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Theoretical Study of Spin-Orbit Coupling in Metallic Ferromagnetism

金属铁磁性中自旋轨道耦合的理论研究

基本信息

批准号：
06640468
负责人：
ASANO Setsuro
金额：
$ 1.41万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-06640468/
关键词：
interstitially modifide intermetallics of Rare earth and Transition metals spin-orbit coupling perpendicular magnetic anisotropy crystalline field magnetic anisotropy ferromagnetic multilayrs metallic ferromagnetism artificial superlattice /

项目摘要

The spin-orbit coupling is the only one interaction, which fixes the spin system to the lattice, but it is too small to make a reliable quantitative calculations in the case of 3d-transition metals. We have investigated the magnetic anisotropy energy (MAE) from the first-principles band calculations in the two cases : interstitially modified intermetallics of rare-earth (R) and 3d transition metals and X/Co or Fe (X=Pd, Pt, Ag, Au) ferromagnetic multilayr system. In the former case, the electronic structures of GdCo_5, GdFe_<12>, Gd_2Fe_<17>, GdFe_<12>N and Gd_2Fe_<17>N_3 were calculated by FLAPW method and the charge distribution around R ions were investigated carefully. Nitrogen interstitial ions make strong bondings with surrounding Fe and R ions. The bonding with Fe leads to a larger spin saturation moment, but that with R makes a strong aspherical charge distribution around R and a crystalline field (CF) as large as that of SmCo_5. We found that this large CF is the microscopic origin of the strong uniaxial magnetic anisotropy in these nitrides. In the case of X/Co or Fe system, the MAE were calculated systematically by the LMTO method including the spin-orbit interaction. We found that the general tendency of the MAE in these systems are well explained by first-principles calculations. The thickness of Co layr dependence and the strain dependence of the MAE were also investigated.

自旋-轨道耦合是唯一一种将自旋系统固定在晶格上的相互作用，但对于3d过渡金属来说，它太小了，无法进行可靠的定量计算。用第一性原理能带计算方法研究了稀土金属间化合物和3d过渡金属间化合物以及X/Co或Fe（X=Pd，Pt，Ag，Au）铁磁多层膜系统的磁各向异性能（MAE）。在前一种情况下，用FLAPW方法计算了GdCo_5，GdFe_3<12>，Gd_2Fe_3<17>，GdFe_<12>N和Gd_2Fe_N_3<17>的电子结构，并详细研究了R离子周围的电荷分布。氮间隙离子与周围的Fe和R离子形成强键。与Fe成键导致较大的自旋饱和磁矩，而与R成键则使R周围的电荷分布呈强非球面分布，并产生与SmCo_5相同的晶场。我们发现，这种大CF是在这些氮化物的强单轴磁各向异性的微观起源。在X/Co或Fe体系中，采用考虑自旋轨道相互作用的LMTO方法系统地计算了MAE。我们发现，在这些系统中的MAE的一般趋势很好地解释了第一性原理计算。研究了磁声发射的厚度依赖性和应变依赖性。