One-Magnon Raman Scattering as a Probe of Longitudinal Excitation Mode in Spin Dimer Systems

Abstract

One-magnon Raman scattering for interacting spin dimer systems is studied theoretically based on exchange light scattering process. We focus on a pressure-induced ordered phase, where a longitudinal excitation mode exists. We find that the Raman scattering probes the longitudinal mode selectively. The Raman intensity is finite only in the ordered phase and develops with pressure. We apply the theory to spin gapped systems such as TlCuCl₃ and NiCl₂–4SC(NH₂)₂ to demonstrate that the Raman scattering is a suitable probe for the longitudinal mode.