Half-metallicity at the (110) interface between a full Heusler alloy and GaAs

The electronic properties of Co2CrAl/GaAs interfaces are investigated by using first-principles calculations with density functional theory. It is found that spin polarization tends to remain relatively high at the (110) interface and reaches almost unity for a specific (110) interfacial structure. Furthermore, the nearly-half-metallic interface turns out to be the most stable of the (110) interfacial structures studied here. Spin polarization calculated only from the sp-projected density of states is also examined in order to eliminate the effects stemming from the localized d components. The analysis shows that the high spin polarization at the (110) interface owes little to the localized d component and, therefore, is expected to be fairly relevant to transport properties. Co2CrSi/GaAs, Co2MnSi/GaAs, and Co2MnGe/GaAs heterostructures are also investigated, and similar half-metal-like behavior at (110) interface is observed for all of them.