Evidence of a Four-Magnon Instability in a Yig Slab by Photothermally Detected FMR
Photothermal methods can be used to visualize spatial behaviour of spin-wave modes in yttrium iron garnet (YIG) slabs . These techniques are based on the detection of heat released during the absorption of intensity modulated electromagnetic radiation . In the present work we report on new results obtained from a YIG slab using the photothermal laser beam deflection (PD). The PD signal relies on the detection of a probe laser beam in the temperature induced gradient of the optical refraction index in the air close to the sample surface. Lateral and depth resolution is achieved by using intensity modulated microwaves.