Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 53: Nanostructures at surfaces: Dots, particles, clusters III
O 53.5: Vortrag
Donnerstag, 26. März 2009, 16:00–16:15, SCH A215
Reduction of the critical temperature in ultrathin superconducting lead nanocrystals — Christophe Brun1, I-Po Hong1, François Patthey1, I .Yu. Sklyadneva2,3, R. Heid4, P. M. Echenique2,5, K. P. Bohnen4, E. V. Chulkov2,5, and •Wolf-Dieter Schneider1 — 1Ecole Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland — 2Donostia International Physics Center (DIPC), 2018 San Sebastian/Donostia, Basque Country, Spain — 3Inst. Strength Physics and Mat. Sci., 634021, Tomsk, Russia — 4Forschungszentrum Karlsruhe, Inst. f. Festkörperphysik, D-76021 Karlsruhe, Germany — 5Departamento de Fisica de Materiales and Centro Mixto CSIC-UPV/EHU, Faculdad de Ciencias Quimicas, 20080 San Sebastian/Donostia Basque Country, Spain
The energy gap of superconducting Pb nanocrystals grown on a Si(111) substrate was probed in situ layer-by-layer between 5 to 60 monolayers by low-temperature scanning tunneling spectroscopy. The critical temperature Tc was found to decrease from its bulk value as a function of inverse island thickness, in quantitative agreement with ex situ magnetic susceptibility measurements, however, in stark contrast to previous scanning probe results. Ab initio density functional calculations of the electron-phonon coupling constant support the experimental findings and show that the decrease of Tc mainly originates from a concomitant decrease of the electronic density of states at the Fermi level.