Thermal Transport in the Kitaev Model

Nasu, Joji; Yoshitake, Junki; Motome, Yukitoshi

doi:10.1103/physrevlett.119.127204

Cited by 138 publications

(126 citation statements)

References 55 publications

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“…Their results obtained at zero field are well consistent with ours, especially a kink around 8 K. In addition, Seung-Hwan Do et al 59 recently reported the temperature dependence of the magnetic specific heat of α-RuCl 3 , and observed a broad peak structure at about 100 K, consistent with our result. We also became aware of theoretical work by Joji Nasu et al 60 . Their computation with the use of the Kitaev model showed that itinerant Majorana fermions contribute to the longitudinal thermal conductivity and the magnetic specific heat within the same temperature range, which qualitatively reproduces our result.…”

Section: Resultsmentioning

confidence: 99%

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Hirobe¹,

Sato²,

Shiomi³

et al. 2017

Phys. Rev. B

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We have investigated the longitudinal thermal conductivity of α-RuCl3, the magnetic state of which is considered to be proximate to a Kitaev honeycomb model, along with the spin susceptibility and magnetic specific heat. We found that the temperature dependence of the thermal conductivity exhibits an additional peak around 100 K, which is well above the phonon peak temperature (∼ 50 K). The higher-temperature peak position is comparable to the temperature scale of the Kitaev couplings rather than the Néel temperatures below 15 K. The additional heat conduction was observed for all five samples used in this study, and was found to be rather immune to a structural phase transition of α-RuCl3, which suggests its different origin from phonons. Combined with experimental results of the magnetic specific heat, our transport measurement suggests strongly that the higher-temperature peak in the thermal conductivity is attributed to itinerant spin excitations associated with the Kitaev couplings of α-RuCl3. A kinetic approximation of the magnetic thermal conductivity yields a mean free path of ∼ 20 nm at 100 K, which is well longer than the nearest Ru-Ru distance (∼ 3Å), suggesting the long-distance coherent propagation of magnetic excitations driven by the Kitaev couplings. IntroductionQuantum spin liquid is a phase of magnetic insulator in which frustration or quantum fluctuation prohibits magnetic order while keeping spin correlation 1-3 . It induces rich physical phenomena depending on the types of spin liquids, which cannot be realized in standard ordered magnets. Several quantum-spin models have been proposed as possible realizations of quantum spin liquids along with candidate frustrated magnets such as κ- ( Among them, the Kitaev honeycomb model is unique in that the ground state is exactly calculated and known to be a two-dimensional (2D) quantum spin liquid 10 . In this model, spin-1/2 moments, S r , sit on a honeycomb lattice and interact via the bond-dependent Ising couplings; different spin components interact via Ising coupling for the three different bonds of the honeycomb lattice. These anisotropic couplings, called the Kitaev couplings J α S

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Section: Resultsmentioning

confidence: 99%

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Hirobe¹,

Sato²,

Shiomi³

et al. 2017

Phys. Rev. B

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“…This may be viewed as a unique signature of chiral Majorana edge modes. At finite temperatures, the thermal Hall conductivity shows a crossover behavior [69] at the two characteristic temperature scales T * and T * * , see Fig. 4.…”

Section: Honeycomb-lattice Kitaev Modelmentioning

confidence: 96%

Heisenberg–Kitaev physics in magnetic fields

Janssen

Vojta

2019

J. Phys.: Condens. Matter

133

104

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Magnetic insulators in the regime of strong spin-orbit coupling exhibit intriguing behaviors in external magnetic fields, reflecting the frustrated nature of their effective interactions.We review the recent advances in understanding the field responses of materials that are described by models with strongly bond-dependent spin exchange interactions, such as Kitaev's celebrated honeycomb model and its extensions. We discuss the field-induced phases and the complex magnetization processes found in these theories and compare with experimental results in the layered Mott insulators α-RuCl 3 and Na 2 IrO 3 , which are believed to realize this fascinating physics.

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“…Figure 2(a) shows the T and h dependence of the specific heat per site, C v , obtained by the cluster-based CTQMC simulation. The data at h = 0 are taken from the previous QMC results [41], which could access down to below T = 0.01 because of the absence of the negative sign problem [25]. At h = 0, C v shows two peaks at T H 0.375 and T L 0.012, as plotted in Fig.…”

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confidence: 99%

Majorana-magnon crossover by a magnetic field in the Kitaev model: Continuous-time quantum Monte Carlo study

et al. 2020

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Kitaev quantum spin liquids host Majorana fermions via the fractionalization of spins. In a magnetic field, the Majorana fermions were predicted to comprise a topological state, which has attracted great attention by the discovery of the half-quantized thermal Hall conductivity. Nevertheless, a reliable theory remains elusive for the field effect, especially at finite temperature. Here we present unbiased large-scale numerical results for the Kitaev model in a wide range of magnetic field and temperature. We find that the unconventional paramagnetic region showing fractional spin dynamics extends at finite temperature, far beyond the field range where the topological state is expected at zero temperature. Our results show the confinement-deconfinement behavior between the fractional Majorana excitations and the conventional magnons.

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Thermal Transport in the Kitaev Model

Cited by 138 publications

References 55 publications

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Magnetic thermal conductivity far above the Néel temperature in the Kitaev-magnet candidate α−RuCl3

Heisenberg–Kitaev physics in magnetic fields

Majorana-magnon crossover by a magnetic field in the Kitaev model: Continuous-time quantum Monte Carlo study

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