In this review, on the basis of our recent theoretical and experimental studies, we discuss the magnetic and electrical properties of γ-phase and L1₀-type antiferromagnetic Mn alloys. The point we wish to stress is that the calculated electronic properties are consistent with the experimental magnetic and electrical resistivity data. Especially, the spin structures and the pseudo-gap at the Fermi level are closely correlated with the antiferromagnetic stability. Our mechanism of the exchange bias-field well describes the biasing properties under the conditions with various spin structures. From the practical viewpoint for spintronic devices, the magnetovolume and elastic properties are also discussed.

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A current-perpendicular-to-the-plane (CPP) spin-valve element structure specifically devised for high-density magnetic recording over 100G bits/in², named a CCP-CPP spin valve, was studied both by experiment and by simulation. One or more current-confining (CC) layers are included in the structure so that its resistance may exhibit a high enough resistance to be applicable to read heads. A micro-structured sample with a nominal area of 50μm², fabricated by means of multi-step photolithography using a multilayer of Si/SiO₂ (200nm)/Cu (150nm)/CoFe (6nm)/SiO₂ (0.3nm)/Cu (3nm)/CoFe (5nm)/IrMn (15nm)/Cu (50nm), showed a high ΔR-value (the resistance change due to the GMR effect) of 10mΩ, although the GMR ratio was only 0.25%. Simulation performed by using a combination of an equivalent resistor-network model and Mott's two-current model has suggested that insertion of a CC-layer on each side of the spacing conducting-layer would enhance both ΔR and the GMR ratio substantially.

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Magnetic nanostructures embedded in silicon wafers were successfully fabricated by the damascene technique using electron beam lithography. The magnetic properties of embedded square dots (1μm in width and 100nm in height), rectangular dots (300nm×100nm in area and 100nm in height), and circular dots (100nm in diameter and 100nm in height) were investigated. Magnetic force microscopy (MFM) and vibrating sample magnetometer (VSM) measurements showed that the perpendicular anisotropy increased with the aspect ratio, due to a decrease in the areal size. Fine magnetic structures of the 300nm×100nm pattern were clearly resolved by using a special MFM with a low-moment tip.

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