Broadband microwave absorption in [NiFe/FeMn]n exchange-coupled multilayer films

[NiFe/FeMn]n exchange-coupled multilayer films have been fabricated on the silicon substrate by magnetron sputtering deposition. The static and dynamic magnetic properties of multilayer films have been investigated with varying numbers of layers. The results show that the linewidth and permeability of imaginary resonance peak are increased with increasing numbers of layers. For the NiFe/FeMn/NiFe sample, the resonance frequency shows a different shift with applying external magnetic field along the direction of easy and hard magnetization axis of the sample, respectively, indicating a different magnetic reversal process in two ferromagnetic layers. It proved that the increase of linewidth was originated from the different interface exchange coupling.