First-principles calculations for formation energy and magnetism of defect structures in Heusler alloys Mg -V -Z (Z = Al, Ga, In)

The defect formation energies and magnetic properties of Mg-V-Z (Z = Al, Ga, In) are systematically investigated by the method of first-principles calculations. The Z atom plays an important role in cube structural stability. The substitutions (exchanges) between second neighbor atoms are energetically favorable than that between first neighbor atoms. The Mg-rich V-poor, V-rich Mg-poor and V-rich In-poor alloys tend to form direct antisite defect, while the other off-stoichiometry alloys tend to form indirect antisite defects. The indirect antisite defect pairs consisting of MgV and VMg1 are the easiest to form in stoichiometric alloys. The magnetic moments of V atoms at defect sites are antiparallel to and smaller than those at normal sites. The magnetic moments of V at normal sites are sensitive to the distances between themselves and defect atoms.

Automated summary

The study indicates that Z atoms play an important role in structural stability, substitutions between second neighbor atoms are energetically favorable, and Mg-rich V-poor, V-rich Mg-poor, and V-rich In-poor alloys tend to form direct antisite defects, while other alloys tend to form indirect antisite defects. Indirect antisite defects are easier to form in stoichiometric alloys.