Evidence for Two Superconducting Energy Gaps in MgB2 by Point-Contact Spectroscopy

P. Szabó, P. Samuely, J. Kačmarčík, T. Klein, J. Marcus, D. Fruchart, S. Miraglia, C. Marcenat, and A. G. M. Jansen
Phys. Rev. Lett. 87, 137005 – Published 11 September 2001
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Abstract

Experimental support is found for the multiband model of the superconductivity in the recently discovered system MgB2 with the transition temperature Tc=39K. By means of Andreev reflection, evidence is obtained for two distinct superconducting energy gaps. The sizes of the two gaps ( ΔS=2.8meV and ΔL=7meV) are, respectively, smaller and larger than the expected weak coupling value. Because of the temperature smearing of the spectra the two gaps are hardly distinguishable at elevated temperatures, but when a magnetic field is applied the presence of two gaps can be demonstrated close to the bulk Tc in the raw data.

  • Received 18 June 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.137005

©2001 American Physical Society

Authors & Affiliations

P. Szabó1,2, P. Samuely1, J. Kačmarčík1, T. Klein2, J. Marcus2, D. Fruchart3, S. Miraglia3, C. Marcenat4, and A. G. M. Jansen5

  • 1Institute of Experimental Physics, Slovak Academy of Sciences, SK-04353 Košice, Slovakia
  • 2Laboratoire d'Etudes des Propriétés Electroniques des Solides, Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, France
  • 3Laboratoire de Cristallographie, Centre National de la Recherche Scientifique, BP 166, 38042 Grenoble Cedex 9, France
  • 4CEA-Grenoble, Département de Recherche Fondamental sur la Matiére Condensée, F-38054 Grenoble Cedex 9, France
  • 5Grenoble High Magnetic Field Laboratory, Max-Planck-Institut für Festkörperforschung and Centre National de la Recherche Scientifique, B.P. 166, F-38042 Grenoble Cedex 9, France

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Issue

Vol. 87, Iss. 13 — 24 September 2001

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