Half-metallic behavior of Co2MnSi/Co2MnAl/MgO interface and its coherent tunneling conductance

Abstract

We study electronic and transport properties of Co2MnSi/Co 2MnAl/MgO(001) junctions on the basis of the first-principles density functional calculations. We found that an insertion of thin Co2MnAl layers into a Co2MnSi/MgO junction can eliminate interface states in the minority-spin gap and provide a 100% spin-polarization at the interface. A transfer of electrons from the minority- to majority-spin states of interfacial Mn atoms plays an important role to recover the half-metallic gap in the MnAl-terminated interface. Furthermore, the magnetic tunnel junction with Co2MnSi/(Co2MnAl)n/MgO(001) (n=1∼3) retains coherent tunneling of the Δ1-band electrons in parallel magnetization, which is in contrast to that with Co2MnSi/(Co 2CrAl)n/MgO(001) where the tunneling of the Δ1-band electrons is reduced significantly at the Co 2CrAl layer. © 2010 IOP Publishing Ltd.