Atomic disorder in Heusler alloy Cr2CoGa

• Published in: Physica. B, Condensed matter Condensed matter, 2015-11, Vol.476, p.110-113
• Main Authors: Luo, Hongzhi, Yang, Ling, Liu, Bohua, Meng, Fanbin, Liu, Enke
• Format: Article
• Language: English
• Subjects: Atomic disorder; Electronic structure; Half-metal; Heusler alloys
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2015.04.030

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 5.88Å and the total moment is as small as 0.09μB. This near zero moment is mainly determined by the antiparallel aligned Cr (A) and Cr (B) spin moments, which are −2.16μB and 2.17μB, 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 ~0.14eV. 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 0.16μB. 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.