Low Temperature Physics: 46, 400 (2020); https://doi.org/10.1063/10.0000873
Fizika Nizkikh Temperatur: Volume 46, Number 4 (April 2020), p. 481-496    ( to contents , go back )

Break-junction tunneling spectra of Bi2212 superconducting ceramics: Influence of inhomogeneous d-wave-Cooper-pairing and charge-density-wave order parameters

Toshikazu Ekino1, Alexander M. Gabovich2, Mai Suan Li3, Henryk Szymczak3, and Alexander I. Voitenko2

1Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan
E-mail: ekino@hiroshima-u.ac.jp

2Institute of Physics, 46 Nauka Ave., Kyiv 03680, Ukraine
E-mail: gabovich@iop.kiev.ua

3Institute of Physics, 32/46 Al. Lotników, Warsaw PL-02-668, Poland
E-mail: masli@ifpan.edu.pl

pos Анотація:

Received November 25, 2019, published online February 28, 2020


Conductance-voltage characteristics (CVCs) of tunnel break junctions made of Bi2Sr2CaCu2O8+δ crystals were measured. It was demonstrated that the CVCs have a V-shaped inner gap region, similar to those typical of CVCs for tunnel junctions between d-wave superconductors. The CVCs have different forms for different junctions, but all of them reveal weak dip-hump structures outside the inner gap region. Calculations of the tunnel current in the ab plane of the break junctions were carried out in the model of the inhomogeneous d-wave superconductor partially gapped by charge density waves (CDWs). The averaging of the tunnel current over the statistical distributions of both the superconducting and CDW order parameters was carried out. The theoretical results qualitatively reproduce the behavior of experimental curves. A conclusion was made that tunnel directionality and the statistical distributions of both order are crucial factors governing the observed CVC shapes for break junctions made of high-Tc oxides.

Key words: superconductivity, charge density waves, electronic inhomogeneity, break-junction tunneling, high-temperature oxides.

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