Low-energy edge signatures of the Kitaev spin liquid

TL;DR

This paper predicts a distinctive low-energy edge signature in the dynamical spin structure factor of the Kitaev spin liquid, which can be experimentally detected and is robust against disorder and additional interactions.

Contribution

It introduces a robust nanoscale signature based on edge states in the Kitaev spin liquid, useful for experimental identification near zero magnetic field.

Findings

A singular peak in the dynamical spin structure factor at zigzag edges.

The peak energy scales linearly with one magnetic field component.

Signature persists despite edge disorder and non-Kitaev interactions.

Abstract

Recent experimental work indicates that the Kitaev spin liquid may be realizable close to zero magnetic field in exfoliated $\alpha$-RuCl$_3$ flakes, thus providing a more versatile setting for studying non-Abelian anyons. Here, we propose a robust nanoscale signature of the Kitaev spin liquid that results from its edge states and manifests in the low-energy spin dynamics. In particular, we highlight a singular peak in the dynamical spin structure factor of a zigzag edge whose energy scales linearly with only one component of the magnetic field. This sharp feature in the local spin dynamics directly reflects the bond-directional Kitaev spin interactions and, more generally, the projective symmetries of the Kitaev spin liquid. We demonstrate that our proposed signature survives in the presence of edge disorder as well as non-Kitaev interactions, and provide detailed guidelines for experimentally observing it using inelastic electron tunneling spectroscopy and color-center relaxometry.