Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Surface Magnetism: Atoms and Molecules
O 4.6: Vortrag
Montag, 7. März 2016, 11:45–12:00, S052
Investigation of the superconducting gap of nano-sized Pb-islands in high magnetic fields — •Steffen Rolf-Pissarczyk1,2, Jacob Burgess1,2, Shichao Yan1,2, and Sebastian Loth1,2 — 1Max Planck Institute for the Structure and Dynamics of Matter, Hamburg, Germany — 2Max Planck Institute for Solid State Research, Stuttgart, Germany
Superconductors change drastically their properties when they are confined in geometries with dimensions of the order or less than the London penetration depth or coherence length of the bulk material. To get experimental access to the effects of strong confinement we prepared small hexagonal Pb-islands with diameter of less than 50 nm and a uniform height of 7 atomic layers on Si(111) 7x7. The islands were formed by depositing Pb at low temperature and annealing at 300 K. We investigated the Pb-islands with scanning tunneling spectroscopy in magnetic fields up to 9 T and at 0.6 K temperature.
We found the critical magnetic field in such small islands to be several Tesla, which represents an enhancement greater than 50 compared to the bulk value. The critical field was directly measured and verified by the vanishing superconducting gap. By independently measuring the size of the superconducting gap and the critical magnetic field that quenches superconductivity we were able to correlate these two fundamental parameters. This correlations allows us to estimate the highest critical field expected for 7 atomic layer thin Pb-islands.