Eur. Phys. J. B 60, 281-287 (2007)
https://doi.org/10.1140/epjb/e2007-00359-0

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 zpniu@163.com

Received: 23 September 2007
Revised: 18 November 2007
Published online: 22 December 2007

Abstract

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.