Confinement-deconfinement transition in a generalized Kitaev model

TL;DR

This paper introduces a generalized Kitaev spin model with additional interactions, revealing complex phase transitions including confinement-deconfinement and topological quantum phase changes, analyzed through fermionic mean-field theory.

Contribution

It extends the Kitaev model by adding a loop term and Ising perturbation, providing a detailed phase diagram and stability analysis of spin liquid phases.

Findings

Identifies confinement-deconfinement transitions between various magnetic phases.

Discovers topological quantum phase transitions between gapped and gapless spin liquids.

Suggests some first-order transitions may become second order via defect condensation.

Abstract

We present a spin model, namely, the Kitaev model augmented by a loop term and perturbed by an Ising Hamiltonian and show that it exhibits both confinement-deconfinement transitions from spin liquid to antiferromagnetic/spin-chain/ferromagnetic phases and topological quantum phase transitions between gapped and gapless spin liquid phases. We develop a Fermionic mean-field theory to chart out the phase diagram of the model and estimate the stability of its spin liquid phases which might be relevant for attempts to realize the model in optical lattices. We also conjecture that some of the confinement-deconfinement transitions in the model, predicted to be first order within the mean-field theory, may become second order via a defect condensation mechanism.