Excitations in the field-induced quantum spin liquid state of alpha-RuCl3

TL;DR

This study provides evidence that applying an 8 Tesla magnetic field to alpha-RuCl3 suppresses magnetic order and induces a quantum spin liquid state characterized by fractionalized excitations, supporting the realization of Kitaev physics in this material.

Contribution

The paper demonstrates the emergence of a field-induced quantum spin liquid in alpha-RuCl3 through inelastic neutron scattering, revealing fractionalized excitations absent in the ordered state.

Findings

Magnetic order in alpha-RuCl3 is suppressed at 8 Tesla.

A broad continuum of excitations appears, indicating fractionalization.

Evidence supports the realization of a quantum spin liquid state.

Abstract

The Kitaev model on a honeycomb lattice predicts a paradigmatic quantum spin liquid (QSL) exhibiting Majorana Fermion excitations. The insight that Kitaev physics might be realized in practice has stimulated investigations of candidate materials, recently including alpha-RuCl3. In all the systems studied to date, non-Kitaev interactions induce magnetic order at low temperature. However, in-plane magnetic fields of roughly 8 Tesla suppress the long-range magnetic order in alpha-RuCl3 raising the intriguing possibility of a field-induced QSL exhibiting non-Abelian quasiparticle excitations. Here we present inelastic neutron scattering in alpha-RuCl3 in an applied magnetic field. At a field of 8 Tesla, the spin waves characteristic of the ordered state vanish throughout the Brillouin zone. The remaining single dominant feature of the response is a broad continuum centered at the Gamma point, previously identified as a signature of fractionalized excitations. This provides compelling evidence that a field-induced QSL state has been achieved.