Skip to content

Measurement of the Current-Phase Relation of SFS pi-Josephson junctions

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

cond-mat.supr-conarXiv:cond-mat/0402434

Abstract

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. Junctions fabricated with a thin (~ 22 nm) barrier of Cu0.47Ni0.53 sandwiched between Nb electrodes exhibit a re-entrant critical current with temperature, vanishing at T =Tpi ~ 2-4 K. We find that the critical current is negative for T < Tpi, indicating that the junction is a pi-Josephson junction. We find no evidence for second-order Josephson tunneling near Tpi in the CPR predicted by several theories.

Create a lesson