The Co2MnGe Heusler compound: a first principles study of the bulk phase and of the interface with GaAs

Within density functional theory, full-potential linearized augmented plane wave calculations have been performed to study the structural, electronic and magnetic properties of the Co₂MnGe Heusler compound. As a result of the semiconducting (metallic) character found in the minority (majority) band structure, this material is predicted to be half-metallic, with an integer magnetic moment of 5 μ_B. This peculiar property, highly desired for spintronics applications, stimulated the study of the Co₂MnGe/GaAs interface. Our calculations show that the predicted band offset is not suitable for spin-injection and that, due to interface states, the half-metallicity is lost in proximity to the junction.