Relative contributions of surface and grain boundary scattering to the spin-polarized electrons transport in the AlN/NiFe/AlN heterostructures

When the film thickness approaches the electron mean free path (MFP), the relative contributions of surface/grain boundary scattering to the resistivity remain indefinitive. In this work, series of NiFe films sandwiched by AlN barriers were employed to study the transport properties. Surface scattering is found to provide the strongest contribution to the resistivity increase for very thin films (dNiFe ≤ 10 nm). With the increase of the film thickness, the effect of the grain boundary scattering gradually increases while the surface scattering decreases. When the thickness of the film is over 30 nm, the former becomes predominant.