Structural stability and magnetic and electronic properties of Co₂MnSi(001)/MgO heterostructures: A density-functional theory study

A computational study of the epitaxial Co₂MnSi(001)=MgO(001) interface relevant to tunneling magnetoresistive devices is presented. Employing ab initio atomistic thermodynamics, we show that the Co or MnSi planes of bulk-terminated Co₂MnSi form stable interfaces, while pure Si or pure Mn termination requires nonequilibrium conditions. Except for the pure Mn interface, the half-metallic property of bulk Co₂MnSi is disrupted by interface bands. Even so, at homogeneous Mn or Co interfaces these bands contribute little to the minority-spin conductance through an MgO barrier, and hence such terminations could perform strongly in tunneling magnetoresistive devices