Kitaev quasiparticles in a proximate spin liquid: A many-body localization perspective

TL;DR

This paper investigates the stability of Kitaev quasiparticles in a spin liquid under perturbations, revealing conditions for their localization and persistence at finite temperatures, with implications for experimental materials.

Contribution

It introduces a many-body localization perspective to analyze Kitaev quasiparticle stability amid Heisenberg interactions, identifying regimes of localization and stability.

Findings

Kitaev states can be localized, fractal, or delocalized in Fock space.

Vison gap and Wilson loop persist into neighboring phases.

Kitaev quasiparticles remain stable below a certain energy scale.

Abstract

We study the stability of Kitaev quasiparticles in the presence of a perturbing Heisenberg interaction as a Fock space localization phenomenon. We identify parameter regimes where Kitaev states are localized, fractal or delocalized in the Fock space of exact eigenstates, with the first two implying quasiparticle stability. Finite temperature calculations show that a vison gap, and a nonzero plaquette Wilson loop at low temperatures, both characteristic of the deconfined Kitaev spin liquid phase, persist far into the neighboring phase that has a concomitant stripy spin-density wave (SDW) order. The key experimental implication for Kitaev materials is that below a characteristic energy scale, unrelated to the SDW ordering, Kitaev quasiparticles are stable.