Brillouin light scattering studies on an iron whisker

Abstract

We have made Brillouin light scattering measurements on a (001) iron whisker that was covered with epitaxial gold and with epitaxial silver under ultrahigh vacuum conditions. The surface mode frequencies have been measured to within ±0.03 GHz, allowing very careful comparisons of experiment with light scattering calculations. Observation of the 180° domain wall enabled an accurate determination of the surface spin pinning coefficient: Ks =0.54 ergs/cm2 for the gold covered whisker and Ks =0.79 ergs/cm2 for the silver covered whisker, with the easy axis perpendicular to the sample surface. An accurate measure of the sample heating due to the incident laser light was also obtained.