A wave-vector selective light scattering magnon spectrometer

Abstract

A new type of magnon spectrometer has been developed, based on inelastic light scattering from magnetic excitations. This spectrometer enables one to study magnetic excitations of a specific frequency and wave vector as a function of static field, microwave power, temperature, or any other external experimental parameter. The sample is excited by an applied microwave field and simultaneously probed by laser light. The inelastically scattered light corresponding to a particular magnon wave vector k is selected and its intensity at a specific frequency ωk is recorded. The intensity of this light is a direct measure of the strength of that particular magnetic excitation at k and ωk. Spectra taken in this way present a direct and localized measurement of specific, selectable magnons, in contrast with standard microwave measurements which give only a measure of the total response of all excited modes over the entire sample.