Wall structure changes in low-loss magnetic bubble materials

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
< \tau_{0} <270
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.