Perturbative Analysis of the Field-Free Josephson Diode Effect in a Multilayered Josephson Junction

Fuente: arXiv
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Autor principal: Hikino, Shin-ichi
Formato: Preprint
Publicado: 2025
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author Hikino, Shin-ichi
author_facet Hikino, Shin-ichi
contents The Josephson diode effect (JDE) is a novel phenomenon in which a superconducting junction exhibits asymmetric Josephson currents with respect to the superconducting phase difference. In this study, we theoretically investigate how the interplay between a static exchange field and Rashba spin-orbit interaction (RSOI) influences the JDE. By employing the quasiclassical Green's function method and perturbative calculations, we derive analytical expressions for the Josephson current in a junction composed of a ferromagnetic layer and a normal metal with RSOI. Remarkably, the JDE is found to emerge even in the absence of any external magnetic field. In this regime, the Josephson current is exclusively carried by spin-triplet Cooper pairs, as spin-singlet components are strongly suppressed by the ferromagnet. Furthermore, our results show that the efficiency of the JDE can be enhanced by tuning the thickness of the normal metal and the strength of the RSOI. These findings offer valuable theoretical guidelines for the design of superconducting devices exhibiting nonreciprocal transport effects.
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Perturbative Analysis of the Field-Free Josephson Diode Effect in a Multilayered Josephson Junction
Hikino, Shin-ichi
Superconductivity
Mesoscale and Nanoscale Physics
The Josephson diode effect (JDE) is a novel phenomenon in which a superconducting junction exhibits asymmetric Josephson currents with respect to the superconducting phase difference. In this study, we theoretically investigate how the interplay between a static exchange field and Rashba spin-orbit interaction (RSOI) influences the JDE. By employing the quasiclassical Green's function method and perturbative calculations, we derive analytical expressions for the Josephson current in a junction composed of a ferromagnetic layer and a normal metal with RSOI. Remarkably, the JDE is found to emerge even in the absence of any external magnetic field. In this regime, the Josephson current is exclusively carried by spin-triplet Cooper pairs, as spin-singlet components are strongly suppressed by the ferromagnet. Furthermore, our results show that the efficiency of the JDE can be enhanced by tuning the thickness of the normal metal and the strength of the RSOI. These findings offer valuable theoretical guidelines for the design of superconducting devices exhibiting nonreciprocal transport effects.
title Perturbative Analysis of the Field-Free Josephson Diode Effect in a Multilayered Josephson Junction
topic Superconductivity
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2507.20595