Scanning tunneling spectroscopy of 1T-TaS₂ between 300 K and 40 K

We have used scanning tunneling spectroscopy to measure temperature dependent tunneling spectra of 1T-TaS₂ from room temperature to ~40 K. An abrupt transition from the charge-density-wave induced broad depletion to an opening of a deep pseudo gap was observed within ~1 K of the nearly commensurate to commensurate transition temperature. This pseudo gap was deep enough to form localized states at the Fermi level. Our tunneling results therefore suggest, in contrast to inverse photoelectron spectroscopy, that the band splitting of the Ta 5d band is due to the electron correlation effect.