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We have investigated the detailed magnetization reversal in 10-nm-thick Ni--Fe elliptical dots with several dot sizes using magnetic field sweeping (MFS)-magnetic force microscopy (MFM). At the dot edges, the shape of the phase (the stray field) curve versus magnetic field changes from a stepped hysteresis loop to a almost nonstepped hysteresis loop with increasing dot size. On the other hand, at the center within the dot, sharp or weak decreases in phase are observed as the magnetic field is varied. From these results, it is found that, in the magnetization reversal of a 10-nm-thick Ni--Fe elliptical dot with several dot sizes, the dominant factor changes from the change in the magnetic domain configuration to the domain wall motion as the length of major axis increases. Index Terms--Magnetic elliptical dot, magnetic force microscopy (MFM), magnetization reversal.

We have studied the effect of the dot separation on the switching behavior of Ni-Fe elliptical dot arrays with major axial distances between the adjacent dots. The magnetization process and the magnetic configuration in the dot arrays apparently differ according to the distance between the adjacent dots. These differences are due to the fact that the dipole-dipole interaction becomes stronger while decreasing the major axial distance between the adjacent dots. From these results, it is evident that the optimal distance at which the magnetization between the adjacent dots couples by the dipole-dipole interaction is below 30 nm. Index Terms--Dipole-dipole interaction, magnetic configuration, magnetic logic gate, magnetization process.

The feasibility of a high-density magnetic particulate recording medium with a thin magnetic layer of evenly dispersed high-coercivity barium-ferrite particles was investigated. Thermal stability, writability, and an areal recording density of 17.5 Gb/[in.sub.2] were confirmed for a flexible disk system using a giant magnetoresistive head. Index Terms--A real recording density, barium-ferrite, flexible disk, giant magnetoresistive (GMR) head, particulate media.

We have explored the temperature dependence of the interlayer coupling in Fe/[Fe.sub.l-x[Si.sub.x] superlattices (0.5 [less than or equal to] x [less than or equal to] 1). It is found that the Si content of the [Fe.sub.l-x][Si.sub.x] spacer greatly affects the temperature dependence of the bilinear and biquadratic coupling constants. Neither the 'thickness fluctuation' model nor the 'loose' spin model proposed by Slonczewski give satisfactory explanations to the temperature-dependent interlayer coupling. Instead, the present experimental results for all spacer compositions can be reproduced very well by the quantum interference model. We discuss the experimental results based on the above interlayer coupling models. Index terms - Fe/Si(Fe) superlattice, interlayer coupling, remanence, biquadratic coupling

Amorphous CoxFe1-x-B particles with magnetic softness were fabricated by chemical reduction of metal ions. Fabrication conditions to obtain particles with good magnetic softness are described. CoxFe1-x-B particles with x= 0.90–0.95 exhibit superb softness because of their nearly zero-magnetostrictive property. The soft properties of the particles are thermally stable compared to other compositions such as Fe-B-P or Co50Fe50-B. Chains of CoxFe1-x-B particles with x=0.95 produced in a magnetic field were studied in detail. The high permeability feature associated with the high aspect ratio of the chain shape exhibits only a slight change after annealing up to 400 degrees. The frequency dispersion of initial permeability exhibits two resonance peaks that are ascribed to the shape anisotropy of the chains. [ABSTRACT FROM AUTHOR]