Nanosecond Switching in Thin Magnetic Films

A special pulse equipment including a pulse-sampling oscilloscope with an over-all response time of 0.35 nanosecond (10
⁻⁹
sec) for the observation of the nanosecond flux change in thin permalloy films is described. Film switching signals as short as 1 nanosecond have been obtained and are discussed with respect to the underlying processes. Inverse switching time versus driving-field curves have been plotted for films of different thicknesses. They show that thinner films switch faster than thicker ones. The slopes of these curves have characteristic values in the nanosecond region of about 10
⁸
per oersted-second. Coherent rotation and oscillation of the magnetization have been clearly detected by picking up the flux change transverse to the driving field.