Enhanced Superconductivity in Nanosized Tips of Scanning Tunnelling Microscope

T. Samuelya, P. Szabóa, V. Komanickýa, J.G. Rodrigob, S. Vieirab and P. Samuelya aCentre of Low Temperature Physics Košice at the Institute of Experimental Physics SAS & Faculty of Sciences, of the P.J. Šafárik University, 040 01 Košice, Slovakia bLaboratorio de Bajas Temperaturas, Universidad Autónoma de Madrid, 28049 Madrid, Spain

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Nanosized Pb junctions exhibit superconducting correlations at magnetic fields more than an order of magnitude higher than the zero-temperature critical field of the bulk Pb. The strongly enhanced critical field is a spectacular demonstration of nanosize effect where the Meissner screening currents become ineffective for junction's tip smaller than the London penetration depth (32 nm for Pb). From the enhanced critical field we characterize the geometry of a particular junction using the variable radius pair breaking theoretical model of Suderow et al.

DOI: 10.12693/APhysPolA.118.1038 PACS numbers: 74.55.+v, 61.46.-w