Formation and destruction of dynamic spiral domains in the anger state of a ferrite-garnet film

Abstract

It is known [1–4] that thin ferrite–garnet films with perpendicular anisotropy and original maze domain structure can transit to a certain excited state, or anger state, in varying spatially uniform magnetic fields of low frequencies (102–104 Hz). In this state, processes of self-organization occur in an ensemble of chaotically moving interacting domains; i.e., ordered stable dynamic domain structures of various geometry (spiral, ring, etc.) arise. It is specific to the anger state that a spiral domain formed in the observed section of the film exists during the time il and then disappears. After a certain time (waiting time iw), one or several new spiral domains arise in this section. Spiral dynamic domains can have different forms in different films [1]. In this work, we analyze the “life” of individual spiral domains in a thin highly anisotropic ferrite–garnet film with the focus on both the first stage in the life of spiral domains, i.e., origin and formation of a multiturn spiral domain, and the last stage, i.e., aging and destruction. We studied a (111) ferrite–garnet film with induced uniaxial perpendicular anisotropy, (YLuBi)3(FeGa)5O12 composition, thickness L = 9.5 μm, and 4 × 4 mm in section at a temperature of 25°C. A sample in the initial demagnetized state had the ordinary maze structure with the period e0 = 33 μm of the strip domains. The static saturation field determined by the collapse of cylinder domains was equal to 50 Oe. The quality factor of