Wall structure changes in low-loss magnetic bubble materials

Abstract

Transitions between underdamped and overdamped radial motion in magnetic bubble domains are investigated in a low-loss rare-earth garnet material. Three distinct types of domain wall structures, which are present during underdamped motion, have been identified. Bubble walls were subjected to a bias field pulse ( H ) and tested for underdamped motion sometime (τ) later. The first type of structure follows the form H = H' \exp (\tau/\tau_{0}) , with 170 nsec nsec for the first transition, and is not statically stable. Transitions associated with the second type are characterized by a constant critical angle ( \bar{\Psi}_{c} ) between the magnetization in the middle of the wall, and the plane of the wall. For the first transition, \bar{\Psi}_{c} = 230\deg , and for the second, \bar{\Psi}_{c} = 370\deg . These structures are statically stable. The third type of structure is not statically stable, and H is independent of τ. The first and second wall structure types are associated with multiple transitions while the third only exhibits a single transition.