Local spectroscopy of a proximity superconductor at very low temperature
Centre de Recherches sur les Très Basses
Températures, CNRS in convention with Université Joseph
Fourier - 25 Avenue des Martyrs, 38042 Grenoble Cedex, France
Accepted: 27 June 2001
We performed the local spectroscopy of a Normal-metal–Superconductor (N-S) junction with the help of a very low-temperature (60 mK) Scanning Tunneling Microscope (STM). The spatial dependence of the local density of states was probed locally in the vicinity of the N-S interface. We observed spectra with a fully developed gap in the regions where a thin normal-metal layer caps the superconductor dot. Close to the S metal edge, a clear pseudo-gap shows up, which is characteristic of the superconducting proximity effect in the case of a long normal metal. The experimental results are compared to the predictions of the quasiclassical theory.
PACS: 74.50.+r – Proximity effects, weak links, tunneling phenomena, and Josephson effects / 74.80.-g – Spatially inhomogeneous structures / 74.80.Fp – Point contacts; SN and SNS junctions
© EDP Sciences, 2001