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研究活動

Analysis of Local Magnetocrystalline Anisotropy of Hard Magnetic Materials

59th Annual Magnetism & Magnetic Materials Conference, Honolulu, Hawaii

2014年11月4日(火)

Daisuke Hirai、Shinji Tsuneyuki、Yoshihiro Gohda

概要/Abstract

Magnetocrystalline anisotropy (MCA) is positively correlated with coercivity that is one ofimportant magnetic figure of merits for applications such as high-density magnetic recordingmedia, high-frequency electromagnetic wave absorbers, and permanent magnets. In general,the MCA is given for an entire phase of a material. In the light of materials science andengineering, however, we need MCA information at each atom in crystals to identify weakparts for possible nucleation cores of magnetization reversal.In this study, we examined the local MCA of hard magnetic materials from first principles onthe basis of density functional theory. OpenMX code [1] was used to calculate the electronicstates, and the perturbation theory was adopted for the spin-orbit interaction to analyze thelocal MCA [2]. First, we tried to clarify the origin of the hugest coercivity of ε-Fe2O3 amongall the metal oxides [3]. Our local MCA analysis shows that the only one Fe site, which is thenearest to an oxygen vacancy, dominantly contributes to the MCA. Next, we performedanalysis of the local MCA of L10-ordered alloys such as FePt, FePd, and FeNi, which areknown to exhibit high MCA [4]. As a result of our analysis, we found that the effect of Fe onMCA in this type of alloys is not always the same: Fe shows the in-plane MCA in FePt andFePd while it exhibits the out-of-plane one in FeNi. We will give the details in the presentation.

Reference

[1] http://www.openmx-square.org
[2] Z. Torbatian et al., Appl. Phys. Lett. 104, 242403 (2014).
[3] S. Ohkoshi et al., Bull. Chem. Soc. Jpn. 86, 897 (2013).
[4] Y. Kohta et al., J. Phys. Soc. Jpn. 81, 084705 (2012).


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