First-principles study of magnetism and phase stabilities of V2 based antiferromagnetic Heusler alloys

Abstract

We investigate the phase stability and magnetism of V2 based antiferromagnetic semiconductors by first-principles calculations. We first analyze the phase stability of the designed alloys by calculating the convex hull and find that keeping Al atoms in the Z sites is crucial to guarantee the stability against the segregation. The V2YAl (Y=V, Nb, and Ta) systems have relatively small hull distances and Néel temperatures higher than 1000 K are evaluated. The strong antiferromagnetic coupling between V atoms is rapidly decreasing with increasing the number of electrons due to the appearance of ferromagnetic double-exchange interaction. By applying a uniaxial strain to induce tetragonal distortion, a relatively large magneto-crystalline anisotropy energy is obtained for V2TaAl. It is claimed that V2YAl are thought to be good candidates for antiferromagnetic spintronics including gate-tunable magnetic properties.