Abstract

Ferromagnetic resonance (FMR) measurements using a broadband microstrip excitation technique were performed at room temperature for an antiferromagnetic/ferromagnetic (AF/FM) bilayer of Ir20Mn80(35.0 nm)/Ni81Fe19(7.5 nm). The angular dependence of the resonance field was measured for several excitation frequencies ranging from 1.5 to 10.0 GHz. From the numerical fitting of the experimental data, it was observed that the exchange bias field (H-E) and the rotatable anisotropy field (H-RA) originating from the exchange interaction at the AF/FM interface are frequency dependent. The results were explained considering the coexistence of ferromagnetic and antiferromagnetic coupling at the AF/FM interface. We also investigated the spin pumping voltage generated in the structure of Ir20Mn80(35.0 nm)/Ni81Fe19(7.5 nm)/Pt(4 nm) and showed that from the voltage peaks occurring at the ferromagnetic resonance condition it is possible to reproduce the FMR dispersion relation.