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Nat Mater. 2016 Jul;15(7):733-40. doi: 10.1038/nmat4604. Epub 2016 Apr 4.

Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet.

Author information

1
Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
2
Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
3
Material Sciences and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
4
Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA.
5
Department of Physics, University of Tennessee, Knoxville, Tennessee 37996, USA.
6
Neutron Data Analysis &Visualization Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
7
Department of Physics, Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, UK.
8
Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany.
9
International Center for Theoretical Sciences, TIFR, Bangalore 560012, India.
10
Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA.
11
Bredesen Center, University of Tennessee, Knoxville, Tennessee 37966, USA.

Abstract

Quantum spin liquids (QSLs) are topological states of matter exhibiting remarkable properties such as the capacity to protect quantum information from decoherence. Whereas their featureless ground states have precluded their straightforward experimental identification, excited states are more revealing and particularly interesting owing to the emergence of fundamentally new excitations such as Majorana fermions. Ideal probes of these excitations are inelastic neutron scattering experiments. These we report here for a ruthenium-based material, α-RuCl3, continuing a major search (so far concentrated on iridium materials) for realizations of the celebrated Kitaev honeycomb topological QSL. Our measurements confirm the requisite strong spin-orbit coupling and low-temperature magnetic order matching predictions proximate to the QSL. We find stacking faults, inherent to the highly two-dimensional nature of the material, resolve an outstanding puzzle. Crucially, dynamical response measurements above interlayer energy scales are naturally accounted for in terms of deconfinement physics expected for QSLs. Comparing these with recent dynamical calculations involving gauge flux excitations and Majorana fermions of the pure Kitaev model, we propose the excitation spectrum of α-RuCl3 as a prime candidate for fractionalized Kitaev physics.

PMID:
27043779
DOI:
10.1038/nmat4604
[Indexed for MEDLINE]
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