Ferromagnetic Resonance Study of Annealed NiFe/FeMn/CoFe Trilayers

摘要

The effect of a thermal treatment on the exchange field in 19-nm NiFe(bottom)/15-nm FeMn/19-nm CoFe(top) trilayers has been investigated by employing a vibrating sample magnetometer (VSM) and a ferromagnetic resonance (FMR) spectrometer. FMR spectra as a function of applied dc field reveal that there are two distinct resonance peaks corresponding to each ferromagnetic layer. It is found that exchange fields determined from the in-plane angular dependence of the resonance field are in accord with that determined through the magnetic hysteresis loops for the NiFe/FeMn interface rather than the CoFe/FeMn one. A FMR linewidth broadening as a function of the annealing temperatures is attributed to the interdiffusion between the two magnetic interfaces across a FeMn layer.