A method for measurement of "Creep" in thin magnetic films

The "creep" phenomenon in thin magnetic films is measured using a field consisting of a static field parallel to the film's easy axis, and a high-frequency sinusoidal field along the transverse axis. A special field-gradient coil is used to establish a two-domain magnetization configuration in the film plane, and the Kerr magneto-optic effect is employed to measure the position of the disturbed domain wall. Measurements on Ni-Fe-Co and NiFe alloy films show the typically sharp threshold field below which there is no wall creep; nonuniform creep gives evidence for wall "pinning" phenomena. With the method described for field calibration and the simple form of fields employed, this procedure should be valuable in establishing comparative creep sensitivity data for films formed from different alloys or by different technologies.