Conductance switching in a voltage-biased superconductor
Résumé
Superconductors are distinguished by the ability to conduct electricity without any resistance. Consequently, a finite electric field is incompatible with the zero resistance state. Here we devise an experiment to apply a voltage-bias across a superconducting film, in order to probe the electric-field-induced breakdown of superconductivity. It is shown that voltage-biasing leads to an extremely sharp feature of negative differential conductance (NDC) with a discontinuity in the current-voltage relation, such that the normal state appears at currents much lesser than the critical current. Alongside the conductance, the net power dissipated also undergoes a drastic reduction with increasing voltage across the superconductor-normal transition. We further observe that an electric field may induce a state with a resistance intermediate between that of superconducting and normal phases. The NDC phenomenon is useful for designing switching devices with low power consumption. We demonstrate how the device parameters can be controlled by the adjustment of an external resistor, offering a great degree of adaptability for different applications. The bistable current-voltage relation demonstrated here is promising for realizing complex non-linear networks having multiple steady state solutions, including states with symmetry-broken voltage distributions.
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