Studies on the magneto-optical and the magnetic properties of 2-dimensional spin photonic crystals

We report on the magneto-optical and the magnetic properties of 2-dimensional (2-D) spin photonic crystals (SPCs), which were fabricated using photolithography and wet-etching processes. Circular-shape holes with rhomboidal lattice symmetry were grooved into the top ferromagnetic layer composed of Co while the bottom Ni layer was kept unpatterned. Such structures having the same lattice symmetry but different periodicities (viz., 1.3 and 1.6 µm) were investigated using magneto-optical Kerr effects (MOKE) measurements. The change in periodicity was found to be useful in tailoring the magnetic properties. An in-plane easy-axis magnetization was observed for both samples. Significant enhancement of the switching field by nearly 2.5 times was noticed for the sample having smaller periodicity. This is attributed to a change in the magnetostatic energy due to the varied lateral dimension. Additionally, the MO measurement showed a strong dependence on the incident angle. These experimental results manifest the ability of controlling the MO, as well as the magnetic, properties of 2-D SPCs by modifying the periodicity and by forming a bilayer structure.