MAGNETIC PROPERTIES OF JOSEPHSON JUNCTIONS WITH A SECOND HARMONIC IN THE CURRENT-PHASE RELATIONSHIP
DOI:
https://doi.org/10.32782/pet-2025-1-10Keywords:
superconducting junction, current-phase relation, critical current, magnetic fluxAbstract
The conducted research is devoted to a relevant problem in superconductivity physics, namely the study of current states in superconducting junctions that exhibit deviations from the standard sinusoidal current-phase relationship. This problem is a subject of intensive scientific research from both fundamental and applied perspectives, as the non-sinusoidal dependence can significantly affect the characteristics of Josephson junctions used in various technological applications.The main goal of the research is to establish the quantitative impact of an external magnetic field on the current-phase relationship and critical current of such junctions, considering the presence of a second harmonic.An analytical study of the influence of the anharmonicity parameter α on the critical current of the junction in the absence of an external magnetic field was performed. It was shown that with an increase in the anharmonicity parameter, the critical current increases, and this dependence is quadratic at small values of α and approaches linear at large values.The dependence of the junction’s critical current on the magnetic flux magnitude and the anharmonicity parameter α was obtained. The research results are presented as graphs of the total current versus the phase difference at different magnetic flux values, the phase at which the current maximum is achieved versus the magnetic flux, and the critical current versus the magnetic flux for different values of the anharmonicity parameter α. It was established that with an increase in the anharmonicity parameter α, the critical current becomes more sensitive to the action of an external magnetic field, especially in the region of small magnetic flux values. This manifests as a faster decrease in the critical current with an increase in the magnetic field for junctions with a non-zero value of α compared to junctions with a purely sinusoidal current-phase relationship.
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