Observation of shell effects in superconducting nanoparticles of Sn

Abstract

In a zero-dimensional superconductor, quantum size effects (QSE) not only set the limit to superconductivity, but are also at the heart of new phenomena such as shell effects, which have been predicted to result in large enhancements of the superconducting energy gap. Here, we experimentally demonstrate these QSE through measurements on single, isolated Pb and Sn nanoparticles. In both systems superconductivity is ultimately quenched at sizes governed by the dominance of the quantum fluctuations of the order parameter. However, before the destruction of superconductivity, in Sn nanoparticles we observe giant oscillations in the superconducting energy gap with particle size leading to enhancements as large as 60%. These oscillations are the first experimental proof of coherent shell effects in nanoscale superconductors. Contrarily, we observe no such oscillations in the gap for Pb nanoparticles, which is ascribed to the suppression of shell effects for shorter coherence lengths. Our study paves the way to exploit QSE in boosting superconductivity in low-dimensional systems.

Spin density wave and superconducting properties of nanoparticle organic conductor assemblies

“…1/3 ), and shielded sample radius r s (≡ [ 3 4 πV s ] 1/3 ). Using the relation 4 3 π(r assem. -∆λ eff ) 3 = V s we find ∆λ eff ∼ 150 µm.…”

“…For instance, in semiconductor devices 1 or type I elemental metal superconductors like aluminum 2,3 the evolution from an insulator to a metal or superconductor is observed with increasing electron density or film thickness, and in nanoparticles of tin 4 or lead 5,6 a modification of the superconducting properties is observed for sizes smaller than the coherence lengths. The single molecule magnet material Mn 12 -acetate has also been produced as a thin film 7 .…”

Interplay between lattice dynamics and superconductivity in Nb3Sn thin films

“…In particular, electron confinement and electronic level quantization have attracted a lot of interest [7][8][9] . When the confinement is strong, i.e.…”

Boron Nitride on Cu(111): An Electronically Corrugated Monolayer

“…[10][11][12] Furthermore h-BN allows to tune the band gap of graphene in heterostructures 8,13 or in hybridized single-layer systems 14 . Regarding the use of epitaxial BN monolayers as templates, several recent reports highlight functionalities gained by the decoupling and ordering properties of BN [15][16][17][18][19] .…”