Puddle formation and persistent gaps across the non-mean-field breakdown of superconductivity in overdoped (Pb,Bi) 2 Sr 2 CuO 6+δ

• Published in: Nature materials Vol. 22; no. 6; p. 703
• Main Authors: Tromp, Willem O, Benschop, Tjerk, Ge, Jian-Feng, Battisti, Irene, Bastiaans, Koen M, Chatzopoulos, Damianos, Vervloet, Amber H M, Smit, Steef, van Heumen, Erik, Golden, Mark S, Huang, Yinkai, Kondo, Takeshi, Takeuchi, Tsunehiro, Yin, Yi, Hoffman, Jennifer E, Sulangi, Miguel Antonio, Zaanen, Jan, Allan, Milan P
• Format: Journal Article
• Language: English
• Published: England 01.06.2023
• ISSN: 1476-4660

The cuprate high-temperature superconductors exhibit many unexplained electronic phases, but the superconductivity at high doping is often believed to be governed by conventional mean-field Bardeen-Cooper-Schrieffer theory . However, it was shown that the superfluid density vanishes when the transition temperature goes to zero , in contradiction to expectations from Bardeen-Cooper-Schrieffer theory. Our scanning tunnelling spectroscopy measurements in the overdoped regime of the (Pb,Bi) Sr CuO high-temperature superconductor show that this is due to the emergence of nanoscale superconducting puddles in a metallic matrix . Our measurements further reveal that this puddling is driven by gap filling instead of gap closing. The important implication is that it is not a diminishing pairing interaction that causes the breakdown of superconductivity. Unexpectedly, the measured gap-to-filling correlation also reveals that pair breaking by disorder does not play a dominant role and that the mechanism of superconductivity in overdoped cuprate superconductors is qualitatively different from conventional mean-field theory.