DYNAMIC PROCESSES IN THIN-FILM HEADS AT FREQUENCIES UP TO 200 MHZ

In this article we present quantitative investigations of dynamic processes in 3380E and 3390 thin-film heads and the dynamic domain configurations of the 3380E head mapped at frequencies up to 200 MHz. The quantitative studies include measuring both the phase and the amplitude of wall motion and rotational magnetization. For a longitudinal domain wall near the back gap of the 3380E head, the phase lag, which was found to be a function of drive field, increases at a rate of 35-degrees per 10 MHz initially. However, when the phase lag reaches the range from 35-degrees to 45-degrees, the wall jumps to a new position where the phase lag is smaller. This wall can still conduct magnetic flux even at 200 MHz. For the rotational process, significant damping was detected above 50 MHz.