2003/04/07 by V. N. Krivoruchko, Krivoruchko, V. N., E. A. Koshina +1
Physics and Astronomy · #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0304155
13 pages, 8 figures
arxiv created 2003/04/07 · arxiv updated 2009/11/30
We study the critical current of a S/F-I-N/S tunnel structure - a proximity coupled superconductor (S) with thin ferromagnetic (F) and nonmagnetic (N) metals separated by an insulating (I) barrier - in an external magnetic field. The dependence of the current on exchange and external magnetic fields, and their mutual orientation is analyzed within the microscopic theory of the proximity effect. We find that the S/F-I-N/S contact with strong magnetism of the F layer is in a ground state with superconducting phase difference on the electrodes about pi/2. Low external magnetic field reverses the critical current sign of such a contact (a π-state of the junction) for parallel field orientation. For antiparallel alignment the dc Josephson current behavior is essentially nonmonotonic: by increasing an external magnetic field the current passes though a maximum, while the 0-phase state is held, and then the junction gets into the π-phase state with an opposite current direction. We demonstrate that the hybrid S/F-I-N/S metal structures possess new effects of the superconductivity in the presence of spin splitting, while an experimental set-up seems to be feasible and it may lead to further understanding of superconducting proximity effects in ferromagnetic materials.