Closing the superconducting gap in small Pb-nanoislands with high magnetic fields

Abstract

Superconducting properties change in confined geometries. Here we study the effects of strong confinement in nanosized Pb-islands on Si(111) 7x7. Small hexagonal islands with diameters less than 50 nm and a uniform height of 7 atomic layers are formed by depositing Pb at low temperature and annealing at 300 K. We measure the tunneling spectra of individual Pb-nanoislands using a low-temperature scanning tunneling microscope operated at 0.6 K, and follow the narrowing of the superconducting gap as a function of magnetic field. We find the critical magnetic field, at which the superconducting gap vanishes, reaches several Tesla, which represents a greater than 50-fold enhancement compared to the bulk value. By independently measuring the size of the superconducting gap, and the critical magnetic field that quenches superconductivity for a range of nanoislands we can correlate these two fundamental parameters and estimate the maximal achievable critical field for 7 ML Pb-nanoislands to 7 T.

References in corpus (6)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Observation of shell effects in superconducting nanoparticles of Sn
• Strong localization of Majorana end states in chains of magnetic adatoms
• Visualizing landscapes of the superconducting gap in heterogeneous superconductor thin films: geometric influences on proximity effects
• Competing effects of surface phonon softening and quantum size effects on the superconducting properties of nanostructured Pb
• Universal Quenching of Superconductivity in Two-dimensional Nano-islands

Cited by in corpus (2)

• Modeling Green's functions measurements with two-tip scanning tunneling microscopy
• Anomalous superconducting proximity effect of planar Pb-RhPb2 heterojunctions in the clean limit