ELECTRON LOCALIZATION PROBED BY TEMPERATURE-DEPENDENT TUNNELING SPECTROSCOPY IN 1T-TAS2

In order to present a clear picture of the density of states at both s ides of the Fermi level (E-F) in 1T-TaS2 near the nearly commensurate to commensurate transition (similar to 187 K) and at low temperatures, we have done a temperature-dependent tunneling spectroscopy study usi ng a scanning tunneling microscope. We observed an abrupt transition f rom a charge-density-wave induced depletion to an opening of a deep ps eudo gap near the E-F of the nearly commensurate to commensurate trans ition within similar to 1 K. The measured pseudo gap turned out to be deep enough to form localized states at E-F. In contrast to an inverse photoelectron spectroscopy study, our tunneling results indicate the gap structures of two Hubbard subbands resulting from band splitting o f the Ta 5d band due to the electron correlation effect.