Fig. 5: Direct-write magnonic crystals.

a Schematic of the propagating spin-wave spectroscopy experiment. A magnonic crystal (MC) consisting of three patterned lines having a width of a = 1.5 µm and a periodicity of l = 25 μm acts as a Bragg reflector for spin waves. Excitation and detection are performed with two stripline antennas separated by 100 μm, applying a 95 mT in-plane static magnetic field in the DE configuration. b MFM image of the magnonic crystal showing two lines with narrower stripe domains due to the laser-induced PMA enhancement. Scale bar: 1.5 µm. c Spin-wave transmission spectra of the pristine material (black curve) and the magnonic crystal (red curve). While the transmission window remains unchanged, the formation of band gaps (vertical dotted lines), consistent with Bragg reflection is observed in the magnonic crystal. d Schematic of the Brillouin light scattering experiment. A magnonic crystal with a periodic circular anti-dot lattice is realized via single-shot irradiation of the red areas. The dot diameter is a = 600 nm and the lattice constant is l = 2 μm. A stripline antenna is fabricated on top of the magnonic crystal for spin-wave excitation. The spin-wave intensity is mapped via micro-BLS in a 75 mT static magnetic field applied along x. e, f Micro-BLS spin-wave intensity maps showing horizontal spin-wave channels between the dots in the 4.0 GHz mode (e), and vertical spin-wave channels with a spatially oscillating intensity in the 2.6 GHz mode (f). g, i Simulated spin-wave intensity maps corresponding to measured spin wave modes in (e, f). h, j Cross-section view of the simulated spin-wave intensity through the thickness of the film, extracted along the dashed lines in (g, i). In both cases, the three-dimensional magnetic properties profiles determine a non-uniform spin-wave intensity and localization within the volume of the film. Scale bars: 500 nm.