SPATIAL VARIATIONS OF THE LOCAL-DENSITY OF STATES MODIFIED BY CDWS IN1T-TAS2-XSEX

Spatial variations of the local density of states (LDOS) near the Ferm i level have been observed on the layered dichalcogenides 1T-TaS2-xSex (x = 0, 0.2, 2) for the first time. The tunneling spectra on the clea ved surfaces were measured by atomic-site tunneling (AST) spectroscopy technique at room temperature. In 1T-TaS2, the LDOS was substantially different among the three inequivalent Ta atomic sites induced by the CDW formation. However, the surface electronic structure became homog eneous, as the Se content was increased. By substituting Se for S, the minimum position of the LDOS was systematically shifted to a higher e nergy side above the Fermi level.