Site preference and tetragonal distortion of Heusler alloy Mn-Ni-V

Abstract

Site preference, tetragonal distortion and phase stability of all d-metal Heusler alloys Mn2−xNi1.5+xV0.5 (x = 0, 0.5, 1), Mn2−xNi1+xV (x = 0, 0.25, 0.5, 0.75, 1) and Mn2−xNi0.5+xV1.5 (x = 0, 0.5, 1, 1.5) are investigated. It has been found that Ni2MnV is stable in Hg2CuTi-type Heusler structure, while Mn2NiV tends to crystallize into Cu2MnAl-type Heusler structure. Mn atoms in both Ni-rich and Mn-rich Mn-Ni-V alloys preferentially occupy A, C sites, suggesting that the site occupation in Mn-Ni-V ternary alloy is not following the conventional site preference rule. A potential tetragonal distortion is expected in cubic structure of Ni-rich alloys MnNi2V, Mn1.25Ni1.75V, MnNi2.5V0.5 and Mn0.5Ni2V1.5. It is found that the tetragonal distortion is mainly attributed to the decrease of intensity for DOS at the Fermi level in the minority spin direction which is caused by the splitting of peaks. This study will guide us to design new tetragonal Heusler materials for spintronic devices. Keywords: A. d-Metal Heusler alloys, B. Tetragonal Heusler, C. Electronic structure