Directional point-contact spectroscopy measurements were performed for the first time in state-of-the-art MgB2 single crystals. The selective suppression of the superconductivity in the π band by means of a suitable magnetic field allowed separation of the partial contribution of each band to the total point-contact conductance. By fitting the partial conductance curves σσ(V) and σπ(V), independent determinations were made of the 2 gaps, Δσ and Δπ, with a strong reduction in the experimental uncertainty. Their temperature dependence was found to agree well with the predictions of 2-band models for MgB2.

Independent Determination of the Two Gaps by Directional Point-Contact Spectroscopy in MgB2 Single Crystals. R.S.Gonnelli, D.Daghero, G.A.Ummarino, V.A.Stepanov, J.Jun, S.M.Kazakov, J.Karpinski: Superconductor Science and Technology, 2003, 16, 171-5