Domain conversion under high frequency excitation in inductive thin fllm heads

Abstract

The response of the domain wall network in the yoke area of inductive thin film heads is studied using a new pseudodynamic observation method. Domain activity in yokes driven with sinusoidal currents (1 to 20 MHz) is observed using the Kerr effect at video frame rates (0 to 30 Hz). Thus, the average location and shape of domains in the top yoke of the head may be recorded. The domain pattern generally undergoes significant changes in a slow repeatable evolution. Some changes lead to abrupt conversions of domain states. Although specific behavior varies from head to head, these conversions follow measurable curves having a common trend in the amplitude versus frequency space. Previous work on analysis of head response has not considered this type of dynamic response, although, from the literature, it appears to be common to many magnetic systems. Three possible mechanisms driving the domain conversions arc outlined. © 1989 IEEE