Tunneling spectroscopy of Tl{sub 2}Ba{sub 2}CuO{sub 6}.

New results from tunneling spectroscopies on near optimally doped single crystals of Tl{sub 2}Ba{sub 2}CuO{sub 6} (Tl-2201) junctions are presented. The superconductor-insulator-normal metal (SIN) tunnel junctions are obtained using the point-contact technique with a Au tip. The tunneling conductances reproducibly show a sharp cusp-like subgap, prominent quasiparticle peaks with a consistent asymmetry, and weakly decreasing backgrounds. A rigorous analysis of the SIN tunneling data is performed using two different models for the d{sub x{sup 2}-y{sup 2}} (d-wave) density of states (DOS). Based on these and earlier results, the tunneling DOS of Tl-2201 has exhibited the most reproducible data that are consistent with a d-wave gap symmetry. We show that the dip feature at 2{Delta} that is clearly seen in SIN tunneling data of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} is also present in Tl-2201, but at a weaker level. The gap values for crystals with a bulk T{sub c}=86 K are in the range of 19-25 meV.