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Origin of crystaline magnetic anisotropy of Sm2Fe17N3 permanent magnet material

ICM2018(San Francisco, USA)

2018年7月18日(水)

H. Akai

Abstract

Electronic structure and magnetic properties of Sm2Fe17Nx are studies on the basis of thefirst- principles electronic structure calculation in the framework of the den- sity functionaltheory within the local density and coherent potential approximations. The magnetic anisotropyof the system as a function of nitrogen concentration x is discussed by taking account notonly of the crystal field effects but also of the effects of the hybridization of f-states of Smwith the neighboring N p-states[1]. Without N atoms, the hybridization of Sm-f states withsurrounding atoms is rather small and the f states keep a feature of narrow atomic-like stateirrespective of the relative angle between the magnetization and crystal axes. In this situation,the rotation of crystal axes has little effect on the Sm-f states and causes no significantmagnetic anisotropy. When N atoms are introduced, the hybridization between Sm-4f and N-2p states occurs. When the magnetization lies along the c-axis, the strongest hybridizationoccurs between N-2p and Sm- 4f with magnetic quantum number m = ±3 states. On theother hand, for the in-plane magnetization, the strongest hybridization is between the Sm m =0 state and N-2p states. Comparing these two cases, we may say that an energy gain isexpected only when the hybridization occurs between m = −3 and the N-2p states. This isbecause the spin- orbit douping pushes up only the m = −3 state above the Fermi level andthus causes the energy gain due to the lowering of the occupied state energy levels[2]. Theimportance of hybridization is also proven by the fact that, if the open-core scheme for Sm-fstates be adopted, where no hybridization occurs between Sm-f and N-2p states, the uniaxialmagnetic anisotropy does not occur.


研究活動

文部科学省

文部科学省
元素戦略プロジェクト(活動紹介)
NIMS磁石パートナーシップ

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