Influence on the transport behaviors of spin-polarized electrons exerted by MgO/NiFe and NiFe/MgO heterointerfaces

This work reports on the influence of different MgO/NiFe and NiFe/MgO heterointerfaces on the transport behaviors of spin-polarized electrons. It is found that the NiFe films with MgO underneath exhibit better transport properties than those coated by an MgO layer. The MgO/NiFe interface can significantly enhance the specular reflection of spin-polarized electrons and favor the electronic transport. In contrast, a greater lattice mismatch between NiFe and MgO will emerge because of the epitaxial relationship at the NiFe(111)/MgO(111) interface, with the resultant formation of oxygen-deficient MgOx phase at the NiFe/MgO interface. Significantly diffusive scattering of conduction electrons from such vacancy defects can substantially degrade the electron transport properties.