Observation of two types of anyons in the Kitaev honeycomb magnet

Understand

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.