Quantum Spin Liquids: Signatures of Fractionalization

In a quantum spin liquid, the spins remain disordered down to zero temperature, and yet, it displays topological order that is stable against local perturbations. The Kitaev model with anisotropic interactions on the bonds of a honeycomb lattice is a paradigmatic model for a quantum spin liquid. I will discuss the effects of a magnetic field and report on our discovery of an intermediate gapless spin liquid sandwiched between the known gapped Kitaev spin liquid and a polarized phase. We show that the gapless spin liquid harbors fractionalized neutral fermionic excitations, dubbed spinons, that remarkably form a Fermi surface in a charge insulator. I will also discuss the current status of experiments on candidate Kitaev QSLs.

Reference: Patel and Trivedi, PNAS 116, 12199 (2019)

Link to the seminar video