Interface structure of half-metallic Heusler alloyCo2MnSithin films facing an MgO tunnel barrier determined by x-ray magnetic circular dichroism

Using x-ray absorption spectroscopy and x-ray magnetic circular dichroism, we performed an element-specific investigation of the spin magnetic moments $({m}_{\text{spin}})$ of Mn and Co of ${\text{Co}}_{2}\text{MnSi}$ ultrathin layers grown on an Fe underlayer to stabilize the ferromagnetism and facing an MgO barrier. The experimentally observed dependence of the ${m}_{\text{spin}}$ values of Co and Mn on the ${\text{Co}}_{2}\text{MnSi}$ layer thickness in the ultrathin region is qualitatively in good agreement with the one theoretically obtained for a MnSi-terminated interface of the ${\text{Co}}_{2}\text{MnSi}$ layer facing an MgO barrier. This clarification would provide a strong basis for further advancement of applications of half-metallic Heusler alloy electrodes into spintronic devices.