Evaluation of the quality of Permalloy gratings by diffracted magneto-optical spectroscopy

Magneto-optical Kerr effect (MOKE) spectroscopy in the -1st diffraction order with p-polarized incidence is applied to study arrays of submicron Permalloy wires at polar magnetization. A theoretical approach combining two methods, the local modes method neglecting the edge effects of wires and the rigorous coupled wave analysis, is derived to evaluate the diffraction losses due to irregularities of the wire edges. A new parameter describing the quality of the edges is defined according to their contribution in the diffracted MOKE. The quality factor, evaluated for two different samples, is successfully compared with irregularities visible on atomic force microscopy pictures.