Fig. 4: Three-dimensional control of spin-wave dispersion and localization.
From: Three-dimensional nanoscale control of magnetism in crystalline Yttrium Iron Garnet
a Sketch of the experimental setup. Extended square areas are irradiated with different uniform laser power. Radiofrequency antennas are fabricated on top of the irradiated regions for exciting spin waves via an oscillating magnetic field HRF. The local spin-wave spectra are acquired via Micro-Brillouin Light Scattering using a focused laser, in presence of a static magnetic field Hext applied parallel to the antenna. b Optical image of the sample. Scale bar: 10 μm. c Micro-BLS spectra for different irradiating laser power, measured for different values of external field Hext. Below threshold (in blue), the spectra are nearly unchanged with respect to the pristine sample (in black). Above threshold (in orange, red), additional low-frequency peaks appear which rapidly evolve increasing the laser power. d–f Micromagnetic simulations of the spin-wave dispersions with μ0Hext = 125 mT in the non-patterned film (d), for a 100 nm thick modified volume (e) and for a 200 nm thick modified volume (f). The corresponding experimental peaks are indicated by color-coded arrows in (c). g–l Simulated spin-wave amplitude profiles through the thickness of the film, for the modes highlighted in (d–f) at k = 0. The simulations show the appearance of additional non-reciprocal modes upon irradiation, localized within the modified volume, and finely controllable with the irradiation power.
