Figure 2: SWaT spectra as a function of external magnetic fields.
From: All-optical observation and reconstruction of spin wave dispersion
(a) A SWaT spectrum obtained for a paramagnetic GGG substrate without spontaneous magnetization. (b) SWaT spectra for the LuIG sample with wavenumber k parallel to the magnetization M, which was aligned along the [100] axis by an in-plane magnetic field H. We observe three different dispersion curves, which are schematically shown in (d). TA, LA and MV represent the transverse acoustic phonon, the longitudinal acoustic phonon and the magnetostatic volume mode branches, respectively. The white dashed curves are calculated by a magnetostatic spin wave theory4 with the following parameters: saturation magnetization 4πMs=780 G, cubic anisotropy Kc=2.3 × 103 erg cm−3 and uniaxial magnetic anisotropy Ku=−1.2 × 104 erg cm−3. (c) A schematic of the experimental configuration. φ is defined as the angle between k of spin waves and the orientation of M. (d) A schematic of the three branches observed in (b). (e) A three-dimensional contour plot (at the intensity of 0.7 in the scale shown in (a) of the SWaT intensity representing spin waves (red) and phonons (blue). The direction of M is indicated by the green arrow.
