HIGH-FREQUENCY DYNAMIC IMAGING OF DOMAINS IN THIN-FILM HEADS

A wide-field magneto-optic domain observation system with a time resolution of 10 nsec has been developed to study magnetization dynamics in thin film heads. In this work, the instantaneous dynamic response on the top yoke of thin film recording heads is examined at any chosen instant within the drive current cycle at frequencies up to 20 MHz. Different phase responses from different domain walls in the head are observed and interpreted in terms of hysteretic wall motion, effective field density variation in the head, and wall orientations relative to the flux conduction direction. Two different flux conduction mechanisms associated with two different domain structures in the central region of the head are observed and discussed. In particular, flux conduction by desirable magnetization rotation in main domains, contrasting with undesirable wall motion near the backgap closure are described. © 1990 IEEE