| Zugriffsnummer | 12969 |
| Dokumenttyp | Zeitschriftenartikel |
| Sprache | Englisch |
| Titel | The lateral proximity effect and long-range energy-gap gradients in Ta/Al and Nb/Al Josephson junctions |
| Autor(in); Institution |
Hartog den, Roland; ESA, Astrophysics Division, Noordwijk, THE NETHERLANDS
Golubov, A.; University of Twente, Enschede, THE NETHERLANDS
Martin, D.; ESA, Astrophysics Division, Noordwijk, THE NETHERLANDS
Verhoeve, P.; ESA, Astrophysics Division, Noordwijk, THE NETHERLANDS
Poelaert, A.; ESA, Astrophysics Division, Noordwijk, THE NETHERLANDS
Peacock, A.; ESA, Astrophysics Division, Noordwijk, THE NETHERLANDS
Krumrey, Michael; 7.12, Röntgenradiometrie, PTB-Berlin
|
| Quelle/Jahr | Nuclear Instruments and Methods in Physics Research A: 444 (2000), 28 - 32 |
| ISSN | 0168-9002 |
| DOI | |
| Verlag | Amsterdam: Elsevier |
| Klassifikationscode | PACS: 85.25.Cp ; PACS: 29.30.kv ; PACS: 74.50.+r ; PACS: 74.76.-W |
| Freie Schlagworte | Josephson devices ; X- and y-ray detectors ; Proximity effects ; Tunneling phenomena ; Superconducting films |
| Zusammenfassung | We present two independent experiments, each of which suggests that the local energy gap in Ta (and Nb) has a lateral spatial variation on a scale of several µm. The first experiment is a series of current-voltage characterizations of Nb/Al/AlO and Ta/Al/AlO Josephson junctions, which reveals a dependence of the measured energy gap on the size of the junction. This implies a geometrical dependence of the energy gap. An extended version of the current theory of the proximity effect could explain this phenomenon when a lateral coherence length is introduced, which is of the order of the bulk coherence length of the materials. The second experiment is a series of coincidence measurements of photon absorption events in a Ta absorber between two Fa/Al junctions. There is a clear distinction in the pulse-height characteristics between events detected in the absorber and the junctions. Interestingly, there are also events indicating the presence of a transition region between the absorber and the junction. Event statistics imply that this region has a size of 6 μm, independent of photon energy, which is quite a bit larger than even the bulk coherence length in Ta. It is argued that an additional effect due to 'smearing' by the relaxed quasi-particle cloud must also be present. These effects are interesting and intriguing; not only from a theoretical viewpoint, but also for energy-gap engineering of superconducting materials for practical applications, e.g. in a variety of photon and particle detectors. |
Zitierung
Hartog den, R., Golubov, A., Martin, D., Verhoeve, P., Poelaert, A., Peacock, A., & Krumrey, M. (2000). The lateral proximity effect and long-range energy-gap gradients in Ta/Al and Nb/Al Josephson junctions. Nuclear Instruments and Methods in Physics Research A, 444, 28–32. https://doi.org/10.1016/s0168-9002(99)01321-2