Pressure and disorder effects on the half-metallic character and magnetic properties of the full-Heusler alloy Co2FeSi

We investigate the pressure and site disorder effects on the half-metallicity and magnetic properties of the full-Heusler alloy Co2FeSi using first-principles density functional theory within the GGA and GGA+U schemes. The calculated lattice constant, bulk modulus and total magnetic moments are in excellent agreement with recent experiments. The volume compression leads to a slight increase of the minority band gap, i.e., the half-metallic properties of Co2FeSi can maintain under pressure. The disorder calculations reveal that Fe-Co type disorder significantly destroys the half-metallic character and reduces the spin polarization of Co2FeSi while disorder between Fe and Si can maintain half-metallic properties. Our results also show that the Fe-Co type disorder leads to degradation of the magnetism while the Fe-Si type disorder affects hardly the magnetism as observed in Co2FeSi.