Observation of two types of fractional excitation in the Kitaev honeycomb magnet

Janša, Nejc; Zorko, Andrej; Gomilšek, Matjaž; Pregelj, Matej; Krämer, Karl W.; Biner, Daniel; Biffin, Alun; Rüegg, Christian; Klanjšek, Martin

doi:10.1038/s41567-018-0129-5

Observation of two types of fractional excitation in the Kitaev honeycomb magnet

Janša, Nejc; Zorko, Andrej; Gomilšek, Matjaž; Pregelj, Matej; Krämer, Karl W.; Biner, Daniel; Biffin, Alun; Rüegg, Christian; Klanjšek, Martin

Authors

Nejc Janša

Andrej Zorko

Matjaž Gomilšek

Matej Pregelj

Karl W. Krämer

Daniel Biner

Alun Biffin

Christian Rüegg

Martin Klanjšek

Abstract

Quantum spin liquid is a disordered but highly entangled magnetic state with fractional spin excitations1. The ground state of an exactly solved Kitaev honeycomb model is perhaps its clearest example2. Under a magnetic field, a spin flip in this model fractionalizes into two types of anyon, a quasiparticle with more complex exchange statistics than standard fermions or bosons: a pair of gauge fluxes and a Majorana fermion2,3. Here, we demonstrate this kind of fractionalization in the Kitaev paramagnetic state of the honeycomb magnet α-RuCl3. The spin excitation gap determined by nuclear magnetic resonance consists of the predicted Majorana fermion contribution following the cube of the applied magnetic field2,4,5, and a finite zero-field contribution matching the predicted size of the gauge flux gap2,6. The observed fractionalization into gapped anyons survives in a broad range of temperatures and magnetic fields, which establishes α-RuCl3 as a unique platform for future investigations of anyons.

Citation

Janša, N., Zorko, A., Gomilšek, M., Pregelj, M., Krämer, K. W., Biner, D., …Klanjšek, M. (2018). Observation of two types of fractional excitation in the Kitaev honeycomb magnet. Nature Physics, 14(8), 786-790. https://doi.org/10.1038/s41567-018-0129-5

Journal Article Type	Article
Acceptance Date	Mar 29, 2018
Online Publication Date	May 7, 2018
Publication Date	Aug 1, 2018
Deposit Date	May 11, 2018
Publicly Available Date	Nov 29, 2018
Journal	Nature Physics
Print ISSN	1745-2473
Electronic ISSN	1745-2481
Publisher	Nature Research
Peer Reviewed	Peer Reviewed
Volume	14
Issue	8
Pages	786-790
DOI	https://doi.org/10.1038/s41567-018-0129-5