title: Longitudinal proximity effects in superconducting transition-edge sensors.
abstract: We have found experimentally that the critical current of a square thin-film superconducting transition-edge sensor (TES) depends exponentially upon the side length L and the square root of the temperature T, a behavior that has a natural theoretical explanation in terms of longitudinal proximity effects if the TES is regarded as a weak link between superconducting leads. As a consequence, the effective transition temperature T{c} of the TES is current dependent and at fixed current scales as 1/L{2}. We have also found that the critical current can show clear Fraunhofer-like oscillations in an applied magnetic field, similar to those found in Josephson junctions. We have observed the longitudinal proximity effect in these devices over extraordinarily long lengths up to 290 microm, 1450 times the mean-free path.
authors.affiliation: Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801-3080, USA. john.e.sadleir@nasa.gov
authors.forename: John E
authors.initials: JE
authors.lastname: Sadleir
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Smith
authors.forename: Simon R
authors.initials: SR
authors.lastname: Bandler
authors.forename: James A
authors.initials: JA
authors.lastname: Chervenak
authors.forename: John R
authors.initials: JR
authors.lastname: Clem