Early Stage of High Speed Switching in Magnetic Thin Films

A new experimental method for studying the early stage of high speed switching is developed on the basis of the following experimental results. (1) The magnetization reversal process caused by short and giant pulse fields relaxes within about 30 nsec. (2) The amount of the irreversibly reversed magnetization, which depends on the each pulse duration, remains without drastic changes beyond this relaxation time. In the present method, in contrast with coventional experiments, the amount of the magnetization is measured in more than several seconds after the irreversibly reversed magnetization caused by the short pulse has relaxed. By using this amount as a measure, the early stage of the switching within nanoseconds can be examined with a sufficient time resolution less than 0.1 nese. The present method reveals for the first time an oscillatory change in the magnetization within 1 nsec at the early stage of the switching.