Huge Tunneling Magnetoresistance in Magnetic Tunnel Junction with Heusler Alloy Co₂MnSi Electrodes

Magnetic tunnel junction with a large tunneling magnetoresistance has attracted great attention due to its importance in the spintronics applications. By performing extensive density functional theory calculations combined with the nonequilibrium Green's function method, we explore the spin-dependent transport properties of a magnetic tunnel junction, in which a non-polar SrTiO_3 barrier layer is sandwiched between two Heusler alloy Co_2MnSi electrodes. Theoretical results clearly reveal that the near perfect spin-filtering effect appears in the parallel magnetization configuration. The transmission coefficient in the parallel magnetization configuration at the Fermi level is several orders of magnitude larger than that in the antiparallel magnetization configuration, resulting in a huge tunneling magnetoresistance (i.e. >10^6), which originates from the coherent spin-polarized tunneling, due to the half-metallic nature of Co_2MnSi electrodes and the significant spin-polarization of the interfacial Ti 3d orbital.