A theoretical investigation of Ferromagnetic Resonance Linewidth and damping constants in coupled trilayer and spin valve systems

The ferromagnetic resonance intrinsic field linewidth ΔH is investigated for a multilayer system such as a coupled trilayer and a spin valve structure. The magnetic coupling between two ferromagnetic layers separated by a nonmagnetic interlayer will be described by the bilinear J₁ and biquadratic J₂ coupling parameters. The interaction at the interface of the first ferromagnetic layer with the antiferromagnetic one is account for by the exchange anisotropy field, H_E. A general formula is derived for the intrinsic linewidth ΔH. The explicit dependence of ΔH with H_E, J₁ and J₂ will be highlighted. Analytical expressions for each mode field linewidth are found in special cases. Equivalent damping constants will be discussed