Abstract
We use microwave excitation to elucidate the dynamics of long superconductor–normal metal–superconductor Josephson junctions. By varying the excitation frequency in the range 10 MHz–40 GHz, we observe that the critical and retrapping currents, deduced from the dc voltage versus dc current characteristics of the junction, are set by two different time scales. The critical current increases when the ac frequency is larger than the inverse diffusion time in the normal metal, whereas the retrapping current is strongly modified when the excitation frequency is above the electron-phonon rate in the normal metal. Therefore the critical and retrapping currents are associated with elastic and inelastic scattering, respectively.
- Received 13 August 2009
DOI:https://doi.org/10.1103/PhysRevLett.103.177002
©2009 American Physical Society
Synopsis
Supercurrents in a junction—it’s all about the timing
Published 26 October 2009
Microwave-frequency excitation of a superconductor-metal-superconductor junction is used to resolve the dynamic mechanisms behind the temporal response.
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