Atomic disorder in Heusler alloy Cr₂CoGa

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• 作者：Hongzhi Luo^a ; ^b ; ^{luo_hongzhi@163.com" class="auth_mail" title="E-mail the corresponding author} ; Ling Yang^a ; Bohua Liu^a ; Fanbin Meng^a ; Enke Liu^b
• 关键词：Heusler alloys ; Half-metal ; Electronic structure ; Atomic disorder
• 刊名：Physica B: Physics of Condensed Matter
• 出版年：2015
• 出版时间：1 November 2015
• 年：2015
• 卷：476
• 期：Complete
• 页码：110-113
• 全文大小：1001 K

文摘

Heusler alloy Cr₂CoGa with 24 valence electrons is a promising candidate for half-metallic completely compensated ferrimagnets. Its electronic structure and atomic disorder have been investigated by using a KKR–CPA method. The equilibrium lattice constant is 5.88 Å and the total moment is as small as 0.09 渭_B. This near zero moment is mainly determined by the antiparallel aligned Cr (A) and Cr (B) spin moments, which are −2.16 渭_B and 2.17 渭_B, respectively and compensate each other. The calculated spin polarization ratio is as high as 95%. Three kinds of atomic disorder have been considered in Cr₂CoGa: Cr (B)-Co, Cr (A)-Co and Cr (B)-Ga. Among them, Cr (A)-Co and especially Cr (B)-Co disorder raise the total energy obviously. While Cr (B)-Ga disorder decreases the total energy by ~0.14 eV. So Cr (B)-Ga disorder is more energetically favored in the sample. The influence of Cr (B)-Ga disorder on the magnetic moment and electronic structure is small. The total moment only increases slightly to 0.16 渭_B. The influence of Cr (A)-Co disorder on the magnetic properties is also not obvious. Whereas Cr (B)-Co disorder increases the total moment obviously, which is mainly related to the ferromagnetic coupling between the Cr spin moments at A, C sites.