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.