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Magnetic and Optical Excitations in Spin-Denstiy-Wave Chromium

自旋密度波铬的磁和光激发

基本信息

批准号：
09640447
负责人：
HIRAI Kunimoto
金额：
$ 0.45万
依托单位：
Nara Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640447/
关键词：
spin density wave chromium magnetic excitation optical excitation superlattice スピン密度波

项目摘要

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.

本研究旨在了解自旋密度波铬中的磁性和光学激发，例如，在中子衍射测量中观察到的未分辨的磁性激发，而不是自旋波激发和光吸收光谱中的磁性圆二色性，根据实际的电子结构。然而，层状结构的铬超晶格实验的大量增长阻碍了研究向最初的目标前进。本论文的研究目标是对铬超晶格，特别是Fe/Cr超晶格中的自旋密度波进行第一性原理研究，主要关注层间磁耦合与自旋密度波之间的关系。采用KKR方法，在LSD方法框架下，对Fe/Cr超晶格这一较大尺度的超晶格进行了第一性原理电子结构计算。计算取得了丰硕的成果，例如，计算解释了两个单层周期的层间磁耦合的振荡和振荡的相位滑移，这对应于Cr层中的磁序从反铁磁到自旋密度波的转变。计算结果表明，Fe/Cr超晶格中的自旋密度波不同于Cr体材料中的自旋密度波，这一结果不仅对理解自旋密度波态的电子结构，而且对理解金属超晶格的电子结构具有重要意义.在这方面，对其他铬超晶格如V/Cr超晶格的进一步研究是有希望的，并且研究仍在进行中。