Interface-assisted magnetoresistance behavior for ultrathin NiFe films

• We studied magnetic and electric transport properties of ultrathin NiFe films.
• Interface chemical states have strong influence on MR in NiFe films.
• Crystallization of the top MgO layer has influence on MR in NiFe films.

Interface-assisted magnetoresistance (MR) behavior has been studied in Ta/MgO/NiFe/MgO/Ta multilayers by inserting a Mg metal layer between the NiFe layer and the top MgO layer. It is shown that MR ratio is about 31% larger than that in the films without Mg insertion. X-ray photoelectron spectroscopy and high resolution transmission electron microscope analyses show that the enhanced MR is primarily ascribed to effective control of chemical states at the NiFe/MgO interface and crystallization of the top MgO layer.