Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1703.10395

Thermal Transport in the Kitaev Model

Joji Nasu·Junki Yoshitake·Yukitoshi Motome
View original source ↗Read source document ↗Export metadata ↓

Abstract

In conventional insulating magnets, heat is carried by magnons and phonons. In contrast, when the magnets harbor a quantum spin liquid state, emergent quasiparticles from the fractionalization of quantum spins can carry heat. Here, we investigate unconventional thermal transport yielded by such exotic carriers, in both longitudinal and transverse components, for the Kitaev model, whose ground state is exactly shown to be a quantum spin liquid with fractional excitations described as itinerant Majorana fermions and localized $Z_2$ fluxes. We find that the longitudinal thermal conductivity exhibits a broad peak at very different temperatures between the zero and nonzero frequency components, reflecting the spin fractionalization. On the other hand, the transverse thermal conductivity induced by the magnetic field shows nonmonotonic temperature dependence, due to thermal excitations of the localized $Z_2$ fluxes. In the low-temperature limit, the temperature-linear coefficient rapidly approaches a quantized value, as expected from the topologically nontrivial nature of itinerant Majorana fermions. The characteristic behaviors provide experimentally-accessible evidences of fractional excitations in the proximity to Kitaev quantum spin liquid.

Explore related subjects

cond-mat.str-elcond-mat.mtrl-sci

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Joji Nasu, Junki Yoshitake, Yukitoshi Motome. 2017-03-30. Thermal Transport in the Kitaev Model. https://doi.org/10.1103/physrevlett.119.127204

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

An Exact Conjugation Identity for the Many-Body Wilson Loop Beyond Quantization

Constraints on unquantized many-body holonomies, such as Wilson loops (or their Berry phases), are less explored than those on their quantized counterparts. Here, we realize an unquantized regime by tuning the bond dimerization $δ$ and the staggered potential $Δ$ in a half-filled dimerized staggered Hubbard ring. For the tuned parameter sets, a finite excitation gap persists along the $U(1)$ twist cycle $θ\in[0,2π]$, so that the ground state $|ψ_δ(θ)\rangle$ remains separated from the excited states. The many-body Wilson loop is therefore well defined from the ground-state family $\{|ψ_δ(θ)\rangle;\,θ\in[0,2π]\}$. In this setup, we show an exact many-body Wilson loop conjugation identity, $W(-δ)=W(δ)^*$, accumulated along a cycle parametrized by $θ$. Importantly, the identity persists in regimes where the Berry phase $γ\equiv-\arg W$ varies continuously. We demonstrate the identity numerically using the density-matrix renormalization group (DMRG) method. The identity extends to other models where the flux-threaded ground-state family along the closed $θ$-cycle is mapped to the reversed cycle. Beyond its conceptual content, the identity provides a symmetry-based consistency check for numerical evaluations of Berry phases in interacting systems. It also justifies the signal-to-noise ratio improvement in Monte Carlo simulations by performing simulations at both $δ$ and $-δ$ and averaging $W(δ)$ with $W(-δ)^{*}$.

cond-mat.str-el↗
arXiv2026

Torus Berry Data Determine All-Genus Abelian Topological Orders

We show that for Abelian Chern-Simons topological orders, torus Berry matrices determine the all-genus extended TQFT. We identify the topological part of the projective Berry holonomy under metric deformations with the mapping-class-group representation of the Abelian Chern-Simons TQFT and prove that the normalized torus data reconstruct its finite quadratic module (G,q). Recent work showed that (G,q) classifies the extended theory up to symmetric monoidal natural isomorphism, and that the associated Abelian defect extension is determined by the pointed modular category C(G,q) arising from the same finite quadratic-module data. Therefore genus-one Berry data determine not only the all-genus bulk theory but also its associated defect structures without choosing a K-matrix presentation. We also prove that, for normalized character row errors $δ$<21.96%, nearest-row decoding recovers the Abelian fusion algebra independently of the number of anyons. The result applies to Abelian fractional quantum Hall and spin-liquid phases described by even-lattice Chern-Simons theories.

cond-mat.str-el↗
arXiv2026

Accidental accuracy and vertex corrections in $GW$: Exact benchmarks for the extended Hubbard model

The $GW$ approximation is the standard tool for quasiparticle predictions in materials, yet its regime of validity in correlated systems remains poorly quantified, because \textit{ab initio} vertex corrections are computationally prohibitive. Using exact diagonalization of the half-filled extended Hubbard model on finite rings as a numerically exact reference, we construct the corresponding model-space $GW$ theory on the identical Hilbert space and quantify its error as a function of local ($U$) and non-local ($V$) interaction strength. We find that the required vertex correction changes character across the phase diagram: in the weak-coupling regime the effective vertex $Γ_{\rm eff} < 1$, reflecting the suppression of RPA charge fluctuations by exact short-range correlations, whereas in the Mott regime $Γ_{\rm eff}$ grows monotonically (to $\sim 3$ at $U=8t$ for $N=6$), reflecting the local dynamical self-energy structure required to open the Hubbard gap. Vertex corrections in the electron-hole (polarizability) channel are shown to \emph{worsen} the gap error, indicating that reproducing the Mott gap requires dynamical self-energy structure rather than improved screening. For $V=0$, static COHSEX is accidentally exact at a single crossover $U^* \approx 3.5\,t$; finite $V$, through non-local Fock exchange, splits this point into a double-crossover window that collapses toward weak coupling. Even at the crossover, however, the exact spectral function retains Hubbard-band structure that no static functional reproduces, so gap agreement does not imply functional accuracy. These results yield quantitative diagnostics for the reliability of $GW$ in correlated materials.

cond-mat.str-el↗