Nonequilibrium Phenomena in Mesoscopic SNS Josephson Junctions
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Date: 10-19-2005
Start Time:
4:00pm
End Time: 5:00pm
Speaker: Norman O. Birge
From:
Michigan State University
Location: Interschool lab - 7th floor - CEPSR
Hosted by:
Center for Integrated Science
Abstract:
Mesoscopic S/N/S Josephson junctions exhibit several intriguing phenomena when driven out of equilibrium. This talk will focus on three experiments in 3-terminal S/N/S devices, in which quasiparticle current is injected into the middle of the junction from a normal (N) reservoir. 1) If one of the superconducting contacts is left floating, the I-V curve measured between the other S contact and the N contact exhibits a change of slope at a critical current, demonstrating coexistence of quasiparticle current and supercurrent in the sample. 2) Pushing the system further from equilibrium reverses the sign of the current-phase relationship in the SNS Josephson junction, creating a controllable "pi" junction. 3) Injection of both quasiparticle current and supercurrent generates a spatial gradient in the effective electron temperature along the junction, whose direction is controllable by the supercurrent. We visualize this effect using tunneling spectroscopy to measure the local electron energy distribution function.