Exactly Solvable Topological Chiral Spin Liquid with Random Exchange

TL;DR

This paper extends an exactly solvable chiral spin liquid model by adding disorder, revealing that disorder can enlarge the topological non-Abelian phase and induce phase transitions related to extended state pair annihilation.

Contribution

It introduces disordered exchange couplings into the Yao-Kivelson Kitaev model and analyzes how disorder affects the topological phases and phase transitions.

Findings

Disorder enlarges the topological non-Abelian phase.

Phase transition involves pair annihilation of extended states.

Analogies to quantum Hall and topological insulator systems.

Abstract

We extend the Yao-Kivelson decorated honeycomb lattice Kitaev model [Phys. Rev. Lett. 99,247203 (2007)] of an exactly solvable chiral spin liquid by including disordered exchange couplings. We have determined the phase diagram of this system and found that disorder enlarges the region of the topological non-Abelian phase with finite Chern number. We study the energy level statistics as a function of disorder and other parameters in the Hamiltonian, and show that the phase transition between the non-Abelian and Abelian phases of the model at large disorder can be associated with pair annihilation of extended states at zero energy. Analogies to integer quantum Hall systems, topological Anderson insulators, and disordered topological Chern insulators are discussed.