Ferromagnetic resonance modes in coupled layers with cubic magnetocrystalline anisotropy

Abstract

The ferromagnetic resonance (FMR) relations of an interfacially coupled two-layer magnetic system have been derived. In the case modeled here, the two films are assumed to be characterized by uniaxial and cubic magnetocrystalline anisotropies. Analytical expressions for the resonance condition have been found for a strong coupling case for both ferromagnetic and antiferromagnetic coupling. The FMR modes have also been studied as a function of the coupling strength. In the strong coupling cases, the system behaves as a single thin film with effective cubic and uniaxial anisotropy fields and effective magnetogyric ratios. When the coupling is antiferromagnetic a “spin-flop” can occur beyond a critical coupling value Kcrit. There will be a discontinuity in mode position. The critical coupling and field have been derived. This analysis could be used to study experimentally the nature and the strength of the magnetic coupling in systems with cubic and/or uniaxial magnetocrystalline anisotropies.