Spinon Fermi surface in the Kitaev model induced by staggered magnetic field

Kitaev model on the honeycomb lattice is an exactly solvable model of realizing quantum spin liquids which exhibits two distinct spin liquids in the parameter space: a gapped phase 'A' carries Z₂ topological order and a gapless phase 'B' carries gapless fermions and gapped vortices. For the B phase, applying a uniform magnetic field would induce a gapped spin liquid phase with non- Ablelian anyons. In this talk, we will discuss the effect of a staggered external magnetic field in the B phase. We show that the original gapless Dirac cone spectra of fermions can be immediately turned into a finite spinon Fermi surface by a weak staggered field. Our analytical perturbative results are further supported by numerical computations.