Quantum spin liquid on the surface of 1T-TaS₂ and its detection scheme

The classification of various topological phases has attracted tremendous interests in recent years. It is understood that certain 2D quantum spin liquids (QSL) cannot be realized in strictly 2D systems, but can be realized on the surface of 3D systems. However, from the material's point of view, the realization of such surface QSL, including those realizable in pure 2D systems, is still lacking.

In this work we propose that 1T-TaS2 can be a candidate to realize 2D QSL on its surface. We calculated the surface states of the two types of surfaces of 1T-TaS2, and found a metallic surface state on the type-II surface when the correlation effect was weak. When the electron correlation is strong, we argue that the type-II surface can be viewed as a spin-1/2 triangular lattice magnet, and a spinon Fermi surface spin liquid can be realized on it.

We further propose a spectroscopic detection scheme for the surface QSL. By coupling the surface QSL to a metallic layer, the spin correlation function of the surface QSL can be detected by angle-resolved photoemission spectroscopy.