Observation of the high frequency spin wave branch and the uniform precession mode in FeBO3 by Brillouin scattering

Brillouin scattering has been used to observe the two spin wave branches of the weak ferromanget FeBO3. The high frequency, quasiantiferromagnetic branch is seen by this method for the first time. The temperature dependence of this branch is measured and compared with previous FMR measurements. An asymmetry is found between the Stokes and anti‐Stokes scattering intensities for this mode which is dependent on the incident polarization. This is attributed to an interference between linear and quadratic magneto‐optic effects. Scattering from the low frequency, quasiferromagnetic branch at very small wave vectors has also been measured. This was done using a forward scattering configuration.