Structural, electronic, magnetic, and transport properties of the quaternary Heusler alloy FeMnVGe

This work presents the structural, electronic, magnetic, mechanical, and transport properties of various crystal structures of the quaternary Heusler alloy FeMnVGe investigated within the framework of the density functional theory. All calculations were performed using the meta-generalized gradient approximation SCAN functional for the exchange correlation energy. It is shown that the ground state of the alloy with a structure in which Mn and Fe atoms are partially disordered, exhibiting an integer value of the magnetic moment, also has an energy gap of ≈0.367 eV at the Fermi level in the spin-up channel, and 100 % spin polarization, which indicates a half-metallic nature. The ordered structure exhibits metallic behavior, however, with an increase in the lattice parameter by ≈8.5 %, the alloy with this structure becomes a semiconductor and possesses a Fermi level energy gap equal to ≈0.227 eV. For type 2S this leads to a higher ZT value of ≈1.37 at a temperature of 900 K compared to other structures considered. Calculations of the formation energy demonstrate the stability of all crystal structures against segregation into constituent elements. Among other things, the elastic constants satisfy the stability criteria, indicating that all structures are mechanically stable.

1. Russian Science Foundation - 22-12-20032