Torque equilibrium spin wave theory of Raman scattering in an anisotropic triangular lattice antiferromagnet with Dzyaloshinskii-Moriya interaction

Abstract

We apply torque equilibrium spin wave theory (TESWT) to investigate an anisotropic XXZ antiferromagnetic model with Dzyaloshinskii-Moriya interaction in a triangular lattice. Considering the quasiparticle vacuum as our reference, we provide an accurate analysis of the noncollinear ground state of a frustrated triangular lattice magnet using the TESWT formalism. We elucidate the effects of quantum fluctuations on the ordering wave vector based on model system parameters. We study the single-magnon dispersion, the two-magnon continuum using the spectral function, and the Raman spectrum of bimagnon and trimagnon excitations. We present our results for the $HH,\phantom{\rule{0.28em}{0ex}}VV$, and the $HV$ polarization Raman geometry dependence of the bimagnon and trimagnon excitation spectra where $H\phantom{\rule{0.28em}{0ex}}(V)$ represents horizontal (vertical) polarization. Our calculations show that both the $HH$ and the $HV$ polarization spectra can be used to determine the degree of anisotropy of our system. We calculate the Raman spectra of ${\mathrm{Ba}}_{3}{\mathrm{CoSb}}_{2}{\mathrm{O}}_{9}$ and ${\mathrm{Cs}}_{2}{\mathrm{CuCl}}_{4}$.