Statics and Dynamics of Bubbles Containing Bloch Lines

Static and dynamic properties of hard magnetic bubbles, both in circular and dumbbell form, are investigated. Exchange repulsion between Bloch lines (BL's) increases the radii of circular domains and makes dumbbells stable. Extension of Thiele's theory accounts simultaneously for the circle‐dumbbell and circle‐collapse boundaries in the diameter versus bias‐field diagram. A theory of hard‐bubble skewed translation is given. Experiments on bubbles translating with small deflection angles show a quantization in angle which supports the theory and makes it possible to identify bubbles with only a few BL's. Dumbbells are observed to rotate in pulsed bias fields. A laser photographic technique with 10 nsec resolution is used to study the rotation as a function of time. Two models of the rotation effect attribute the rotation to gyrotropic reaction caused by the change of domain length in response to the pulse.