Static and microwave properties of amorphous magnets near saturation

Abstract

Static and dynamic properties of magnetically soft amorphous ferromagnets have been studied analytically within the random-field model and numerically within the random-anisotropy model. External field and coherent anisotropy that are weak compared to their random counterparts are sufficient to bring the magnet close to saturation. The scaling of spin–spin correlations in this regime is computed, and its dependence on parameters is confirmed by Monte Carlo simulation. We show that near the ferromagnetic resonance, the spin excitations are damped and spatially localized due to randomness even close to saturation. Uniform precession is not an eigenmode of the system which causes its damping. On increasing the strength of randomness, the localization length goes down in accordance with theoretical expectations, while the damping of the uniform precession goes up.