---

The Kitaev model is an exactly-soluble quantum spin model with frustration. Although the original model was defined on a honeycomb lattice, the model has been extended to various tricoordinate lattices without losing the exact solubility. We analyze two different anisotropic limits of the Kitaev model on a three-dimensional lattice comprising nine-site elementary loops, which we call the hypernonagon lattice. In both cases, the effective Ising-type models retain the time-reversal symmetry, suggesting that the ground states are chiral spin liquids. Using Monte Carlo simulations that respect the local and global constraints on the Ising variables representing Z2 fluxes, we show that there is a first-order phase transition at a finite temperature in each case, but in a different manner.

---

Yasu Kato, University of Tokyo
Seminarraum E0.03
Contact: Simon Trebst