Mobility of a charged wall coupled to a bubble

The dynamic response of bubble domains coupled to charged walls in an ion-implanted layer and circulating or oscillating on disc and square shaped unimplanted structures is investigated. A polarizing microscope equipped with a silicon intensified target TV camera was used to measure the trace of the high frequency oscillatory motions, and a high speed magneto-optic camera using a 7 nsec pulse width laser measured the phase lag stroboscopically during circulatory motions. The data show that the bubble and charged wall are tightly coupled. Moreover, the charged wall mobility is sufficiently high that only the damping by the bubble wall limits the frequency of oscillation. It is shown that the coupled system behaves like an overdamped linear oscillator, and from this model the effective mobility of the coupled system is derived.