The structure of the superconducting gap in MgB2 from point-contact spectroscopy

Y. Bugoslavsky; Y. Miyoshi; G. K. Perkins; A. V. Berenov; Z. Lockman; J. L. MacManus-Driscoll; L. F. Cohen; A. D. Caplin; H. Y. Zhai; M. P. Paranthaman; H. M. Christen; M. Blamire

doi:10.1088/0953-2048/15/4/308

arXiv · cond-mat/0110296

The structure of the superconducting gap in MgB2 from point-contact spectroscopy

Y. Bugoslavsky·Y. Miyoshi·G. K. Perkins·A. V. Berenov·Z. Lockman·J. L. MacManus-Driscoll·L. F. Cohen·A. D. Caplin·H. Y. Zhai·M. P. Paranthaman·H. M. Christen·M. Blamire

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Abstract

We have studied the structure of the superconducting gap in MgB2 thin films by means of point-contact spectroscopy using a gold tip. The films were produced by depositing pure boron on a sapphire substrate, using e-beam evaporation, followed by reaction with magnesium vapour. The films have a Tc of 38.6 +- 0.3 K and resistivity of about 20 microOhm cm at 40 K. The point-contact spectra prove directly the existence of a multi-valued order parameter in MgB2, with two distinct values of the gap, DELTA1=2.3+-0.3 meV and DELTA2=6.2+-0.7 meV at 4.2 K. Analysis of the spectra in terms of the Blonder-Tinkham-Klapwijk model reveals that both gaps close simultaneously at the Tc of the film. Possible mechanisms that can explain the intrinsic co-existence of two values of the gap are discussed.

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Y. Bugoslavsky, Y. Miyoshi, G. K. Perkins, A. V. Berenov, Z. Lockman, J. L. MacManus-Driscoll, L. F. Cohen, A. D. Caplin, H. Y. Zhai, M. P. Paranthaman, H. M. Christen, M. Blamire. 2001-10-15. The structure of the superconducting gap in MgB2 from point-contact spectroscopy. https://doi.org/10.1088/0953-2048%2F15%2F4%2F308

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