Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms
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SuperNanoLab, School of Science and Technology, Physics Division, University of Camerino, via Madonna delle Carceri 9, 62032 Camerino, Italy
2
Istituto Nazionale di Ricerca Metrologica (INRiM), Strada delle Cacce 91, 10135 Torino, Italy
3
IOM-CNR Lab TASC Area Science Park, Basovizza Building MM, SS. 14, 34149 Trieste, Italy
4
SuperNanoLab, School of Pharmacy, Physics Unit, University of Camerino, via Madonna delle Carceri 9, 62032 Camerino, Italy
5
Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
*
Authors to whom correspondence should be addressed.
†
Current address: INFN—Laboratori Nazionali di Frascati, Via Enrico Fermi, Frascati, 40, 00044 Roma, Italy.
Condens. Matter 2019, 4(1), 4; https://doi.org/10.3390/condmat4010004
Received: 18 November 2018 / Revised: 21 December 2018 / Accepted: 26 December 2018 / Published: 30 December 2018
(This article belongs to the Special Issue Selected Papers from Quantum Complex Matter 2018)
Structural and superconducting properties of high-quality niobium nanofilms with different thicknesses are investigated on silicon oxide (SiO2) and sapphire substrates. The role played by the different substrates and the superconducting properties of the Nb films are discussed based on the defectivity of the films and on the presence of an interfacial oxide layer between the Nb film and the substrate. The X-ray absorption spectroscopy is employed to uncover the structure of the interfacial layer. We show that this interfacial layer leads to a strong proximity effect, especially in films deposited on a SiO2 substrate, altering the superconducting properties of the Nb films. Our results establish that the critical temperature is determined by an interplay between quantum-size effects, due to the reduction of the Nb film thicknesses, and proximity effects. The detailed investigation here provides reference characterizations and has direct and important implications for the fabrication of superconducting devices based on Nb nanofilms.
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MDPI and ACS Style
Rezvani, S.J.; Perali, A.; Fretto, M.; De Leo, N.; Flammia, L.; Milošević, M.; Nannarone, S.; Pinto, N. Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms. Condens. Matter 2019, 4, 4.
AMA Style
Rezvani SJ, Perali A, Fretto M, De Leo N, Flammia L, Milošević M, Nannarone S, Pinto N. Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms. Condensed Matter. 2019; 4(1):4.
Chicago/Turabian StyleRezvani, S.J.; Perali, Andrea; Fretto, Matteo; De Leo, Natascia; Flammia, Luca; Milošević, Milorad; Nannarone, Stefano; Pinto, Nicola. 2019. "Substrate-Induced Proximity Effect in Superconducting Niobium Nanofilms" Condens. Matter 4, no. 1: 4.
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