Signatures of multigap superconductivity in tunneling spectroscopy

Yves Noat (1) , Tristan Cren (1) , François Debontridder (1) , Dimitri Roditchev (1) , W. Sacks (2) , Pierre Toulemonde (3) , Alfonso San Miguel (4)

1 INSP - Institut des Nanosciences de Paris
2 IMPMC - Institut de minéralogie et de physique des milieux condensés
3 NEEL - MRS - Matériaux, Rayonnements, Structure
4 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures

We considered a two-band superconductor with a nonzero interband quasiparticle coupling and numerically generated partial elementary excitation spectra for each band. These show deviations from the conventional Bardeen, Cooper, and Schrieffer form, resulting in characteristic signatures in the partial tunneling spectra. The total (measurable) tunneling spectra are calculated considering the k selection in the tunneling process. Due to the thermal smearing, the relevant spectral signatures may not be resolved in superconductor-insulator-normal-metal tunneling while they are clearly revealed in superconductor-insulator-superconductor (SIS) geometry. As an example, the excitation spectrum of 2H-NbSe2 is considered in the framework of the developed tunneling model. A remarkable agreement obtained with the experimental SIS data suggests the material to be a two-band superconductor rather than an anisotropic one.

Domaines: Supraconductivité [cond-mat.supr-con]

Yves Noat, Tristan Cren, François Debontridder, Dimitri Roditchev, W. Sacks, et al.. Signatures of multigap superconductivity in tunneling spectroscopy. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2010, 82, pp.014531. ⟨10.1103/PhysRevB.82.014531⟩. ⟨hal-00511270⟩