Design of two-dimensional magnonic crystals using yttrium iron garnets and non-magnetic metals

Two-dimensional magnonic crystals (2D MCs) for forward volume spin waves were designed using the finite integration technique. The calculated model consisted of a 170 mm × 170 mm × 0.6 mm substrate with two microstrip lines (MSLs), and a 15 mm  × 15 mm × 10 μm yttrium iron garnet (YIG) film placed on top of the MSLs. The 2D MCs consisted of Cu dots with a diameter of 300 μm and a thickness of 1 μm periodically located on the YIG film. Two types of periodic structures, a square configuration and a hexagonal configuration, were fabricated. The reflected spin waves from the edge of the YIG film were suppressed by placing 30-nm thick Au films, and a magnonic bandgap of 2D MCs was observed. In addition, the shift of the magnonic bandgap was obtained when the incident angles of spin waves to 2D MCs were varied.