Excitations of stripe domain lattices in perpendicularly magnetized garnet films

Magnetic garnet films of composition Y3–xBixFe5–yAlyO12 are grown by liquid phase epitaxy on [111] and [110] oriented substrates of gadolinium gallium garnet. They have high uniaxial anisotropy and support lattices of parallel stripe domains. The two branches DR+ and DR− of the domain resonance are excited by rf magnetic fields polarized in the film plane. Resonance frequencies of more than 7 GHz are observed; they are measured as function of a static induction B⟂ applied perpendicular to the film plane. With increasing B⟂ the resonance mode DR+ is confined to the small domain with equilibrium magnetization antiparallel to B⟂, while DR− is confined in the larger stripe having equilibrium magnetization parallel to B⟂. At the collapse induction the DR− mode merges into the ferrimagnetic resonance. The resonance modes DR± are calculated using a new method to determine the demagnetizing energy. Excellent agreement between theory and experiment is obtained.