Easy axis orientation mapping of soft magnetic films using a magneto-optic Kerr BH imager

A novel method of easy-axis orientation (EAO) mapping for thin magnetic films is described. The method employs a magnetooptic Kerr sensor to detect the discrete switches in film magnetization direction that occur when a rotating magnetic field |H|<H_k is applied to a magnetically anisotropic thin film. An instrument implementing this method has been constructed and is capable of generating easy-axis maps at a rate of 3 locations/s with 1° accuracy. Experimental measurements show that the EAO determination is only slightly sensitive to stray fields, such as the Earth´s field. The optical properties of thin layers covering the magnetic film have been observed to lead to distortions in the Kerr signal, although these distortions do not affect the accuracy of the EAO measurements