High-frequency domain wall excitations in magnetic garnet films with in-plane magnetization

Magnetic garnet films of compositions (YBi)₃{Fe}₅O₁₂ and (LuBi)₃{Fe}₅O₁₂ are grown by liquid-phase epitaxy on [110]- and [100]-oriented substrates of gadolinium gallium garnet, respectively. All films have in-plane magnetization. 180^∘{} and 90^∘{} domain walls in these films are studied by microwave technique. In addition to the known low-frequency mode of wall translation new multiple resonant modes of both 90^∘{} and 180^∘{} domain walls with very small linewidth (4.2 MHz) are observed at frequencies near 1 GHz. Resonances are effectively excited by an rf magnetic field which is parallel or perpendicular to the wall plane. Resonance frequencies are shown to have nonlinear dispersion dependence on the mode number: they decrease with increasing in-plane magnetic field normal to the wall plane.