Phase inhomogeneity and scaling in ferromagnet-unconventional superconductor-ferromagnet double tunnel junctions

Biao Jin,1 Gang Su,1,* Qing-Rong Zheng,1 and Masuo Suzuki2

1 Department of Physics, The Graduate School of the Chinese Academy of Sciences, P.O. Box 3908, Beijing 100039, China 2 Department of Applied Physics, Faculty of Science, Science University of Tokyo, 1-3, Kagurazaki, Shinjuku-ku, Tokyo 162, Japan

Received 28 March 2003; published 3 October 2003!

Spin-dependent transport in ferromagnet-unconventional superconductor-ferromagnet double tunnel junctions is investigated. It is shown that the spin accumulation can induce the phase inhomogeneity in the central superconductor at lower temperatures when the magnetizations of both ferromagnet electrodes are antiparallel. A scaling behavior for the critical voltage where superconductivity is suppressed is uncovered for four different gap symmetries ~i.e., s, dx22y2, dx22y21i«s, and dx22y21i«dxy waves, with « the mixing parameter among different orbitals!. It is found that the gap symmetry of the central superconductor does not alter qualitatively the spintronic transport property of the tunnel junction although there are quantitative changes.

DOI: 10.1103/PhysRevB.68.144504 PACS number~s!: 73.40.Gk, 75.47.De, 73.40.Rw