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

Abstract

The physics of underdoped copper-oxide superconductors, including the pseudogap, spin and charge ordering, and their relation to superconductivity 1-3, 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 samples 4-11 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 La 2-xSr xCuO 4 (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 (T c) within a film are very small (< 1 K). At every doping, ρs(T) decreases linearly with temperature. The T c(ρ s0) dependence is linear but with an offset, (T c - T 0) ∝ ρs0 where T0 ≈ 7 K, except very close to the origin where Tc ∝ √ρ s0. Thismore » scaling law defies the standard BCS description, posing a 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:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1302997
Report Number(s):
BNL-112397-2016-JA; BNL-113191-2016-JA
Journal ID: ISSN 0028-0836; R&D Project: MA509MACA; KC0203020
Grant/Contract Number:
SC0012704
Resource Type:
Journal Article: 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
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Božović, I., He, X., Wu, J., and Bollinger, A. T. Dependence of the critical temperature in overdoped copper oxides on superfluid density. United States: N. p., 2016. Web. doi:10.1038/nature19061.
Božović, I., He, X., Wu, J., & Bollinger, A. T. Dependence of the critical temperature in overdoped copper oxides on superfluid density. United States. doi:10.1038/nature19061.
Božović, I., He, X., Wu, J., and Bollinger, A. T. 2016. "Dependence of the critical temperature in overdoped copper oxides on superfluid density". United States. doi:10.1038/nature19061. https://www.osti.gov/servlets/purl/1302997.
@article{osti_1302997,
title = {Dependence of the critical temperature in overdoped copper oxides on superfluid density},
author = {Božović, I. and He, X. and Wu, J. and Bollinger, A. T.},
abstractNote = {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 a challenge to theory.},
doi = {10.1038/nature19061},
journal = {Nature (London)},
number = 7616,
volume = 536,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
Free Publicly Available Full Text
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Citation Metrics:
Cited by: 12works
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  • The physics of underdoped copper oxide superconductors, including the pseudogap, spin and charge ordering and their relation to superconductivity, is intensely debated. The overdoped copper oxides are perceived as simpler, with strongly correlated fermion physics evolving smoothly into the conventional Bardeen–Cooper–Schrieffer (BCS) behaviour. Pioneering studies on a few overdoped samples indicated that the superfluid density was much lower than expected, but this was attributed to pair-breaking, disorder and phase separation. Here we report the way in which the magnetic penetration depth and the phase stiffness depend on temperature and doping by investigating the entire overdoped side of the La 2-xSrmore » xCuO 4 phase diagram. We measured the absolute values of the magnetic penetration depth and the phase stiffness to an accuracy of one per cent in thousands of samples; the large statistics reveal clear trends and intrinsic properties. The films are homogeneous; variations in the critical superconducting temperature within a film are very small (less than one kelvin). At every level of doping the phase stiffness decreases linearly with temperature. The dependence of the zero-temperature phase stiffness on the critical superconducting temperature is generally linear, but with an offset; however, close to the origin this dependence becomes parabolic. In conclusion, this scaling law is incompatible with the standard BCS description.« less
  • Here, we synthesize La 2–xSr xCuO 4 thin films using atomic layer-by-layer molecular beam epitaxy (ALL-MBE). The films are high-quality—singe crystal, atomically smooth, and very homogeneous. The critical temperature (T c) shows a very little (<1 K) variation within a film of 10×10 mm 2 area. The large statistics (over 2000 films) is crucial to discern intrinsic properties. We measured the absolute value of the magnetic penetration depth λ with the accuracy better than 1 % and mapped densely the entire overdoped side of the La 2–xSr xCuO 4 phase diagram. A new scaling law is established accurately for themore » dependence of T c on the superfluid density. The scaling we observe is incompatible with the standard Bardeen-Cooper-Schrieffer picture and points to local pairing.« less
  • We argue that the standard Abrikosov-Gorkov (AG)-type theory of T{sub c} in disordered d-wave superconductors breaks down in short coherence length high-T{sub c} cuprates. Numerical calculations within the Bogoliubov{endash}de Gennes formalism demonstrate that the correct description of such systems must allow for the spatial variation of the order parameter, which is strongly suppressed in the vicinity of impurities but mostly unaffected elsewhere. Suppression of T{sub c} is found to be significantly weaker than that predicted by the AG theory, in good agreement with experiment. {copyright} {ital 1997} {ital The American Physical Society}
  • It is shown that the stability condition of a helium film is maintained for any thickness in the region of existence of superfluidity. Dependence of the mean density of a superfluid component in the film on its thickness and temperature is examined.