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Physical Review B 86 (2012) 064510
Geometry-related magnetic interference patterns in long S N S Josephson junctions
F. Chiodi1, M. Ferrier1, S. Gueron1, J. C. Cuevas, G. Montambaux1, F. Fortuna2, A. Kasumov1, H. Bouchiat1

We have measured the critical current dependence on the magnetic flux of two long S N S junctions differing by the normal wire geometry. The samples are made by a Au wire connected to W contacts, via focused ion beam assisted deposition. We could tune the magnetic pattern from the monotonic Gaussian-like decay of a quasi-one-dimensional (1D) normal wire to the Fraunhofer-like pattern of a square normal wire. We explain the monotonic limit with a semiclassical 1D model, and we fit both field dependencies with numerical simulations of the two-dimensional Usadel equations. Furthermore, we observe both integer and fractional Shapiro steps. The magnetic flux dependence of the integer steps reproduces as expected that of the critical current I-c, while fractional steps decay slower with the flux than I-c.
1:  LPS - Laboratoire de Physique des Solides
2:  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
Physics/Condensed Matter/Materials Science

Engineering Sciences/Materials