Measurement of exchange anisotropy in NiFe/FeMn bilayers using different methods

摘要

Due to the influence of some factors, the Exchange bias (EB) field (H_E) that leads us to use different thin film magnetic measurements is different. So we want to give fixed magnetic material parameters in order to explore different methods for the measurement of the EB field. A series of NiFe(15 nm)/FeMn(t_(AF)) exchange-biased bilayers were fabricated by magnetron sputtering. Three different methods were used to measure the exchange bias field of the thin films. The first method used a traditional vibrating sample magnetometer (VSM), the second one was the anisotropic magnetoresistance (AMR) technique and the last method was the vector network analyzer ferromagnetic resonance (VNA-FMR) technique. The results show that for the sample at the critical thickness, the exchange bias fields obtained by AMR and VNA-FMR were much larger than those from the VSM, which can be explained by the unstable coupled grains at the interface. For the sample at the saturation thickness, the measurement values of the three methods are almost the same.