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Nanocomposite permanent magnets are of commercial interest as an expensive magnetic alignment step is not needed to obtain maximum performance, and less of the costly rare earth element is required. Remanence enhancement is linked to exchange coupling at interfaces separating nanocrystalline magnetic phases. Crystallization temperature is found to be important in determining the magnetic properties.

Molecule-based preparation and characterization are of interest, although details of the coupling mechanisms have remained elusive. Attention has concentrated on controlling magnetic properties via low-temperature organic synthetic methodologies, achieved with the amorphous V(TCNE)s.y(solvent) magnet. The high Tc of the V(TCNE)x magnet shows the utility of the use of metal ion/organic radical systems in designing molecular materials. A comprehensive analysis of the orientation of (TCNE).- bound to a (MnIII(por))+ is reported, correlated with magnetic data. Changes correlated with the resulting magnetic properties may help the developed of higher Tc molecule-based magnets.

The effect of Fe, Cu, Zr, and Ti substitution on magnetic properties of SmCo 1:7 magnets at temperatures up to 500[degrees]C were studied. As-milled amorphous Sm[(Co,Fe,Cu,Ti-Zr).sub.7] magnets crystallized in the Tb[Cu.sub.7]-type structure after annealing at 750[degrees]C for 2 h. A room-temperature intrinsic coercivity of around 2.5 T is obtained for compositions Sm[Co.sub.6.4] [Zr.sub.0.2] [Ti.sub.0.4] and Sm[Co.sub.6.4][Fe.sub.0.1][Zr.sub.0.1][Ti.sub.0.4]. The high coercivity of the bail-milled Sm[Co.sub.7-x][Ti.sub.x] magnets is attributed to the strong pinning of the wails of the 'interaction domains' by the network of grain boundaries between the nanocrystalline grains. The virgin curve of the bail-milled samples is suggestive of strong domain wall pinning. Index Terms--Coercivity, Curie temperature, magnetization, X-ray diffraction.

Nd-Fe-B film magnets were prepared by a laser ablation technique. The suppression of oxidation is a key point to obtain Nd-Fe-B film magnets with high coercivity. The following methods were used. 1) Ta substrates and a Ti sublimation pump as an auxiliary pump were used during deposition. 2) The composition of a target was set to [Nd.sub.2.6][Fe.sub.14]B which included a larger amount of Nd compared with the stoichiometric composition of [Nd.sub.2.6][Fe.sub.14]B. In addition, the distance between a target and a substrate was approximately 5 mm to ensure a high deposition rate. One-hour deposition using laser ablation technique enabled us to obtain Nd-Fe-B amorphous films with the thickness of approximately 50 [micro]m. After annealing the films under an optimum condition, the coercivity and the remanence were more than 800 kA/m and approximately 0.6 T, respectively. In addition, the maximum energy product was 56 kJ/[m.sup.3]. Index Terms--Laser ablation technique, maximum energy products, Nd-Fe-B magnet, remanence.

In this paper, the magnetic properties of an exchange-coupled hard-soft bilayer system have been analyzed based on its energy-barrier characteristics. Analytical solutions of the magnetic and structural parameters such as the energy barriers, the coercivities, the critical coupling-constant, the critical coupling dimension of soft phase, and the energy product have been derived. These analytical solutions reveal the correlation between the magnetic properties and the physical dimensions of its soft and hard phase constituents. Index Terms--Energy barrier, energy product, exchange coupling, hard phase, soft phase, spring magnet.

Two-dimensional colossal magnetoresistance (CMR) compounds are considered. The theoretical approach is based on the single site mean field theory, emphasizing the hopping-mediated nature of the double exchange (DE) contribution. The problem of off-diagonal disorder, linked to a single impurity atom is considered, and contrasted with alternative approaches, introducing an exchange interaction to represent such DE effects.

The magnetic interactions in hybrid magnets have been investigated. Bonded magnets provide an opportunity to investigated systems where the dipole interactions are the predominant form of particle interaction. Magnetic interactions were studied using isothermal remanence (IRM) and dc-magnetization (DCD) remanence curves and Henkel plots.

The hydrogenation, disproportionation, desorption, recombination (HDDR) is a unique process whereby a noncoercive cast Nd-Fe-B-type material can be transformed easily into a coercive one. It is interesting to understand the changes of mechanical strength of the Nd-Fe-B-type material during solid-HDDR. A sintered magnet was used in the study and the optimally HDDR processed material showed comparable strength with regard to the initial sintered material prior to solid-HDDR.

Sintered Sm(sub2)(Co,Fe,Cu,Zr)(sub17) magnets with enhanced high temperature performance have been produced through a reduction of the iron content in the magnet alloys. 2:17 magnets with low iron content have exhibited lower irreversible loss of magnetic flux, higher maximum energy product and lower temperature coefficient of (sub1)HC, at 400-600 degrees C. Both Curie temperature and anistropy field are increased when iron content is reduced.

The Lyapunov exponents have been widely used in chaos investigations, and the frequency versus Lyapunov exponent map can offer significant information about the controlling properties of a systems. Thin circular YIG films have been used as an appropriate model to investigate the origin and growth of the auto-oscillations, as an example of the applicability of the map. The resulting map provided new information about the link between the underlying dynamics and growth.

The temperature and bias-voltage dependence of tunnel-type giant magnetoresistance (MR) in insulating granular films Co-A1-0. At low temperatures, enhancement of MR larger than the theoretical value, was observed, decreasing sharply with increasing temperature. MR did not decrease with rising bias voltage. The effect of temperature was different from that of bias voltage.

A numerical micromagnetic three-dimensional calculation has been developed and tested to complement an experimental analysis of a two-phase magnetization reversal system. Application to a set of 64 nanometer-scale hard (Nd(sub2)Fe(sub14)B) and soft (Fe(sub3)B) cubic grains, reproduced the experimentally observed processes and gave a better understanding of the relation between the structure and the coercivity mechanism.

Studies of the electrical resistivity and ac magnetic susceptibility of the 5f-metamagnet UCoAI show the presence of strong spin fluctuation effects at temperatures below 30 K. A step-wise rise of residual resistivity and the a prominent Fermi liquid T(super2) term of resistivity is seen as the field is raised through a metamagnetic transition.

Several types of magnetic actuators have been proposed in the development of strong metal magnets. A linear actuator has been proposed and applied to a pump. The output power of the actuator and efficiency of the pump have been obtained by experiments. Pump efficiency attains to around 45%, and the efficiency of the actuator is high as there is no copper and iron losses and only small eddy current loss.

Nd-Fe-B type anisotropic magnetic powder can be produced by hydrogenation, disproportionation, desorption and recombination (HDDR) process, although the application of HDDR treatment to Pr-Fe-B alloys lacks research. The effects of minor elements Co, Ga and Zr on hydrogen absorption and desorption behaviour of Pr-Fe-B alloys have been examined, concentrating on the disproportionation and recombination reaction in HDDR process. The addition of Co and Ga was found to improve the recombination reaction.

The magnequench method for the production of Nd-Fe-B magnets involves melt spinning the alloy to produce ribbons. Quenched melt-spun ribbons have equiaxed and randomly oriented Nd(sub2)Fe(sub14)B grains. There is a lack of detailed analysis of the way local stress and strain influences the crystallographic alignment. A simulation of the die-upset process has been undertaken to assess stresses and strains in the magnet, correlated with texture measurements using x-ray diffraction.

Mechanical alloying, followed by heat treatment, was used to produce a series of densified exchanged-enhanced SmFeCo magnets. Magnet measurements were analyzed for magnetization and coercivity temperature behaviour. The random anisotropy model predicted that decreased coercivity occurred with increased Mr/Ms ratios.

Lowest order coefficients of an open magnet are eliminated by the location of an active material between ferromagnetic layered plates. The shielding of active layers by the ferromagnetic materials forms a sandwich structure which enables functioning as a spatial filter that eliminates lower-order spatial harmonics.

Observations concerning the properties of refrigerator magnets and magnetism are presented. Topics addressed include horseshoe magnets, magnetic fields, and the health aspects of magnets.

A physics teacher shares techniques for facilitating critical thinking skills in the classroom. A writing assignment that analyzes the claims of alternative medicine reveals a favorable student response.