Exchange bias adjust resonance frequency in FeNi/FeMn nanofilm based on polarized neutron reflectometer

摘要

To study the relationship between the exchange bias effect and the resonance frequency of magnetic nanofilms, FeNi and FeNi/FeMn exchange-coupled films were fabricated on a silicon substrate by magnetron sputtering deposition. The static and dynamic magnetic properties of the multilayer films were investigated using a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA). The VSM results indicate that after introducing the FeMn layer, the exchange bias field increased to 62 Oe and the magnetic anisotropy field shifted from 6 to 107 Oe. The VNA results show that the resonance frequency increased from 0.72 to 2.8 GHz, originating from the interface exchange coupling strength. In addition, as a probe for the surface and interface structure, a time-of-flight polarized neutron reflectometer was used to observe the microstructure of the multilayer films. The diffusion with a 2.5 nm thickness between the multilayer films was observed by the polarized neutron reflection experiment, further illustrating that the exchange bias effect is derived from the interaction between the FeNi/FeMn layers. It is concluded that the magnetic induction of a FeNi layer is 0.98 T through fitting the data obtained from the polarized neutron reflection experiment.