Stroboscopic observation of cylindrical domain propagation in a T-bar structure

A technique of stroboscopic observation has been applied to the examination of the dynamic behavior of cylindrical magnetic domains, in a single crystal platelet of Sm 0.55 Tb 0.45 FeO 3 , propagating around a closed path Permalloy film T-bar structured overlay. Domain propagation is achieved by means of the time-varying magnetic pole configuration induced by a rotating magnetic field in the plane of the Permalloy film. Semiquantitative measurements under conditions of continuous propagation show instantaneous wall velocities varying from almost zero to greater than six times the time-averaged domain velocity. The speed of propagation in this T-bar structure is limited by the design of the comer where domains become trapped. The stroboscopic technique used here should find important application in the dynamic evaluation of designs for domain-propagation structures.