Dynamics of magnetic domains in microwave fields

Abstract

Using special microwave structures, strong spin precessions can be excited locally in LPE garnet films by microwaves near the ferrimagnetic resonance frequency. As soon as the precession angle θ exceeds a critical value, the spins tip over creating a bubble domain. If the bubble is small compared with the excitation region, it is ejected out of this region along a spiral path. In the other case, the bubble is trapped at the excitation region and reaching another critical value of θ the spins again tip over, creating a ring domain. Single-ring domains can only be stabilized by the microwave induced spin precession inside the ring. Amplitude modulation of the microwaves leads to a corresponding radial oscillation of the ring. Stripe domains are forced to align either parallel or perpendicular to the gradient of the spin precession. At high bias fields a new type of domain is observed.