Atomic layer superconductivity.
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| Title: | Atomic layer superconductivity. |
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| Authors: | Stępniak, Agnieszka1, Leon Vanegas, Augusto1,2, Caminale, Michael1, Oka, Hirofumi1, Sander, Dirk1, Kirschner, Jürgen1,2 |
| Source: | Surface & Interface Analysis: SIA. Dec2014, Vol. 46 Issue 12/13, p1262-1267. 6p. |
| Subjects: | Superconductivity, Scanning tunneling microscopy, Proximity effect (Superconductivity), Silicon, Lead, Silver, Spectrum analysis |
| Abstract: | We present scanning tunneling microscopy (STM) studies of superconductivity of single layer Pb and Pb islands on Si(111). We perform temperature-dependent measurements of the differential conductance from 0.38 to 4 K in fields of up to 6 T to extract the critical temperature TC for the onset of superconductivity. We find TC = 1.5 K for a single layer Pb on Si(111), and a critical out-of-plane field of 150 mT. This deviates from bulk Pb, where TC = 7.2 K and HC = 80 mT are reported. Our results provide the temperature dependence of the superconducting gap 2 Δ. A description of this dependence in the framework of the Bardeen-Cooper-Schrieffer theory indicates an energy gap of 2 Δ0 = 0.7 meV, considerably less than the 2.7 meV found for bulk Pb. We observe that the insertion of a single layer Ag between Pb and Si suppresses superconductivity in the Pb film even at the lowest temperature of 0.38 K. Pb islands on Ag/Si(111) exhibit superconductivity. Our position-dependent STM studies from a nine-layer tall Pb island into the surrounding non-superconducting Pb wetting layer on Ag/Si(111) reveal an extension of a superconducting gap in spectroscopy up to 20 nm away from the Pb island edge at 0.38 K. © 2014 The Authors Surface and Interface Analysis Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | We present scanning tunneling microscopy (STM) studies of superconductivity of single layer Pb and Pb islands on Si(111). We perform temperature-dependent measurements of the differential conductance from 0.38 to 4 K in fields of up to 6 T to extract the critical temperature TC for the onset of superconductivity. We find TC = 1.5 K for a single layer Pb on Si(111), and a critical out-of-plane field of 150 mT. This deviates from bulk Pb, where TC = 7.2 K and HC = 80 mT are reported. Our results provide the temperature dependence of the superconducting gap 2 Δ. A description of this dependence in the framework of the Bardeen-Cooper-Schrieffer theory indicates an energy gap of 2 Δ0 = 0.7 meV, considerably less than the 2.7 meV found for bulk Pb. We observe that the insertion of a single layer Ag between Pb and Si suppresses superconductivity in the Pb film even at the lowest temperature of 0.38 K. Pb islands on Ag/Si(111) exhibit superconductivity. Our position-dependent STM studies from a nine-layer tall Pb island into the surrounding non-superconducting Pb wetting layer on Ag/Si(111) reveal an extension of a superconducting gap in spectroscopy up to 20 nm away from the Pb island edge at 0.38 K. © 2014 The Authors Surface and Interface Analysis Published by John Wiley & Sons Ltd. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 01422421 |
| DOI: | 10.1002/sia.5516 |
