Study of Pseudogap State in NbN using Scanning Tunneling Spectroscopy

摘要

We present scanning tunneling spectroscopy, transport and magneto-transport measurements on disordered epitaxial thin films of NbN as a function of disorder. The studies show a spatial variation of the superconducting energy gap and provide evidence for a pseudogap state where the gap persists well above the superconducting transition temperature (T_(C)) up to a characteristic temperature T~(*) in the strong disorder limit. This result is supported by magnetoresistance (MR) measurements where we observe that a strong positive MR persists up to the pseudogap temperature T~(*).