Triplet pairing states with equal spins in ferromagnet/superconductor heterojunctions for noncollinear magnetizations
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
Corresponding author: a email@example.com
Revised: 18 November 2007
Published online: 22 December 2007
Four-component Bogoliubov-de Gennes equations are applied to study tunneling conductance spectra of ferromagnet/ferromagnet/d-wave superconductor (F1/F2/d-wave S) tunnel junctions and to find out signs of spin-triplet pairing correlations induced in the proximity structure. The pairing correlations with equal spins arises from the novel Andreev reflection (AR), which requires at least three factors: the usual AR at the F2/S interface, spin flip in the F2 layer, and superconducting coherence kept up in the F2 layer. Effects of angle α between magnetizations of the two F layers, polarizations of the F1 and F2 layers, the thickness of the F2 layer, and the orientation of the d-wave S crystal on the tunneling conductance are investigated. A conversion from a zero-bias conductance dip at α = 0 to a zero-bias conductance peak at a certain value of α can be seen as a sign of generated spin-triplet correlations.
PACS: 74.45.+c – Proximity effects; Andreev effect; SN and SNS junctions / 74.50.+r – Tunneling phenomena; point contacts, weak links, Josephson effects / 72.25.-b – Spin polarized transport
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007