ELECTRON-TUNNELING STUDY IN THE NBSE3 CHARGE-DENSITY-WAVE STATE

A study using tunneling spectroscopy of the density of states in the v icinity of Fermi level has been performed on NbSe3 at low temperature. The tunneling conductance data reveal an asymmetry with respect to th e Fermi level and below 4.2 K two minima. These results definitely est ablish the semimetallic character of NbSe3 at low temperature. Tunneli ng spectra have been analyzed assuming an anisotropic gap structure, a nd the transverse coupling energy derived is in good agreement with ba nd calculations.