Evidence for Two Energy Scales in the Superconducting State of Optimally Doped (Bi,Pb)2(Sr,La)2CuO6+δ

Abstract

We use angle-resolved photoemission spectroscopy to investigate the energy gap(s) in (Bi,Pb)2(Sr,La)2CuO6+δ. 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 Tc that closes at Tc. Near the antinode, spectra are broad with a large energy gap of ∼40 meV above and below Tc. The latter spectral shape and gap magnitude are almost constant across Tc, indicating that the pseudogap state coexists with the superconducting state below Tc, 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.

Source-reported materials — not catalogue approval

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