First-principles study on structural, electronic, elastic and thermodynamic properties of the full-Heusler alloys Co₂YZ (Y=Sc, Cr and Z=Al, Ga)

Abstract

First-principles calculations based on density functional theory (DFT) and quasi-harmonic Debye model are performed to study the structural, elastic, electronic and thermodynamic properties of the Co2YZ (Y=Sc, Cr and Z=Al, Ga) Heusler alloys. It is found that the spin polarization of Co2CrZ at Fermi level raises considerably, and Co2ScZ keeps the non-magnetic feature when the external pressure increases. Although outstanding performance of half-metallicity appears to Co2CrZ, the dynamical stability order exhibits that Co2ScZ > Co2CrZ as the result of phonon dispersion analysis. The influence of external pressure and temperature on the volume compression ratio, bulk modulus, heat capacity and thermal expansion coefficient are took fully into account and the outcomes from calculation obey the corresponding thermomechanics laws in the quasi-harmonic Debye model.