Effect of biquadratic coupling and in-plane anisotropy on the resonance modes of a trilayer system
Abstract
Ferromagnetic resonance modes are investigated for a trilayer system consisting of two ferromagnetic films interacting through a nonmagnetic interlayer. Included in the model are the bilinear J1 and biquadratic J2 couplings and in-plane uniaxial magnetocrystalline anisotropies with anisotropy axis directions in the two layers making a δ angle. An analytical expression for the mode intensity is derived. The saturation (Hsat) and critical (Hcrit) fields, the resonant frequency, and the mode intensity are discussed as functions of J1, J2, and δ. For a given positive J1, an additional J2(J2<0) will lead to an increase (a decrease) of the optical (acoustic) mode intensity. For fixed J1<0, and if the magnetizations are parallel (H>Hsat) only the acoustic mode will appear with constant mode position and intensity for all J2 values, making it difficult to detect any additional biquadratic coupling. On the other hand, and for the same parameters, if the magnetizations are antiparallel (H<Hcrit), then two modes are predicted; as \|J2\| increases the intensity of the acoustic (optical) mode will increase (decrease), while the resonant frequency of both modes decrease.
- Publication:
-
Physical Review B
- Pub Date:
- March 2002
- DOI:
- 10.1103/PhysRevB.65.104422
- Bibcode:
- 2002PhRvB..65j4422L
- Keywords:
-
- 76.50.+g;
- 76.20.+q;
- 75.70.Cn;
- 75.30.Gw;
- Ferromagnetic antiferromagnetic and ferrimagnetic resonances;
- spin-wave resonance;
- General theory of resonances and relaxations;
- Magnetic properties of interfaces;
- Magnetic anisotropy