# Fileset

[250-7_研究会資料.pdf](https://mdr.nims.go.jp/filesets/8d1ee30c-6e17-41ea-9fde-a1349c5b5bcc/download)

## Creator

[西野 正理](https://orcid.org/0000-0002-2060-2303)

## Rights

[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

## Other metadata

[原子論を基礎としたスピンモデルによる永久磁石の磁気特性の研究](https://mdr.nims.go.jp/datasets/1ee10539-09e9-456a-9e3c-34698ba3da60)

## Fulltext

250研究会資料_本文_ノンフル+柱.indd250   - 1 -  AAbbssttrraacctt  We introduce atomistic spin model studies, a new approach for theoretical investigations, on magnetic properties of permanent magnets such as neodymium magnets. In the atomistic modeling, the microscopic details of magnetic parameters and lattice structures are realistically considered, and the temperature effect, including thermal fluctuation, is properly treated based on statistical mechanics methods. Among our studies of the atomistic modeling from the ESICMM project to the present, we pick up the topic of the dysprosium substitution effect for coercivity enhancement of neodymium magnets and review the results.     [1]~[3][4][5] Fig.1 Unit cell of Nd2Fe14B magnet. Side view (left) and top view (right). Red, blue, and yellow spheres denote Nd, Fe, and B atoms, respectively.  − 39 −日本磁気学会　第 250 回研究会資料2  [5,6] [7],[8][7],[8] [9]~[11] [12][13],[14] [15],[16] [17][18] = 2 ( ) + , ,,,   (1)== += (= )(= )(=+ )[6][19,20] Fig.2 (a) Magnetic coupling between Nd and Fe atoms. The total moment in an Nd atom and that in an Fe atom are ferromagnetically coupled. Ex and SOI represent the exchange interaction and spin–orbit interaction, respectively. (b) Magnetic coupling between Dy and Fe atoms. The total magnetic moment of a Dy atom and that of an Fe atom are antiferromagnetically coupled.− 40 −3  = 1 + × + (1 + ) × × + (2) = (3)( ) = 0,   ( ) ( ) = 2 ( ),   = , , or, (4) = (5)[19,20]   Fig.3 (a) System A. The Nd surface layers are in contact with vacuum. In this example, Nd atoms (red) in the first Nd layer are substituted by Dy atoms (orange). (b) System B. The Nd surface layers are in contact with a soft magnet phase.  − 41 −4  [12]    Fig. 5  Snapshots of the spin configuration in nucleation for (a) n= 1 and (b) n=5 at the threshold fields h=3.70 T and h=5.05 T, respectively, at 0.46 Tc Troom in system B. The yellow–boxed regions correspond to the soft magnetic phase. Red and blue parts denote up–spin and down–spin ones, respectively. Fig. 4 n-dependence of the threshold filed in systems A (dotted lines) and B (solid lines) at (a) 0 K, (b) 0.34Tc, (c) 0.46 Tc, and (d) 0.69Tc. − 42 −5    DyDy DyA B DyNdDy Fe[18] Dy Fig. 6 Crystal electric field energy (a) for a Nd atom and (b) for a Dy atom as a function of  at zero and finite temperatures. to the c axis.  − 43 −6    [[ ]]  “”− 44 −2024 年 9 月 6 日受理