MAGNETIZATION DISTRIBUTIONS IN THIN-FILM RECORDING-HEADS BY TYPE-II CONTRAS T

The magnetic domain structure of the polepieces of thin film magnetic recording heads and its variation with drive current and frequency is of interest in understanding the read/write properties of the head. This paper describes the setting up of the synchronous detection mode of Type I I backscattered electron contrast in a 200kV electron microscope and its application to the study of domain wall movement in the P2 polepieces of heads with and without the 15-20pm thick alumina overlayer in place. The extension of the method to allow evaluation of the changes in magnetisation directions under ac drive conditions is described. The remanent state of domain structure and its change under dc drive condition are also of interest and a new imaging technique to achieve this is discussed. © 1990 IEEE