Evidence for two energy scales in the superconducting state of optimally doped (Bi,Pb)(2)(Sr,La)(2)CuO6+delta

TitleEvidence for two energy scales in the superconducting state of optimally doped (Bi,Pb)(2)(Sr,La)(2)CuO6+delta
Publication TypeJournal Article
Year of Publication2007
AuthorsKondo T, Takeuchi T, Kaminski A, Tsuda S, Shin S
Journal TitlePhysical Review Letters
Volume98
Pages267004
Date PublishedJun
Type of ArticleArticle
ISBN Number0031-9007
Accession NumberISI:000247625100053
KeywordsBI2SR2-XLAXCUO6+DELTA, COPPER-OXIDE METALS, critical-point, gap, liquid, phase, PHOTOEMISSION-SPECTROSCOPY, pseudogap, T-C SUPERCONDUCTORS
Abstract

We use angle-resolved photoemission spectroscopy to investigate the energy gap(s) in (Bi,Pb)(2)(Sr,La)(2)CuO6+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 similar to 40 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.

DOI10.1103/PhysRevLett.98.267004
Alternate JournalPhys. Rev. Lett.