Unusual critical currents in quasi-one-dimensional superconducting aluminum two-width structures in a magnetic field
V. I. Kuznetsov, O. V. Trofimov
TLDR
This paper reports unusual critical currents in quasi-one-dimensional aluminum superconducting structures that challenge existing theoretical descriptions.
Key contributions
- Measured critical currents in quasi-1D aluminum two-width superconducting structures.
- Found experimental critical switching current is nonlocal, dependent on the junction area.
- Observed radical differences between experimental and Ginzburg-Landau calculated switching currents.
- Detected nonzero switching current in magnetic fields exceeding the maximum critical field.
Why it matters
This research uncovers unexpected superconducting behavior in aluminum two-width structures. The observed nonlocal critical currents and their persistence in high magnetic fields challenge established Ginzburg-Landau theory. These findings highlight gaps in our understanding of superconductivity in complex geometries, paving the way for new theoretical models.
Original Abstract
We measured unusual critical currents as functions of temperature in the zero field and as functions of a magnetic field perpendicular to the substrate surface at a given temperature close to the critical temperature in thin-film long quasi-one-dimensional superconducting aluminum two-width structures consisting of narrow and wide wires with different critical temperatures. It is found that the experimental critical switching current as a function of the field at a given temperature, determined by the appearance of a dc voltage on a short section of the structure, is nonlocal (dependent on electron transport in the area containing the junction line between the narrow and wide wires). When current flows through the narrow and wide wires of the structure, the switching currents, experimental and calculated within the framework of the Ginzburg-Landau theory, differ radically from each other. A nonzero switching current exists in high fields greater than the maximum critical magnetic field in a quasi-one-dimensional superconducting wire. In the aluminum two-width structures studied here, the unusual measured switching current challenges description by known theories.
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