2017/09/28 by Joonas T. Peltonen, Peltonen, J. T., Antti Moisio +9
Physics and Astronomy · #FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Surface and Thin Film Phenomena
paper · pdf · doi:10.48550/arxiv.1709.09832
openalex publication_date 2017/09/28 · openalex created_date 2017/10/06 · openalex updated_date 2026/07/28
We demonstrate shadow evaporation-based fabrication of high-quality ultrasmall normal metal -- insulator -- superconductor tunnel junctions where the thickness of the superconducting electrode is not limited by the requirement of small junction size. The junctions are formed between a film of manganese-doped aluminium acting as the normal conducting electrode, covered by a thicker, superconducting layer of pure Al. We characterize the junctions by sub-gap current--voltage measurements and charge pumping measurements in a gate-driven hybrid single-electron transistor, operated as a turnstile for single electrons. The technique allows to advance towards turnstiles with close to ideally thermalized superconducting reservoirs, prerequisite for reaching metrological current quantization accuracy in a hybrid turnstile. We further present an alternative way to realize small junctions with thick Al leads based on multi-angle deposition. The work enables the future investigation of turnstiles based on superconductors other than Al, and benefits various other Al tunnel junction devices for which quasiparticle thermalization is essential.