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

¹ School of Physical Science and Technology, Southwest University, 400715 Chongqing, P.R. China
² Department of Physics, Chongqing University of Arts and Sciences, 402160 Chongqing, P.R. China
³ Department of Physics, Longdong University, 745000 Qingyang, P.R. China

^a e-mail: chenh@swu.edu.cn

Received: 15 January 2015
Revised: 25 March 2015
Accepted: 26 May 2015
Published online: 24 June 2015

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.