ホーム > 研究活動 > 口頭発表(2013) > Magnetocrystalline anisotropy of the Fe-sublattice in R2Fe14B systems

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Magnetocrystalline anisotropy of the Fe-sublattice in R2Fe14B systems

The 58th Annual Conference on Magnetism and Magnetic Materials (MMM)

Y.Miura ( Tohoku Univ )
H.Tsuchiura ( Tohoku Univ )
T.Yoshioka ( Tohoku Univ )

Abstract

Because of the recent developments of renewable and sustainable technology, there has beenemerging interest in improving the coercivity of Nd-Fe-B permanent magnets, and in revealingits mechanism.
Several recent experimental studies have shown that local structures aroundthe grain boundaries of sintered Nd-Fe-B magnets significantly affect their coercivity.
Theoretically, one of the authors and his co-workers have estimated the crystal field of Ndions around the surface of the crystalline Nd2Fe14B based on first-principles calculations, andfound that the Nd ions exposed on the (001) surface exhibit c-plane magnetic anisotropy [1,2],resulting in a reduction of coercivity of a single Nd2Fe14B grain by half of the anisotropy fieldHK [3].
For further understanding of the magnetic anisotropy and the coercivity of Nd-Fe-B,the information of the role of the Fe sublattice is needed.
Thus in this paper, as a first step,we study the magnetic anisotropy of Y2Fe14B, and in particular, estimate the contributions tothe MCA energy from each Fe site, based on the first-principles density-functionalcalculations within the generalized gradient approximation (GGA).
The magnetocrystallineanisotropy (MCA) energy is obtained on the basis of the force-theorem, i.e., the difference inthe sum of energy eigenvalues for the magnetization oriented along the in-plane (100) andout-of-plane (001) directions.
These calculations are implemented within the Vienna ab initioSimulation Program (VASP). Our results are summarized in Figure 1.
We can see that Fe ionslocated on the 4c sites of Nd2Fe14B structure exhibit strong in-plane anisotropy.
Theseresults may be a physical origin of the anomalous temperature dependence of the anisotropycoefficient of K1.



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