Scanning tunneling spectroscopy of NbSe2-Au proximity junctions

The proximity induced excitation spectrum of thin gold layers on superconducting NbSe2 (S) has been measured as a function of gold thickness with a low temperature scanning tunneling microscope. The resulting conductance spectrum is dominated by a quasiparticle bound state below Delta(S) with an energy dependence strongly influenced by the suppression of the order parameter in S near the interface. In addition, a significant change in the induced spectrum can be directly related to the sample morphology as determined by imaging. A simple model will be used to interpret the results.