[13a-S302-1~11] 10.1 新物質・新機能創成（作製・評価技術）

▲ [13a-S302-10] First-Principles Disordered Local-Moment Study on Temperature Dependence of Spin Polarization in Co₂Fe(Ga_0.5Ge_0.5) Heusler Alloy

〇(D)Ivan Kurniawan^1,2、Kenji Nawa^1,3、Keisuke Masuda¹、Yoshio Miura^1,4、Kazuhiro Hono^1,2 (1.NIMS、2.Univ. of Tsukuba、3.Mie Univ.、4.Osaka Univ.)

キーワード：First-principles, Disordered Local-Moment, Temperature dependence

Co-based Heusler alloys such as Co₂Fe(Ga_0.5Ge_0.5) (CFGG) and Co₂MnSi (CMS) have been demonstrated large magnetoresistance (MR) ratio when used as ferromagnetic electrode in MR devices. However, the large MR ratio is significantly reduced at elevated temperature, which may originate from the degradation of intrinsic spin polarization at finite temperature. Therefore, in this work, the finite temperature electronic structure was studied on the basis of the disordered-local moment (DLM) method, which combines the classical statistical physics and mean-field approximation to treat spin-fluctuation in magnetic systems. It is found that the calculated temperature dependence of sp spin polarization of CFGG is smaller than CMS due to the larger Curie temperature of CFGG which may also affects sp density of states through the s-d and p-d intra-atomic orbital coupling. In addition, the effect of electron and hole doping in off-stoichiometric Co-rich and Fe-rich alloys is also discussed.