Universal superconducting gap inhomogeneity in cuprates revealed by nonlinear response

03:00 PM - 04:00 PM 
Prof. Miroslav Pozek 
University of Zagreb, Faculty of Science, Department of Physics, Croatia 
main topic
Materials: Superconductors, Magnetic Materials, Nano Structures
Physics: Condensed Matter (incl. Soft, Solid)
Christine Malbrich 

After almost three decades of extraordinary scientific efforts, the cuprate high-temperature superconductors continue to pose challenging queries. One of the important open questions is the nature of superconducting pre-pairing above the macroscopic transition temperature Tc. A pivotal step toward understanding pre-paring regime would be to figure out how superconductivity emerges from the unusual normal state. Hitherto existing investigations of superconducting traces above Tc has led to controversial conclusions. The main difficulty has been to separate superconducting contributions from complex normal-state behavior. Here we employ an unconventional probe – nonlinear conductivity [1] – which is zero in the normal state, to avoid this problem. We find for several representative cuprates that the nonlinear conductivity vanishes exponentially above Tc and exhibits temperature-scaling characterized by a universal scale Eo, irrespective of hole doping and cuprate family [2]. Similar behavior is observed in nonlinear torque magnetization measurements [3] and in linear conductivity experiments [4].
Standard Ginzburg-Landau theory failed to fit the observed results. Instead, to explain the data we have successfully employed a simple percolative model based on inhomogeneity of superconducting gaps. We thus show that the superconducting precursor in the cuprates is strongly affected by intrinsic, universal nanoscale inhomogeneity.

[1] M. Doslic, D. Pelc,& M. Pozek, Rev. Sci. Instrum. 85,073905 (2014)
[2] D. Pelc et al., Nature Commun. 9, 4327 (2018)
[3] G. Yu et al., arXiv: 1710.10957 (2017)
[4] P. Popcevic et al., npj Quantum Materials 3, 42 (2018)


Last update: 16.11.2018 00:08.


Leibniz Institut für Festkörper- und Werkstoffforschung Dresden (D2E.27, IFW Dresden) 
Helmholtzstraße 20
01069 Dresden


Leibniz Institut für Festkörper- und Werkstoffforschung Dresden (IFW)
Helmholtzstraße 20
01069 Dresden
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