Phys. Rev. B 70, 144505 (2004) [5 pages]Measurement of the current-phase relation of superconductor/ferromagnet/superconductor π Josephson junctionsReceived 1 June 2004; published 13 October 2004 We present measurements of the current-phase relation (CPR) of superconductor-ferromagnet-superconductor (SFS) Josephson junctions as a function of temperature. The CPR is determined by incorporating the junction into a superconducting loop coupled to a dc SQUID, allowing measurement of the junction phase difference. We find that the critical current of Nb-Cu0.47Ni0.53-Nb Josephson junctions with barrier thickness ∼22 nm changes sign at T<Tπ∼2–4 K, indicating that the junction becomes a π Josephson junction. We find no evidence for second-order Josephson tunneling near Tπ in the CPR predicted by several theories. © 2004 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.70.144505
DOI:
10.1103/PhysRevB.70.144505
PACS:
74.50.+r
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