Ferromagnetic Resonance in Exchange-Coupled NiFe/FeMn Films and Its Control

The static and dynamic magnetization properties in an exchange-coupled NiFe/FeMn/Cu trilayer system have been investigated. Although a clear loop shift was observed in the magnetization versus field curve, the magnitude of the exchange bias does not show a systematic dependence on the Cu thickness. On the other hand, from the ferromagnetic resonance measurements, the exchange bias is found to increase with increasing the Cu thickness. This result indicates that the resonant frequency can be controlled by the Cu thickness. The correlation between the coercivity and the damping constant is also discussed.