Exchange coupled bilayer thin films with tilted out-of-plane anisotropy easy axis

Abstract

The ferromagnetic resonance (FMR) modes are worked out for the case of exchange coupled bilayer thin films where the anisotropy axis in the ferromagnetic film is tilted out of the plane. General formulas are obtained for the mode position, frequency and field linewidths, and intensity for an arbitrary tilt angle. The analysis is then applied for the in-plane, weak and strong perpendicular anisotropies. Analytical expressions for the magnetization curve and the FMR modes are derived. It will be shown how the exchange anisotropy field HE, the uniaxial anisotropy HK, and the magnetization angle are related to the FMR spectrum characteristics and how they can be found in a straightforward manner.