We use angle-resolved photoemission spectroscopy to investigate the energy gap(s) in $(\mathrm{Bi},\mathrm{Pb}{)}_2(\mathrm{Sr},\mathrm{La}{)}_2{\mathrm{CuO}}_{6+\delta }$. We find that the spectral gap has two components in the superconducting state: a superconducting gap and pseudogap. Differences in their momentum and temperature dependence suggest that they represent two separate energy scales. Spectra near the node reveal a sharp peak with a small gap below $T_c$ that closes at $T_c$. Near the antinode, spectra are broad with a large energy gap of $\sim 40\mathrm{meV}$ above and below $T_c$. The latter spectral shape and gap magnitude are almost constant across $T_c$, indicating that the pseudogap state coexists with the superconducting state below $T_c$, and it dominates spectra around the antinode. We speculate that the pseudogap state competes with the superconductivity by diminishing spectral weight in antinodal regions, where the superconducting gap is largest.

• Received 20 November 2006

DOI:https://doi.org/10.1103/PhysRevLett.98.267004