Abstract The bond-disordered Kitaev model attracts much attention due to the experimental relevance in α-RuCl3 and A3LiIr2O6 (A = H, D, Ag, etc.). Applying a magnetic field to break the time-reversal symmetry leads to a strong modulation in mass terms for Dirac cones. Because of the smallness of the flux gap of the Kitaev model, a small bond disorder can have large influence on itinerant Majorana fermions. The quantization of the thermal Hall conductivity κxy/T disappears by a quantum Hall transition induced by a small disorder, and κxy/T shows a rapid crossover into a state with a negligible Hall current. We call this immobile liquid state Anderson–Kitaev spin liquid (AKSL). Especially, the critical disorder strength δJc1 ~ 0.05 in the unit of the Kitaev interaction would have many implications for the stability of Kitaev spin liquids.
Frustration in spin systems can prevent ordering even at
T=0, creating quantum spin liquids that have been sought since Anderson's pioneering work in 1973 and his influential 1987 paper connecting them to high-temperature superconductivity. Kitaev's solvable spin-1/2 models on a honeycomb lattice brought renewed attention to this field, with Jackeli and Khaliullin later revealing how to engineer Kitaev interactions in real materials. This review highlights theoretical and experimental developments in Kitaev spin liquids, emphasizing leading candidate materials and their broad topological properties such as chiral edge modes. Consequently, it provides essential insights for both experimentalists and theorists working on quantum spin liquid problems.
Thermalization is a probabilistic process. As such, it is generally expected that when we increase the temperature of a system, its classical behavior dominates its quantum coherences. By employing the Gibbs state of a translationally invariant quantum spin liquid---Kitaev's honeycomb lattice model---we demonstrate that an insulating phase at
T=0 becomes metallic purely by increasing temperature. In particular, we compute the finite-temperature distribution of energies and show that it diverges logarithmically, as we move to small energies. The corresponding wave functions become critical like at Anderson transitions. These characteristics are obtained within an exact Monte Carlo method that simulates the finite-temperature behavior of the Kitaev model. In particular, we take into account the projection onto the physical parity sectors, required for identifying the topological degeneracy of the model. Our work opens the possibility to detect thermal metal behavior in spin liquid experiments.