3 research outputs found
Puddle formation, persistent gaps, and non-mean-field breakdown of superconductivity in overdoped (Pb,Bi)2Sr2CuO6+{\delta}
The cuprate high-temperature superconductors exhibit many unexplained
electronic phases, but it was often thought that the superconductivity at
sufficiently high doping is governed by conventional mean-field
Bardeen-Cooper-Schrieffer (BCS) theory[1]. However, recent measurements show
that the number of paired electrons (the superfluid density) vanishes when the
transition temperature Tc goes to zero[2], in contradiction to expectation from
BCS theory. The origin of this anomalous vanishing is unknown. Our scanning
tunneling spectroscopy measurements in the overdoped regime of the
(Pb,Bi)2Sr2CuO6+{\delta} high-temperature superconductor show that it is due to
the emergence of puddled superconductivity, featuring nanoscale superconducting
islands in a metallic matrix[3,4]. Our measurements further reveal that this
puddling is driven by gap filling, while the gap itself persists beyond the
breakdown of superconductivity. 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
Proceedings of the Virtual 3rd UK Implementation Science Research Conference : Virtual conference. 16 and 17 July 2020.
Puddle formation and persistent gaps across the non-mean-field breakdown of superconductivity in overdoped (Pb,Bi)<sub>2</sub>Sr<sub>2</sub>CuO<sub>6+δ</sub>
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 theory1. However, it was shown that the superfluid density vanishes when the transition temperature goes to zero2,3, in contradiction to expectations from Bardeen–Cooper–Schrieffer theory. Our scanning tunnelling spectroscopy measurements in the overdoped regime of the (Pb,Bi)2Sr2CuO6+δ high-temperature superconductor show that this is due to the emergence of nanoscale superconducting puddles in a metallic matrix4,5. 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.</p