[9p-M101-1~7] 10.1 新物質・新機能創成（作製・評価技術）

▲ [9p-M101-1] Ab-initio search for half-metal Co-based full Heusler alloy

〇Kenji Nawa¹、Yoshio Miura¹ (1.NIMS)

キーワード：Co-based Heusler alloy, Half-metal, Density functional theory

Co-based full Heusler alloy is a key material due to a high Curie temperature and a possibility to show half-metallic ferromagnetism (HMF). The ab-initio calculations have been expected to play a great role in search of HM materials, but most of theoretical studies have a lack of electron correlation effect while this interaction is essential to understand physical property of Heusler alloys.
In this study, the DFT+U calculations, in which the correlation term U is determined theoretically, were performed to reinvestigate fundamental electronic structure of Co-based full Heusler alloys in bulk and to explore a capability of the HMF. For Co₂MnSi, our calculations revealed the correlation effect of Mn is more significant than that of Co to obtain the electronic and magnetic structures where in good agreement with experiments. Then the DFT+U calculations including only Mn-correlation concluded the HMF is appeared in Co₂MnSi. Furthermore, in quaternary system, we found the most promising candidates for HMF materials are the Co₂(Ti_0.25,Mn_0.75)Si and Co₂(Fe_0.25,Mn_0.75)Si in terms of the Fermi energy locating at around the center of conduction and valence states.