The Structural, Mechanical, Half-Metallic, and Magnetic Properties of Quaternary Heusler Alloy CrFeVAl: A First-Principles Study

Abstract

Heusler alloys are promising spintronic materials. For spintronics, it is essential to explore magnetic materials with high spin polarization and high Curie temperature. Theoretical methods based on first-principles calculations have been extensively used for studies of materials because these methods can reduce material costs. Hence, a quaternary Heusler alloy, CrFeVAl, in which one Fe atom in the Fe2VAl crystal structure is replaced with Cr atom, was investigated by first-principles calculations using the CASTEP package. The results showed that the CrFeVAl alloy is a type-2 stable compound with a LiMgPdSn-type structure, having an equilibrium lattice constant of 5.842 Å. An investigation of its mechanical properties showed that the alloy is similar to Fe2VAl and that it is an anisotropic brittle material. Notably, the inclusion of Cr was found to effectively reduce the brittleness compared to that of Fe2VAl. In addition, its Debye temperature was calculated to be 368.3 K, which is lower than that of the Fe2VAl alloy. Electronic structure calculations indicated that CrFeVAl is an excellent half-metallic ferromagnetic material, with a spin polarization of 100%. Examination of the electronic structure further showed that the magnetism in CrFeVAl originates mainly from the spin contribution of the d electrons of the transition metal atoms in the alloy and the hybridisation between their d orbitals. The deformation range of the alloy under stress was between −2.7 and 2.0%, demonstrating that the alloy can maintain excellent half-metallic behaviour. Therefore, we believe that CrFeVAl can be employed as a new spintronic material.