Large enhancement of anisotropic magnetoresistance and thermal stability in Ta/NiFe/Ta trilayers with interfacial Pt addition

Abstract

Ta/NiFe/Ta trilayers, extensively used for anisotropic magnetoresistance (AMR) sensors, exhibit severely reduced MR ratio at small NiFe thickness and appreciable moment loss, especially after annealing. By inserting ultrathin Pt layers at the interfaces of the trilayers, AMR can be significantly enhanced for thin NiFe films due to the strong electron spin-orbit scattering at Pt/NiFe interfaces along with suppression of interfacial magnetic dead layers. Furthermore, the Pt layers also reduce Ta and NiFe interdiffusion and result in negligible moment loss and AMR degradation after annealing at 350 °C.