Mottness versus unit-cell doubling as the driver of the insulating state in 1T-TaS₂.

ABSTRACT: If a material with an odd number of electrons per unit-cell is insulating, Mott localisation may be invoked as an explanation. This is widely accepted for the layered compound 1T-TaS₂, which has a low-temperature insulating phase comprising charge order clusters with 13 unpaired orbitals each. But if the stacking of layers doubles the unit-cell to include an even number of orbitals, the nature of the insulating state is ambiguous. Here, scanning tunnelling microscopy reveals two distinct terminations of the charge order in 1T-TaS₂, the sign of such a double-layer stacking pattern. However, spectroscopy at both terminations allows us to disentangle unit-cell doubling effects and determine that Mott localisation alone can drive gap formation. We also observe the collaps

SUBMITTER: Butler CJ 

PROVIDER: S-EPMC7235044 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature