Magneto-optical diffraction by periodic lateral arrays composed of GMR structures of Pt/Co free layers having perpendicular magnetization

A first-order beam diffracted by periodic arrays of GMR structures consisting of Pt/Co free layers having perpendicular magnetization without a top electrode is investigated. Linear and two-dimensional arrays of various shapes having sizes of 10–50 μm and periods of 20–100 μm embedded in SiO2 are fabricated. The angles of the plane of polarization for first or (1,0) diffraction spots at a wavelength of 633 nm are measured to be approximately 0.5° for all samples. The polarization angles for one- and two-dimensional arrays of magnetic patterns are studied theoretically by assuming that the structures have sinusoidal magnetic distributions. They are found to depend on the Kerr rotation angle of the Pt/Co multilayer and on the difference in reflectance between the Pt/Co and SiO2, but they are independent of the periodicities, sizes, and shapes of the patterns. On the other hand, the diffraction efficiencies due to the magneto-optical effect depend on the reflectance and Kerr rotation angles of the magnetic materials. The diffraction efficiency of the component arising from the magneto-optical effect is discussed.