The European Physical Journal B - Condensed Matter and Complex Systems

, Volume 22, Issue 4, pp 411–414

Evidence for pseudogap and phase-coherence gap separation by Andreev reflection experiments in Au/ La2 - xSrxCuO4 point-contact junctions

Authors

  • R.S. Gonnelli
    • INFM - Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy
  • A. Calzolari
    • INFM - Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy
  • D. Daghero
    • INFM - Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy
  • L. Natale
    • INFM - Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy
  • G.A. Ummarino
    • INFM - Dipartimento di Fisica, Politecnico di Torino, 10129 Torino, Italy
  • V.A. Stepanov
    • P.N. Lebedev Physical Institute, Russian Academy of Sciences, 117924 Moscow, Russia
  • M. Ferretti
    • Dipartimento di Chimica e Chimica Industriale, Università di Genova, 16146 Genova, Italy

DOI: 10.1007/PL00011150

Cite this article as:
Gonnelli, R., Calzolari, A., Daghero, D. et al. Eur. Phys. J. B (2001) 22: 411. doi:10.1007/PL00011150

Abstract:

We present new Au/La2-xSrxCuO4 (LSCO) point-contact conductance measures as a function of voltage and temperature in samples with 0.08 ?x? 0.2. Andreev reflection features disappear at about the bulk Tc, giving no evidence of gap for T > Tc. The fit of the normalized conductance at any T < Tc supports a (s + d)-wave symmetry of the gap, whose dominant low-Ts component follows the Tc(x) curve in contrast with recent angle-resolved photoemission spectroscopy and quasiparticle tunneling data. These results prove the separation between pseudogap and phase-coherence superconducting gap in LSCO at x 0.2.

PACS. 74.50.+r Proximity effects; weak links; tunneling phenomena and Josephson effects – 74.25.Dw Superconductivity phase diagrams – 74.72.Dn La-based cuprates

Copyright information

© EDP Sciences, Springer-Verlag 2001