POINT-CONTACT TUNNELING STUDY OF HGBA2CUO4+DELTA - BCS-LIKE GAP STRUCTURE

We report on point-contact tunneling into polycrystalline HgBa2CuO4+delta superconductors with a T-c onset of 97 K. Tunneling data follow the general trend of the best curves seen in cuprate high-temperature superconductors, but these show significantly lower and flatter subgap conductance values than any other cuprate and they can be reproducibly obtained. By fitting the data to a smeared BCS density of states, the energy gap has been determined and the smearing parameter is so small that it is comparable to thermal smearing.