Current-induced SQUID behavior of superconducting Nb nano-rings

Omri J. Sharon, Avner Shaulov, Jorge Berger, Amos Sharoni, Yosef Yeshurun

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The critical temperature in a superconducting ring changes periodically with the magnetic flux threading it, giving rise to the well-known Little-Parks magnetoresistance oscillations. Periodic changes of the critical current in a superconducting quantum interference device (SQUID), consisting of two Josephson junctions in a ring, lead to a different type of magnetoresistance oscillations utilized in detecting extremely small changes in magnetic fields. Here we demonstrate current-induced switching between Little-Parks and SQUID magnetoresistance oscillations in a superconducting nano-ring without Josephson junctions. Our measurements in Nb nano-rings show that as the bias current increases, the parabolic Little-Parks magnetoresistance oscillations become sinusoidal and eventually transform into oscillations typical of a SQUID. We associate this phenomenon with the flux-induced non-uniformity of the order parameter along a superconducting nano-ring, arising from the superconducting leads ('arms') attached to it. Current enhanced phase slip rates at the points with minimal order parameter create effective Josephson junctions in the ring, switching it into a SQUID.

Original languageEnglish
Article number28320
JournalScientific Reports
Volume6
DOIs
StatePublished - 20 Jun 2016

Bibliographical note

Funding Information:
This research was supported by a Grant from the GIF, the German-Israeli Foundation for Scientific Research and Development.

Funding

This research was supported by a Grant from the GIF, the German-Israeli Foundation for Scientific Research and Development.

FundersFunder number
German-Israeli Foundation for Scientific Research and Development

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