The many faces of 1T-TaS₂: the role of dynamics, layer stacking, and defects in the electronic ground state

1T-TaS₂ is a structurally metastable phase of TaS2 with a rich phase diagram including a series of charge density wave transitions starting well above room temperature. The ground state has long been claimed to be a Mott insulator with potential to exhibit quantum spin liquid behavior because of its triangular lattice of localized spins from the commensurate charge density wave that forms below 180 K. Controversy persists in this system because of inconsistencies in experimental results and theoretical predictions. We present a large survey of 1T-TaS₂ crystals in which we find that the majority of samples grown in the standard way (chemical vapor transport) show topography that has a high density of defects that strongly affect the local electronic states. We were unable to detect consistent differences between samples that were quench-cooled versus slow-cooled through their nearly-commensurate to commensurate charge density wave transition, in contrast to transport experiments that found metallic behavior upon quench cooling and predictions about CDW stacking dynamics. However, quench cooling through the incommensurate to nearly-commensurate charge density wave transition at 350 K yielded a completely different ground state, with the incommensurate CDW locked in down to 10 K.