Ferromagnet-superconductor proximity effect: The clean limit

Abstract

We study theoretically the influence of ferromagnetic metals on a superconducting film in the clean limit. Using a self-consistent solution of the Bogoliubov-de Gennes equation for a ferromagnetsuperconductor-ferromagnet double junction we calculate the pair potential and conductance spectra as a function of the superconducting layer thickness d for different strengths of ferromagnets and interface transparencies. We find that the pair potential and the critical temperature are weakly perturbed by the exchange interaction and do not drop to zero for any finite d. On the other hand, for thin superconducting films charge transport is spin polarized and exhibits a significant dependence on the ferromagnetic strength and magnetization alignment.

Ballistic transport in ferromagnet–superconductor–ferromagnet trilayers with arbitrary orientation of magnetisations

“…In Ref. 39 the averaged self-consistent pair potential is calculated and can be used instead of the bulk value. Fully selfconsistent numerical calculations have been performed recently for FSF 12,40 and NS 41 geometries (here N stands for a normal non-magnetic metal).…”

“…For thin S layers, d s k F 10 3 , the bulk value ∆ 0 is replaced by the averaged self-consistent pair potential, calculated in Ref. 39. The spin-polarized subgap transmission of quasiparticles, and consequently a strong suppression of the Andreev reflection, are significant in junctions with thin S films, whereas the conductance oscillations above the gap be- come pronounced as d s is increased.…”

Crossover between short and long range proximity effects in SFS junctions with Ni-based ferromagnets

“…A competition between superconductivity and ferromagnetism leads to an unconventional proximity effect, studied both theoretically [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and experimentally . In strong ferromagnets (F) Fe, Co, Ni, exchange energies, E ex ∼ 1000 K, are much larger than the energy gap, ∆ ∼ 1 − 10 K, in low-T c superconductors (S).…”

Triplet superconductivity and proximity effect induced by Bloch and Néel domain walls

“…On the theoretical side, equal-spin spin-triplet pairing correlations have been investigated using Green's function techniques based on solutions of the Usadel equations [12,14,15,21], and self-consistent solutions of the Bogoliubov−de Gennes (BdG) equations [16,17]. While the Green's function techniques allow for an easier inclusion of scattering effects describing a shorter electron mean free path in the diffusive limit, these effects can in principle be incorporated into the BdG equations as well via additional impurity scattering potentials.…”