ホーム > 研究活動 > 口頭発表(2015) > Real-space calculations of uniaxial magnetic anisotropy at surfaces of bcc Fe films and of Y2Fe14B compounds

研究活動

Real-space calculations of uniaxial magnetic anisotropy at surfaces of bcc Fe films and of Y2Fe14B compounds

20th International Conference on Magnetism (ICM2015)

J. Inoue, T. Yoshioka, H. Tsuchiura

概要/Abstract

The fundamental origin of the magnetic anisotropy (MA) may be attributed to lowering of crystal symmetry and the spin-orbit interaction (SOI), and intensive search for high performance permanent magnets is currently conducted both experimentally and theoretically. Nevertheless, materials dependence of MA is unpredictably complicated. The complication could be partly due to structural inhomogeneity in magnets, such as grain boundaries and lattice disorder. Therefore, a theoretical approach to treat effects of grain boundaries and random lattice structures is desirable. To this end, we have developed real- space formalism to calculated MA energy for any lattice structures by expanding the thermodynamic potential in terms of SOI by using multi-orbital tight-binding model. By using the method, site-resolved MA is easily obtained with high numerical accuracy. The applicability has already been examined by comparing the numerical results with those obtained in the first-principles method [1]. Here we apply the method to calculate the uniaxial MA at bcc Fe (001) surfaces with several surface structures, and that at surfaces of Y2Fe14B compounds. Our findings are as follows:(1) The out-of-plane MA at bcc Fe (001) surface is strongly enhanced due to surface resonant states as compared with bulk MA. As a result, dependence of the out-of-plane MA at surface on charge density becomes stronger than that of bcc bulk Fe.(2) The uniaxial MA at surface sites of Y2Fe14B compounds is also enhanced. For example, in-plane MA at 4c-Fe sites on (001) surface becomes twice as large as the bulk value, and the uniaxial MA at 8j2-Fe sites on (010) surface is enhanced as compared with the bulk value. These results may implicate important roles of surface/interface Fe sites on the MA and magnetization process of ferromagnetic thin films and grains.Reference:[1] J. Inoue, T. Yoshioka, and H. Tsuchiura, J. Appl. Phys. to be published.



研究活動

元素戦略拠点

触媒・電池元素戦略拠点
触媒・電池元素戦略研究拠点 (京都大学)
東工大元素戦略拠点
東工大元素戦略拠点 (東京工業大学)
構造材料元素戦略研究拠点
構造材料元素戦略研究拠点 (京都大学)
高効率モーター用磁性材料技術研究組合
高効率モーター用 磁性材料技術研究組合