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

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., Biffin, A., Rüegg, C., & 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
• Public URL: https://durham-repository.worktribe.com/output/1331405