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Independent determination of the two gaps by directional point-contact spectroscopy in MgB_2 single crystals

R. S. Gonnelli·D. Daghero·G. A. Ummarino·V. A. Stepanov·J. Jun·S. M. Kazakov·J. Karpinski
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Abstract

Directional point-contact spectroscopy measurements were performed for the first time in state-of-the-art MgB_2 single crystals. The selective suppression of the superconductivity in the "pi" band by means of a suitable magnetic field allowed separating the partial contribution of each band to the total point-contact conductance. By fitting the partial conductance curves sigma_sigma(V) and sigma_pi(V), we got an independent determination of the two gaps, Delta_sigma and Delta_pi, with a strong reduction of the experimental uncertainty. Their temperature dependence was found to agree well with the predictions of the two-band models for MgB_2.

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R. S. Gonnelli, D. Daghero, G. A. Ummarino, V. A. Stepanov, J. Jun, S. M. Kazakov, J. Karpinski. 2002-10-24. Independent determination of the two gaps by directional point-contact spectroscopy in MgB_2 single crystals. https://doi.org/10.1088/0953-2048%2F16%2F2%2F308

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