Half-metallic interface between a Heusler alloy and Si

Abstract

The interface between the half-Heusler alloy CoFeSi and Si is investigated by usingfirst-principles density-functional calculations. Although CoFeSi has not been fabricatedyet, its formation energy turns out to be negative. Within the generalized gradientapproximation, CoFeSi shows nearly half-metallic properties, and its lattice constant isabout 5.38 Å; this value is relatively close to the lattice constant of Si. We herechiefly investigate the CoFeSi/Si (110) interface, and find that the half-metallicproperties are almost preserved at a specific (110) interface. Furthermore, theinterfacial structure which leads to the high spin polarization has the lowest energy ofthe (110) interfacial patterns examined in this work. The half-metallicity at theinterfaces is similarly observed in the densities of states projected onto delocalized spstates, and this suggests the relevance of the high spin polarization to transportproperties.