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arXiv · 1706.08455

Observation of two types of anyons in the Kitaev honeycomb magnet

N. Janša·A. Zorko·M. Gomilšek·M. Pregelj·K. W. Krämer·D. Biner·A. Biffin·Ch. Rüegg·M. Klanjšek
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Abstract

Quantum spin liquid is a disordered magnetic state with fractional spin excitations. Its clearest example is found in an exactly solved Kitaev honeycomb model where a spin flip fractionalizes into two types of anyons, quasiparticles that are neither fermions nor bosons: a pair of gauge fluxes and a Majorana fermion. Here we demonstrate this kind of fractionalization in the Kitaev paramagnetic state of the honeycomb magnet $\alpha$-RuCl$_3$. The spin-excitation gap measured by nuclear magnetic resonance consists of the predicted Majorana fermion contribution following the cube of the applied magnetic field, and a finite zero-field contribution matching the predicted size of the gauge-flux gap. The observed fractionalization into gapped anyons survives in a broad range of temperatures and magnetic fields despite inevitable non-Kitaev interactions between the spins, which are predicted to drive the system towards a gapless ground state. The gapped character of both anyons is crucial for their potential application in topological quantum computing.

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N. Janša, A. Zorko, M. Gomilšek, M. Pregelj, K. W. Krämer, D. Biner, A. Biffin, Ch. Rüegg, M. Klanjšek. 2017-06-26. Observation of two types of anyons in the Kitaev honeycomb magnet. https://doi.org/10.1038/s41567-018-0129-5

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