Diode effect in Shapiro steps in an asymmetric SQUID with a superconducting nanobridge

Fuente: arXiv
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Main Authors: Kalashnikov, Dmitrii S., Seleznev, Gleb S., Kudriashov, Andrei, Babich, Ian, Vodolazov, Denis Yu., Fominov, Yakov V., Stolyarov, Vasily S.
Format: Preprint
Published: 2025
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author Kalashnikov, Dmitrii S.
Seleznev, Gleb S.
Kudriashov, Andrei
Babich, Ian
Vodolazov, Denis Yu.
Fominov, Yakov V.
Stolyarov, Vasily S.
author_facet Kalashnikov, Dmitrii S.
Seleznev, Gleb S.
Kudriashov, Andrei
Babich, Ian
Vodolazov, Denis Yu.
Fominov, Yakov V.
Stolyarov, Vasily S.
contents We investigate the Josephson diode effect in an asymmetric SQUID consisting of a sinusoidal Josephson junction formed by a Bi$_2$Te$_2$Se flake and a superconducting Nb nanobridge with a linear and multivalued current-phase relation (CPR). Current-voltage characteristics were measured both in the absence (dc regime) and presence (ac regime) of external microwave irradiation. Our dc measurements reveal only weak critical current asymmetry (i.e. weak Josephson diode effect), while confirming the multivalued behavior of the SQUID. At the same time, the key finding of this work is the observation of strong Shapiro step asymmetry (concerning the dc current direction) in the ac regime at finite magnetic flux. This peculiarity oscillates as a function of magnetic field with the SQUID's periodicity and varies non-monotonically with the increase in microwave power. Our theoretical model shows that the pronounced Shapiro step asymmetry, despite the small diode effect in critical current, arises from the interplay between the sinusoidal and multivalued CPRs of the junctions.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15526
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Diode effect in Shapiro steps in an asymmetric SQUID with a superconducting nanobridge
Kalashnikov, Dmitrii S.
Seleznev, Gleb S.
Kudriashov, Andrei
Babich, Ian
Vodolazov, Denis Yu.
Fominov, Yakov V.
Stolyarov, Vasily S.
Superconductivity
We investigate the Josephson diode effect in an asymmetric SQUID consisting of a sinusoidal Josephson junction formed by a Bi$_2$Te$_2$Se flake and a superconducting Nb nanobridge with a linear and multivalued current-phase relation (CPR). Current-voltage characteristics were measured both in the absence (dc regime) and presence (ac regime) of external microwave irradiation. Our dc measurements reveal only weak critical current asymmetry (i.e. weak Josephson diode effect), while confirming the multivalued behavior of the SQUID. At the same time, the key finding of this work is the observation of strong Shapiro step asymmetry (concerning the dc current direction) in the ac regime at finite magnetic flux. This peculiarity oscillates as a function of magnetic field with the SQUID's periodicity and varies non-monotonically with the increase in microwave power. Our theoretical model shows that the pronounced Shapiro step asymmetry, despite the small diode effect in critical current, arises from the interplay between the sinusoidal and multivalued CPRs of the junctions.
title Diode effect in Shapiro steps in an asymmetric SQUID with a superconducting nanobridge
topic Superconductivity
url https://arxiv.org/abs/2510.15526