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Title: Dependence of the critical temperature in overdoped copper oxides on superfluid density

The physics of underdoped copper-oxide superconductors, including the pseudogap, spin and charge ordering, and their relation to superconductivity1-3, is intensely debated. The overdoped side is perceived as simpler, with strongly-correlated fermion physics evolving smoothly into the conventional Bardeen-Cooper-Schrieffer (BCS) behavior. Pioneering studies on a few overdoped samples4-11 indicated that the superfluid density was much smaller than expected, but this was attributed to pair-breaking, disorder, and phase separation. Here, we test this conjecture by studying how the magnetic penetration depth λ and the phase stiffness ρs depend on temperature and doping, scanning densely the entire overdoped side of the La2-xSrxCuO4 (LSCO) phase diagram. We have measured the absolute values of λ and ρs to the accuracy of ±1% in thousands of cuprate samples; the large statistics reveals clear trends and intrinsic properties. The films are quite homogeneous; variations in the critical temperature (Tc) within a film are very small (< 1 K). At every doping, ρs(T) decreases linearly with temperature. The Tc(ρ s0) dependence is linear but with an offset, (Tc - T0) ∝ ρs0 where T0 ≈ 7 K, except very close to the origin where Tc ∝ √ρ s0. This scaling law defies the standard BCS description, posing amore » challenge to theory.« less
Authors:
 [1] ;  [1] ;  [2] ;  [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Yale Univ., New Haven, CT (United States). Applied Physics Dept.
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
OSTI Identifier:
1302997
Report Number(s):
BNL--112397-2016-JA
Journal ID: ISSN 0028-0836; R&D Project: MA509MACA; KC0203020
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Nature (London)
Additional Journal Information:
Journal Name: Nature (London); Journal Volume: 536; Journal Issue: 7616; Journal ID: ISSN 0028-0836
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY