Competing Phases Found in High-Temperature Superconductor
December 2012 SSRL Science
Summary by Lori Ann White, SLAC Office of Communications
Although the behavior of conventional superconductors has been explained via the BCS theory, the mechanism of superconductivity in the cuprate high temperature superconductors remains unresolved. One approach to this problem is to explore the phases next to superconductivity on the temperature-doping phase diagram. The pseudogap phase above Tc has been a particular stumbling block because it is not a Fermi liquid as with conventional superconductors.
There has been increasing evidence that the pseudogap phase is distinct from superconductivity and persists below Tc, and not simply a precursor to superconductivity. In a study recently published in PNAS, researchers at SSRL Beam Line 5-4 and Stanford explored the full doping, temperature, and momentum dependence of spectral gaps in the superconducting state of Bi2Sr2CaCu2O8+δ (Bi-2212) with unprecedented precision and completeness. This study had three components: low-temperature measurements that revealed three distinct ground states at different dopings; temperature-dependence measurements that revealed that superconductivity suppresses the pseudogap in a momentum-dependent manner; and a revised phase diagram motivated by these data that resolves important discrepancies in the literature.
What emerged in the study was a clear picture of how the gap in the superconducting state sensitively reflects phases which coexist with superconductivity. For more information regarding the interplay between these phases, see the accompanying technical highlight.
Primary CitationI. M. Vishik, M Hashimoto, R.-H. He, W. S. Lee, F. Schmitt, D. H. Lu, R. G. Moore, W. Meevasana, T. Sasagawa, S. Uchida, K. Fujita, S. Ishida, M. Ishikado, Y. Yoshida, H. Eisaki, Z. Hussain, T. P. Devereaux, and Z. X. Shen. Phase competition in trisected superconducting dome. PNAS 109 (45) 18332-18337 (2012) [DOI: 10.1073/pnas.1209471109]
ContactsInna M. Vishik and Z. X. Shen, Stanford University