Distinctly Different Switching Characteristics of Interface and Bulk Magnetization in Fe/AlGaAs(001) and Fe/MgO(001)

The interface magnetization processes of Fe/AlGaAs(001) and Fe/MgO(001) are investigated by magnetization induced second harmonic generation (MSHG). The interface switching characteristics of Fe/AlGaAs(001) are distinctly different from the bulk Fe film due to magnetization curling in nano-islands located at the interface. We estimate the thickness of Fe interface to be a few atomic layers thick and the interface exchange stiffness to be three orders of magnitude less than the bulk. In Fe/MgO(001) interface, the cubic magnetic anisotropy is dominant, but the interface magnetization exhibits an exchange bias which is absent in the bulk. The implications of these findings for spintronic applications will be discussed.