, West Pomeranian University of Technology, Szczecin, Pułaskiego 10, 70-322 Szczecin (Poland)

    2016-09-15

    Four nanocomposites containing mixed phases of Co{sub 3}Mo{sub 3}N and Co{sub 2}Mo{sub 3}N doped with chromium have been prepared. A linear fit is found for relation between Co{sub 2}Mo{sub 3}N and chromium concentrations. The magnetization in ZFC and FC modes at different temperatures (2–300 K) and in applied magnetic fields (up to 70 kOe) have been investigated. It has been detected that many magnetic characteristics of the studied four nanocomposites correlate not with the chromium concentration but with nanocrystallite sizes. The obtained results were interpreted in terms of magnetic core-shell model of a nanoparticle involving paramagnetic core with two magnetic sublattices and a ferromagnetic shell related to chromium doping. - Highlights: • A new chromium doped mixed Co-Mn-N nanocomposites were synthesized. • Surface ferromagnetism was detected in a wide temperature range. • Core-shell model was applied to explain nanocomposites magnetism.

  12. Long wave dispersion relations for surface waves in a magnetically structured atmosphere

    International Nuclear Information System (INIS)

    Rae, I.C.; Roberts, B.

    1983-01-01

    A means of obtaining approximate dispersion relations for long wavelength magnetoacoustic surface waves propagating in a magnetically structured atmosphere is presented. A general dispersion relation applying to a wide range of magnetic profiles is obtained, and illustrated for the special cases of a single interface and a magnetic slab. In the slab geometry, for example, the dispersion relation contains both the even (sausage) and odd (kink) modes in one formalism

  13. Posterior Reversible Encephalopathy Syndrome in Patients who Underwent Cardiovascular Surgery

    International Nuclear Information System (INIS)

    Granados, Ana Maria; Bueno Melo, Juliana; Acosta Puentes, Diana

    2012-01-01

    The etiology of posterior reversible encephalopathy syndrome (pres) is not well understood. This entity has been reported in relation to multiple clinical conditions. It has been proposed that the vertebrobasilar circulation is more sensitive to injuries sustained by the central nervous system. Consequently, the main radiologic manifestations of this condition occur in the pareto-occipital regions. As its name implies, pres has a reversible nature. Once the noxious factors are withdrawn, both the vasogenic edema in affected areas, as well as neurological symptoms tends to resolve, whereas if the situation persists the lesions may progress to parenchymal ischemia. Cerebral computed tomography (CT) in pres may show hypodense areas in the affected white matter. Magnetic resonance (MR) imaging is used to better characterize the abnormal regions. This modality is capable of displaying an increased signal intensity in these areas on T2-weighted FLAIR sequences that is less apparent on diffusion-weighted images. In order to confirm this diagnosis, a follow up imaging study either with CT or MR can be performed approximately four weeks after the onset of symptoms. Nevertheless, an exact consensus with respect to the follow-up period has not been reached. The supporting findings for this diagnosis include resolution of the affected white matter and clinical remission without neurological sequelae. We hereby report three proven cases of pres in patients of different age groups that had undergone major cardiovascular surgery with extracorporeal circulation, a common factor that was thought to have been the precursor to this condition in these individuals.

  14. Electronic Structure Calculation of Permanent Magnets using the KKR Green's Function Method

    Science.gov (United States)

    Doi, Shotaro; Akai, Hisazumi

    2014-03-01

    Electronic structure and magnetic properties of permanent magnetic materials, especially Nd2Fe14B, are investigated theoretically using the KKR Green's function method. Important physical quantities in magnetism, such as magnetic moment, Curie temperature, and anisotropy constant, which are obtained from electronics structure calculations in both cases of atomic-sphere-approximation and full-potential treatment, are compared with past band structure calculations and experiments. The site preference of heavy rare-earth impurities are also evaluated through the calculation of formation energy with the use of coherent potential approximations. Further, the development of electronic structure calculation code using the screened KKR for large super-cells, which is aimed at studying the electronic structure of realistic microstructures (e.g. grain boundary phase), is introduced with some test calculations.

  15. Structural and magnetic properties of core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

    2002-01-01

    We present studies of the structural and magnetic properties of core-shell iron-iron oxide nanoparticles. alpha-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (gamma-Fe2O3) or partially oxidized...... magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mossbauer spectroscopy at high applied magnetic fields and low temperatures revealed a stable form of partly oxidized magnetite. The nanocrystalline structure of the oxide shell results in strong canting...... of the spin structure in the oxide shell, which thereby modifies the magnetic properties of the core-shell nanoparticles....

  16. X-ray magnetic microscopy for correlations between magnetic domains and crystal structure

    International Nuclear Information System (INIS)

    Denbeaux, G.; Anderson, E.; Bates, B.; Chao, W.; Liddle, J.A.; Harteneck, B.; Pearson, A.; Salmassi, F.; Schneider, G.; Fischer, P.; Eimuller, T.; Taylor, S.; Chang, H.; Kusinski, G.J.

    2002-01-01

    Accurately determining the resolution of x-ray microscopes has been a challenge because good test patterns for x-ray microscopy have been hard to make. We report on a sputter-deposited multilayer imaged in cross section as a test pattern with small features and high aspect ratios. One application of high-resolution imaging is magnetic materials. Off-axis bend magnet radiation is known to have a component of circular polarization which can be used for x-ray magnetic circular dichroism. We calculate the integrated circular polarization collected by the illumination optics in the XM-1 full-field x-ray microscope. (authors)

  17. MAGNET

    CERN Multimedia

    B. Curé

    2013-01-01

    The magnet is fully stopped and at room temperature. The maintenance works and consolidation activities on the magnet sub-systems are progressing. To consolidate the cryogenic installation, two redundant helium compressors will be installed as ‘hot spares’, to avoid the risk of a magnet downtime in case of a major failure of a compressor unit during operation. The screw compressors, their motors, the mechanical couplings and the concrete blocks are already available and stored at P5. The metallic structure used to access the existing compressors in SH5 will be modified to allow the installation of the two redundant ones. The plan is to finish the installation and commissioning of the hot spare compressors before the summer 2014. In the meantime, a bypass on the high-pressure helium piping will be installed for the connection of a helium drier unit later during the Long Shutdown 1, keeping this installation out of the schedule critical path. A proposal is now being prepared for the con...

  18. CFA Films in Amorphous Substrate: Structural Phase Induction and Magnetization Dynamics

    Science.gov (United States)

    Correa, M. A.; Bohn, F.; Escobar, V. M.

    We report a systematic study of the structural and quasi-static magnetic properties, as well as of the dynamic magnetic response through MI effect, in Co2FeAl and MgO//Co2FeAl single layers and a MgO//Co2FeAl/Ag/Co2FeAl trilayered film, all grown onto an amorphous substrate. We present a new route to induce the crystalline structure in the Co2FeAl alloy and verify that changes in the structural phase of this material leads to remarkable modifications of the magnetic anisotropy and, consequently, dynamic magnetic behavior. Considering the electrical and magnetic properties of the Co2FeAl, our results open new possibilities for technological applications of this full-Heusler alloy in rigid and flexible spintronic devices.

  19. Crystal structure and magnetism of layered perovskites compound EuBaCuFeO5

    Science.gov (United States)

    Lal, Surender; Mukherjee, K.; Yadav, C. S.

    2018-04-01

    Layered perovskite compounds have interesting multiferroic properties.YBaCuFeO5 is one of the layered perovskite compounds which have magnetic and dielectric transition above 200 K. The multiferroic properties can be tuned with the replacement of Y with some other rare earth ions. In this manuscript, structural and magnetic properties of layered perovskite compound EuBaCuFeO5 have been investigated. This compound crystallizes in the tetragonal structure with P4mm space group and is iso-structural with YBaCuFeO5. The magnetic transition has been found to shift to 120 K as compared to YBaCuFeO5 which has the transition at 200 K. This shift in the magnetic transition has been ascribed to the decrease in the chemical pressure that relaxes the magnetic moments.

  20. Relation between Kitaev magnetism and structure in α -RuCl3

    Science.gov (United States)

    Glamazda, A.; Lemmens, P.; Do, S.-H.; Kwon, Y. S.; Choi, K.-Y.

    2017-05-01

    Raman scattering has been employed to investigate lattice and magnetic excitations of the honeycomb Kitaev material α -RuCl3 and its Heisenberg counterpart CrCl3. Our phonon Raman spectra give evidence for a first-order structural transition from a monoclinic to a rhombohedral structure for both compounds. Significantly, only α -RuCl3 features a large thermal hysteresis, consistent with the formation of a wide phase of coexistence. In the related temperature interval of 70 -170 K, we observe a hysteretic behavior of magnetic excitations as well. The stronger magnetic response in the rhombohedral compared to the monoclinic phase evidences a coupling between the crystallographic structure and low-energy magnetic response. Our results demonstrate that the Kitaev magnetism concomitant with fractionalized excitations is susceptible to small variations of bonding geometry.

  1. Electronic structure and magnetic properties of Ni-doped SnO2 thin films

    Science.gov (United States)

    Sharma, Mayuri; Kumar, Shalendra; Alvi, P. A.

    2018-05-01

    This paper reports the electronic structure and magnetic properties of Ni-doped SnO2 thin film which were grown on Si (100) substrate by PLD (pulse laser deposition) technique under oxygen partial pressure (PO2). For getting electronic structure and magnetic behavior, the films were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and DC magnetization measurements. The NEXAFS study at Ni L3,2 edge has been done to understand the local environment of Ni and Sn ions within SnO2 lattice. DC magnetization measurement shows that the saturation magnetization increases with the increase in substitution of Ni2+ ions in the system.

  2. Structural and Magnetic Properties of Co-Mn-Sb Thin films

    Energy Technology Data Exchange (ETDEWEB)

    Meinert, M.; Schmalhorst, J.-M.; Ebke, D.; Liu, N. N.; Thomas, A.; Reiss, G.; Kanak, J.; Stobiecki, T.; Arenholz, E.

    2009-12-17

    Thin Co-Mn-Sb films of different compositions were investigated and utilized as electrodes in alumina based magnetic tunnel junctions with CoFe counterelectrode. The preparation conditions were optimized with respect to magnetic and structural properties. The Co-Mn-Sb/Al-O interface was analyzed by x-ray absorption spectroscopy and magnetic circular dichroism with particular focus on the element-specific magnetic moments. Co-Mn-Sb crystallizes in different complex cubic structures depending on its composition. The magnetic moments of Co and Mn are ferromagnetically coupled in all cases. A tunnel magnetoresistance ratio of up to 24% at 13 K was found and indicates that Co-Mn-Sb is not a ferromagnetic half-metal. These results are compared to recent works on the structure and predictions of the electronic properties.

  3. Modelling of Surface Fault Structures Based on Ground Magnetic Survey

    Science.gov (United States)

    Michels, A.; McEnroe, S. A.

    2017-12-01

    The island of Leka confines the exposure of the Leka Ophiolite Complex (LOC) which contains mantle and crustal rocks and provides a rare opportunity to study the magnetic properties and response of these formations. The LOC is comprised of five rock units: (1) harzburgite that is strongly deformed, shifting into an increasingly olivine-rich dunite (2) ultramafic cumulates with layers of olivine, chromite, clinopyroxene and orthopyroxene. These cumulates are overlain by (3) metagabbros, which are cut by (4) metabasaltic dykes and (5) pillow lavas (Furnes et al. 1988). Over the course of three field seasons a detailed ground-magnetic survey was made over the island covering all units of the LOC and collecting samples from 109 sites for magnetic measurements. NRM, susceptibility, density and hysteresis properties were measured. In total 66% of samples with a Q value > 1, suggests that the magnetic anomalies should include both induced and remanent components in the model.This Ophiolite originated from a suprasubduction zone near the coast of Laurentia (497±2 Ma), was obducted onto Laurentia (≈460 Ma) and then transferred to Baltica during the Caledonide Orogeny (≈430 Ma). The LOC was faulted, deformed and serpentinized during these events. The gabbro and ultramafic rocks are separated by a normal fault. The dominant magnetic anomaly that crosses the island correlates with this normal fault. There are a series of smaller scale faults that are parallel to this and some correspond to local highs that can be highlighted by a tilt derivative of the magnetic data. These fault boundaries which are well delineated by the distinct magnetic anomalies in both ground and aeromagnetic survey data are likely caused by increased amount of serpentinization of the ultramafic rocks in the fault areas.

  4. Fabrication, morphological, structural and magnetic properties of electrodeposited Fe{sub 3}Pt nanowires and nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Khan, U. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Adeela, N. [Centre for High Energy Physics, University of the Punjab, Lahore 54000 (Pakistan); Li, Wenjing; Irfan, M.; Javed, K.; Riaz, S. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Han, X.F., E-mail: xfhan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-02-15

    Highly ordered Fe{sub 3}Pt nanowires (NWs) and nanotubes (NTs) embedded in anodic aluminum oxide (AAO) template have been fabricated by dc electrodeposition method. Response of heat treatment on structural and magnetic properties of the samples has been studied with and without the presence of magnetic field (1 T). X-Ray Diffraction analysis shows chemically ordered L1{sub 2} face centered cubic (FCC) as the dominant phase for Fe{sub 3}Pt NWs and heat treatment improves crystallinity with retained its phase. Whereas, Fe{sub 3}Pt NTs show amorphous behavior with and without magnetic field annealing. Furthermore, magnetic properties of the samples have been investigated by vibrating sample magnetometer (VSM). Magnetic parameters of Fe{sub 3}Pt including magnetic coercivity, saturation magnetization, squareness and shape of MH-loops have been investigated as a result of simple and MF annealing. - Highlights: • Fe{sub 3}Pt NWs and NTs embedded into anodic alumina templates have been synthesized by dc electrodeposition method. • Structural analysis (XRD) confirmed the formation of fcc structure. • Magnetic properties have been measured as a function of simple and magnetic field annealing.

  5. First principle study of structural, electronic and magnetic properties of zigzag boron nitride nanoribbon: Role of vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Arun [Department of Physics, Govt. College Banjar, Kullu, Himanchal Pradesh, 175123 India (India); Bahadur, Amar, E-mail: abr.phys@gmail.com [Department of Physics, Kamla Nehru Institute of Physical and Social Sciences, Sultanpur, Uttar Pradesh, 228118 India (India); Mishra, Madhukar [Department of Physics, Birla Institute of Technology and Science, Pilani, Rajasthan, 333031 India (India); Vasudeva, Neena [Department of Physics, S. V. G. College, Ghumarwin, Bilaspur, Himanchal Pradesh, 1714021 India (India)

    2015-05-15

    We study the effect of vacancies on the structural, electronic and magnetic properties of zigzag boron nitride nanoribbon (ZBNNR) by using first principle calculations. We find that the shift of the vacancies with respect to the ribbon edges causes change in the structural geometry, electronic structure and magnetization of ZBNNR. These vacancies also produce band gap modulation and consequently results the magnetization of ZBNNR.

  6. Magnetization Dynamics in Two Novel Current-Driven Spintronic Memory Cell Structures

    KAUST Repository

    Velazquez-Rizo, Martin

    2017-07-01

    In this work, two new spintronic memory cell structures are proposed. The first cell uses the diffusion of polarized spins into ferromagnets with perpendicular anisotropy to tilt their magnetization followed by their dipolar coupling to a fixed magnet (Bhowmik et al., 2014). The possibility of setting the magnetization to both stable magnetization states in a controlled manner using a similar concept remains unknown, but the proposed structure poses to be a solution to this difficulty. The second cell proposed takes advantage of the multiple stable magnetic states that exist in ferromagnets with configurational anisotropy and also uses spin torques to manipulate its magnetization. It utilizes a square-shaped ferromagnet whose stable magnetization has preferred directions along the diagonals of the square, giving four stable magnetic states allowing to use the structure as a multi-bit memory cell. Both devices use spin currents generated in heavy metals by the Spin Hall effect present in these materials. Among the advantages of the structures proposed are their inherent non-volatility and the fact that there is no need for applying external magnetic fields during their operation, which drastically improves the energy efficiency of the devices. Computational simulations using the Object Oriented Micromagnetic Framework (OOMMF) software package were performed to study the dynamics of the magnetization process in both structures and predict their behavior. Besides, we fabricated a 4-terminal memory cell with configurational anisotropy similar to the device proposed, and found four stable resistive states on the structure, proving the feasibility of this technology for implementation of high-density, non-volatile memory cells.

  7. Magnetic structure of the magnetocaloric compound AlFe2B2

    Czech Academy of Sciences Publication Activity Database

    Cedervall, J.; Andersson, M. S.; Sarkar, T.; Delczeg-Czirjak, E. K.; Bergqvist, L.; Hansen, T. C.; Beran, Přemysl; Nordblad, P.; Sahlberg, M.

    2016-01-01

    Roč. 664, APR (2016), s. 784-791 ISSN 0925-8388 Institutional support: RVO:61389005 Keywords : X-ray diffraction * neutron diffraction * magnetic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.133, year: 2016

  8. Effects of crystallite size on the structure and magnetism of ferrihydrite

    NARCIS (Netherlands)

    Wang, Xiaoming; Zhu, Mengqiang; Koopal, L.K.; Li, Wei; Xu, Wenqian; Liu, Fan; Zhang, Jing; Liu, Qingsong; Feng, Xionghan; Sparks, D.L.

    2016-01-01

    The structure and magnetic properties of nano-sized (1.6 to 4.4 nm) ferrihydrite samples are systematically investigated through a combination of X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS) and magnetic analyses. The XRD, PDF and Fe K-edge

  9. Magnetic Properties and Structure of Chromium Niobium Oxide and Iron Tantalum Oxide

    DEFF Research Database (Denmark)

    Nørlund Christensen, A.; Johansson, T.; Lebech, Bente

    1976-01-01

    Crystal structures were obtained from X-ray powder patterns. The magnetic properties were investigated between 4.2 and 300K by magnetization measurements and neutron diffraction. Both compounds show spin-glass transitions at low temperatures. In CrNbO4, the cusp in the susceptibility is observed ...

  10. Nanocrystalline structure formation and magnetic hysteresis properties of Y-Fe-Co-B alloys

    Czech Academy of Sciences Publication Activity Database

    Tereshina, I. S.; Tereshina, Evgeniya; Burkhanov, G.S.; Dobatkin, S.V.

    2010-01-01

    Roč. 25, č. 1 (2010), s. 82-87 ISSN 1606-5131. [International Symposium on Bulk Nanostructures Materials /2./. Ufa, 22.09.2009-26.09.2009] Institutional research plan: CEZ:AV0Z10100520 Keywords : R-Fe-B magnets * melt spinning * structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.649, year: 2010

  11. Effect of hydrostatic and uniaxial pressure on structural and magnetic transitions in TbNiAl

    Czech Academy of Sciences Publication Activity Database

    Kaštil, Jiří; Klicpera, M.; Prchal, J.; Míšek, Martin; Prokleška, J.; Javorský, P.

    2014-01-01

    Roč. 585, Feb (2014), s. 98-102 ISSN 0925-8388 Institutional support: RVO:68378271 Keywords : magnetic ordering * electrical resistivity * hydrostatic pressure * structural transition Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.999, year: 2014

  12. An investigation of the magnetic structure of PrO2

    DEFF Research Database (Denmark)

    Gardiner, C.H.; Boothroyd, A.T.; Lister, S.J.S.

    2002-01-01

    We present a neutron-diffraction study of the crystal structure and magnetic ordering of PrO2. The magnetic moment of the Pr4+ ion is determined from separate single-crystal and powder measurements, and both values are found to agree with a previous powder study. Our powder data reveal a new aspect...

  13. Crystal structure and magnetic properties of Cr doped barium hexaferrite

    Science.gov (United States)

    Kumar, Sunil; Supriya, Sweety; Pandey, Rabichandra; Pradhan, Lagen Kumar; Kar, Manoranjan

    2018-04-01

    The Cr3+ substituted BaFe12O19 has been synthesized by modified sol-gel method to tailor the magnetic anisotropy and coercivity for technological applications. Some basic studies have revealed that this substitution leads to unusual interactions among the magnetic sublattices of the M-type hexaferrite. In order to investigate these interactions, BaFe12-xCrxO19 (x = 0.0, 0.5, 1.0, 2.0, and 4.0) M-type hexaferrites were characterized by employing XRD (X-ray Diffractometer). It is confirmed that, all the samples are in nanocrystalline and single phase, no impurity has been detected within the XRD limit. The magnetic hysteresis (m-H) loops revealed the ferromagnetic nature of nanoparticles (NPs). The coercive field were increasing with the increasing Cr3+ content, but after the percolation limit it decreases. The magnetocrystalline anisotropy is increasing with the Cr3+ concentration in samples and high values of magnetocrystalline anisotropy revealed that all samples are hard magnetic materials. Magnetic hysteresis loops were analyzed using the Law of Approach to Saturation method.

  14. Design and heat load analysis of support structure of CR superconducting dipole magnet for FAIR

    International Nuclear Information System (INIS)

    Zhu Yinfeng; Wu Songtao; Wu Weiyue; Xu Houchang; Liu Changle

    2008-01-01

    In order to meet the requirement of the Collector ring (CR) dipole superconducting magnet of FAIR in the process of operation, meanwhile, and to ensure the heat loads coming from the support structures to be lower than the design demands, the 3D models of support structures have been constructed with CATIA, then the calculation of low-temperature heat-load and the structure analysis have been done with ANSYS, the support structure material, 316LN+G10, is decided according to the heat-load calculation and the structure optimization, these results are necessary for manufacturing the formal magnet. (authors)

  15. Observational limits on the magnetic-monopole structure of protons

    International Nuclear Information System (INIS)

    Broderick, J.J.; Ficenec, J.R.; Teplitz, D.C.; Teplitz, V.L.

    1979-01-01

    We report the results of a search for absorption of 42-cm radiation in neutral galactic hydrogen. One explanation of a positive result would be the existence of a type of anomalous proton whose magnetic moment arises from a distribution of magnetic charge rather than from a distribution of circulating currents. No absorption of 42-cm radiation was seen; this implies an upper limit of 2.3 x 10 -4 for the abundance of this type of anomalous proton relative to protons which radiate at 21 cm. The observed absence of anomalous protons also implies an absence of primordial anomalous protons since they could not have been swept up by heavier elements during cosmic nucleosynthesis. The observation is sensitive only to anomalous protons with exactly the same value for their magnetic moment that conventional ones have

  16. Structural, magnetic and electrical properties of ferromagnetic/ferroelectric multilayers

    International Nuclear Information System (INIS)

    Sirena, M.; Kaul, E.; Guimpel, J.; Steren, L. B.; Pedreros, M. B.; Rodriguez, C. A.

    2011-01-01

    The La 0.75 Sr 0.25 MnO 3 (LSMO)/Ba 0.7 Sr 0.3 TiO 3 (BSTO) superlattices and bilayers, where LSMO is ferromagnetic and BSTO is ferroelectric, were grown by dc sputtering. X-ray diffraction indicates that the samples present a textured growth with the c axis perpendicular to the substrate. Magnetization measurements show a decrease of the sample's magnetization for decreasing ferromagnetic thickness. This effect could be related to the presence of biaxial strain and a magnetic dead layer in the samples. Conductive atomic force microscopy indicates that the samples present a total covering of the ferromagnetic layer for a ferroelectric thickness higher than four unit cells. Transport tunneling of the carriers seems to be the preferred conduction mechanism through the ferroelectric layer. These are promising results for the development of multiferroic tunnel junctions.

  17. Aspects of Dzyaloshinskii-Moriya Interaction in Two Dimensional Magnetic Structures

    Science.gov (United States)

    Kundu, Anirban

    Research on topologically protected chiral magnetic structures such as magnetic domain walls (DWs) and skyrmions, have gained extensive interest because of their possible applications in magnetic data storage industries. The recently observed chiral DW structures in ultrathin ferromagnetic lms with perpendicular magnetic anisotropy has been attributed to the presence of a strong Dzyaloshinskii-Moriya interaction (DMI). In this thesis, the DMI mediated by the conduction electrons in two dimensional magnetic systems such as magnetic thin lms or at the interfaces between two magnetic materials has been studied. I calculate the Ruderman-Kittel- Kasuya-Yosida (RKKY) type indirect exchange coupling between two magnetic moments at nite temperature using the free electron band. At high temperature, the coupling strength decays with distance faster than the coupling at zero temperature but the period of oscillation remains same. However, the free electron band alone could not produce DMI. In the next step, I show addition of Rashba spin-orbit coupling (RSOC) with the spin-polarized conduction electron band produces the DMI between two magnetic ions. The essential feature of this DMI is: the coupling strength increases with the strength of RSOC, but decreases signi cantly with the Heisenberg exchange coupling. The DMI calculated with this model well explains the possibility of preferred Neel or Bloch DW structures with specifc chirality. In addition: I study switching of magnetization with ultrafast laser pulse by inverse Faraday e ect (IFE) where an optically induced non-equilibrium orbital momentum generates an e ective magnetic eld via spin-orbit coupling for magnetization switching. I calculate the magnitude of induced orbital moment for the generic itinerant band and show that magnitude is not large enough to make the switching by a single pulse, however, switching could be possible if multiple pulses are applied to the material.

  18. Electron thermal confinement in a partially stochastic magnetic structure

    Science.gov (United States)

    Morton, L. A.; Young, W. C.; Hegna, C. C.; Parke, E.; Reusch, J. A.; Den Hartog, D. J.

    2018-04-01

    Using a high-repetition-rate Thomson scattering diagnostic, we observe a peak in electron temperature Te coinciding with the location of a large magnetic island in the Madison Symmetric Torus. Magnetohydrodynamic modeling of this quasi-single helicity plasma indicates that smaller adjacent islands overlap with and destroy the large island flux surfaces. The estimated stochastic electron thermal conductivity ( ≈30 m 2/s ) is consistent with the conductivity inferred from the observed Te gradient and ohmic heating power. Island-shaped Te peaks can result from partially stochastic magnetic islands.

  19. Magnetooptics and electronic structure of the magnetic ordering europium chalcogenides

    International Nuclear Information System (INIS)

    Schoenes, J.

    1975-01-01

    The absorption coefficient and the interband Faraday rotation of EuS, EuSe and EuTe thin films have been measured as function of the photon energy (1-6 eV), the temperature (2.7-300 K) and the applied magnetic field (0-11.5 kOe). In addition a magnetic field modulation technique has been developed, with a resolution of 2 x 10 -4 deg. This allows the measurement of the Faraday rotation in fields of only 100 Oe, which is important for metamagnetic samples with low critical fields. (orig./HPoe) [de

  20. Electronically- and crystal-structure-driven magnetic structures and physical properties of RScSb (R = rare earth) compounds. A neutron diffraction, magnetization and heat capacity study

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, C [Institut Lauer-Langevin, Grenoble (France); Dhar, S K [TIFR, Mumbai (India); Kulkarni, R [TIFR, Mumbai (India); Provino, A [Inst. SPIN-CNR, Genova (Italy); Univ. of Genova (Italy); Ames Lab., Ames, IA (United States); Paudyal, Durga [Ames Lab., Ames, IA (United States); Manfrinetti, Pietro [Inst. SPIN-CNR, Genova (Italy); Univ. of Genova (Italy); Ames Lab., Ames, IA (United States); Gschneidner, Karl A [Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

    2014-08-14

    The synthesis of the new equiatomic RScSb ( R = La-Nd, Sm, Gd-Tm, Lu, Y) compounds has been recently reported. These rare earth compounds crystallize in two different crystal structures, adopting the CeScSi-type ( I 4/ mmm) for the lighter R (La-Nd, Sm) and the CeFeSi-type (P4 /nmm) structure for the heavier R ( R = Gd-Tm, Lu, Y). Here we report the results of neutron diffraction, magnetization and heat capacity measurements on some of these compounds ( R = Ce, Pr, Nd, Gd and Tb). Band structure calculations have also been performed on CeScSb and GdScGe (CeScSi-type), and on GdScSb and TbScSb (CeFeSi-type) to compare and understand the exchange interactions in CeScSi and CeFeSi structure types. The neutron diffraction investigation shows that all five compounds order magnetically, with the highest transition temperature of 66 K in TbScSb and the lowest of about 9 K in CeScSb. The magnetic ground state is simple ferromagnetic (τ = [0 0 0]) in CeScSb, as well in NdScSb for 32 >T > 22 K. Below 22 K a second magnetic transition, with propagation vector τ = [¼ ¼ 0], appears in NdScSb. PrScSb has a magnetic structure within, determined by mostly ferromagnetic interactions and antiferromagnetic alignment of the Pr-sites connected through the I-centering ( τ = [1 0 0]). A cycloidal spiral structure with a temperature dependent propagation vector τ = [δ δ ½] is found in TbScSb. The results of magnetization and heat capacity lend support to the main conclusions derived from neutron diffraction. As inferred from a sharp peak in magnetization, GdScSb orders antiferromagnetically at 56 K. First principles calculations show lateral shift of spin split bands towards lower energy from the Fermi level as the CeScSi-type structure changes to the CeFeSi-type structure. This rigid shift may force the system to transform from exchange split ferromagnetic state to the antiferromagnetic state in RScSb compounds (as seen for example in GdScSb and TbScSb) and is proposed to

  1. Mechanism and scaling for convection of isolated structures in nonuniformly magnetized plasmas

    DEFF Research Database (Denmark)

    Garcia, O.E.; Bian, N.H.; Naulin, V.

    2005-01-01

    Large-scale radial advection of isolated structures in nonuniformly magnetized plasmas is investigated. The underlying mechanism considered is due to the nonlinear evolution of interchange motions, without any presumption of plasma sheaths. Theoretical arguments supported by numerical simulations...

  2. Nuclear resonant scattering of synchrotron radiation: Applications in magnetism of layered structures

    International Nuclear Information System (INIS)

    Schlage, Kai; Röhlsberger, Ralf

    2013-01-01

    Highlights: •Depth-resolved determination of magnetic spin structures. •Isotopic probe layers allow for probing selected depths in the sample. •High sensitivity to magnetic domain patterns via diffuse scattering. -- Abstract: Nuclear resonant scattering of synchrotron radiation has become an established tool within condensed-matter research. Synchrotron radiation with its outstanding brilliance, transverse coherence and polarization has opened this field for many unique studies, for fundamental research in the field of light-matter interaction as well as for materials science. This applies in particular for the electronic and magnetic structure of very small sample volumes like micro- and nano-structures and samples under extreme conditions of temperature and pressure. This article is devoted to the application of the technique to nanomagnetic systems such as thin films and multilayers. After a basic introduction into the method, a number of our experiments are presented to illustrate how magnetic spin structures within such layer systems can be revealed

  3. Synthesis, structure and magnetism of manganese and iron dipicolinates with N,N '-donor ligands

    Czech Academy of Sciences Publication Activity Database

    Uhrecký, Róbert; Svoboda, I.; Růžičková, Z.; Koman, M.; Dlháň, L.; Pavlík, J.; Moncol, J.; Boca, R.

    2015-01-01

    Roč. 425, JAN (2015), s. 134-144 ISSN 0020-1693 Institutional support: RVO:61388980 Keywords : Manganese * Iron * Dipicolinate complexes * Crystal structure * Magnetism Subject RIV: CA - Inorganic Chemistry Impact factor: 1.918, year: 2015

  4. Structural, Electronic, Magnetic, and Vibrational Properties of Graphene and Silicene: A First-Principles Perspective

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-01-01

    This thesis covers the structural, electronic, magnetic, and vibrational properties of graphene and silicene. In Chapter I, we will start with an introduction to graphene and silicene. In Chapter II, we will briefly discuss about the methodology (i

  5. Magnetization Dynamics in Two Novel Current-Driven Spintronic Memory Cell Structures

    KAUST Repository

    Velazquez-Rizo, Martin

    2017-01-01

    In this work, two new spintronic memory cell structures are proposed. The first cell uses the diffusion of polarized spins into ferromagnets with perpendicular anisotropy to tilt their magnetization followed by their dipolar coupling to a fixed

  6. Structural and magnetic studies of Cr doped nickel ferrite thin films

    International Nuclear Information System (INIS)

    Panwar, Kalpana; Heda, N. L.; Tiwari, Shailja; Bapna, Komal; Ahuja, B. L.; Choudhary, R. J.; Phase, D. M.

    2016-01-01

    We have studied the structural and magnetic properties of Cr doped nickel ferrite thin films deposited on Si (100) and Si (111) using pulsed laser deposition technique. The films were deposited under vacuum and substrate temperature was kept at 700°C. X-ray diffraction analysis revealed that films on both substrates have single phase cubic spinel structure. However, the film grown on Si (111) shows better crystalline behavior. Fourier transform infrared spectroscopy suggests that films on both substrates have mixed spinel structure. These films show magnetic hysteresis behavior and magnetization value of film on Si (100) is larger than that on Si (111). It turns out that structural and magnetic properties of these two films are correlated.

  7. Delineation of structural lineaments from marine magnetic anomalies off Lawson's Bay (Visakhapatnam), East Coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Murthy, K.S.R.; Rao, T.C.S.; Rao, M.M.M.

    Marine magnetic surveys have recorded total field anomalies that correspond to structural lineaments extending from the coast into the sea. The significant anomalies recorded in this area are along wavelength high amplitude negative anomaly...

  8. Testing the structure of magnetic paints with and without superimposed shear

    NARCIS (Netherlands)

    Potanin, A.; Potanin, Andrei A.; Shrauti, Suresh M.; Arnold, David W.; Lane, Alan M.; Mellema, J.

    1997-01-01

    The structure development in dispersions of magnetic barium ferrite particles in cyclohexanone with polyvinylchloride wetting resin was tested by oscillatory rheological measurements and orthogonal superposition of steady and oscillatory shear. The optimum dispersion is achieved at the resin

  9. A video-image study of electrolytic flow structure in parallel electric-magnetic fields

    International Nuclear Information System (INIS)

    Gu, Z.H.; Fahidy, T.Z.

    1987-01-01

    The structure of free convective flow propagating from a vertical cathode into the electrolyte bulk has been studied via video-imaging. The enhancing effect of imposed horizontal uniform magnetic fields is manifest by vortex propagation and bifurcating flow

  10. Gradual pressure-induced change in the magnetic structure of the noncollinear antiferromagnet Mn3Ge

    Science.gov (United States)

    Sukhanov, A. S.; Singh, Sanjay; Caron, L.; Hansen, Th.; Hoser, A.; Kumar, V.; Borrmann, H.; Fitch, A.; Devi, P.; Manna, K.; Felser, C.; Inosov, D. S.

    2018-06-01

    By means of powder neutron diffraction we investigate changes in the magnetic structure of the coplanar noncollinear antiferromagnet Mn3Ge caused by an application of hydrostatic pressure up to 5 GPa. At ambient conditions the kagomé layers of Mn atoms in Mn3Ge order in a triangular 120∘ spin structure. Under high pressure the spins acquire a uniform out-of-plane canting, gradually transforming the magnetic texture to a noncoplanar configuration. With increasing pressure the canted structure fully transforms into the collinear ferromagnetic one. We observed that magnetic order is accompanied by a noticeable magnetoelastic effect, namely, spontaneous magnetostriction. The latter induces an in-plane magnetostrain of the hexagonal unit cell at ambient pressure and flips to an out-of-plane strain at high pressures in accordance with the change of the magnetic structure.

  11. Structural performance of the first SSC [Superconducting Super Collider] Design B dipole magnet

    International Nuclear Information System (INIS)

    Nicol, T.H.

    1989-09-01

    The first Design B Superconducting Super Collider (SSC) dipole magnet has been successfully tested. This magnet was heavily instrumented with temperature and strain gage sensors in order to evaluate its adherence to design constraints and design calculations. The instrumentation and associated data acquisition system allowed monitoring of the magnet during cooldown, warmup, and quench testing. This paper will focus on the results obtained from structural measurements on the suspension system during normal and rapid cooldowns and during quench studies at full magnet current. 4 refs., 9 figs

  12. Design optimization of seal structure for sealing liquid by magnetic fluids

    International Nuclear Information System (INIS)

    Liu Tonggang; Cheng Yusheng; Yang Zhiyi

    2005-01-01

    The durability of the magnetic fluid seal clearly decreases when sealing another liquid because of the interface instability caused by the applied magnetic field and the velocity difference of the two liquids. With an intention to establish a stable interface during sealing liquid, a new magnetic fluid seal was developed in this paper. The parameters of the structure were optimized by a simulation apparatus. And the magnetic fluid seal designed based on the optimum parameters shows good performance and long life for sealing lubricating oil

  13. Magnetic topology of Co-based inverse opal-like structures

    Science.gov (United States)

    Grigoryeva, N. A.; Mistonov, A. A.; Napolskii, K. S.; Sapoletova, N. A.; Eliseev, A. A.; Bouwman, W.; Byelov, D. V.; Petukhov, A. V.; Chernyshov, D. Yu.; Eckerlebe, H.; Vasilieva, A. V.; Grigoriev, S. V.

    2011-08-01

    The magnetic and structural properties of a cobalt inverse opal-like crystal have been studied by a combination of complementary techniques ranging from polarized neutron scattering and superconducting quantum interference device (SQUID) magnetometry to x-ray diffraction. Microradian small-angle x-ray diffraction shows that the inverse opal-like structure (OLS) synthesized by the electrochemical method fully duplicates the three-dimensional net of voids of the template artificial opal. The inverse OLS has a face-centered cubic (fcc) structure with a lattice constant of 640±10 nm and with a clear tendency to a random hexagonal close-packed structure along the [111] axes. Wide-angle x-ray powder diffraction shows that the atomic cobalt structure is described by coexistence of 95% hexagonal close-packed and 5% fcc phases. The SQUID measurements demonstrate that the inverse OLS film possesses easy-plane magnetization geometry with a coercive field of 14.0 ± 0.5 mT at room temperature. The detailed picture of the transformation of the magnetic structure under an in-plane applied field was detected with the help of small-angle diffraction of polarized neutrons. In the demagnetized state the magnetic system consists of randomly oriented magnetic domains. A complex magnetic structure appears upon application of the magnetic field, with nonhomogeneous distribution of magnetization density within the unit element of the OLS. This distribution is determined by the combined effect of the easy-plane geometry of the film and the crystallographic geometry of the opal-like structure with respect to the applied field direction.

  14. Frustrated Heisenberg Antiferromagnets on Cubic Lattices: Magnetic Structures, Exchange Gaps, and Non-Conventional Critical Behaviour

    OpenAIRE

    Ignatenko, A. N.; Irkhin, V. Yu.

    2016-01-01

    We have studied the Heisenberg antiferromagnets characterized by the magnetic structures with the periods being two times larger than the lattice period. We have considered all the types of the Bravais lattices (simple cubic, bcc and fcc) and divided all these antiferromagnets into 7 classes i.e. 3 plus 4 classes denoted with symbols A and B correspondingly. The order parameter characterizing the degeneracies of the magnetic structures is an ordinary Neel vector for A classes and so-called 4-...

  15. Crystal structure and magnetism of UOsAl

    Czech Academy of Sciences Publication Activity Database

    Andreev, Alexander V.; Daniš, S.; Šebek, Josef; Henriques, Margarida Isabel Sousa; Vejpravová, Jana; Gorbunov, Denis; Havela, L.

    2017-01-01

    Roč. 428, Apr (2017), s. 144-147 ISSN 0304-8853 R&D Projects: GA ČR GA16-03593S Institutional support: RVO:68378271 Keywords : uranium intermetallics * laves phases * Pauli paramagnetism Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.630, year: 2016

  16. Pressure-induced magnetic structures in UNiGa

    Czech Academy of Sciences Publication Activity Database

    Sechovský, V.; Prokeš, K.; Honda, F.; Ouladdiaf, B.; Kulda, Jiří

    2002-01-01

    Roč. 74, č. 1 (2002), s. S834-S836 ISSN 0947-8396 R&D Projects: GA AV ČR KSK1010104 Keywords : magnetoelastic phenomena Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.231, year: 2002

  17. Structural and magnetic anomalies among the spin-chain ...

    Indian Academy of Sciences (India)

    Unknown

    on temperature/field cycling-history, which are difficult to understand. On the other hand, the compound, Ca3CoIrO6, exhibits magnetic frustration effects around 30–50 K in the ac and dc M .... data points serve as guides to the eye. sition is a ...

  18. Structural, electronic and magnetic properties of MnB2

    Indian Academy of Sciences (India)

    5Hassan II Academy of Science and Technology, Rabat, Morocco ... Abstract. The self-consistent ab-initio calculations, based on density functional theory approach and using the full ... The exchange interactions between the magnetic atoms Mn–Mn in MnB2 are ... involved, and on the local environment of the transition-.

  19. Structure and magnetic properties of nickel nanoparticles preparedby selective leaching

    Czech Academy of Sciences Publication Activity Database

    Michalcová, A.; Svobodová, P.; Nováková, R.; Len, A.; Heczko, Oleg; Vojtěch, D.; Marek, I.; Novák, P.

    2014-01-01

    Roč. 137, Dec (2014), s. 221-224 ISSN 0167-577X R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:68378271 Keywords : nanoparticles * magnetic materials * metals and alloys * route * size Subject RIV: JG - Metallurgy Impact factor: 2.489, year: 2014

  20. Structures, energetics and magnetic properties of AunSFem and ...

    African Journals Online (AJOL)

    Bheema

    For a better efficiency of the cancer treatment, magnetically directed drug ... to treat a variety of tumors such as anaplastic astrocytomas or glioblastomas. .... the two Au atom clusters, figure 1 (II-a,b), the Fe atom tends to stay between the Au ...

  1. Magnetic structure and resonance properties of hexagonal antidot lattice

    International Nuclear Information System (INIS)

    Marchenko, A.I.; Krivoruchko, V.N.

    2012-01-01

    Static and resonance properties of ferromagnetic films with an antidot lattice (pores in the film) are studied. The description of the system is based on micromagnetic modeling and analytical solution of the Landau-Lifshitz equation. The dependences of ferromagnetic resonance spectra on the in-plane direction of applied magnetic field and on the lattice parameters are investigated. The dependences of a dynamic system response on frequency at fixed magnetic field and on field at fixed frequency, when the field changes cause the static magnetic order to change are explored. It is found that the specific peculiarities of the system dynamics leave unchange for both of these experimental conditions. Namely, for low damping the resonance spectra contain three quasi-homogeneous modes which are due to the resonance of different regions (domains) of the antidot lattice cell. It is shown the angular field dependences of each mode are characterized by a twofold symmetry and the related easy axes are mutually rotated by 60 degrees. As the result, a hexagonal symmetry of the system static and dynamic magnetic characteristics is realized. The existence in the resonance spectrum of several quasi-homogeneous modes related to different regions of the unit cell could be fundamental for working elements of magnonic devices.

  2. Strain-induced structural, magnetic and ferroelectric properties of ...

    Indian Academy of Sciences (India)

    2017-07-25

    Jul 25, 2017 ... deposited on the composite film surface by DC sputtering techniques. The magnetic measurements of these composite films were performed using a vibratory sample magnetometer. (VSM). Ferroelectric properties of films were measured using a Precision multiferroic analyser. All measurements were per-.

  3. A Monolithic Perovskite Structure for Use as a Magnetic Regenerator

    DEFF Research Database (Denmark)

    Pryds, Nini; Clemens, Frank; Menon, Mohan

    2011-01-01

    A La0.67Ca0.26Sr0.07Mn1.05O3 (LCSM) perovskite was prepared for the first time as a ceramic monolithic regenerator used in a regenerative magnetic refrigeration device. The parameters influencing the extrusion process and the performance of the regenerator, such as the nature of the monolith paste...

  4. Electronic structure and magnetic properties of KCrSe2

    NARCIS (Netherlands)

    Fang, C.M.; Tolsma, P.R.; Groot, R.A. de; Wiegers, G.A.; Haas, C.; vanBruggen, C.F.; deGroot, R.A.

    1996-01-01

    KCrSe2 characterized by x-ray powder diffraction is a layered compound isostructural with NaCrSe2: a = 3.80 Angstrom; c = 22.19 Angstrom; space group R (3) over bar m. The magnetic properties are similar to those of NaCrSe2 but with ari even more pronounced difference between the intralayer and

  5. Structure from the chaos: magnetic fields of cosmic objects

    Energy Technology Data Exchange (ETDEWEB)

    Krause, F

    1987-01-01

    The study deals with phenomenological and theoretical models in order to explain the existence of cosmic magnetic fields. Following aspects are considered: non-linear recursions, the theory of chaotic motions, turbulence, convection, the turbulent dynamo theory and magnetohydrodynamics. In the frame of these model assumptions it is tried to explain the causes of the solar activity cycle and the geomagnetic field.

  6. Density functional theory study of structure, electronic and magnetic ...

    Indian Academy of Sciences (India)

    ABHIJIT DUTTA

    2018-01-30

    Jan 30, 2018 ... magnetic properties of non-metal (Group 13) doped stable. Rhn(n = 2−8) ... Deformed electron density was found to be higher in the case of Rh5B, Rh4Al, Rh7Al and ...... systems: Modeling of surface alloys and alloy surfaces.

  7. Size effect on magnetic properties of a nano-graphene bilayer structure: A Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Masrour, R. [Laboratory of Materials, Process, Environment and Quality, Cady Ayyad University, National School of Applied Sciences, Safi (Morocco); Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco); Bahmad, L., E-mail: bahmad@fsr.ac.ma [Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco); Benyoussef, A. [Laboratoire de Magnetisme et Physique des Hautes Energies L.M.P.H.E.URAC 12, Universite Mohammed V-Agdal, Faculte des Sciences, B.P. 1014 Rabat (Morocco)

    2012-11-15

    In this paper we use the Monte Carlo simulations to investigate the magnetic properties of an Ising ferromagnetic-antiferromagnetic model. The system is based on a nano-graphene structure-like bilayer with two bloc sizes: N=24 and 42 spins. For each size N, the upper layer A is formed with spin -3/2, whereas the lower layer B is composed of spin -5/2. We only consider the first nearest-neighbor interactions between the sites i and j. The magnetic properties are studied, in the absence as well as in the presence of a crystal magnetic field, and an external magnetic field. The increasing temperature and crystal field as well as the inter-layer coupling constant, are also studied for this system sizes N=24 and 42 spins. The zero-field-cooled and the field cooled magnetization behaviors are investigated for different values of external magnetic field and a fixed value of exchange interaction between the two blocs. The magnetizations as well as the magnetic susceptibilities versus the temperature are used in order to obtain blocking temperature. The saturation magnetization and coercive field are also obtained for the two sizes of the studied system. It is found that the blocking temperature decreases on increasing the crystal magnetic field and/or the external magnetic field, for a fixed system size. On the other hand, it is found that the blocking temperature increases on increasing the system size from N=24 to 42 spins, for fixed values of external and the crystal magnetic fields. - Highlights: Black-Right-Pointing-Pointer Magnetic properties of an Ising ferromagnetic-antiferromagnetic bilayer is studied. Black-Right-Pointing-Pointer Monte Carlo simulations are used. Black-Right-Pointing-Pointer Zero-field-cooled (ZFC) and field cooled (FC) magnetization behaviors for nano-graphene are obtained.

  8. Structural and magnetic studies on spark plasma sintered SmCo{sub 5}/Fe bulk nanocomposite magnets

    Energy Technology Data Exchange (ETDEWEB)

    Rama Rao, N.V. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Gopalan, R. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India)]. E-mail: rg_gopy@yahoo.com; Manivel Raja, M. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Chandrasekaran, V. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Chakravarty, D. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500 005 (India); Sundaresan, R. [International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad 500 005 (India); Ranganathan, R. [Saha Institute of Nuclear Physics, Kolkata 700 064 (India); Hono, K. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305 0047 (Japan)

    2007-05-15

    SmCo{sub 5}+xwt% Fe (x=0, 5 and 10) nanocomposite powders were synthesized by mechanical milling and were consolidated into bulk shape by spark plasma sintering (SPS) technique. The evolution of structure and magnetic properties were systematically investigated in milled powders as well as in SPS samples. A maximum coercivity of 8.9kOe was achieved in spark plasma sintered SmCo{sub 5}+5wt% Fe sample. The exchange spring interaction between the hard and soft magnetic phases was evaluated using {delta}M-H measurements and the analysis revealed that the SPS sample containing 5wt% Fe had a stronger exchange coupling between the magnetic phases than that of the sample with10wt% Fe.

  9. Structural and magnetic characterization of martensitic Ni-Mn-Ga thin films deposited on Mo foil

    International Nuclear Information System (INIS)

    Chernenko, V.A.; Anton, R. Lopez; Kohl, M.; Barandiaran, J.M.; Ohtsuka, M.; Orue, I.; Besseghini, S.

    2006-01-01

    Three martensitic Ni 51.4 Mn 28.3 Ga 20.3 thin films sputter-deposited on a Mo foil were investigated with regard to their crystal and magnetic domain structures, as well as their magnetic and magnetostrain properties. The film thicknesses, d, were 0.1, 0.4 and 1.0μm. X-ray and electron diffraction patterns revealed a tetragonal modulated martensitic phase (10M) in the films. The surface topography and micromagnetic structure were studied by scanning probe microscopy. A maze magnetic domain structure featuring a large out-of-plane magnetization component was found in all films. The domain width, δ, depends on the film thickness as δ∼d. The thickness dependencies of the saturation magnetization, saturation magnetic field and magnetic anisotropy were clarified. Beam cantilever tests on the Ni-Mn-Ga/Mo composite as a function of magnetic field showed reversible strains, which are larger than ordinary magnetostriction

  10. Moessbauer determination of magnetic structure of Fe3BO6 crystal

    International Nuclear Information System (INIS)

    Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

    1984-01-01

    The magnetic structure of a Fe 3 BO 6 crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer γ-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV γ-quanta from the Fe 3 BO 6 monocrystal has been studied experimentally. A high sensitivity of the interference of γ-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe 3 BO 6 . Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail

  11. Moessbauer determination of magnetic structure of Fe/sub 3/BO/sub 6/ crystal

    Energy Technology Data Exchange (ETDEWEB)

    Kovalenko, P.P.; Labushkin, V.G.; Ovsepyan, A.K.; Sarkisov, Eh.R.; Smirnov, E.V.; Prokopov, A.R.; Seleznev, V.N.

    1984-10-01

    The magnetic structure of a Fe/sub 3/BO/sub 6/ crystal belonging to space group Dsub(2h)sup(16)(Psub(nma)) is determined by the Moessbauer ..gamma..-radiation diffraction. The bragg reflection (700) of Moessbauer 14.4 keV ..gamma..-quanta from the Fe/sub 3/BO/sub 6/ monocrystal has been studied experimentally. A high sensitivity of the interference of ..gamma..-quantum diffraction scattering on Fe nuclei being in crystallographically non-equivalent 8d- and 4s-positions to the type of magnetic ordering in the crystal is used for determination of the magnetic structure. Agreement of the experimental results with the theoretical calculations, conducted for types of magnetic ordering resolved by the symmetry of the crystal, permitted to reliably determine the magnetic structure of this compound. The results obtained confirm the data of neutrondiffraction studies on magnetic ordering in Fe/sub 3/BO/sub 6/. Advantages of the Moessbauer-diffraction study, as compared to the magnetic neutrondiffraction method, in particular, for investigation of crystals, in which the hyperfine magnetic fields on Fe nuclei have different values, are revealed and discussed in detail.

  12. The method of inversion of magnetic island two-dimensional structure by magnetic probes and its application on HL-2A tokamak

    International Nuclear Information System (INIS)

    Sun Tengfei; Liu Yi; Ji Xiaoquan; Xu Yuan; Feng Beibin

    2011-01-01

    The new method that reconstructs the polar two-dimensional structure of the magnetic island using magnetic pickup coils data is introduced on HL-2A tokamak and dynamic analysis method that set up based on it for tearing mode is also introduced. In this experiment, the perturbation current which is the source of the perturbation magnetic field can be determined using the data measured by magnetic probes. Superimposing the perturbation flux and equilibrium flux reconnected by EFIT, the structure and the width of the magnetic islands can be obtained. Then two-dimensional structure maps are set up chronologically and recorded in turn. After that these maps are revealed in turn and magnetic island can be analyzed dynamically. This method is applied to analyzing tearing mode. The conclusion that magnetic island rotating direction is in accordance with electronic diamagnetic drift direction is reached. The relationship between the magnetic island width and the magnetic perturbation field is proved and the suppression of magnetic island by ECRH is also verified.It shows the immediacy of the method of inversion of magnetic island structure by magnetic probes and it is very useful for watching and controlling MHD instability. (authors)

  13. Auroral electrojet dynamics during magnetic storms, connection with plasma precipitation and large-scale structure of the magnetospheric magnetic field

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    1999-04-01

    Full Text Available Effect of the equatorward shift of the eastward and westward electrojets during magnetic storms main phase is analyzed based on the meridional chains of magnetic observatories EISCAT and IMAGE and several Russian observatories (geomagnetic longitude ~110°, corrected geomagnetic latitudes 74°F 51°. Magnetic storms of various Dst index intensity where the main phase falls on 1000 UT - 2400 UT interval were selected so that one of the observatory chains was located in the afternoon - near midnight sector of MLT. The eastward electrojet center shifts equatorward with Dst intensity increase: when Dst ~ - 50 nT the electrojet center is located at F ~ 62°, when Dst ~ -300 nT it is placed at F ~54°. The westward electrojet center during magnetic storms main phase for intervals between substorms shifts equatorward with Dst increase: at F~ 62° when Dst ~ -100 nT and at F ~ 55° when Dst ~ -300 nT. During substorms within the magnetic storms intervals the westward electrojet widens poleward covering latitudes F~ 64°- 65°. DMSP (F08, F10 and F11 satellite observations of auroral energy plasma precipitations at upper atmosphere altitudes were used to determine precipitation region structure and location of boundaries of various plasma domains during magnetic storms on May 10-11, 1992, February 5-7 and February 21-22, 1994. Interrelationships between center location, poleward and equatorward boundaries of electrojets and characteristic plasma regions are discussed. The electrojet center, poleward and equatorward boundaries along the magnetic observatories meridional chain were mapped to the magnetosphere using the geomagnetic field paraboloid model. The location of auroral energy oxygen ion regions in the night and evening magnetosphere is determined. Considerations are presented on the mechanism causing the appearance in the inner magnetosphere during active intervals of magnetic storms of ions with energy of tens KeV. In the framework of the

  14. Structural and morphological investigation of magnetic nanoparticles based on iron oxides for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, Paula S. [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil)], E-mail: pferreira@lnls.br; Martins, Tatiana M. [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil); Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6165, CEP 13083-970, Campinas-SP (Brazil); D' Souza-Li, Lilia [Laboratorio de Endocrinologia Pediatrica da Faculdade de Ciencias Medicas (FCM), UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Li, Li M. [Departamento de Neurologia da FCM, UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Metze, Konradin; Adam, Randall L. [Grupo interdisciplinar ' Patologia Analitica Celular' , Departamento de Anatomia Patologica da FCM, UNICAMP, Caixa Postal 6111, CEP 13083-970, Campinas-SP (Brazil); Knobel, Marcelo [Instituto de Fisica Gleb Wataghin (IFGW), Universidade Estadual de Campinas (UNICAMP), Caixa Postal 6165, CEP 13083-970, Campinas-SP (Brazil); Zanchet, Daniela [Laboratorio Nacional de Luz Sincrotron (LNLS), Caixa Postal 6192, CEP 13083-970, Campinas-SP (Brazil)

    2008-05-01

    The present work reports the synthesis, characterization and properties of magnetic iron oxide nanoparticles for biomedical applications, correlating the nanoscale tunabilities in terms of size, structure, and magnetism. Magnetic nanoparticles in different conditions were prepared through thermal decomposition of Fe(acac){sub 3} in the presence of 1,2 hexadecanodiol (reducing agent) and oleic acid and oleylamine (ligands) in a hot organic solvent. The 2,3-dimercaptosuccinic acid (DMSA) was exchanged onto the nanocrystal surface making the particles stable in water. Nanoparticles were characterized by X-ray diffraction (XRD) measurements, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Preliminary tests of incorporation of these nanoparticles in cells and their magnetic resonance image (MRI) were also carried out. The magnetization characterizations were made by isothermal magnetic measurements.

  15. Magnetic characterization of creep-fatigue damage for energy structural materials

    International Nuclear Information System (INIS)

    Suzuki, Takayuki; Hashidate, Ryuta; Harada, Yoshihisa

    2012-01-01

    Magnetic characterization of creep-fatigue damage for welded specimens of austenitic stainless steel (SUS316FR) and high-chromium steel (Mod.9Cr-1Mo) steel was performed using magnetic force microscope and Hall sensor. In SUS316FR volume fraction of δ-ferrite at weld metal region decreased by creep or creep-fatigue and the remanent magnetic flux density at weld metal region also decreased. In Mod.9Cr-1Mo steel magnetic characteristics at weld metal region were different from those at base metal initially, however, during creep or creep fatigue the difference of magnetic characteristics between welded metal and base metal became small. It was found that the degradation mechanism for these energy structural materials during creep or creep fatigue could be clarified by magnetic characterization techniques. (author)

  16. Experimental Investigation of the Spiral Structure of a Magnetic Capsule Endoscope

    Directory of Open Access Journals (Sweden)

    Wanan Yang

    2016-06-01

    Full Text Available Fitting a wireless capsule endoscope (WCE with a navigation feature can maximize its functional benefits. The rotation of a spiral-type capsule can be converted to translational motion. The study investigated how the spiral structure and rotational speed affected the capsule's translation speed. A hand-held instrument, including two permanent magnets, a stepper motor, a controller and a power supplier, were designed to generate rotational magnetic fields. The surfaces of custom-built permanent magnet rings magnetized radially were mounted in spiral lines with different lead angles and diameters, acting as mock-up capsules. The experimental results demonstrate that the rotational speed of the magnetic field and the spiral have significant effects on the translational speed of a capsule. The spiral line with a larger lead angle and the rotating magnetic field with a higher speed can change the capsule's rotation into a translational motion more efficiently in the intestine.

  17. Magnetic and structural characterization of the semiconductor FeIn2Se4

    International Nuclear Information System (INIS)

    Torres, T.; Sagredo, V.; Chalbaud, L.M. de; Attolini, G.; Bolzoni, F.

    2006-01-01

    Plate-like single crystals of magnetic semiconductor FeIn 2 Se 4 were grown with a chemical vapour transport technique. The X-ray powder diffraction analyses suggest that the compound crystallize in the hexagonal structure with space group P3m1. We have performed dc magnetization measurements at different magnetic fields on the diluted magnetic semiconductor FeIn 2 Se 4 . Low field magnetizations measurements shows irreversibility in the DC magnetization, as evidenced by field cooled and zero field cooled measurements below 17 K, suggesting a spin-glass like behaviour. The high-temperature susceptibility data follow a typical Curie-Weiss law with θ=-183±2 K which suggest the presence of predominant antiferromagnetic interactions with high degree of frustration. The randomness and frustration necessary for spin-glass behaviour are explained in a manner compatible with the cation and charge ordering present in the material

  18. Orbital and magnetic structure of quasi-1D cobaltites: Ab initio calculations and experiment

    International Nuclear Information System (INIS)

    Pardo, V.; Baldomir, D.; Rivas, J.; Castro, J.; Arias, J.E.

    2006-01-01

    The magnetic properties of the orbitally degenerate quasi-one-dimensional cobaltites Sr x Ba 1-x CoO 3 are explained on the basis of a phase separation phenomenon. Noninteracting magnetic particles embedded in a nonferromagnetic matrix develop in the system. Details are given about the electronic and magnetic structure for x=0,0.2 and 0.5. At x=0.5, the geometry of the CoO 6 trigonally distorted octahedra changes by about 1-2%, but magnetic particles get 3 times bigger, compared to the parent compound, with the corresponding changes in the magnetic properties. The electronic structure of the Co 4+ ion, however, stays roughly unchanged

  19. Transition metal implanted ZnO. A correlation between structure and magnetism

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shengqiang

    2008-07-01

    Nowadays ferromagnetism is often found in potential diluted magnetic semiconductor systems. However, many authors question the origin of this ferromagnetism, i.e. if the observed ferromagnetism stems from ferromagnetic precipitates rather than from carriermediated magnetic coupling of ionic impurities, as required for a diluted magnetic semiconductor. In this thesis, this question will be answered for transition-metal implanted ZnO single crystals. Magnetic secondary phases, namely metallic Fe, Co and Ni nanocrystals, are formed inside ZnO. They are - although difficult to detect by common approaches of structural analysis - responsible for the observed ferromagnetism. Particularly Co and Ni nanocrystals are crystallographically oriented with respect to the ZnO matrix. Their structure phase transformation and corresponding evolution of magnetic properties upon annealing have been established. Finally, an approach, pre-annealing ZnO crystals at high temperature before implantation, has been demonstrated to sufficiently suppress the formation of metallic secondary phases. (orig.)

  20. Structural Health Monitoring of Superconducting Magnets at CERN Using Fiber Bragg Grating Sensors

    CERN Document Server

    Chiuchiolo, A; Perez, J C; Bajas, H; Guinchard, M; Giordano, M; Breglio, G; Consales, M; Cusano, A

    2014-01-01

    The use of Fiber Bragg Grating sensors is becoming particularly challenging for monitoring different parameters in extreme operative conditions such as ultra-low temperatures, high electromagnetic fields and strong mechanical stresses. This work reports the use of the FBG for a new generation of accelerator magnets with the goal to develop an adequate sensing technology able to provide complementary or alternative information to the conventional strain gauges through the whole service life of the magnet. The study is focused on the mechanical performances of the magnet structure, which has to preserve the sensitive coils from any damage during the entire magnet fabrication process preventing even microscopic movements of the winding that can eventually initiate a transition from superconducting to normal conducting state of the material used (called in the specific literature as “quench”). The FBGs have been glued on the aluminium structure of two magnets prototypes by using an adhesive suitable for cryog...

  1. Magnetic structure driven ferroelectricity and large magnetoelectric coupling in antiferromagnet Co4Nb2O9

    Science.gov (United States)

    Srivastava, P.; Chaudhary, S.; Maurya, V.; Saha, J.; Kaushik, S. D.; Siruguri, V.; Patnaik, S.

    2018-05-01

    Synthesis and extensive structural, pyroelectric, magnetic, dielectric and magneto-electric characterizations are reported for polycrystalline Co4Nb2O9 towards unraveling the multiferroic ground state. Magnetic measurements confirm that Co4Nb2O9 becomes an anti-ferromagnet at around 28 K. Associated with the magnetic phase transition, a sharp peak in pyroelectric current indicates the appearance of strong magneto-electric coupling below Neel temperature (TN) along with large coupling constant upto 17.8 μC/m2T. Using temperature oscillation technique, we establish Co4Nb2O9 to be a genuine multiferroic with spontaneous electric polarization in the anti-ferromagnetic state in the absence of magnetic field poling. This is in agreement with our low temperature neutron diffraction studies that show the magnetic structure of Co4Nb2O9 to be that of a non-collinear anti-ferromagnet with ferroelectric ground state.

  2. Competing effect of spin-orbit torque terms on perpendicular magnetization switching in structures with multiple inversion asymmetries

    OpenAIRE

    Yu, Guoqiang; Akyol, Mustafa; Upadhyaya, Pramey; Li, Xiang; He, Congli; Fan, Yabin; Montazeri, Mohammad; Alzate, Juan G.; Lang, Murong; Wong, Kin L.; Khalili Amiri, Pedram; Wang, Kang L.

    2016-01-01

    Current-induced spin-orbit torques (SOTs) in structurally asymmetric multilayers have been used to efficiently manipulate magnetization. In a structure with vertical symmetry breaking, a damping-like SOT can deterministically switch a perpendicular magnet, provided an in-plane magnetic field is applied. Recently, it has been further demonstrated that the in-plane magnetic field can be eliminated by introducing a new type of perpendicular field-like SOT via incorporating a lateral structural a...

  3. Modification of Turbulence Structures in a Channel Flow by Uniform Magnetic Fluxes

    Science.gov (United States)

    Lee, D.; Choi, H.; Kim, J.

    1997-11-01

    Effects of electromagnetic forcing on the near-wall turbulence are investigated by applying a uniform magnetic flux in a turbulent channel flow in the streamwise and spanwise directions, respectively. The base flow is a fully developed turbulent channel flow and the direct numerical simulation technique is used. The electromagnetic force induced from the magnetic fluxes reduces the intensity of the wall-layer structures and thus drag is significantly reduced. The wall-normal and spanwise velocity fluctuations and the Reynolds shear stress decrease with the increased magnetic flux in both directions. The streamwise velocity fluctuations increase with the streamwise magnetic flux, whereas they decrease with the spanwise magnetic flux. It is also shown that the spanwise magnetic flux is much more effective than the streamwise magnetic flux in reducing the skin-friction drag. Instantaneous Lorentz force vectors show that the flow motions by the near-wall vortices are directly inhibited by the spanwise magnetic flux, while they are less effectively inhibited by the streamwise magnetic flux. Other turbulence statistics that reveal the effects of the applied magnetic forcing will be presented. ^* Supported by KOSEF Contract No. 965-1008-003-2 and ONR Grant No. N00014-95-1-0352.

  4. Subsurface Structure Determination of Geotermal Area in Siogung-ogung Samosir District by Using Magnetic Method

    Science.gov (United States)

    Tampubolon, Togi; Hutahaean, Juniar; Siregar, Suryani N. J.

    2018-03-01

    Underwater research often uses geomagnets. It is one of the geophysical methods for measuring magnetic field variations. This research was done to identify how the subsurface rock structure is and determine kinds of rock based on its susceptibility value in Siogung-ogung geothermal area, Pangururan, Samosir District. The tool measurement of total magnetic field called Proton Precission Magnetometer, positioning using Global Position System, and north axis determination using geological compass. Data collection was done randomly with total 51 measuring points obtained. Data analysis started with International geomagnetics Reference Field correction to obtain the total magnetic field anomaly. Then, the data analysis of total magnetic anomaly was done by using surfer program 12. To get a magnetic anomaly cross section used Magdc For Windows program. Magnetic measurement results indicated that the variation of magnetic field strength in each point with the lowest magnetic intensity value of 41785.67 nano tesla. The highest magnetic intensity value is 43140, 33. From the results of qualitative interpretation, the magnetic anomaly value is at -200.92 to 1154.45 whereas the quantitative interpretive results of model show the existence of degradation and andesitic rocks, with the value of susceptibility

  5. Magnetic structure of cross-shaped permalloy arrays embedded in silicon wafers

    International Nuclear Information System (INIS)

    Machida, Kenji; Tezuka, Tomoyuki; Yamamoto, Takahiro; Ishibashi, Takayuki; Morishita, Yoshitaka; Koukitu, Akinori; Sato, Katsuaki

    2005-01-01

    This paper describes the observed magnetic structure and the micromagnetic simulation of cross-shaped, permalloy (Ni 80 Fe 20 ) arrays embedded in silicon wafers. The nano-scale-width, cross-shaped patterns were fabricated using the damascene technique, electron beam lithography, and chemical mechanical polishing. The magnetic poles were observed as two pairs of bright and dark spots at the ends of the crossed-bars using a magnetic force microscope. The force gradient distributions were simulated based on micromagnetic calculations and tip's stray field calculations using the integral equation method. This process of calculation successfully explains the appearance of the poles and complicated spin structure at the crossing region

  6. Formation of uniform magnetic structures and epitaxial hydride phases in Nd/Pr superlattices

    DEFF Research Database (Denmark)

    Goff, J.P.; Bryn-Jacobsen, C.; McMorrow, D.F.

    1997-01-01

    , and that the stacking sequence is coherent over many bilayer repeats. The neutron measurements show that for the hexagonal sites of the dhcp structure, the Nd magnetic order propagates coherently through the Pr, whereas the order on the cubic sites is either suppressed or confined to single Nd blocks. It is also shown...... that the singlet ground state of Pr is perturbed to produce a local moment on the hexagonal sites, so that in some cases there is a uniform magnetic structure throughout the superlattice. These results cast new light on the theory of magnetic interactions in rare-earth superlattices. Within a few months of growth...

  7. Structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7

    Science.gov (United States)

    Kumar, Harish; Chaurasia, Rachna; Kumari, Pratibha; Paramanik, A. K.

    2018-04-01

    We have studied the structural, magnetic, and electronic transport properties of pyrochlore iridate Pr2Ir2O7. Structural investigation has been done using x-ray powder diffraction and Rietveld analysis. Pr2Ir2O7 crystallize in cubic crystallographic phase with Fd-3m space group. Temperature dependent magnetization data does not show magnetic bifurcation down to 2 K. Electrical resistivity data of Pr2Ir2O7 exhibits metallic behavior throughout temperature range. Below 50 K, a small rise in resistivity data of Pr2Ir2O7 is observed down to 12 K.

  8. Structural properties and magnetic susceptibility of iron-intercalated titanium ditelluride

    International Nuclear Information System (INIS)

    Pleshchev, V.G.; Titov, A.N.; Titova, S.G.; Kuranov, A.V.

    1997-01-01

    Structural peculiarities and magnetic susceptibility of titanium ditelluride, intercalated by iron, are studied. It is established that the basic motive of crystal structure by intercalation is preserved and the iron atoms are locates in the van der Waals gaps in positions with octahedral coordination. It is shown that the magnetic susceptibility of the Fe 0.25 TiT 2 sample increases approximately by 20 times. The magnetic susceptibility for the Fe 0.33 TiTe 2 samples becomes even much higher

  9. Ballistic charge carrier transmission through graphene multi-barrier structures in uniform magnetic field

    International Nuclear Information System (INIS)

    Zubarev, A; Dragoman, D

    2014-01-01

    We investigate charge carrier transport in graphene multi-barrier structures placed in a uniform magnetic field. The transmission coefficient is found analytically by generalizing the transfer matrix method for the case of graphene regions subjected to a uniform magnetic field. The transmission coefficient through the structure can be modulated by varying the gate voltages, the magnetic field and/or the width of the gated regions. Such a configuration could be used in multiple-valued logic circuits, since it has several output states with discrete and easily selectable transmission/current values. (paper)

  10. Design of end magnetic structures for the Advanced Light Source wigglers

    International Nuclear Information System (INIS)

    Humphries, D.; Akre, J.; Hoyer, E.; Marks, S.; Minamihara, Y.; Pipersky, P.; Plate, D.; Schlueter, R.

    1995-01-01

    The vertical magnetic structures for the Advanced Light planar wiggler and 20 cm period elliptical hybrid permanent magnet design. The ends of these structures are characterized by diminishing scalar potential distributions the poles which control beam trajectories. They incorporate electromagnetic correction coils to dynamically correct for variations in the first integral of the field as a function of gap. A permanent magnet trim mechanism is incorporated to minimize the transverse integrated error field distribution. The ends were designed using analytic and computer modeling techniques. The design and modeling results are presented

  11. Magnetic and structural properties of yellow europium oxide compound and Eu(OH){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwook, E-mail: dongwookleedl324@gmail.com [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom); Seo, Jiwon, E-mail: jiwonseo@yonsei.ac.kr [Department of Physics and IPAP, Yonsei University, Seoul 120-749 (Korea, Republic of); Valladares, Luis de los Santos [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom); Avalos Quispe, O. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima, Perú (Peru); Barnes, Crispin H.W. [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom)

    2015-08-15

    A new material based on a yellow europium oxide compound was prepared from europium oxide in a high vacuum environment. The structural and magnetic properties of the material were investigated. Owing to the absence of a crystal structure, the material exhibited a disordered magnetic behavior. In a reaction with deionized (DI) water without applied heat, the compound assumed a white color as soon as the DI water reached the powder, and the structure became polycrystalline Eu(OH){sub 3}. The magnetic properties, such as the thermal hysteresis, disappeared after the reaction with DI water, and the magnetic susceptibility of the yellow oxide compound weakened. The magnetic properties of Eu(OH){sub 3} were also examined. Although Eu{sup 3+} is present in Eu(OH){sub 3}, a high magnetic moment due to the crystal field effect was observed. - Graphical abstract: (top left) Optical image of the yellow europium oxide compound. (top right) Optical image of the product of DI water and yellow europium oxide. (bottom) Magnetization curves as a function of temperature measured in various magnetic field. - Highlights: • We prepared a new material based on a yellow europium oxide compound from europium oxide. • We characterized the magnetic properties of the material which exhibits a disordered magnetic behavior such as thermal hysteresis. • The compound turned white (Eu(OH){sub 3}) as soon as the DI water reached the powder. • The thermal hysteresis disappeared after the reaction with DI water and the magnetic susceptibility of the yellow oxide compound weakened.

  12. Experimental test of nuclear magnetization distribution and nuclear structure models

    International Nuclear Information System (INIS)

    Beirsdorfer, P; Crespo-Lopez-Urrutia, J R; Utter, S B.

    1999-01-01

    Models exist that ascribe the nuclear magnetic fields to the presence of a single nucleon whose spin is not neutralized by pairing it up with that of another nucleon; other models assume that the generation of the magnetic field is shared among some or all nucleons throughout the nucleus. All models predict the same magnetic field external to the nucleus since this is an anchor provided by experiments. The models differ, however, in their predictions of the magnetic field arrangement within the nucleus for which no data exist. The only way to distinguish which model gives the correct description of the nucleus would be to use a probe inserted into the nucleus. The goal of our project was to develop exactly such a probe and to use it to measure fundamental nuclear quantities that have eluded experimental scrutiny. The need for accurately knowing such quantities extends far beyond nuclear physics and has ramifications in parity violation experiments on atomic traps and the testing of the standard model in elementary particle physics. Unlike scattering experiments that employ streams of free particles, our technique to probe the internal magnetic field distribution of the nucleus rests on using a single bound electron. Quantum mechanics shows that an electron in the innermost orbital surrounding the nucleus constantly dives into the nucleus and thus samples the fields that exist inside. This sampling of the nucleus usually results in only minute shifts in the electron s average orbital, which would be difficult to detect. By studying two particular energy states of the electron, we can, however, dramatically enhance the effects of the distribution of the magnetic fields in the nucleus. In fact about 2% of the energy difference between the two states, dubbed the hyperfine splitting, is determined by the effects related to the distribution of magnetic fields in the nucleus, A precise measurement of this energy difference (better than 0.01%) would then allow us to place

  13. Magnetism of Ba4Ru3O10 revealed by density functional calculations: Structural trimers behaving as coupled magnetic dimers

    Science.gov (United States)

    Saul, Andres; Radtke, Guillaume; Klein, Yannick; Rousse, Gwenaelle

    2013-03-01

    From a simple ionic picture, the only magnetically active ions in this compound are the three Ru4+ atoms which form trimers of faced shared RuO6 octahedral. The Ru atom in the middle of the trimer (named Ru(1)) is cristallographically inequivalent to the ones at the corners (named Ru(2)). A naïve analysis of the magnetic properties of this compound compatible with the expected low spin magnetic configuration of the Ru ions would predict a complicate magnetic order at low temperature involving the Ru(1) and Ru(2) ions and a high temperature susceptibility corresponding to three S=1 ions per unit cell. In spite of that, we demonstrate in this work, from density functional calculations, that under the influence of Ru-Ru covalent bonding, the structural trimers behave in an extended range of temperature from 0 to 600K, as strong (S = 1) antiferromagnetic dimers. Our calculations of the effective exchange interactions show a strong intra-dimer interaction and a weaker inter-dimer one which explains the antiferromagnetic order observed below TN = 105 K and the magnetic susceptibility in the intermediate and high temperature range (from TN=105K up to 612 K).

  14. Field-induced non-collinear magnetic structures in amorphous Co80-xDy xB20 alloys

    International Nuclear Information System (INIS)

    Annouar, F.; Roky, K.; Lassri, H.; Elmoussaoui, A.; Driouch, L.; Ayadi, M.; Omri, M.; Krishnan, R.

    2005-01-01

    Amorphous Co 80-x Dy x B 20 alloys have been prepared by melt spinning technique and their magnetic properties have been studied. The mean field theory has been used to explain the temperature dependence of the magnetization. High-field magnetization studies performed at 4.2 K in magnetic fields up to 38 T have revealed, for samples with stoichiometry close to that of a compensated ferrimagnet, a magnetic behavior that is characteristic of a non-collinear magnetic structure of the Dy and Co sublattices. From the non-collinear regime the exchange interactions between the Co and Dy magnetic sublattices and the magnetic anisotropy constants have been evaluated

  15. Incommensurate and commensurate magnetic structures of the ternary germanide CeNiGe3

    International Nuclear Information System (INIS)

    Durivault, L; Bouree, F; Chevalier, B; Andre, G; Weill, F; Etourneau, J; Martinez-Samper, P; Rodrigo, J G; Suderow, H; Vieira, S

    2003-01-01

    The structural properties of CeNiGe 3 have been investigated via electron diffraction and neutron powder diffraction (NPD). This ternary germanide crystallizes in the orthorhombic SmNiGe 3 -type structure (Cmmm space group). Electrical resistivity, ac- and dc-magnetization measurements show that CeNiGe 3 orders antiferromagnetically below T N = 5.5(2) K and exclude the occurrence at low temperatures of a spin-glass state for CeNiGe 3 as previously reported. Specific heat measurements and NPD both reveal two magnetic transitions, observed at T N1 = 5.9(2) K and T N2 = 5.0(2) K. Between T N1 and T N2 , the Ce magnetic moments in CeNiGe 3 are ordered in a collinear antiferromagnetic structure associated with the k 1 = (100) wavevector and showing a relationship with the magnetic structure of the Ce 3 Ni 2 Ge 7 ternary germanide. Below T N2 , this k 1 = (100) commensurate magnetic structure coexists with an incommensurate helicoidal magnetic structure associated with k 2 = (00.409(1)1/2). This last magnetic structure is highly preponderant below T N2 (93(5)% in volume). At 1.5 K, the Ce atoms in CeNiGe 3 carry a reduced ordered magnetic moment (0.8(2) μ B ). This value, smaller than that obtained in Ce 3 Ni 2 Ge 7 , results from an important hybridization of the 4f(Ce) orbitals with those of the Ni and Ge ligands

  16. Electric field with bipolar structure during magnetic reconnection without a guide field

    Science.gov (United States)

    Guo, Jun

    2014-05-01

    We present a study on the polarized electric field during the collisionless magnetic reconnection of antiparallel fields using two dimensional particle-in-cell simulations. The simulations demonstrate clearly that electron holes and electric field with bipolar structure are produced during magnetic reconnection without a guide field. The electric field with bipolar structure can be found near the X-line and on the separatrix and the plasma sheet boundary layer, which is consistent with the observations. These structures will elongate electron's time staying in the diffusion region. In addition, the electric fields with tripolar structures are also found in our simulation.

  17. Magnetic structure evolution in mechanically milled nanostructured ZnFe2O4 particles

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Wynn, P.; Mørup, Steen

    1999-01-01

    Nanostructured partially-inverted ZnFe2O4 particles have been prepared from bulk ZnFe2O4 by high-energy ball milling in an open container. The grain size reduction, cation site distributions, and the evolution of magnetic structures have been studied by x-ray diffraction with Rietveld structure...... refinements, transmission electron microscopy, and Mossbauer spectroscopy. It is found that a change of magnetic structure from an antiferromagnetic to a ferrimagnetic (or ferromagnetic) structure occurs in the milled samples. This change is correlated with the redistribution of the cations, Zn and Fe...

  18. Three-dimensional analysis of the magnetic structure in Hokkaido, Japan; Hokkaido no sanjigen jiki kozo kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Makino, M [Geological Survey of Japan, Tsukuba (Japan)

    1996-10-01

    The magnetic structure in Hokkaido was quantitatively analyzed by the magnetic anomaly distribution. This paper describes its characteristics. Detection of structural boundaries and 3-D analysis of double-layer structure were conducted for the regional magnetic data in a region with about 500 km square. There was not so large difference in patterns of magnetic anomaly distribution between the case that the direction of magnetization was set at 45{degree} to the west during the geomagnetic conversion according to Segawa and Oshima and the case that it was set as same as the current geomagnetic direction. The method of Blakely and Simpson was useful to detect the boundaries of magnetic structures. The structural boundaries obtained were more linear than the iso-magnetic contour lines. A new method has been conceived in which the approximation of 3-D magnetic structure analysis can be deduced, and the irregularity of magnetic basement can be determined by the repeated calculation. In practice, this method was applied to the magnetic data in the whole Hokkaido. The calculation was stably converged. It was found that the magnetic structure obtained in the Kamuikotan/Ishikari-Kitakami magnetic belt exhibited a fault structure having steep slopes accompanied by the basin structure in the western boundaries. 19 refs., 6 figs.

  19. Magnets

    International Nuclear Information System (INIS)

    Young, I.R.

    1984-01-01

    A magnet pole piece for an NMR imaging magnet is made of a plurality of magnetic wires with one end of each wire held in a non-magnetic spacer, the other ends of the wires being brought to a pinch, and connected to a magnetic core. The wires may be embedded in a synthetic resin and the magnetisation and uniformity thereof can be varied by adjusting the density of the wires at the spacer which forms the pole piece. (author)

  20. On the structure of the tail magnetic field

    International Nuclear Information System (INIS)

    Candidi, M.; Orsini, S.; Stokholm, M.; Elphic, R.C.

    1990-01-01

    The authors present a study comparing the magnetic field configuration in the magnetotail lobes with that in the plasma sheet boundary layer. The results indicate a systematic enhancement of the By component of the plasma sheet boundary layer field over that of the lobe. The value of such enhancement increases with distance from the midnight meridian plane and has the same sense in the northern and southern plasma sheet boundary layer. Such a By enhancement corresponds to a smaller rate of flaring of the magnetic field lines in the lobe with respect to the plasma sheet boundary layer. This observation is interpreted as a signature of field-aligned currents at the boundary. The direction of the field-aligned currents agrees with the nightside region 1 current system, which is the most poleward system in the nightside polar ionosphere at low altitude

  1. Magnetic mapping for structural geology and geothermal exploration in Guadeloupe, Lesser Antilles

    Science.gov (United States)

    Mercier de Lépinay, jeanne; munschy, marc; geraud, yves; diraison, marc; navelot, vivien; verati, christelle; corsini, michel; lardeaux, jean marc; favier, alexiane

    2017-04-01

    This work is implemented through the GEOTREF program which benefits from the support of both the ADEME and the French public funds "Investments for the future". The program focuses on the exploration for geothermal resources in Guadeloupe, Lesser Antilles, where a geothermal power plant is in production since 1986 (Bouillante, Basse Terre). In Les Saintes archipelago, in the south of Guadeloupe, the outcrop analysis of Terre-de-Haut Island allows to point out an exhumed geothermal paleo-system that is thought to be an analogue of the Bouillante active geothermal system. We show that a detailed marine magnetic survey with a quantitative interpretation can bring information about the offshore structures around Les Saintes archipelago in order to extend the geological limits and structural elements. A similar survey and workflow is also conducted offshore Basse-Terre where more geophysical data is already available. In order to correctly link the offshore and onshore structures, the magnetic survey must be close enough to the shoreline and sufficiently detailed to correctly outline the tectonic structures. An appropriate solution for such a survey is to use a three component magnetometer aboard a speedboat. Such a boat allows more navigation flexibility than a classic oceanic vessel towing a magnetometer; it can sail at higher speed on calm seas and closer to the shoreline. This kind of magnetic acquisition is only viable because the magnetic effect of the ship can be compensated using the same algorithms than those used for airborne magnetometry. The use of potential field transforms allows a large variety of structures to be highlighted, providing insights to build a general understanding of the nature and distribution of the magnetic sources. In particular, we use the tilt angle operator to better identify the magnetic lineaments offshore in order to compare them to the faults identified onshore during the outcrop analysis. All the major faults and fractures

  2. Magnetic structure of molecular magnet Fe[Fe(CN)6]·4H2O

    Indian Academy of Sciences (India)

    perature disordered (paramagnetic) to an ordered magnetic phase transition at 22.6 K. ... three-dimensional network of straight Fe3+–C≡N–Fe3+ chains along the edges of the ... powder diffractometer (λ = 1.249 Å) at Dhruva reactor, Trombay.

  3. Temperature Variation of the Magnetic Structure of HoSb

    DEFF Research Database (Denmark)

    Andersen, Nils Axel; Kjems, Jørgen; Vogt, O.

    1980-01-01

    Neutron diffraction has been used to show that the magnetic moment vector in the antiferromagnet HoSb changes direction as a function of temperature below TN=5.7K. The experimental results are in qualitative agreement with a recent theoretical prediction by Jensen et al. (1980) which ascribe the ...... the changing directions to a competition between the crystal fields and the dipolar interactions....

  4. Magnetic structure of a nanoparticle in mean-field approximation

    International Nuclear Information System (INIS)

    Usov, N.A.; Gudoshnikov, S.A.

    2005-01-01

    Quantum mechanical Hartree-Fock approximation is used to calculate a magnetic state of a nanoparticle. The cases of ferromagnetic (FM), antiferromagnetic (AFM) and composite particles having an FM core surrounded by an AFM shell are considered in a unified manner. It is shown that effective interaction at the boundary between FM and AFM areas rotates FM and AFM spins perpendicular to each other. The coercive force of a composite particle increases as a function of the AFM shell thickness

  5. Modeling and measurement of the ALS U5 undulator end magnetic structures

    International Nuclear Information System (INIS)

    Humphries, D.; Halbach, K.; Hoyer, E.; Kincaid, B.; Marks, S.; Schlueter, R.

    1993-05-01

    The end structures for the ALS U5.0 undulators utilize a system of dual permanent magnet rotors intended to establish gap independent field performance. They may also be used for tuning of the first and second magnetic field integrals of these devices. The behavior of these structures has been studied by means of a two dimensional modeling with the POISSON Group of computer codes. A parametric study of the magnetic field distribution and first and second integrals of the fields has been conducted. In parallel, magnetic measurements of the final completed structures have been performed using an automated Hall probe measurement system. Results of the modeling and measurements are compared. Implications for tuning of the ends of the devices within the context of the electron beam parameters of the ALS are discussed

  6. The effect of magnetic nanoparticle concentration on the structure organisation of a microferrogel

    Science.gov (United States)

    Ryzhkov, A. V.; Melenev, P. V.; Balasoiu, M.; Raikher, Yu L.

    2018-03-01

    Coarse-grained molecular dynamics simulation is applied to study the structural response of micro-sized magnetopolymer objects – microferrogels (MFG). The results for MFGs with different magnetic properties and concentrations of magnetic filler nanoparticles are analysed to detect the transition between non-aggregated configurations and the states with pronounced chains. The nanoparticles are assumed to be either magnetically isotropic or to possess infinite magnetic anisotropy. It is shown that, depending on the type of the particle anisotropy, an applied field in rather different ways affects the MFG structure and shape. Diagrams describing the degree of aggregation as a function of the parameter of the interparticle magnetodipolar interaction and concentration are presented. In particular, it is found that in the case of infinitely anisotropic nanoparticles the aggregation transitions undergoes via a non-trivial scenario. The effect of the structure transformations on the volume change of the MFG objects is studied as well.

  7. Conductive, magnetic and structural properties of multilayer films

    Science.gov (United States)

    Kotov, L. N.; Turkov, V. K.; Vlasov, V. S.; Lasek, M. P.; Kalinin, Yu E.; Sitnikov, A. V.

    2013-12-01

    Composite-semiconductor and composite-dielectric multilayer films were obtained by the ion beam sputtering method in the argon and hydrogen atmospheres with compositions: {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si]}120, {[(Co45-Ta45-Nb10)x(SiO2)y]-[SiO2]}56, {[(Co45-Fe45-Zr10)x(Al2O3)y]-[α-Si:H]}120. The images of surface relief and distribution of the dc current on composite layer surface were obtained with using of atomic force microscopy (AFM). The dependencies of specific electric resistance, ferromagnetic resonance (FMR) fields and width of line on metal (magnetic) phase concentration x and nanolayers thickness of multilayer films were obtained. The characteristics of FMR depend on magnetic interaction among magnetic granules in the composite layers and between the layers. These characteristics depend on the thickness of composite and dielectric or semiconductor nanolayers. The dependences of electric microwave losses on the x and alternating field frequency were investigated.

  8. Magnetism, structure and chemical order in small CoPd clusters: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Mokkath, Junais Habeeb, E-mail: Junais.Mokkath@kaust.edu.sa

    2014-01-15

    The structural, electronic and magnetic properties of small Co{sub m}Pd{sub n}(N=m+n=8,m=0−N) nanoalloy clusters are studied in the framework of a generalized-gradient approximation to density-functional theory. The optimized cluster structures have a clear tendency to maximize the number of nearest-neighbor CoCo pairs. The magnetic order is found to be ferromagnetic-like (FM) for all the ground-state structures. Antiferromagnetic-like spin arrangements were found in some low-lying isomers. The average magnetic moment per atom μ{sup ¯}{sub N} increases approximately linearly with Co content. A remarkable enhancement of the local Co moments is observed as a result of Pd doping. This is a consequence of the increase in the number of Co d holes, due to CoPd charge transfer, combined with the reduced local coordination. The influence of spin–orbit interactions on the cluster properties is also discussed. - Highlights: • This work analyses the structural and magnetic properties of CoPd nanoclusters. • The magnetic order is found to be ferromagnetic-like for all the ground-state structures. • The average magnetic moment per atom increases approximately linearly with Co content. • The influence of spin–orbit interactions on the cluster properties is discussed.

  9. Use of Magnetic Nanoparticles to Visualize Threadlike Structures inside Lymphatic Vessels of Rats

    Directory of Open Access Journals (Sweden)

    Hyeon-Min Johng

    2007-01-01

    Full Text Available A novel application of fluorescent magnetic nanoparticles was made to visualize a new tissue which had not been detectable by using simple stereomicroscopes. This unfamiliar threadlike structure inside the lymphatic vessels of rats was demonstrated in vivo by injecting nanoparticles into lymph nodes and applying magnetic fields on the collecting lymph vessels so that the nanoparticles were taken up by the threadlike structures. Confocal laser scanning microscope images of cryosectioned specimens exhibited that the nanoparticles were absorbed more strongly by the threadlike structure than by the lymphatic vessels. Further examination using a transmission electron microscope revealed that the nanoparticles had been captured between the reticular fibers in the extracellular matrix of the threadlike structures. The emerging technology of nanoparticles not only allows the extremely elusive threadlike structures to be visualized but also is expected to provide a magnetically controllable means to investigate their physiological functions.

  10. Magnetic structure of the YbMn2SbBi compound

    International Nuclear Information System (INIS)

    Morozkin, A.V.; Manfrinetti, P.

    2011-01-01

    Graphical abstract: Display Omitted Research highlights: → A neutron diffraction investigation in zero applied field of La 2 O 2 S-type YbMn 2 SbBi shows antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. → Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). → Below 112(3) K, the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. → The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions. - Abstract: A neutron diffraction investigation has been carried out on the trigonal La 2 O 2 S-type (hP5, space group P3-bar ml, No. 164; also CaAl 2 Si 2 -type) YbMn 2 SbBi intermetallic compound. The YbMn 2 SbBi presents antiferromagnetic ordering below 138(3) K and ferrimagnetic ordering below 112(3) K. Between 138 and 112 K, the magnetic structure of YbMn 2 SbBi consists of antiferromagnetically coupled ab-plane magnetic moments of the manganese atoms (D 1d magnetic point group). Below 112(3) K, the ferromagnetic components of Yb and Mn begin to develop, and the magnetic structure of YbMn 2 SbBi becames the sum antiferromagnetic component with D 1d magnetic point group and ferromagnetic one with C 2 magnetic point group. The magnitude of Yb and Mn magnetic moments in YbMn 2 SbBi at 2 K (M Yb = 3.6(2) μ B , M Mn = 3.5(2) μ B ) correspond to the trivalent state of the Yb ions and tetravalent state of the Mn ions.

  11. Global enhancement and structure formation of the magnetic field in spiral galaxies

    Science.gov (United States)

    Khoperskov, Sergey A.; Khrapov, Sergey S.

    2018-01-01

    In this paper we study numerically large-scale magnetic field evolution and its enhancement in gaseous disks of spiral galaxies. We consider a set of models with the various spiral pattern parameters and the initial magnetic field strength with taking into account gas self-gravity and cooling and heating processes. In agreement with previous studies we find out that galactic magnetic field is mostly aligned with gaseous structures, however small-scale gaseous structures (spurs and clumps) are more chaotic than the magnetic field structure. In spiral arms magnetic field often coexists with the gas distribution, in the inter-arm region we see filamentary magnetic field structure. These filaments connect several isolated gaseous clumps. Simulations reveal the presence of the small-scale irregularities of the magnetic field as well as the reversal of magnetic field at the outer edge of the large-scale spurs. We provide evidences that the magnetic field in the spiral arms has a stronger mean-field component, and there is a clear inverse correlation between gas density and plasma-beta parameter, compared to the rest of the disk with a more turbulent component of the field and an absence of correlation between gas density and plasma-beta. We show the mean field growth up to >3-10 μG in the cold gas during several rotation periods (>500-800 Myr), whereas ratio between azimuthal and radial field is equal to >4/1. We find an enhancement of random and ordered components of the magnetic field. Mean field strength increases by a factor of >1.5-2.5 for models with various spiral pattern parameters. Random magnetic field component can reach up to 25% from the total strength. By making an analysis of the time-dependent evolution of the radial Poynting flux, we point out that the magnetic field strength is enhanced more strongly at the galactic outskirts which is due to the radial transfer of magnetic energy by the spiral arms pushing the magnetic field outward. Our results also

  12. New magnetic rails with double-layer Halbach structure by employing NdFeB and ferrite magnets for HTS maglev

    Science.gov (United States)

    Sun, Ruixue; Zheng, Jun; Zheng, Botian; Qian, Nan; Li, Jipeng; Deng, Zigang

    2018-01-01

    In the high temperature superconducting (HTS) maglev system, the magnetic rail as an essential infrastructure is needed all along the route to carry passengers and goods to the destinations. Thus, large amount of rare earth magnetic materials are required in the magnetic rail construction. In order to decrease the dependence of magnetic rails on rare earth elements, the ferrite magnet is employed to replace part of the NdFeB magnets containing rare earth elements. Consequently, a new type rail with double-layer Halbach structure is presented, which is consisted of NdFeB and ferrite magnets. In this paper, we designed and fabricated the proposed rail, and further measured its magnetic flux density distribution and electromagnetic force interacting with HTS bulks. Experimental results indicate that, this new type rail, in double-layer Halbach structure, can achieve an equivalent distribution of magnetic flux density and levitation performance as the pure NdFeB Halbach rail, while a 10% reduction in NdFeB magnet consumption can be realized at the same time. In addition this work explores another magnetic material selection for HTS maglev applications. The dependence on rare earth element and the cost of magnetic rails can be further reduced, as the coercive force of ferrite magnets improved.

  13. Magnetic and structural behavior of Sr2ZrMnO6 double perovskite

    International Nuclear Information System (INIS)

    Llamosa, D.P.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2009-01-01

    We report synthesis and characterization of new Sr 2 ZrMnO 6 manganite-like material. Samples were produced by the solid state reaction method with sinterization temperatures up to 1400 deg. C. X-ray diffraction experiments reveal that structure belongs to the perovskite system, space group Fm3-barm(no. 225). Lattice parameter a=7.86A was obtained by means of Rietveld-type refinement, through the GSAS code. Magnetic properties were studied by using an MPMS Quantum Design SQUID. From measurements of magnetization as a function of temperature, we determine the occurrence of a paramagnetic-antiferromagnetic transition with Neel temperature 50 K. Curie-Weiss fitting permitted to obtain the magnetic characteristic parameters. At temperature regimes below the Neel temperature, strong evidences of frustration and an irreversibility temperature between zero field cooling (ZFC) and field cooling (FC) measurements were observed. Curves of magnetization as a function of applied field were performed at T=4K. Results show a hysteretic feature for Sr 2 ZrMnO 6 magnetic material. This response is attributed to formation of magnetic clusters as a consequence of cationic (magnetic and no magnetic) disorder along the double perovskite structure.

  14. Possible effects of drift wave turbulence on magnetic structure and plasma transport in tokamaks

    International Nuclear Information System (INIS)

    Callen, J.D.

    1977-07-01

    A new mechanism is proposed by which low level, drift wave type fluctuations, such as those observed in the ATC and TFR experiments, can cause anomalous radial electron heat transport in tokamaks. The model is based on the fact that since transport processes parallel to the magnetic field are many orders of magnitude more rapid than perpendicular ones, very small helically resonant magnetic perturbations that cause field lines to move radially allow the parallel transport process to contribute to radial electron heat transport. It is hypothesized that the small magnetic perturbations accompanying drift waves at any nonzero plasma β are large enough to produce significant effects in present tokamak experiments. The helical magnetic component of drift waves produces magnetic island structures whose spatial widths can easily exceed the ion gyroradius. In a drift wave oscillation period, electrons circumnavigate a magnetic island, whereas the slower moving ions see only a tilt of the magnetic field lines. Thus, electrons try to diffuse radially more rapidly than ions; however, a radialpotential builds up on a very short time scale to confine the electrons electrostatically and thereby keep the particle diffusion ambipolar. Nonetheless, this parallel electron diffusion process does cause net radial electron heat conduction through an ensemble of closely packed island structures. The heat conduction coefficient is estimated. Other effects that these magnetic flutters may have on plasma transport and runaway electron processes are also discussed

  15. Magnetized jets driven by the Sun: The structure of the heliosphere revisited—Updates

    Energy Technology Data Exchange (ETDEWEB)

    Opher, M., E-mail: mopher@bu.edu [Astronomy Department, Boston University, Boston, Massachusetts 02215 (United States); Drake, J. F.; Swisdak, M. [University of Maryland, College Park, Maryland 20742 (United States); Zieger, B. [Center for Space Physics, Boston University, Massachusetts 02215 (United States); Toth, G. [Department of Climate and Space, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2016-05-15

    As the solar system moves through the interstellar medium, the solar wind is deflected forming the heliosphere. The standard picture of the heliosphere is a comet-shape like structure with the tail extending for 1000s of astronomical units. This standard picture stems from a view where magnetic forces are negligible and the solar magnetic field is convected passively down the tail. Recently, we showed that the magnetic tension of the solar magnetic field plays a crucial role on organizing the solar wind in the heliosheath into two jet-like structures. The two jets are separated by the interstellar medium that flows between them. The heliosphere then has a “croissant”-like shape where the distance to the heliopause downtail is almost the same as towards the nose. This new view of the heliosphere is in agreement with the energetic neutral atoms maps taken by the Interstellar Boundary Explorer and INCA/CASSINI. We developed as well an analytic model of the heliosheath in the axisymmetric limit that shows how the magnetic tension force is the driver for the north and south jets. We confirmed that the formation of these jets with magnetohydrodynamic (MHD) simulations. The main reason why previous global MHD simulations did not see these jets is due to spurious magnetic dissipation that was present at the heliospheric current sheet. We instead kept the same polarity for the interplanetary (solar) magnetic field in both the northern and southern hemispheres, eliminating spurious magnetic dissipation effects at the heliospheric current sheet. In this paper, we extend these previous results to include additional cases where we used: (a) weaker solar magnetic field; (b) solar magnetic field that reverses polarity at the solar equator in the axisymmetric limit; and (c) slower motion through the interstellar system. We discuss as well future challenges regarding the structure of the heliosphere.

  16. Enhancement of structural and magnetic properties of M-type hexaferrite permanent magnet based on synthesis temperature

    Science.gov (United States)

    Anjum, Safia; Sehar, Fatima; Mustafa, Zeeshan; Awan, M. S.

    2018-01-01

    The main purpose of this research work is to develop the single domain magnetic particles of M-type barium hexaferrite (BaFe12O19) using oxide precursors employing conventional powder metallurgy technique. The phase formation and magnetic performance of the powders and magnets will be optimized by adjusting calcination and sintering temperatures. The synthesis of M-type barium hexaferrite was carried out in two sections. A series of four samples have been prepared by initial wet mixed powders calcined at different temperatures, i.e., 750, 850, 950 and 1050 °C. On the basis of structural analysis, the sample calcined at 950 °C has been selected and further divided into four parts to sintered them at 1100, 1150, 1200 and 1250 °C. The structural measurements depict the confirmation of M-type barium hexaferrite structure. SEM micrographs show the hexagonal-shaped grains. The abrupt decrease in coercivity for the sample sintered at 1250 °C has been seen which may be due to high sintering temperature, at which the particles have multi-domain properties.

  17. Anisotropic behavior and complex colinear magnetic structures of cerium and actinide intermetallics

    International Nuclear Information System (INIS)

    Cooper, B.R.

    1977-01-01

    A review is given of the experimental situation and degree of theoretical understanding for the occurrence of complex colinear magnetic structures in cerium and actinide intermetallics of NaCl structure. In doing this, emphasis is on the qualitative nature of the anisotropic effects necessary to understand the behavior. With this in mind we focus on the I to IA magnetic structure transition, and indeed more simply, on the occurrence of the IA magnetic structure which appears for CeBi, UAs, and some of the mixed uranium monopnictide-monochalcogenides. We show how the experimental observations involving properties related to the IA magnetic structure indicate important qualitative features of the physical mechanism involved. Through discussion of the possible analogue to the situation in UO 2 , the idea is introduced that magnetoelastic effects involving internal rearrangement modes may play a key role in the occurrence of the IA structure. Internal rearrangement modes are modes where one ionic species remains at its site in the undistorted crystal structure, and the other species is displaced from its position in the undistorted structure. We show that in a very natural way one can anticipate the possible occurrence of an internal rearrangement mode having a four-layer, periodic displacement sequence for planes for one species in the NaCl structure crystals, while the other species remains undisplaced. The presence of such a static lattice mode is susceptible to direct experimental observation. (author)

  18. Fabrication, characterization, and heuristic trade space exploration of magnetically actuated Miura-Ori origami structures

    Science.gov (United States)

    Cowan, Brett; von Lockette, Paris R.

    2017-04-01

    The authors develop magnetically actuated Miura-Ori structures through observation, experiment, and computation using an initially heuristic strategy followed by trade space visualization and optimization. The work is novel, especially within origami engineering, in that beyond final target shape approximation, Miura-Ori structures in this work are additionally evaluated for the shape approximation while folding and for their efficient use of their embedded actuators. The structures consisted of neodymium magnets placed on the panels of silicone elastomer substrates cast in the Miura-Ori folding pattern. Initially four configurations, arrangements of magnets on the panels, were selected based on heuristic arguments that (1) maximized the amount of magnetic torque applied to the creases and (2) reduced the number of magnets needed to affect all creases in the pattern. The results of experimental and computational performance metrics were used in a weighted sum model to predict the optimum configuration, which was then fabricated and experimentally characterized for comparison to the initial prototypes. As expected, optimization of magnet placement and orientation was effective at increasing the degree of theoretical useful work. Somewhat unexpectedly, however, trade space results showed that even after optimization, the configuration with the most number of magnets was least effective, per magnet, at directing its actuation to the structure’s creases. Overall, though the winning configuration experimentally outperformed its initial, non-optimal counterparts, results showed that the choice of optimum configuration was heavily dependent on the weighting factors. These results highlight both the ability of the Miura-Ori to be actuated with external magnetic stimuli, the effectiveness of a heuristic design approach that focuses on the actuation mechanism, and the need to address path-dependent metrics in assessing performance in origami folding structures.

  19. Electronic structure and quantum spin fluctuations at the magnetic phase transition in MnSi

    Science.gov (United States)

    Povzner, A. A.; Volkov, A. G.; Nogovitsyna, T. A.

    2018-05-01

    The effect of spin fluctuations on the heat capacity and homogeneous magnetic susceptibility of the chiral magnetic MnSi in the vicinity of magnetic transition has been investigated by using the free energy functional of the coupled electron and spin subsystems and taking into account the Dzyaloshinsky-Moriya interaction. For helical ferromagnetic ordering, we found that zero-point fluctuations of the spin density are large and comparable with fluctuations of the non-uniform magnetization. The amplitude of zero-point spin fluctuations shows a sharp decrease in the region of the magnetic phase transition. It is shown that sharp decrease of the amplitude of the quantum spin fluctuations results in the lambda-like maxima of the heat capacity and the homogeneous magnetic susceptibility. Above the temperature of the lambda anomaly, the spin correlation radius becomes less than the period of the helical structure and chiral fluctuations of the local magnetization appear. It is shown that formation of a "shoulder" on the temperature dependence of the heat capacity is due to disappearance of the local magnetization. Our finding allows to explain the experimentally observed features of the magnetic phase transition of MnSi as a result of the crossover of quantum and thermodynamic phase transitions.

  20. Structural and magnetic investigation of dilute magnetic semiconductors based on GaN and ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Kammermeier, Tom

    2010-01-19

    The two wide band gap dilute magnetic semiconductors (DMS) Gd:GaN and Co:ZnO are among the most favored materials for spintronic applications. Despite intense research efforts during the last years, the origin of the magnetic order is still under debate. This work reports structural and magnetic investigations on these DMS materials employing several complementary techniques. The X-ray linear dichroism (XLD) has been used to gain element-specific insight into the local structure of dopants and cations. X-ray diffraction (XRD) was used to probe the global structural properties. Magnetic characterization by superconducting quantum interference device (SQUID) has been complemented by electron spin resonance (ESR) and X-ray magnetic circular dichroism (XMCD). Gd:GaN samples were fabricated by focused-ion-beam (FIB) implantation and molecular beam epitaxy (MBE). Room temperature ferromagnetic-like behavior as found for some of our samples by SQUID could not be reliably reproduced. Instead XMCD measurements at the Gd L{sub 3}-edge reveal paramagnetic behavior of the dopant. Additionally a possible magnetic polarization of Ga atoms of the host crystal is shown to be too small to explain the total magnetization of these samples. In some samples the formation of Gd and GdN clusters was evidenced by ESR measurements but it can only account for low temperature ferromagnetic-like behavior. Intrinsic room temperature ferromagnetism of this material as seen by SQUID cannot be confirmed by any other technique - neither ESR nor XMCD. Co:ZnO samples used for this work were predominantly grown by reactive magnetron sputtering (RMS). As shown by XLD analysis, 95% of the Co atoms are incorporated on substitutional Zn-sites in samples of best structural quality. These samples consistently show paramagnetic behavior as found by SQUID, XMCD and ESR. RMS growth of Co:ZnO with reduced oxygen partial pressure yields a magnetic behavior known from ferromagnetic nanoclusters. The X

  1. Structure of magnetic particles studied by small angle neutron scattering. [Magnetic colloid particles in stable liquid dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Cebula, D J; Charles, S W; Popplewell, J

    1981-03-01

    The purpose of this note is to show how the use of small angle neutron scattering (SANS) can provide fundamental information on the structure of magnetic colloid particles in stable liquid dispersion. A more detailed account elaborating the use of the technique to provide fundamental information on interactions will appear later. This contribution contains some principal results on particle structure. The technique of SANS provides a very sensitive means of measuring particle size by measuring the scattered neutron intensity, I(Q), as a function of scattered wave vector, Q.

  2. Magnetic Processing of Structural Components for Transportation Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Mackiewicz-Ludtka, G.; Ludtka, G. M.; Fleming, S. [Metalsa Roanoke, Inc.; del Prado Villasana, J. [Metalsa Roanoke, Inc.

    2011-09-30

    The specific goal of this project was to develop and evaluate the effect of magnetic processing as a viable and new technology to manufacture side‐rails for heavy trucks; and to demonstrate the applicability of this technology for an industrial truck/automotive process. The targeted performance enhancements for this project were to increase the hardness or strength of two families of alloys (comparable carbon contents but one alloy system incorporating hardenability improving additions of titanium and boron) by 15 to 20%. Thermomagnetic processing has been shown to make significant and unprecedented, simultaneous improvements in yield strength and ultimate tensile strength with no loss of ductility for the truck rail application investigated in this project. Improvements in the ultimate tensile strength and yield strength in the range 20 to 30% have been measured even for the lower hardenability alloy samples that only received a very low magnetic field tempering treatment at a tempering temperature that was 67% lower than the current non-magnetic field enhanced commercial process and for a brief tempering time of 20% of the time required in their current process at the higher temperature. These significant developments, that require further demonstration and investigation on current commercial and other alloy systems, promise the evolution of a much more energy efficient and lower-carbon footprint process to be used in the future to produce stronger, tougher, and lighter weight truck rails. The property increases in the truck rails themselves will enable lighter weight truck side-rails to be produced which will reduce the overall weight of heavy duty trucks which will reduce fuel consumption and be an enabler of the goals of the DOE EERE SuperTruck Program where fuel consumption reductions of 50% are targeted for the future generation of trucks.

  3. Structural and magnetic transformations in NdMn2Hx hydrides

    International Nuclear Information System (INIS)

    Budziak, A.; Zachariasz, P.; Pełka, R.; Figiel, H.; Żukrowski, J.; Woch, M.W.

    2012-01-01

    Highlights: ► Full structural phase diagram is presented for the NdMn 2 H x (2.0 ≤ x ≤ 4.0) hydrides in the temperature range of 70–385 K. ► For samples x = 2.0, 2.5, and 4.0 a splitting into two phases with different hydrogen concentrations are observed. ► Only for samples with x = 3.0 and 3.5 no spinodal decompositions are detected. ► The effects of hydrogen absorption on structural properties are shown to be reflected in magnetic behavior. ► A huge jump of magnetic ordering temperatures from ∼104 K for host NdMn 2 to above 200 K for its hydrides is observed or anticipated. - Abstract: X-ray powder diffraction and bulk magnetization measurements were used to study structural and magnetic properties of hydrides NdMn 2 H x (2.0 ≤ x ≤ 4.0). The X-ray investigations performed in the temperature range 70–385 K have revealed many structural transformations at low temperatures. In particular, a transformation from the hexagonal to the monoclinic phase and spinodal decompositions were observed. The magnetic behavior of the hydrides is correlated with the structural transitions. A tentative structural diagram is presented. The obtained results are compared with the properties of other cubic and hexagonal RMn 2 H x hydrides.

  4. Vacuum structure of the electroweak theory in high magnetic fields

    International Nuclear Information System (INIS)

    Olesen, P.

    1991-05-01

    In the electroweak theory one can reach the unbroken phase SU(2) x U y (1) by pumping enough magnetic energy into the system. The whole energy is then carried by the fields associated with U y (1), whereas the fields corresponding to SU(2) are in a vacuum state. We show that the vacuum is non-trivial in the sense that it consists of a condensate of zero-field twists which arise in a smooth way from a condensate of vortex lines existing in the broken phase. An explicit vacuum solution is constructed in terms of Weierstrass' elliptic function. (orig.)

  5. Atomic-level structures and physical properties of magnetic CoSiB metallic glasses

    International Nuclear Information System (INIS)

    Shan, Guangcun; Liang Zhang, Ji; Li, Jiong; Zhang, Shuo; Jiang, Zheng; Huang, Yuying; Shek, Chan-Hung

    2014-01-01

    Two CoSiB metallic glasses of low Co contents, which consist of different clusters, have recently been developed by addition of solute atoms. In this work, the atomic structure and the magnetic properties of the two CoBSi metallic glasses were elucidated by state-of-the-art extended X-ray absorption fine structure spectroscopy (EXAFS) combining with ab initio molecular-dynamics (AIMD) computational techniques. Besides, the origin of these magnetic behaviors was discussed in view of the EXAFS results and atomic structures of the metallic glasses. - Graphical abstract: The atomic structure and the origins of the magnetic properties of two ternary CoBSi metallic glasses were elucidated by state-of-the-art extended X-ray absorption fine structure spectroscopy (EXAFS) combining with ab initio molecular-dynamics (AIMD) techniques. - Highlights: • The atomic structure and the origins of the magnetic properties of two ternary CoBSi metallic glasses were revealed. • The atomic structures were elucidated by state-of-the-art extended X-ray absorption fine structure spectroscopy (EXAFS) combining with ab initio molecular-dynamics (AIMD) techniques. • The experimental spectra were in good agreement with the predictions of ab initio full multiple scattering theory using the FEFF8.4 code. • The origin of these magnetic behaviors was discussed in view of the EXAFS results and atomic structures of the metallic glasses. • These two metallic glasses consist of different clusters, and hence different magnetic properties, which are dominated by short-range orders (SROs)

  6. Effects of magnetized walls on the particle structure and the yield stress of magnetorheological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jianfeng, E-mail: zhoujianfeng@njtech.edu.cn [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu (China); Mo, Jingwen [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Shao, Chunlei [School of Mechanical and Power Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu (China); Li, Zhigang [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2015-09-01

    In this work, we investigate the quasi-static shear deformation of magnetic particles (MPs) in a Couette flow of magnetorheological (MR) fluids through Stokesian dynamic simulations. The magnetized walls are modeled by a congregation of magnetic dipoles and their effects on the MPs are considered. The simple shear flow of the base fluid with linear velocity distribution is used to generate the shear deformation of the MP structure and the yield stresses under different shear rates are obtained. Comparing with the relatively long chains forming in base fluid without the effect of magnetized walls, the initial structure of MPs is mainly in the form of short chains due to the attractive force of walls. At the beginning of the shear deformation of the MP structure, the concentration of MPs near the walls is found. As the shear deformation develops, however, the chains concentrate at the center of the simulation domain and the MPs near wall boundaries are attracted to the center. The yield stress depends on the initial structure of MPs which is affected by the magnetized walls. It is revealed that the larger shear rate of base fluid results in the larger yield stress, and the effects of the magnetization intensity of the walls and their space distance on the yield stress are also investigated. - Highlights: • We model a Couette flow of magnetorheological fluid considering magnetized walls. • The walls are modeled by a congregation of magnetic dipoles. • Initial structure of MPs is remarkably affected by the walls, so is yield stress. • Larger base fluid shear rate causes the larger shear deformation and larger yield stress.

  7. Effects of magnetized walls on the particle structure and the yield stress of magnetorheological fluids

    International Nuclear Information System (INIS)

    Zhou, Jianfeng; Mo, Jingwen; Shao, Chunlei; Li, Zhigang

    2015-01-01

    In this work, we investigate the quasi-static shear deformation of magnetic particles (MPs) in a Couette flow of magnetorheological (MR) fluids through Stokesian dynamic simulations. The magnetized walls are modeled by a congregation of magnetic dipoles and their effects on the MPs are considered. The simple shear flow of the base fluid with linear velocity distribution is used to generate the shear deformation of the MP structure and the yield stresses under different shear rates are obtained. Comparing with the relatively long chains forming in base fluid without the effect of magnetized walls, the initial structure of MPs is mainly in the form of short chains due to the attractive force of walls. At the beginning of the shear deformation of the MP structure, the concentration of MPs near the walls is found. As the shear deformation develops, however, the chains concentrate at the center of the simulation domain and the MPs near wall boundaries are attracted to the center. The yield stress depends on the initial structure of MPs which is affected by the magnetized walls. It is revealed that the larger shear rate of base fluid results in the larger yield stress, and the effects of the magnetization intensity of the walls and their space distance on the yield stress are also investigated. - Highlights: • We model a Couette flow of magnetorheological fluid considering magnetized walls. • The walls are modeled by a congregation of magnetic dipoles. • Initial structure of MPs is remarkably affected by the walls, so is yield stress. • Larger base fluid shear rate causes the larger shear deformation and larger yield stress

  8. Superconductivity and electronic structure of superpure niobium. 3. Magnetoconductivity and magnetic breakdown in large magnetic fields

    International Nuclear Information System (INIS)

    Alekseevskij, N.E.; Nizhankovskij, V.I.; Bertel', K.-X.

    1976-01-01

    Measurements have been of electric conductivity and magnetoresistance of niobium monocrystals with various orientations in helium and hydrogen temperature regions in steady-state magnetic fields of up to 175 ke. At helium temperatures the resistance is shown to be proportional to the square of temperature. A significant longitudinal magnetoresistance of niobium has been established, depending on the sample orientation. Its initiation is attributed to the open nature of the niobium Fermi surface. As a result of studying the lateral magnetoresistance in fields of up to 92 ke, a stereographic projection of niobium open directions has been constructed. Open trajectories exist both in two-dimensional regions around the directions [100] and [111] and along the symmetry lines. Studies conducted in fields of up to 175 ke have revealed a magnetic break- own leading to the conversion of the open trajectories to the closed ones. A comprehensive picture of the magnetic break-down in niobium has been obtained, and on the basis of the coherent model an expression has been derived describing the impact of this break-down on the resistance. Comparison between experimental and theoretical dependences of the magnetoresistance on the field characteristics has provided the value of the break-down field H 0 =280 ke

  9. Magnetoresistance in magnetic nanoconstrictions: The role of structural defects Magnetoresistance in magnetic nanoconstrictions: The role of structural defects

    OpenAIRE

    Biziere , Nicolas; Clochard , M.-C; Do , Pham; Wegrowe , J.-E; Viret , M

    2013-01-01

    International audience; The resistance of a ferromagnetic cylindrical Ni nano-constriction has been measured as a function of the external magnetic field. Typical profiles of the resistance versus external field are observed with irreversible jumps separated by stable plateaus, showing systematic slow relaxation effects. An interpretation in terms of magnetomechanical strain at the level of the constriction is proposed. This scenario allows the slow relaxation behaviour to be understood in te...

  10. Coupling between crystal structure and magnetism in transition-metal oxides

    Science.gov (United States)

    Barton, Phillip Thomas

    Transition-metal oxides exhibit a fascinating array of phenomena ranging from superconductivity to negative thermal expansion to catalysis. This dissertation focuses on magnetism, which is integral to engineering applications such as data storage, electric motors/generators, and transformers. The investigative approach follows structure-property relationships from materials science and draws on intuition from solid-state chemistry. The interplay between crystal structure and magnetic properties is studied experimentally in order to enhance the understanding of magnetostructural coupling mechanisms and provide insight into avenues for tuning behavior. A combination of diffraction and physical property measurements were used to study structural and magnetic phase transitions as a function of chemical composition, temperature, and magnetic field. The systems examined are of importance in Li-ion battery electrochemistry, condensed-matter physics, solid-state chemistry, and p-type transparent conducting oxides. The materials were prepared by solid-state reaction of powder reagents at high temperatures for periods lasting tens of hours. The first project discussed is of a solid solution between NiO, a correlated insulator, and LiNiO2, a layered battery cathode. Despite the deceptive structural and compositional simplicity of this system, a complete understanding of its complex magnetic properties has remained elusive. This study shows that nanoscale domains of chemical order form at intermediate compositions, creating interfaces between antiferromagnetism and ferrimagnetism that give rise to magnetic exchange bias. A simple model of the magnetism is presented along with a comprehensive phase diagram. The second set of investigations focus on the Ge-Co-O system where the spin-orbit coupling of Co(II) plays a significant role. GeCo2O 4 is reported to exhibit unusual magnetic behavior that arises from Ising spin in its spinel crystal structure. Studies by variable

  11. Magnetic Doppler imaging considering atmospheric structure modifications due to local abundances: a luxury or a necessity?

    Science.gov (United States)

    Kochukhov, O.; Wade, G. A.; Shulyak, D.

    2012-04-01

    Magnetic Doppler imaging is currently the most powerful method of interpreting high-resolution spectropolarimetric observations of stars. This technique has provided the very first maps of stellar magnetic field topologies reconstructed from time series of full Stokes vector spectra, revealing the presence of small-scale magnetic fields on the surfaces of Ap stars. These studies were recently criticised by Stift et al., who claimed that magnetic inversions are not robust and are seriously undermined by neglecting a feedback on the Stokes line profiles from the local atmospheric structure in the regions of enhanced metal abundance. We show that Stift et al. misinterpreted published magnetic Doppler imaging results and consistently neglected some of the most fundamental principles behind magnetic mapping. Using state-of-the-art opacity sampling model atmosphere and polarized radiative transfer codes, we demonstrate that the variation of atmospheric structure across the surface of a star with chemical spots affects the local continuum intensity but is negligible for the normalized local Stokes profiles except for the rare situation of a very strong line in an extremely Fe-rich atmosphere. For the disc-integrated spectra of an Ap star with extreme abundance variations, we find that the assumption of a mean model atmosphere leads to moderate errors in Stokes I but is negligible for the circular and linear polarization spectra. Employing a new magnetic inversion code, which incorporates the horizontal variation of atmospheric structure induced by chemical spots, we reconstructed new maps of magnetic field and Fe abundance for the bright Ap star α2 CVn. The resulting distribution of chemical spots changes insignificantly compared to the previous modelling based on a single model atmosphere, while the magnetic field geometry does not change at all. This shows that the assertions by Stift et al. are exaggerated as a consequence of unreasonable assumptions and

  12. Effects of proton irradiation on electronic structure of NdFeB permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, L. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: lzhen@hit.edu.cn; Xu, C.Y.; Sun, X.Y.; Shao, W.Z. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2009-09-15

    Effects of proton irradiation on electronic structure and atomic local structure of N35EH-type NdFeB permanent magnet were investigated by soft X-ray absorption spectrometry and Moessbauer spectrometry. The local coordination environment of Fe atoms changes after proton irradiation, and the average hyperfine field H{sub in} of the magnets decreases from 288.4 to 286.9 kOe. The effects of irradiation on Fe atoms local environment at different lattice sites are different. The near edge structure of Fe L{sub 3} edge is changed, indicating the density of unoccupied state of Fe 3d electrons increases after proton irradiation.

  13. Structures, energetics and magnetic properties of AunSFem and ...

    African Journals Online (AJOL)

    Bheema

    relating the number of atoms needed to form a compact symmetric structure to an enhanced stability. If the d orbitals ...... This is in agreement with the experimental result of Zhang et al. (1996). .... Extended x-ray absorption fine structure study ...

  14. Threedimensional imaging of organ structures by nuclear magnetic resonance

    International Nuclear Information System (INIS)

    Waters, W.; Smolorz, J.; Wellner, U.

    1985-01-01

    A simple method for threedimensional imaging of organ structures is presented. The method is based on a special acquisition mode in a nuclear resonance tomograph, exciting layers of 20 cm thickness at different angulations. The display is done by cinematography (which is usually used in nuclear cardiology) projecting the structures in a rotating movement. (orig.) [de

  15. Magnetic Decoupling Design and Experimental Validation of a Radial-Radial Flux Compound-Structure Permanent-Magnet Synchronous Machine for HEVs

    Directory of Open Access Journals (Sweden)

    Zhiyi Song

    2012-10-01

    Full Text Available The radial-radial flux compound-structure permanent-magnet synchronous machine (CS-PMSM, integrated by two concentrically arranged permanent-magnet electric machines, is an electromagnetic power-splitting device for hybrid electric vehicles (HEVs. As the two electric machines share a rotor as structural and magnetic common part, their magnetic paths are coupled, leading to possible mutual magnetic-field interference and complex control. In this paper, a design method to ensure magnetic decoupling with minimum yoke thickness of the common rotor is investigated. A prototype machine is designed based on the proposed method, and the feasibility of magnetic decoupling and independent control is validated by experimental tests of mutual influence. The CS-PMSM is tested by a designed driving cycle, and functions to act as starter motor, generator and to help the internal combustion engine (ICE operate at optimum efficiency are validated.

  16. Magnetic structures, phase diagram and spin waves of magneto-electric LiNiPO4

    DEFF Research Database (Denmark)

    Jensen, Thomas Bagger Stibius

    2007-01-01

    LiNiPO4 is a magneto-electric material, having co-existing antiferromagnetic and ferroelectric phases when suitable magnetic fields are applied at low temperatures. Such systems have received growing interest in recent years, but the nature of the magneticelectric couplings is yet to be fully...... through the last three years, it is not the primary subject of this thesis. The objective of the phD project has been to provide groundwork that may be beneficiary to future studies of LiNiPO4. More specifically, we have mapped out the magnetic HT phase diagram with magnetic fields below 14.7 T applied...... along the crystallographic c-axis, determined the magnetic structures for the phases in the phase diagram, and have set up a spin model Hamiltonian describing the spin wave dynamics and estimating the relevant magnetic interactions....

  17. Analysis of the structure of Saturn's magnetic field using charged particle absorption signatures

    International Nuclear Information System (INIS)

    Chenette, D.L.; Davis, L. Jr.

    1982-01-01

    A new technique is derived for determining the structure of Saturn's magnetic field. This technique uses the observed positions of charged particle absorption signatures due to the satellites and rings of Saturn to determine the parameters of an axially symmetric, spherical harmonic model of the magnetic field using the method of least squares. Absorption signatures observed along the Pioneer 11, Voyager 1, and Voyager 2 spacecraft trajectories are used to derive values for the orientation of the magnetic symmetry axis relative to Saturn's axis of rotation, the axial displacement of the center of the magnetic dipole from the center of Saturn, and the magnitude of the external field component. Comparing these results with the magnetic field model parameters deduced from analyses of magnetometer data leads us to prefer models that incorporate a northward offset of the dipole center by about 0.05 R/sub s/

  18. Resolved magnetic-field structure and variability near the event horizon of Sagittarius A.

    Science.gov (United States)

    Johnson, Michael D; Fish, Vincent L; Doeleman, Sheperd S; Marrone, Daniel P; Plambeck, Richard L; Wardle, John F C; Akiyama, Kazunori; Asada, Keiichi; Beaudoin, Christopher; Blackburn, Lindy; Blundell, Ray; Bower, Geoffrey C; Brinkerink, Christiaan; Broderick, Avery E; Cappallo, Roger; Chael, Andrew A; Crew, Geoffrey B; Dexter, Jason; Dexter, Matt; Freund, Robert; Friberg, Per; Gold, Roman; Gurwell, Mark A; Ho, Paul T P; Honma, Mareki; Inoue, Makoto; Kosowsky, Michael; Krichbaum, Thomas P; Lamb, James; Loeb, Abraham; Lu, Ru-Sen; MacMahon, David; McKinney, Jonathan C; Moran, James M; Narayan, Ramesh; Primiani, Rurik A; Psaltis, Dimitrios; Rogers, Alan E E; Rosenfeld, Katherine; SooHoo, Jason; Tilanus, Remo P J; Titus, Michael; Vertatschitsch, Laura; Weintroub, Jonathan; Wright, Melvyn; Young, Ken H; Zensus, J Anton; Ziurys, Lucy M

    2015-12-04

    Near a black hole, differential rotation of a magnetized accretion disk is thought to produce an instability that amplifies weak magnetic fields, driving accretion and outflow. These magnetic fields would naturally give rise to the observed synchrotron emission in galaxy cores and to the formation of relativistic jets, but no observations to date have been able to resolve the expected horizon-scale magnetic-field structure. We report interferometric observations at 1.3-millimeter wavelength that spatially resolve the linearly polarized emission from the Galactic Center supermassive black hole, Sagittarius A*. We have found evidence for partially ordered magnetic fields near the event horizon, on scales of ~6 Schwarzschild radii, and we have detected and localized the intrahour variability associated with these fields. Copyright © 2015, American Association for the Advancement of Science.

  19. Generation of uniform magnetic field using a spheroidal helical coil structure

    International Nuclear Information System (INIS)

    Öztürk, Yavuz; Aktaş, Bekir

    2016-01-01

    Uniformity of magnetic fields are of great importance especially in magnetic resonance studies, namely in magnetic resonance spectroscopy applications (NMR, FMR, ESR, EPR etc.) and magnetic resonance imaging applications (MRI, FMRI). Field uniformity is also required in some other applications such as eddy current probes, magnetometers, magnetic traps, particle counters etc. Here we proposed a coil winding regime, which follows the surface of a spheroid (an ellipsoid of rotation); in light of previous theoretical studies suggesting perfect uniformity for a constant ampere per turn in the axial direction thereof. We demonstrated our theoretical results from finite element calculations suggesting 0.15% of field uniformity for the proposed structure, which we called a Spheroidal Helical Coil. (paper)

  20. First-principles study on electronic structures and magnetic properties of Eu-doped phosphorene

    Science.gov (United States)

    Luan, Zhaohui; Zhao, Lei; Chang, Hao; Sun, Dan; Tan, Changlong; Huang, Yuewu

    2017-11-01

    The structural, electronic and magnetic properties of Eu-doped phosphorene with different doping concentrations were investigated by first-principles calculations for the first time. The calculations show that Eu-doped phosphorene systems are stable and have the large magnetic moments of more than 6 μB by 2.7, 6.25 and 12.5 at.% doping concentrations. The major contribution to the magnetic moment stems from the 4f states of Eu-doped atom. Meanwhile, Eu-doped atom introduces the impurity bands which can be changed by different doping concentrations. In order to determine the magnetic interaction, the different configurations for two Eu atoms doping in 3 × 3 × 1 phosphorene supercell were studied, which reveals that all of the configurations tend to form ferromagnetic. These results can provide references for inducing large magnetism of two-dimensional phosphorene, which are valuable for their applications in spintronic devices and novel semiconductor materials.