Generation of chirality and orbital magnetization by Stone-Wales-type lattice defects in the Kitaev spin liquid

TL;DR

This paper investigates how Stone-Wales lattice defects in the Kitaev spin liquid induce chirality and orbital magnetization, leading to topological phases and finite temperature transitions.

Contribution

It identifies a specific defect type that preserves solvability and reveals how defect-induced chirality creates topological gaps and phase transitions in the Kitaev model.

Findings

Defects host chiral flux configurations with large net chirality.

Defect chiralities generate a topological gap protecting a Chern number.

Finite temperature phase transition into the chiral spin liquid occurs at a critical temperature proportional to defect density.

Abstract

In this work we extend our study of the effect of certain crystallographic defects on the spin-1/2 Kitaev honeycomb spin liquid (arXiv:2511.19409), focusing on its gapless phase and contrasting with the gapped phase. We identify a Stone-Wales (SW) local defect consisting of a 90$^\circ$ bond rotation that preserves Kitaev bond labels for edge-sharing octahedra and thereby enables exact solvability. These SW-type defects involve odd-sided plaquettes with $\pm \pi/2$ fluxes, but can be created locally. An isolated defect hosts a time-reversal pair of ground-state flux configurations with large net chirality. Certain excitations are also chiral. The chirality manifests in Majorana local Chern marker and in scalar spin chirality, producing electronic orbital magnetization. T-matrix analysis and numerics at finite defect density $n_d$ show that defect chiralities generate a topological gap of $11 n_d$ protecting a Chern number $C=\pm 1$. Emergent ferromagnetic long range Ising interactions $r^{-\gamma}$ with $2<\gamma < 3$ between defect chiralities lead to a finite temperature $T_c$ phase transition into the chiral spin liquid. The $T_c$ is proportional to $n_d$ and diverges when $\gamma\rightarrow 2$. We also consider additional solvable impurity potentials and find that $\gamma$ can be reduced to below $2.3$ and correspondingly enhance $T_c$. Our results offer applications to 2D Dirac cone systems with a finite density of fluctuating Ising magnetic impurities and to identifying spin liquids with lattice defects.