Heusler alloy Mn2CoAl: structural, magnetic and electronic properties

Abstract

Abstract In this study, we report on the detailed atomic ordering, magnetic and electrical properties of the Heusler alloy Mn2CoAl, studied via combined experimental methods and a theoretical calculation approach. Our studies confirm the Hg2CuTi-type crystal structure of Mn2CoAl with 25% anti-site disorder between Mn (B:1/4,1/4,1/4) and Co(C:1/2,1/2,1/2) sites. Neutron powder diffraction measurements identify the antiparallel spin couplings between Mn:A↓ and Mn:B↑, Co:C↑, resulting in a ferrimagnetic structure with a net magnetic moment of ∼1.6 μ B at room temperature. In terms of the electronic calculations, we find that the anti-site atoms will contribute large densities of states at the Fermi level, thus destroying the spin gapless band structure and making Mn2CoAl a normal ferrimagnetic metal. This report is intended to establish a basic understanding of the structure and physical properties of Mn2CoAl.