$Z_3$ generalization of the Kitaev's spin-1/2 model

TL;DR

This paper generalizes Kitaev's spin-1/2 model to a $Z_3$ clock model, revealing a low-energy theory with $Z_3$ parafermions and gauge fields, and proposes a pathway to Fibonacci phase via interlayer pairing.

Contribution

It introduces a $Z_3$ generalization of Kitaev's model, analyzes its low-energy $Z_3$ parafermion and gauge field description, and explores phase transitions to Fibonacci phase.

Findings

Low-energy theory described by $Z_3$ parafermions coupled to a $Z_3$ gauge field.

Mean-field analysis yields a Chern-Simons gauge theory identical to (221) fractional quantum Hall state.

Fluctuations induce interlayer pairing, enabling a phase transition to Fibonacci phase.

Abstract

We generalize the Kitaev's spin-1/2 model on the honeycomb by introducing a two-dimensional $Z_3$ clock model on the triangular lattice with three body interaction. We discuss various properties of this model and show that the low energy theory of the $Z_3$ generalized Kitaev model (GKM) is described by a single $Z_3$ parafermion per lattice site coupled to a $Z_3$ gauge field. We also introduce a slave-fermion approach for this GKM, treat the resulting fermionic Hamiltonian at the mean-field level, solve the mean field parameters self-consistently, and obtain the low energy effective Chern-Simons (CS) gauge theory. The resulting CS gauge theory is identical to that of a (221) fractional quantum Hall state. We then go beyond the mean-field approximation and demonstrate that fluctuations generate a uniform interlayer pairing for the dual (221) bilayer state. We argue that this perturbed system can undergo a phase transition to the Fibonacci phase by tuning the interlayer pairing strength.