Josephson diode effects in twisted nodal superconductors
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arXiv
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2023
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| _version_ | 1866910426828111872 |
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| author | Volkov, Pavel A. Lantagne-Hurtubise, Étienne Tummuru, Tarun Plugge, Stephan Pixley, J. H. Franz, Marcel |
| author_facet | Volkov, Pavel A. Lantagne-Hurtubise, Étienne Tummuru, Tarun Plugge, Stephan Pixley, J. H. Franz, Marcel |
| contents | Recent Josephson tunneling experiments on twisted flakes of high-$T_c$ cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ revealed a non-reciprocal behavior of the critical interlayer Josephson current - i.e., a Josephson diode effect. Motivated by these findings we study theoretically the emergence of the Josephson diode effect in twisted interfaces between nodal superconductors, and highlight a strong dependence on the twist angle $θ$ and damping of the junction. In all cases, the theory predicts diode efficiency that vanishes exactly at $θ= 45^\circ$ and has a strong peak at a twist angle close to $θ= 45^\circ$, consistent with experimental observations. Near $45^\circ$, the junction breaks time-reversal symmetry ${\cal T}$ spontaneously. We find that for underdamped junctions showing hysteretic behavior, this results in a \emph{dynamical} Josephson diode effect in a part of the ${\cal T}$-broken phase. The direction of the diode is trainable in this case by sweeping the external current bias. This effect provides a sensitive probe of spontaneous ${\cal T}$-breaking. We then show that explicit ${\cal T}$-breaking perturbations with the symmetry of a magnetic field perpendicular to the junction plane lead to a {\em thermodynamic} diode effect that survives even in the overdamped limit. We discuss an experimental protocol to probe the double-well structure in the Josephson free energy that underlies the tendency towards spontaneous ${\cal T}$-breaking even if ${\cal T}$ is broken explicitly. Finally, we show that in-plane magnetic fields can control the diode effect in the short junction limit, and predict the signatures of explicit ${\cal T}$-breaking in Shapiro steps. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2307_01261 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Josephson diode effects in twisted nodal superconductors Volkov, Pavel A. Lantagne-Hurtubise, Étienne Tummuru, Tarun Plugge, Stephan Pixley, J. H. Franz, Marcel Superconductivity Mesoscale and Nanoscale Physics Strongly Correlated Electrons Recent Josephson tunneling experiments on twisted flakes of high-$T_c$ cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ revealed a non-reciprocal behavior of the critical interlayer Josephson current - i.e., a Josephson diode effect. Motivated by these findings we study theoretically the emergence of the Josephson diode effect in twisted interfaces between nodal superconductors, and highlight a strong dependence on the twist angle $θ$ and damping of the junction. In all cases, the theory predicts diode efficiency that vanishes exactly at $θ= 45^\circ$ and has a strong peak at a twist angle close to $θ= 45^\circ$, consistent with experimental observations. Near $45^\circ$, the junction breaks time-reversal symmetry ${\cal T}$ spontaneously. We find that for underdamped junctions showing hysteretic behavior, this results in a \emph{dynamical} Josephson diode effect in a part of the ${\cal T}$-broken phase. The direction of the diode is trainable in this case by sweeping the external current bias. This effect provides a sensitive probe of spontaneous ${\cal T}$-breaking. We then show that explicit ${\cal T}$-breaking perturbations with the symmetry of a magnetic field perpendicular to the junction plane lead to a {\em thermodynamic} diode effect that survives even in the overdamped limit. We discuss an experimental protocol to probe the double-well structure in the Josephson free energy that underlies the tendency towards spontaneous ${\cal T}$-breaking even if ${\cal T}$ is broken explicitly. Finally, we show that in-plane magnetic fields can control the diode effect in the short junction limit, and predict the signatures of explicit ${\cal T}$-breaking in Shapiro steps. |
| title | Josephson diode effects in twisted nodal superconductors |
| topic | Superconductivity Mesoscale and Nanoscale Physics Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2307.01261 |