Resonance frequency of ferromagnetic/ferromagnetic bilayers with bilinear and biquadratic coupling

The effects of bilinear coupling, biquadratic coupling and stress anisotropy on ferromagnetic resonance frequency are investigated in ferromagnetic/ferromagnetic bilayers with in-plane uniaxial anisotropy. The intensity of applied magnetic field dependence of resonance frequencies is studied for different bilinear couplings, biquadratic couplings and stress anisotropies. It is shown that resonance frequency can be tunable by the intensity of bilinear coupling, biquadratic coupling and stress anisotropy. Moreover, the biquadratic coupling is more important than bilinear coupling for the optical mode. Simultaneously, we find the frequencies of two modes have a very distinct dependence on stress anisotropy. These results may be useful in designing new microwave devices.