p – 0 Transition in Superconductor - Ferromagnet - Superconductor Junctions 1

Superconductor–ferromagnet–superconductor (SFS) Josephson junctions are known to exhibit a transition between π and 0 states. In this letter, we find the π–0 phase diagram of an SFS junction depending on the transparency of an intermediate insulating layer (I). We show that, in general, the Josephson critical current is nonzero at the π–0 transition temperature. Contributions to the current from the two spin channels nearly compensate each other, and the first harmonic of the Josephson current as a function of phase difference is suppressed. However, higher harmonics give a nonzero contribution to the supercurrent. © 2001 MAIK “Nauka/Interperiodica”.