Delayed Relaxation in Thin-Film Heads

Abstract

The delayed relaxation after writing with a permalloy thin-film head has been studied. The irreversible wall motion involved in this relaxation process produces in the head output isolated noise transients of both polarities as well as bipolarity transients. This observation is explained. Modelling this noise transient generating process as a Poisson process gives good agreement with the observed behaviour of this “noise-after-write” phenomenon. The time of arrival distribution and the probability of occurrence as a function of the write current and threshold setting have been measured and compared to the model predictions. © 1989 IEEE