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arXiv · 2307.15386

Nonreciprocal charge transport and subharmonic structure in voltage-biased Josephson diodes

A. Zazunov·J. Rech·T. Jonckheere·B. Grémaud·T. Martin·R. Egger
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Abstract

We study charge transport in voltage-biased single-channel junctions involving helical superconductors with finite Cooper pair momentum. For a Josephson junction, the equilibrium current-phase relation shows a superconducting diode effect: the critical current depends on the propagation direction. We formulate a scattering theory for voltage-biased Josephson diodes and show that multiple Andreev reflection processes cause a rich subharmonic structure in the DC current-voltage curve at low temperatures and small voltages due to Doppler shifts of the spectral gap. In the current-biased case, the diode efficiency has maximal rectification efficiency $\eta_0\approx 0.4$ for this model. In the voltage-biased case, however, the rectification efficiency can reach the ideal value $\eta=1$. We also discuss charge transport for NS junctions between a normal metal and a helical superconductor and comment on related models with spin-orbit interactions and magnetic Zeeman fields.

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A. Zazunov, J. Rech, T. Jonckheere, B. Grémaud, T. Martin, R. Egger. 2023-07-28. Nonreciprocal charge transport and subharmonic structure in voltage-biased Josephson diodes. https://doi.org/10.1103/physrevb.109.024504

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