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Hot-pressed [Nd.sub.13.5][Fe.sub.77][Si.sub.1][B.sub.8] alloy compacts with various grain sizes ranging from approximately 50 nm to 200 nm were prepared using melt-spun material. The compacts were then subjected to die-upsetting. The effect of grain size in the hot- pressed compact on the texture in die-upset magnet was investigated. The effect of die-upset temperature on the texture in die-upset magnet was also investigated. Texture in the die-upset [Nd.sub.13.5][Fe.sub.77][Si.sub.1][B.sub.8] alloy samples decreased with increasing the grain size in the hot-pressed compact before the die-upsetting. This dependence of texture on the initial grain size could be explained by the unique texture formation mechanism of a stress-induced preferential grain growth via dissolution and precipitation. Texture of the die-upset sample was also influenced by the die-upsetting temperature. The samples die-upset at 700[degrees]C and 900[degrees]C had poorer texture compared to the samples die-upset at the temperature range of 750[degrees]C-850[degrees]C. The poor texture in the sample die-upset at lower temperature of 700[degrees]C was attributed to the less dissolution of the unfavorable [Nd.sub.2][Fe.sub.14]B grains and low fluidity of the liquid Nd-rich grain boundary phase. The poor texture in the sample die-upset at higher temperature of 900[degrees]C was explained by the reduced elastic modulus and the excessive grain growth of the [Nd.sub.2][Fe.sub.14]B grains. Index Terms--Hard magnetic materials, magnetic materials, magnets, permanent magnets.

Electronic and thermodynamic properties of the ternary Dy[Ni.sub.4]Si compound, crystallizing in the hexagonal Ca[Cu.sub.5] structure (P6/mmm space group) were studied by X-ray photoelectron spectroscopy (XPS) and heat capacity measurements. Dy[Ni.sub.4]Si is ferromagnetic with magnetic moment 7.9 [micro]B/f.u. at 4.2 K (in H = 9 T) and Curie temperature [T.sub.C] = 11 K. The heat capacity measurements have shown that Dy[Ni.sub.4]Si is characterized by electronic heat capacity coefficient [gamma] = 72 mJ/mol K. Zero field heat capacity reveals a peak close to the magnetic ordering temperature, which gets suppressed in an applied field of 5 T. The valence band of the XPS spectra is determined mainly by the Ni(3d) and Dy(4f) contributions. The slight shift of peaks' positions towards the higher binding energy by about 0.3 eV in respect to the pure Dy is probably due to the different crystalline electric field for Dy in the Dy[Ni.sub.4]Si compound. Index Terms--Ferromagnetic materials, magnetic field effects, transition metal alloys, X-ray spectroscopy.

In this paper, we report on temperature effects associated with elastic electromagnetic forming by pulsed electromagnetic fields in inhomogeneous, linear, and lossy media. In a previous paper, we discussed the electromagnetic forces associated with these pulsed electromagnetic fields. Here, we calculate the temperature rise from the equation of heat flow in an isolated object to be deformed. The temperature rise is included in the elastodynamic problem to be solved for the presence of electromagnetic forces, and as a consequence the thermoelastic field can be obtained. As an example, we calculate the thermoelastic field in a hollow cylindrical object. Index Terms--Conducting magnetic materials, elastic field, electromagnetic forming, electromechanical forces, temperature rise, thermoelastic field.

This paper reapproaches the very classic problem of the analytic study of nonlinear diffusion of electromagnetic fields in conducting media. Significant contributions that appeared in the literature on this topic are cited in order to highlight the interest and the efforts provided by the scientific community on this topic as well as the aim and the main results of this work. The capabilities of two analytic procedures for estimating the energy losses in magnetic materials with hysteresis are shown and discussed. One formulation reduces the full nonlinear diffusion problem to a linear problem through an optimization procedure and is suited for thick cores. A second formulation approximates the magnetic field behavior by means of polynomials and provides good results for thin laminations. Energy losses are evaluated for magnetic materials with different B-H relations operating in wide frequency intervals. A scalar Preisach model, numerically treated, is used as a benchmark and, finally, calculations are compared with experimental data provided by other authors. Index Terms--Analytical technique, magnetic materials, nonlinear diffusion equation, thin lamination.

The thermal of property of magnetic materials at higher temperatures us examined and used in Active Magnetic Regenerative Refrigeration (AMRR) project. The results provide a deep insight into thermal properties of rare earth compounds and is useful for designing and development of the practical AMRR for hydrogen liquefaction.

Research presents magnetic susceptibility and high-resolution crystal absorption spectra of single-crystals of the title compound at cryogenic temperatures. Results indicate that both exchange splittings and exchange parameters in the ground and excited states are ferromagnetic.

Research shows that when a horizontal ferromagnetic liquid layer is heated from above and under a time-sinusoidal external magnetic field, the magnetic Rayleigh number is altered. Data indicate that the magnetic modulation is similar to the gravitational one. The convective threshold of the free-free and rigid-rigid cases are presented.

Research discusses the low-temperature magnetic behavior of a metastable, single-phased HoMnO(sub)3 perovskite crystal and compare its properties to the known RMnO(sub)3 perovskites. The manganese(sup)3=magnetic moments exhibit an antiferromagnetic order below T(sub)N=41K.

Results reveal that the new series of germanium antimonides are metallic and those containing RE = Nd, Sm, Gd-Dy exhibit kinks in their temperature resistivity behavior. Further, the compounds reveal long-range antiferromagnetic ordering in their atomic structures.

The magnetic properties of the one-dimensional polymer of copper(II) complex exhibits the existence of a prominent ferromagnetic interaction. Data indicate that the ferromagnetic interaction is due to the monoatomic-bridged copper(II) dimeric part of the polymer chain.

Results show that monomeric octacoordinated U(IV) complexes do not exhibit long-range magnetic ordering at low temperatures. However, organically templated uranium(IV) compounds display antiferromagnetic and metamagnetic-like transitions.

Results demonstrate the synthesis and characterization of five ternary rare-earth selenides conforming to U(sub)3ScS(sub)6 structural configuration. Data on magnetic measurements reveal that the new compounds exhibit paramagnetic properties down to 5 K.

A dual-axial anisotropy film which consists of two uniaxial sandwiches of [Co.sub.91] [Nb.sub.6] [Zr.sub.3]/Si[O.sub.2]/[Co.sub.91] [Nb.sub.6][Zr.sub.3] with their easy axes orthogonally oriented, was fabricated by RF-sputtering using a water-cooled, magnetic substrate holder, for application in a new type of submicron trackwidth thin film head. The thermal stability of the induced uniaxial anisotropy of the film was studied by heat treatment in a magnetic field and subsequent magnetic measurements. The magnetic properties of the films before and after rotational field annealing (RFA) were studied by their B-H loops and permeability spectrum along various directions in the film plane. It was found that the B-H loops of the as-deposited dual-axial film along either axis were the superposition of the easy axis and hard axis B-H loops of the two uniaxial sandwiches along that axis. The two uniaxial sandwiches appear to behave independently before RFA. In-plane isotropic B-It loops and isotropic permeability of 2640 at 10 MHz were obtained for the dual-axial films after RFA at 320 [degrees] C. The small [H.sub.[Kappa]] and the magneto-static interaction between the two sandwiches may be mainly responsible for the isotropic magnetic properties of the dual-axial film after RFA. Index Terms - CoNbZr, dual-axial anisotropy, isotropic permeability, rotational field annealing, submicron trackwidth, thin-film head.

The effect of substrate bias applied during the deposition of NiO on the properties of unshielded NiO/[Ni.sub.81][Fe.sub.19] and NiO/[Co.sub.87][Fe.sub.13] biased spin-valve sensors was investigated. The addition of substrate bias of -40 V increased the blocking temperature [T.sub.b] from 100-190 [degrees] C for NiO/NiFe biased spin valves, and from 70-190 [degrees] C for NiO/CoFe biased spin valves. The thermal stability upon anneal increased with substrate bias from 150-200 [degrees] C for NiO/NiFe biased spin-valve sensors, and from 200-280 [degrees] C for NiO/CoFe biased spin-valve sensors. At an operating temperature of 80 [degrees] C, sensor magnetoresistance decreases 15% from its room temperature value for NiO/CoFe sensors where NiO was deposited under -40 V bias. At this temperature, the sensor transfer curves are well linearized and Barkhausen noise free. NiO films prepared with varying substrate bias were examined by atomic force microscopy (AFM) and X-ray diffraction. Substrate bias decreases surface morphology and grain size of NiO, which probably contributes to the observed improvement of blocking temperature. Index Terms - Blocking temperature, exchange field, magnetoresistance, spin valve, substrate bias, surface morphology, thermal stability.

An experimental technique has been developed to accurately measure the time dependence of playback voltage due to the decay of recorded magnetization patterns. A 'calibration' procedure is utilized to minimize the effect of magnetoresistive head sensitivity variations. This technique is applied to a systematic study of the dependence of the signal decay on recording bit density and magnetic layer thickness in longitudinal thin film media. A Neel-Arrhenius type model is introduced to calculate the degradation of a square wave magnetization pattern subject to thermal agitation. Because the equivalent external field which reduces the energy barrier is the time and spatially varying magnetostatic field produced by magnetic transitions, an iterative procedure is utilized to obtain the time dependent magnetization. The model takes into account distributions of grain volume and anisotropy axis. The calculation results are compared with the experimental data and good agreement is obtained. Index Terms - Magnetic disk recording, stability.

This paper discusses several approximate analytic techniques for calculating power dissipation and forces in ferromagnetic fluids subjected to a spatially uniform but time varying magnetic field. This power dissipation results in a rising temperature in a ferrofluid sample. Several possible heating mechanisms in magnetic fluids have been investigated, including electromagnetic and hydrodynamic processes, and a simple method for prediction of power dissipation in a sample has been developed. Experimental results are given for an induction heating problem where it is shown that the power dissipation in a sample of ferrofluid cannot be explained by induction heating of the individual suspended particles. A simple viscous drag model is introduced which shows better agreement with measured power dissipation in the sample than an eddy current model for excitation frequencies under 1 MHz. Index Terms - Ferrofluid, induction heating, magnetic circuits, magnetic liquids, modeling.

Structural and magnetic properties of fine particles of magnetite are investigated with respect to the application for hyperthermia. Magnetic hysteresis losses are measured in dependence on the field amplitude for selected commercial powders and arc discussed in terms of grain size and structure of the particles. For ferromagnetic powders as well as for ferrofluids, results of heating experiments within organic gels in a magnetic high frequency field are reported. The heating effect depends strongly on the magnetic properties of the magnetite particles which may vary appreciably for different samples in dependence on the particle size and microstructure. In particular, the transition from ferromagnetic to superparamagnetic behavior causes changes of the loss mechanism, and accordingly, of the heating effect. The maximum attainable heating effect is discussed in terms of common theoretical models. Rise of temperature at the surface of a small heated sample as well as in its immediate neighborhood in the surrounding medium is measured in dependence on time and is compared with solutions of the corresponding heat conductivity problem. Conclusions with respect to clinical applications are given. Index Terms - Hysteresis, losses, relaxation, superparamagnetism.

A new scheme is proposed, which can treat electromagnetic field of the type-II superconductor under transient temperature field. In the analysis, one of the critical state models, the Bean model was employed to determine the current distribution in the superconductors and effect of magnetic flux flow was also taken into account. We chose both low and high Tc superconducting materials. Numerical results indicate that the flux flow strongly affects the stability against the quench in both materials. Index terms - High-temperature superconductors, Superconducting filaments/wires, Eddy currents

Research was conducted to examine the temperature dependence and the Faraday rotation (FR) spectra in Rh4+-substituted magnetic garnets based on a molecular field approximation. Single crystalline films of (Y, Ca2+)3(Fe, Rh4+)5O12 grown by a liquid phase epitaxy method onto (111)-oriented gadolinium galium garnet substrates were used as samples. Results indicate that the FR spectra is strongly reliant on temperature and it decreases as temperature increases.

(meso-Tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphinato)manganese(III) tetracyanoethenide, (MnTP'P)(TCNE), is a soluble molecule-based magnet made of trans-mu(sub 2)-bound (TCNE).- subunits. With interchain distances, the Curie temperature becomes unusually high. The magnetic susceptibility obeys the Curie-Weiss relation between 115 and 250 K. The (MnTP'P)(TCNE) polymer has short intrachain and long interchain Mn...Mn separations.

We have carried out a numerical analysis of the magnetic field on high-frequency induction heating. This analysis includes the dependence of various magnetic properties on temperature. The required characteristics are obtained experimentally. We compare the experimental results with the theoretical values obtained by approximations. Until now, the current density inside the exciting coil on this kind of problem has been assumed to be uniform, which is different from actual phenomena. We propose a new method which takes the inhomogeneous distribution of exciting current into account. In this analysis, the eddy current of the exciting coil is also taken into account.

A review of the theory of thermally-induced magnetization reversal in small particles involves an analysis of Kramers's rate theory that helps derive the Neel-Brown theory for uniform magnetization reversal. A nonuniform energy barrier has a lower energy than the uniform barrier for adequately elongated particles and provides a low coercivity. Diminishing hard-axis anisotropy, where the nucleus splits the rotational symmetry around the easy axis, also shows a decrease in coercivity.

Analysis of the exchange paths for coupled 40 nm Ni81Fe19/NiO films using cooling experiments shows that several exchange paths are present for the films, each path having a distinct unidirectional anisotropy. The local blocking temperature for the exchange paths is 215 degrees Celsius, while the temperature range is from room temperature to 230 degrees Celsius. Microscopic studies show that inhomogeneous Ni81Fe19-NiO interfaces with fluctuating atomic organization and interfacial disorder induce various exchange pathways.

The deposition of thin films is long established, but the recent development of highly sophisticated techniques has made it possible to build up layered films, at the nanometre level, to very strict specifications. In such layers materials exhibit properties quite different from those displayed in bulk. Apart from their theoretical significance, such layered devices have very interesting practical possibilities, for example in magneto-optical recording and magnetic sensing devices.

A 200 degrees centigrade blocking temperature and a large exchange coupling field is observed in antiferromagnetic NiO films/bilayered ferromagnetic Ni81Fe19 films. The Nb of the intermediate film of the ferromagnetic (Ni81Fe19)100-xNbx/NiO/trilayered Ni81Fe19 films, when increased, enables exchange coupling field regulation. Unidirectional anisotropy constant and exchange coupling field are proportional. The ferromagnetic film's magnetic field does not determine the exchange coupling field.

We have studied the giant magnetoresistance (GMR) in granular Co- Ag, Co-Cu, and Fe-Ag systems, as well as in the metastable alloy state. The absolute values of the resistivity at zero field (Rho(sub 0)), the magnetic resistivity (Rho)(sub 0)), and GMR have been determined. The resistivity of an alloy is found to be significantly larger than that of a granular solid. As the composition (x) of Co or Fe is increased, Rho(sub m) shows a broad maximum at x = 20 to 30%. Among the three systems, Co-Ag has the smallest Rho(0), the largest Rho(m), hence the largest GMR. Both Rho(0) and Rho(sub m) at 5 K in all three systems show a similar dependence on the annealing temperature (T(sub A)). They decrease with increasing T(sub A), having the largest values in the as- deposited samples regardless of the sample being alloy or granular. Because Rho(0) and Rho(sub m) decrease with T(sub A) at different rates there may or may not be a peak in the GMR at certain value of T(sub A).

We report measurements on the thermal conductivity and thermoelectric power of granular Co20Ag80 solids annealed at various temperatures. Thermal conductivity is dominated by its electronic contribution and the Wiedemann-Franz law is found to be satisfied between 2K and 300K, which is mainly ascribed to dominant large-angle elastic scattering processes. The thermoelectric power is negative and is considerably reduced by the annealing process. Giant magnetothermal conductivity and giant magnetothermopower are found to be correlated with the giant magnetoresistance.

The magnetic ordering in the three title materials, all tetrabromoferrates(III), was characterized. The three substances, (4-Cl(py)H)3Fe2Br9, (4-Br(py)H)3Fe2Br9 and (4-Cl(py)H)1.1(4-Br(py)H)1.9Fe2Br9, display two closely-spaced lambda-anomalies in their specific heats. The magnetic ordering phenomena in the three compositions are three-dimensional in nature, as is evident from the magnetic entropy distributions.

This paper deals with a new formulation of the Spectral Domain Technique (SDT) for the analysis of the general case of uniaxial/biaxial, electric/magnetic anisotropic multilayer planar structures. As an illustration of the capabilities of this formulation we apply it to the analysis of shielded CPW structures. The dispersive properties of the fundamental and higher order modes in various cases of electric/magnetic anisotropy as well as the induction electric and magnetic lines are calculated. Such results, and particularly the induction lines, may be used to predict the behaviour of the studied structure as well as to point out its sensitive geometrical and electrical parameters. Some general rules will be discussed which lead to a better understanding of the effect of anisotropy.

We have developed a method for isothermal calorimetry for the determination of the entropy change in magnetic materials. Heat absorbed and released by the sample at constant temperature is measured by means of Peltier cells, used in an active way to simultaneously measure the heat current and keep constant the sample temperature. In the paper we describe the method, the Peltier cell calibration and the test apparatus. The results obtained on a Gadolinium sample at room temperature under a magnetic field up to 0.9 T are discussed. The comparison with other methods demonstrates the validity of the proposed approach to fulfill the isothermal conditions ([DELTA]T[less than or equal to]5 mK) and to obtain a faster time response. Index Terms--Calorimetry, gadolinium, magnetocaloric, thermoelectric.

Soft magnetic composite (SMC) material is formed by surface-insulated iron powder particles, generating unique properties like magnetic and thermal isotropy, and very low eddy currents. This paper presents the design and analysis of a high-speed claw pole motor with an SMC stator core for reducing core losses and cost. The analyses of magnetic and thermal fields are conducted based on a comprehensive understanding of the property of SMC materials. The 3-D finite-element analysis (FEA) is performed for accurate parameter calculation, design optimization, and thermal calculation. Because of the importance of core loss in high-speed motors, rotational core loss model is employed, and the core losses are coupled directly into thermal calculation by keeping the same hexahedral mesh structure between magnetic field analysis and thermal analysis. Since the rotor modal analysis is very important to high-speed motors, the natural frequencies and mode of the rotor are studied. Index Terms--Core losses, finite-element field analysis, high-speed motors, modal analysis, soft magnetic composite (SMC) materials, thermal analysis.

A study of the magnetostructural phase transition and related magnetic entropy changes, [DELTA] [S.sub.M], in the vicinity of a first-order magnetostructural transition, in polycrystalline shape memory alloys [Ni.sub.2+x][Mn.sub.1-x] Ga (x = 0.16, 0.17, 0.18, 0.19, 0.20) have been done. Thermal expansion measurements reveal the gradual overlap of the first- and second-order phase transitions that results in the large magnetic entropy changes in the alloys. We observed a magnetic entropy change of [DELTA] [S.sub.M] = -66.2 J/[kg.sup.-1] * [K.sup.-1] between 350 K and 350.5 K in a field change of 5 T in [Ni.sub.2+x][Mn.sub.1-x] Ga for x = 0.19. Index Terms--Magnetic materials, magnetoelasticity.

A study is conducted on the magnetic properties of multilayer structures with two magnetic layers of the same metal (Co) but with different crystallographic structures. It is shown that the single crystalline fcc Co layer has nearly ideal switching of the magnetization when the field was applied along the easy axis. On the other hand, the magnetization of the hcp Co layer changes smoothly within a wide field range because of its polycrystalline structure.

A robust giant magnetoresistance (GMR) material system that comprises an exchange-biased artificial antiferromagnet was described. The material was capable of withstanding magnetic fields >150 kA/m and annealing at temperatures >275 degrees C without irreversible damage. The GMR effect started to decrease at higher temperatures due to atomic diffusion. Results suggested that exchange biasing is no longer the limiting factor for thermal stability.