Year: 2025
Type: article
Abstract: We investigate the Josephson diode effect in an asymmetric SQUID consisting of a sinusoidal Josephson junction formed by a ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{2}\mathrm{Se}$ 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 nonmonotonically 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.
DOI: 10.1103/zvzr-flw6
Institutions: Moscow Institute of Physics and Technology, Landau Institute for Theoretical Physics, Russian Academy of Sciences, Institute for Physics of Microstructures, National Research University Higher School of Economics, National University of Science and Technology, National University of Science and Technology, All Russia Research Institute of Automatics
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G3076473269, G4224665907
OpenAlex ID: W4414912753