Magneto-optical study of the magnetization reversal process of Fe nanowires

We discuss results of magneto-optical Kerr effect (MOKE) measurements performed on a thin Fe film of 13 nm thickness, which has been patterned into a periodic arrangement of nanowires by means of optical interference lithography. The resulting array of nanowires consist of stripes having a width of 150 nm and a periodicity of 300 nm. MOKE hysteresis loops are measured within magnetic fields which are aligned in different directions, both parallel and perpendicular with respect to the direction of the nanowires as well as for various angles in between. A particular arrangement of the longitudinal Kerr effect measurement allows us to identify both the longitudinal and the transverse component of the magnetization of Fe nanowires. From this both the angle and the magnitude of the magnetization vector are derived. For a non-parallel alignment of the nanowires with respect to the direction of the external magnetic field, the hysteresis loops consist of a plateau region with two coercive fields H_c1 and H_c2, which is discussed as resulting from an anisotropic pinning behaviour of magnetic domains in directions along and perpendicular to the nanowires.