BCS-like gap structure of HgBa/sub 2/CuO/sub 4+/spl delta// tunnel junctions

We report point-contact tunneling into polycrystalline HgBa/sub 2/CuO/sub 4+/spl delta// superconductors with a T/sub c/ onset of 97 K using a superconducting Nb counterelectrode. These SIS' tunnel junctions are of unusually high quality for cuprate superconductors, exhibiting low and flat sub-gap conductances and sharp conductance peaks as expected from a BCS density of states. These features are obtained reproducibly and are consistent with earlier published SIN results using a Au counterelectrode. Use of experimental data to simulate performance of a quasiparticle mixer indicates HgBa/sub 2/CuO/sub 4+/spl delta// may be suitable for use in low noise heterodyne receivers operating at a few THz.<
>