2006/05/31 by Z. Pajovic, M. Bozovic, Z. Radovic +2
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.74.184509
7 pages, 8 figures
arxiv created 2006/07/31 · arxiv updated 2009/12/01
We study the Josephson effect in clean heterojunctions that consist of superconductors connected through two metallic ferromagnets with insulating interfaces. We solve the scattering problem based on the Bogoliubov--de Gennes equation for any relative orientation of in-plane magnetizations, arbitrary transparency of interfaces, and mismatch of Fermi wave vectors. Both spin singlet and triplet superconducting correlations are taken into account, and the Josephson current is calculated as a function of the ferromagnetic layers thicknesses and of the angle α between their magnetizations. We find that the critical Josephson current Ic is a monotonic function of α when the junction is far enough from 0-π transitions. This holds when ferromagnets are relatively weak. For stronger ferromagnets, variation of α induces switching between 0 and π states and Ic(α) is non-monotonic function, displaying characteristic dips at the transitions. However, the non-monotonicity is the effect of a weaker influence of the exchange potential in the case of non-parallel magnetizations. No substantial impact of spin-triplet superconducting correlations on the Josephson current has been found in the clean limit. Experimental control of the critical current and 0-π transitions by varying the angle between magnetizations is suggested.