| Research Abstract |
The Present research was aiming to understand magnetic and optical excitations in spin-density-wave chromium, such as, unresolved magnetic excitations observed in neutron diffraction measurements other than a spin-wave one and magnetic circular dichroism in photoabsorption spectra, in the light of a realistic electronic structure. Consider-able growth of experiments for chromium superlattices with layered structures, however, has prevented the research from advancing toward the original aim. The research has turned its aim to a first-principles study of spin-density wave in chromium superlattices, in particular, Fe/Cr superlattices, where much attention is paid to the relation between interlayer magnetic coupling and spin-density wave. The first-principles electronic structure calculation for Fe/Cr superlattices, which is a fairly large-scale one, is satisfactorily performed by means of the KKR method within the framework of the LSD formalism. The calculation attains fruitful results ; for example, the calculation explains an oscillation of the interlayer magnetic coupling with a two-monolayer period and also a phase slip of the oscillation, which corresponds to a transition of the magnetic order in the Cr layer from an antiferromagnetic one to a spin-density-wave one. The calculation reveals that the spin-density-wave in Fe/Cr superlattices differs from that in bulk Cr, which result is significant for understanding of the electronic structure of not only a spin-density-wave state but also metallic superlattices. In this respects, a further study of other chromium superlattices like V/Cr superlattices is promising, and the research is still in progress.
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