Josephson interferometry and Shapiro step measurements of superconductor-ferromagnet-superconductor 0-π junctions

S. M. Frolov, D. J. Van Harlingen, V. V. Bolginov, V. A. Oboznov, V. V. Ryazanov

Research output: Contribution to journalArticle

Abstract

We report the observation of the 0-π junction state in superconductor-ferromagnet-superconductor Josephson junctions arising from variations in the effective barrier thickness d ξF. By varying the temperature, the junctions can be tuned from the 0- to the π -state through an intermediate regime in which parts of the junction are in each state. A signature of the 0-π regime is that the usual peak in the critical current diffraction pattern at zero magnetic field becomes a dip, evidence for sign changes in the critical current density. In some junctions, the zero-field critical current does not vanish at any temperature and half-integer Shapiro steps are observed, indicating the presence of spontaneous supercurrents circulating within the junctions around the 0-π interfaces.

Original languageEnglish (US)
Article number020503
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume74
Issue number2
DOIs
StatePublished - Jul 24 2006

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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