Spatial evolution of the electronic states near a domain wall on different stacking surfaces in 1T-TaS2

Abstract

1T-TaS₂ is a quasi-two-dimensional layered material that exhibits two distinct insulating surfaces with varying energy gaps at low temperature. The cause of these different insulating states has been investigated in the context of a band-insulating state resulting from the dimerization of a commensurate charge-density wave or a Mott-insulating state, in literatures. To elucidate the characteristics of these two insulating states, we observed the spatial evolution of the electric states near a domain wall on both surfaces of V-substituted 1T-TaS₂ by scanning tunneling microscopy and scanning tunneling spectroscopy. On both surfaces, we observed the collapse of gap structures, accompanied by the emergence of in-gap states at the domain wall. We found that the decay lengths of these in-gap states varied depending on the surface type. The short decay length observed on the small-gap surface is in good agreement of the first principles calculation.