Interparticle interactions in metal evaporated tape were studied. Due to magnetic interaction fields in the media, two kinds of normalized remanence curves, DC De-magnetization remanence (DCD) and Isothermal Remanent Magnetization (IRM) curves, are not always consistent. In this paper, a new analysis method is considered. The difference between the remanence curves is interpreted as a magnetic interaction field, δH, which is defined as the difference between two kinds of remanence coercivities, Hr and Ha, which are obtained from the DCD and IRM curves, respectively. Parameter δH was confirmed to be useful for evaluating the interparticle interaction in the media. Also, the magnetic anisotropy energy derived from the interparticle interaction, which is estimated from the angular dependence of δH, is useful in discussing the thermal stability of the media’s recorded pattern.
Nano-size MnSb clusters with a nominal thickness of 3 ML were grown on GaAs(111)B substrates by molecular beam epitaxy. The films were capped with GaAs, and the magnetoresistance effect was investigated at room temperature. A large positive magnetoresistance effect of over 50% was observed. The dependency on the sweep rate of magnetic field and an effect of Cr-doping in GaAs capping layers were investigated. The photoinduced MR effect was also observed under laser-irradiation with a photon energy above the band gap of GaAs. It is shown that these phenomena can be attributed to the enhancement of the conductivity by photogenerated carriers.
Two types of laminated structures for free layers were investigated to avoid the increase in the switching field of the free layer caused by the reduction of the size of the TMR element. Laminated free layers of NiFe(5)/Ru(0.7)/NiFe(3) and NiFe(4)/Ta(3)/NiFe(4) showed a lower switching field than a single free layer of NiFe(8). The low switching field of the synthetic free layer is due to the decrease in the net moment, which results in a decrease of the demagnetizing field. In the case of the NiFe(4)/Ta(3)/NiFe(4) free layer, there is a possibility that magnetostatic coupling plays an important role in the decrease in the demagnetizing field.
In this paper, we examine the influence of the optical spot diameter on the magneto-optical recording properties. An optical spot with a reduced diameter of 380 nm was obtained by using a semiconductor blue laser and a solid immersion lens. As a medium, we used magnetic bilayer media, which can be read with GMR heads and are available for hybrid recording. It was proved that the shrinkage of the spot considerably changed the recording properties. Calculation based on Huth’s theory explained the increase in the shrinking force that acts on the domain wall. This increase is mainly caused by the steeper temperature variation in the focused spot. However, this force can be compensated for by controlling the film composition, and we successfully wrote domains with a diameter of 30% of the recording optical spot diameter.
The alloy Ni2(Pd0.16Mn0.84)Ga is a ferromagnetic shape memory alloy that has coexistent orthorhombic and monoclinic structures at low temperatures and a cubic structure at high temperatures. To study the characteristic properties, the electronic structures were calculated for the three structures. The total energy and the band energy suggest that the orthorhombic and monoclinic structures may more stable than the cubic structure; that is, they may become the martensitic structure. It is also predicted that the monoclinic structure is the most stable and that the orthorhombic structure may be metastable. The Pd atoms play an important role in stabilizing the monoclinic structure.