Electronic structure and magnetic properties of quaternary Heusler alloy Co2CrGa1−xGex (x=0−1)

The electronic structure of Co-based quaternary Heusler compounds Co2CrGa1−xGex (x=0.00, 0.25, 0.50, 0.75, 1.00) are calculated by first-principles density functional theory. The substitution of Ga by Ge leads to increase in the number of valence electrons. With increasing concentration of Ge, lattice constant decreases linearly whereas bulk modulus and total magnetic moment increases. This shows that the magnetic properties of the compound are dependent on electron concentration of main group element. The calculations show that the alloys with x=0.00, 0.25, 0.50 are not true half-metallic materials whereas alloy with x=0.75, 1.00 exhibit 100% spin polarization at the Fermi level. It shows that the Fermi level can be shifted within the energy-gap to achieve 100% spin polarization. The effect of volumetric and tetragonal strain on magnetic properties is also studied.