Quantum critical dynamical response of the twisted Kitaev spin chain

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Main Authors: Khodaeva, Uliana E., Kovrizhin, Dmitry L., Knolle, Johannes
Format: Preprint
Published: 2025
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author Khodaeva, Uliana E.
Kovrizhin, Dmitry L.
Knolle, Johannes
author_facet Khodaeva, Uliana E.
Kovrizhin, Dmitry L.
Knolle, Johannes
contents The dynamical structure factor of the transverse field Ising model (TFIM) shows universal power-law divergence at its quantum critical point, signatures of which have been arguably observed in inelastic neutron scattering studies of quantum spin chain materials, for example CoNb2O6. However, it has been recently suggested that its microscopic description is better captured in terms of a twisted Kitaev spin chain (TKSC) with bond-anisotropic couplings. Here, we present exact results for the dynamical structure factor of the TKSC across its quantum critical point, analyzing both the universal low-frequency response and the non-universal high-energy features. In addition, we explore extensions of the model including broken glide symmetry as well as the case of random, and incommensurate magnetic fields. Notably, in the latter case the fermionic excitations exhibit a localization-delocalization transition, which is manifest in the dynamical response as a distinct signature at finite frequency. We discuss the relevance of these features for the observation of quantum critical response in experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2506_18766
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum critical dynamical response of the twisted Kitaev spin chain
Khodaeva, Uliana E.
Kovrizhin, Dmitry L.
Knolle, Johannes
Strongly Correlated Electrons
The dynamical structure factor of the transverse field Ising model (TFIM) shows universal power-law divergence at its quantum critical point, signatures of which have been arguably observed in inelastic neutron scattering studies of quantum spin chain materials, for example CoNb2O6. However, it has been recently suggested that its microscopic description is better captured in terms of a twisted Kitaev spin chain (TKSC) with bond-anisotropic couplings. Here, we present exact results for the dynamical structure factor of the TKSC across its quantum critical point, analyzing both the universal low-frequency response and the non-universal high-energy features. In addition, we explore extensions of the model including broken glide symmetry as well as the case of random, and incommensurate magnetic fields. Notably, in the latter case the fermionic excitations exhibit a localization-delocalization transition, which is manifest in the dynamical response as a distinct signature at finite frequency. We discuss the relevance of these features for the observation of quantum critical response in experiments.
title Quantum critical dynamical response of the twisted Kitaev spin chain
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2506.18766