Bubble domain propagation dynamics in field-access permalloy driving circuits

To improve the understanding of the bubble domain propagation a stroboscopic investigation of bubble displacement with a permalloy T-bar overlay was undertaken at various values of drive field rotation rate. In addition to stepwise change of bubble wall velocity, variation distortion of the bubble shape in the process of propagation and an asynchronous lag of the bubble relative to the drive field vector were also observed, the lag increasing with the rotation rate. To explain these results a simplified method for determining the bubble position in a magnetostatic well was proposed whereby elements of the permalloy overlay was divided into elementary rectangular components. The computed data are in good agreement with the experimental findings and this permits explanation of a number of phenomena observed in bubble circuits.