Influence of chromium doping on the properties of Co2FeGe full Heusler alloys: First-principles calculations and Monte Carlo simulations

Abstract

The effect of chromium substitution on novel full Heusler alloys on the structural, mechanical, electronic, magnetic, and thermomagnetic properties of Co₂Fe_1-xCr_xGe has been studied through first-principles calculations and Monte Carlo simulations. The chromium substitution induces a phase change due to differences in crystal symmetry. The materials are all stable according to formation energy and the Born-Huang criteria. The band gap of Co₂Fe_1-xCr_xGe materials ranges from 0.876 eV to 1.566 eV The analysis of spin polarization indicates that all amounts of chromium concentration led to full polarization, suggesting that the material exhibits half-metallic behavior. A decrease in total magnetic moments and exchange coupling interactions is observed with increasing Cr concentration, which modifies the magnetic moment and electronic structure. The most robust exchange coupling occurs between the nearest neighbor Co-Fe pairs. The analysis of thermomagnetic properties shows that substituting chromium decreases the Curie temperature from 1020 K to 660K.