Interface structure of half-metallic Heusler alloy Co_2MnSi thin films facing an MgO tunnel barrier determined by x-ray magnetic circular dichroism

摘要

Using x-ray absorption spectroscopy and x-ray magnetic circular dichroism, we performed an element-specific investigation of the spin magnetic moments (m_(spin)) of Mn and Co of Co_2MnSi ultrathin layers grown on an Fe underlayer to stabilize the ferromagnetism and facing an MgO barrier. The experimentally observed dependence of the m_(spin) values of Co and Mn on the Co_2MnSi layer thickness in the ultrathin region is qualitatively in good agreement with the one theoretically obtained for a MnSi-terminated interface of the Co_2MnSi 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.