Dynamical structure factor of quasi-2D antiferromagnet in high fields

TL;DR

This paper investigates the high-field magnon dynamics and dynamical structure factor in quasi-2D antiferromagnets, revealing how interlayer coupling influences spectral features and broadening effects in the excitation spectrum.

Contribution

It demonstrates that interlayer coupling reduces singular corrections in high-field magnon spectra within spin-wave theory, providing insights into spectral broadening and redistribution in realistic materials.

Findings

Interlayer coupling mitigates singular spectrum corrections.

Spectral weight shifts from quasiparticle peaks to two-magnon continuum.

Observation of spectrum broadening and two-peak structures across the Brillouin zone.

Abstract

We study high-field magnon dynamics and examine the dynamical structure factor in the quasi-2D tetragonal Heisenberg antiferromagnet with interlayer coupling corresponding to realistic materials. Within spin-wave theory, we show that a non-zero interlayer coupling mitigates singular corrections to the excitation spectrum occurring in the high-field regime that would otherwise require a self-consistent approach beyond the 1/S approximation. For the fields between the threshold for decays and saturation field we observe widening of the two-magnon sidebands with significant shifting of the spectral weight away from the quasiparticle peak. We find spectrum broadening throughout large regions of the Brillouin zone, dramatic redistributions of spectral weight to the two-magnon continuum, two-peak structures and other features clearly unlike conventional single-particle peaks.