Dynamic structure factor of the antiferromagnetic Kitaev model in large magnetic fields

TL;DR

This study analyzes the dynamic structure factor of the antiferromagnetic Kitaev honeycomb model under large magnetic fields, revealing quasiparticle behaviors and novel antibound states through perturbative transformations.

Contribution

It introduces a perturbative approach to compute quasiparticle properties and spectral features in the high-field phase of the Kitaev model, highlighting the formation of antibound states.

Findings

Identification of dominant quasiparticle contributions to spectral weight

Observation of three antibound states above the two-quasiparticle continuum

Analysis of spectral evolution with magnetic field strength

Abstract

We investigate the dynamic structure factor of the antiferromagnetic Kitaev honeycomb model in a magnetic field by applying perturbative continuous unitary transformations about the high-field limit. One- and two-quasiparticle properties of the dressed elementary spin-flip excitations of the high-field polarized phase are calculated which account for most of the spectral weight in the dynamic structure factor. We discuss the evolution of spectral features in these quasiparticle sectors in terms of one-quasiparticle dispersions, two-quasiparticle continua, the formation of antibound states, and quasiparticle decay. In particular, a comparably strong spectral feature above the upper edge of the upmost two-quasiparticle continuum represents three antibound states which form due to nearest-neighbor density-density interactions.