Time-Resolved Brillouin Light Scattering Measurements of Spin Wave Propagation in a 1D Magnonic Crystal

Magnonic crystals can be used to control the transmission of spin waves through the periodic modulation of material properties. The periodic modulations act as a Bragg reflector, which leads to the formation of a band structure with band pass frequency ranges where spin waves can pass through the crystal, and band gaps where spin wave propagation is suppressed. We used time- and space-resolved Brillouin light scattering (BLS) measurements to investigate 200-ns long spin wave pulses in a 1D yttrium iron garnet (YIG) magnonic crystal in the magnetostatic surface wave configuration, where the magnetization is perpendicular to the direction of spin wave propagation. The 1D YIG magnonic crystal consists of 20, 25μm wide and 3.5μm deep, groves with a repetition rate of 275μm. Microwave and BLS measurements show frequency-dependent transmission profiles with band pass and band gap ranges that agree well with theory. The BLS measurements also show the presence of multiple width-quantized modes, and the presence of these modes must be taken into consideration to obtain improved rejection efficiencies.