Coupled oscillations of domain-domain wall system in garnet films

Abstract

Interactions between the domain wall resonance mode (DWR) and the domain ferromagnetic resonance modes ω− and ω+ were observed for the first time in unsaturated Ga- and La-doped thin YIG films. The samples were around 10 μm thick, their 4πM ranged from 1470 to 525 G, uniaxial anisotropy field ranged between 400 and 800 Oe and the in-plane saturation field was between 110 and 690 Oe. A transmission rf spectrometer using a slotted rf structure in the 10–2500 MHz range was used to observe the signals. The zero in-plane field DWR frequencies were an order of magnitude higher than those of typical bubble materials and ω+ and ω− fell in the same frequency-field regime as the DWR. The interactions between the modes resulted in frequency gaps of 70–500 MHz for the DWR-ω− modes and 200–10 MHz for the DWR-ω+ modes. A generalized theory of dynamics of a system of domains and domain walls is proposed. The results of the theory, which predicts a coupling of the form hc sin 2θ between DWR and ω−, are discussed.