Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1605.09390 · Physical review. B./Physical review. B

Thermal transport in a one-dimensional Z2 spin liquid

Alexandros Metavitsiadis, Wolfram Brenig

Published Jul 14, 2017• 16 citations
arXivHTMLPDF

Abstract

We study the dynamical thermal conductivity of the Kitaev spin model on a two-leg ladder. In contrast to the majority of conventional one-dimensional spin systems, we show the ladder to exhibit no ballistic channel and a zero-frequency pseudogap. This is a direct consequence of the fractionalization of spins into mobile Majorana matter and a static ${\mathbb{Z}}_{2}$ gauge field, which acts as an emergent thermally activated disorder. Our finding rests on complementary calculations of the current correlation function, comprising a phenomenological mean-field treatment of thermal gauge fluctuations, a complete summation over all gauge sectors, as well as exact diagonalization of the original spin model. The results will also be contrasted against the conductivity discarding gauge fluctuations.

DOI
10.1103/physrevb.96.041115

Related papers

Thermal transport in a two-dimensional Z 2 spin liquid

Alexandros Metavitsiadis, Angelo Pidatella, Wolfram Brenig

We study the dynamical thermal conductivity of the two-dimensional Kitaev spin model on the honeycomb lattice. We find a strongly temperature dependent low-frequency spectral intensity as a direct consequence of fractionalization of spins into mobile Majorana matter and a static ${\mathbb{Z}}_{2}$ gauge field. The latter acts as an emergent thermally activated disorder, leading to the appearance of a pseudogap which closes in the thermodynamic limit, indicating a dissipative heat conductor. Our analysis is based on complementary calculations of the current correlation function, comprising exact diagonalization by means of a complete summation over all gauge sectors, as well as a phenomenological mean-field treatment of thermal gauge fluctuations, valid at intermediate and high temperatures. The results will also be contrasted against the conductivity discarding gauge fluctuations.

arXiv:1707.03836•Physical review. B./Physical review. B•Nov 13, 2017•34 citations

Finite-momentum energy dynamics in a Kitaev magnet

Alexandros Metavitsiadis, Wolfram Brenig

We study the energy-density dynamics at finite momentum of the two-dimensional Kitaev spin model on the honeycomb lattice. Due to fractionalization of magnetic moments, the energy relaxation occurs through mobile Majorana matter, coupled to a static ${\mathbb{Z}}_{2}$ gauge field. At finite temperatures, the ${\mathbb{Z}}_{2}$ flux excitations act as a thermally induced disorder, which strongly affects the energy dynamics. We show that sufficiently far above the flux proliferation temperature, but not yet in the high-temperature classical regime, disordered gauge configurations modify the coherent low-temperature energy-density dynamics into a form which is almost diffusive, with a diffusion kernel that is nearly momentum independent, but which remains retarded, primarily due to the presence of two distinct relaxation channels of particle-hole and particle-particle nature. Relations to the thermal conductivity are clarified. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge configuration and a mean-field treatment of thermal gauge fluctuations, valid above the flux proliferation temperature.

arXiv:2102.12492•Physical review. B./Physical review. B•Sep 24, 2021•3 citations

Phonon renormalization in the Kitaev quantum spin liquid

Alexandros Metavitsiadis, Wolfram Brenig

We study the self-energy of phonons, magnetoelastically coupled to the two-dimensional Kitaev spin model on the honeycomb lattice. Fractionalization of magnetic moments into mobile Majorana matter and a static ${\mathbb{Z}}_{2}$ gauge field lead to a continuum of relaxation processes comprising two channels. Thermal flux excitations, which act as an emergent disorder, strongly affect the phonon renormalization. Above the flux proliferation temperature, the dispersion of a narrow quasiparticle-hole channel is suppressed in favor of broad and only weakly momentum-dependent features, covering large spectral ranges. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge and a mean-field treatment of thermal gauge fluctuations, valid at intermediate and high temperatures.

arXiv:1909.09360•Physical review. B./Physical review. B•Jan 6, 2020•41 citations

Heat transport in the anisotropic Kitaev spin liquid

Angelo Pidatella, Alexandros Metavitsiadis, Wolfram Brenig

We present a study of longitudinal thermal transport in the Kitaev spin model on the honeycomb lattice, focusing on the role of anisotropic exchange to cover both gapless and gapped phases. Employing a complementary combination of exact diagonalization on small systems and an average gauge configuration approach for up to $\ensuremath{\sim}O({10}^{4})$ spinful sites, we report results for the dynamical energy current autocorrelation function as well as the dc thermal conductivity over a wide range of temperatures and exchange anisotropies. Despite a pseudogap in the current correlation spectra, induced by emergent thermal gauge disorder on any finite system, we find that in the thermodynamic limit, gapless and gapful phases both feature normal dissipative transport, with a temperature dependence crossing over from power law to exponentially activated behavior upon gap opening.

arXiv:1810.04674•Physical review. B./Physical review. B•Feb 20, 2019•19 citations

Spin liquid fingerprints in the thermal transport of a Kitaev-Heisenberg ladder

Alexandros Metavitsiadis, Christina Psaroudaki, Wolfram Brenig

We identify fingerprints of a proximate quantum spin liquid (QSL), observable by finite-temperature dynamical thermal transport within a minimal version of the idealized Kitaev model on a two-leg ladder if subjected to inevitably present Heisenberg couplings. Using exact diagonalization and quantum typicality, we uncover (i) an insulator-conductor crossover induced by recombination of fractionalized excitations at small Heisenberg couplings, (ii) low- and high-energy signatures of fractionalized excitations, which survive far off the pure QSL point, and (iii) a nonmonotonous current lifetime versus Heisenberg couplings. Guided by perturbation theory, we find (iv) a Kitaev-exchange-induced ``one-magnon'' contribution to the dynamical heat transport in the strong Heisenberg rung limit.

arXiv:1806.02344•Physical review. B./Physical review. B•May 17, 2019•8 citations

Effects of anisotropy on the dynamical and static spin conductivity of an anisotropic spin-1/2 two-leg ladder

Hamed Rezania

We address a detailed analysis of the dynamical spin conductivity of an anisotropic spin ladder in the direction of the legs by means of a quantum many-particle approach. Bond operator transformation has been employed in order to map the original spin model Hamiltonian to a bosonic one. This bosonic Hamiltonian should include an infinite hard-core repulsion to preserve the SU(2) algebra of the original model. Using a Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. Linear response theory has been implemented to obtain spin conductivity via calculation of time-ordered energy current correlation. The results show the spin conductivity possessing a nonzero value in a finite frequency interval. Increasing the rung-coupling exchange constant moved this frequency interval to higher frequencies. Also, the spin conductivity presents a small nonzero value at very low frequency for low rung-coupling constants. Furthermore, the effects of spin anisotropies on both leg and rung couplings are investigated. A tiny dependence of the spin transport on the anisotropy in the leg direction is observed in contrast to the strong one on the anisotropy along the rung direction, due to the direct effect of the triplet density. Additionally, the frequency behavior of the spin conductivity of the isotropic case has been studied due to the temperature effects. The temperature dependence of static spin conductivity has been found for various rung-coupling exchange constants and anisotropies in both coupling strengths.

Progress of Theoretical and Experimental Physics•Mar 1, 2014•3 citations
We study the dynamical thermal conductivity of the Kitaev spin model on a two-leg ladder. In contrast to the majority of conventional one-dimensional spin systems, we show the ladder to exhibit no ballistic channel and a zero-frequency pseudogap. This is a direct consequence of the fractionalization of spins into mobile Majorana matter and a static Z2{\mathbb{Z}}_{2}Z2​ gauge field, which acts as an emergent thermally activated disorder. Our finding rests on complementary calculations of the current correlation function, comprising a phenomenological mean-field treatment of thermal gauge fluctuations, a complete summation over all gauge sectors, as well as exact diagonalization of the original spin model. The results will also be contrasted against the conductivity discarding gauge fluctuations.
We study the dynamical thermal conductivity of the two-dimensional Kitaev spin model on the honeycomb lattice. We find a strongly temperature dependent low-frequency spectral intensity as a direct consequence of fractionalization of spins into mobile Majorana matter and a static Z2{\mathbb{Z}}_{2}Z2​ gauge field. The latter acts as an emergent thermally activated disorder, leading to the appearance of a pseudogap which closes in the thermodynamic limit, indicating a dissipative heat conductor. Our analysis is based on complementary calculations of the current correlation function, comprising exact diagonalization by means of a complete summation over all gauge sectors, as well as a phenomenological mean-field treatment of thermal gauge fluctuations, valid at intermediate and high temperatures. The results will also be contrasted against the conductivity discarding gauge fluctuations.
We study the energy-density dynamics at finite momentum of the two-dimensional Kitaev spin model on the honeycomb lattice. Due to fractionalization of magnetic moments, the energy relaxation occurs through mobile Majorana matter, coupled to a static Z2{\mathbb{Z}}_{2}Z2​ gauge field. At finite temperatures, the Z2{\mathbb{Z}}_{2}Z2​ flux excitations act as a thermally induced disorder, which strongly affects the energy dynamics. We show that sufficiently far above the flux proliferation temperature, but not yet in the high-temperature classical regime, disordered gauge configurations modify the coherent low-temperature energy-density dynamics into a form which is almost diffusive, with a diffusion kernel that is nearly momentum independent, but which remains retarded, primarily due to the presence of two distinct relaxation channels of particle-hole and particle-particle nature. Relations to the thermal conductivity are clarified. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge configuration and a mean-field treatment of thermal gauge fluctuations, valid above the flux proliferation temperature.
We study the self-energy of phonons, magnetoelastically coupled to the two-dimensional Kitaev spin model on the honeycomb lattice. Fractionalization of magnetic moments into mobile Majorana matter and a static Z2{\mathbb{Z}}_{2}Z2​ gauge field lead to a continuum of relaxation processes comprising two channels. Thermal flux excitations, which act as an emergent disorder, strongly affect the phonon renormalization. Above the flux proliferation temperature, the dispersion of a narrow quasiparticle-hole channel is suppressed in favor of broad and only weakly momentum-dependent features, covering large spectral ranges. Our analysis is based on complementary calculations in the low-temperature homogeneous gauge and a mean-field treatment of thermal gauge fluctuations, valid at intermediate and high temperatures.
We present a study of longitudinal thermal transport in the Kitaev spin model on the honeycomb lattice, focusing on the role of anisotropic exchange to cover both gapless and gapped phases. Employing a complementary combination of exact diagonalization on small systems and an average gauge configuration approach for up to $\ensuremath{\sim}O({10}^{4})$ spinful sites, we report results for the dynamical energy current autocorrelation function as well as the dc thermal conductivity over a wide range of temperatures and exchange anisotropies. Despite a pseudogap in the current correlation spectra, induced by emergent thermal gauge disorder on any finite system, we find that in the thermodynamic limit, gapless and gapful phases both feature normal dissipative transport, with a temperature dependence crossing over from power law to exponentially activated behavior upon gap opening.
We identify fingerprints of a proximate quantum spin liquid (QSL), observable by finite-temperature dynamical thermal transport within a minimal version of the idealized Kitaev model on a two-leg ladder if subjected to inevitably present Heisenberg couplings. Using exact diagonalization and quantum typicality, we uncover (i) an insulator-conductor crossover induced by recombination of fractionalized excitations at small Heisenberg couplings, (ii) low- and high-energy signatures of fractionalized excitations, which survive far off the pure QSL point, and (iii) a nonmonotonous current lifetime versus Heisenberg couplings. Guided by perturbation theory, we find (iv) a Kitaev-exchange-induced ``one-magnon'' contribution to the dynamical heat transport in the strong Heisenberg rung limit.
We address a detailed analysis of the dynamical spin conductivity of an anisotropic spin ladder in the direction of the legs by means of a quantum many-particle approach. Bond operator transformation has been employed in order to map the original spin model Hamiltonian to a bosonic one. This bosonic Hamiltonian should include an infinite hard-core repulsion to preserve the SU(2) algebra of the original model. Using a Green's function approach, the energy spectrum of quasiparticle excitation has been obtained. Linear response theory has been implemented to obtain spin conductivity via calculation of time-ordered energy current correlation. The results show the spin conductivity possessing a nonzero value in a finite frequency interval. Increasing the rung-coupling exchange constant moved this frequency interval to higher frequencies. Also, the spin conductivity presents a small nonzero value at very low frequency for low rung-coupling constants. Furthermore, the effects of spin anisotropies on both leg and rung couplings are investigated. A tiny dependence of the spin transport on the anisotropy in the leg direction is observed in contrast to the strong one on the anisotropy along the rung direction, due to the direct effect of the triplet density. Additionally, the frequency behavior of the spin conductivity of the isotropic case has been studied due to the temperature effects. The temperature dependence of static spin conductivity has been found for various rung-coupling exchange constants and anisotropies in both coupling strengths.