High energy spin excitations in the quantum spin liquid candidate Zn-barlowite probed by resonant inelastic x-ray scattering

TL;DR

This study investigates the high-energy spin excitations in the quantum spin liquid candidate Zn-barlowite using resonant inelastic X-ray scattering, revealing a broad continuum extending up to 200 meV indicative of fractionalized spinons.

Contribution

First direct measurement of high-energy spin excitations in Zn-barlowite, demonstrating a broad continuum consistent with fractionalized spinons in a quantum spin liquid.

Findings

Broad magnetic continuum extends up to ~200 meV

Significant contributions from multiple pairs of spinons

Evidence supporting fractionalized excitations in Zn-barlowite

Abstract

A quantum spin liquid is a novel ground state that can support long-range entanglement between magnetic moments, resulting in exotic spin excitations involving fractionalized $S=\frac{1}{2}$ spinons. Here, we measure the excitations in single crystals of the spin liquid candidate Zn-barlowite using resonant inelastic X-ray scattering. By analyzing the incident polarization and temperature dependences, we deduce a clear magnetic scattering contribution forming a broad continuum that surprisingly extends up to $\sim$200 meV ($\sim$14$J$, where $J$ is the magnetic exchange). The excitation spectrum reveals that significant contributions arise from multiple pairs of spinons and/or antispinons at high energies.