Dynamical structure factor of triangular-lattice antiferromagnet

TL;DR

This paper investigates the complex spin dynamics of the triangular-lattice Heisenberg antiferromagnet, revealing unconventional features like broadened peaks and spectral weight redistribution due to magnon interactions and decays, with implications for neutron scattering experiments.

Contribution

It provides explicit theoretical calculations of the dynamical structure factor for spins S=1/2 and S=3/2, highlighting decay effects and spectral features in the triangular-lattice antiferromagnet.

Findings

Quasiparticle peaks are broadened by decays

Spectral weight shifts to the two-magnon continuum

Unconventional non-Lorentzian lineshapes observed

Abstract

We elucidate the role of magnon interaction and spontaneous decays in the spin dynamics of the triangular-lattice Heisenberg antiferromagnet by calculating its dynamical structure factor within the spin-wave theory. Explicit theoretical results for neutron-scattering intensity are provided for spins S=1/2 and S=3/2. The dynamical structure factor exhibits unconventional features such as quasiparticle peaks broadened by decays, non-Lorentzian lineshapes, and significant spectral weight redistribution to the two-magnon continuum. This rich excitation spectrum illustrates the complexity of the triangular-lattice antiferromagnet and provides distinctive qualitative and quantitative fingerprints for experimental observation of decay-induced magnon dynamics.