Spin-polarized proximity effect in superconducting junctions

Abstract

We study spin dependent phonomena in superconducting junctions in both ballistic and diffusive regimes. For ballistic junctions we study both ferromagnet / $s$- and d-wave superconductor junctions and two dimensional electron gas / s-wave superconductor junctions with Rashba spin-orbit coupling. It is shown that the exchange field alway suppresses the conductance while the Rashba spin-orbit coupling can enhance it. In the latter part of the article we study the diffusive ferromagnet / insulator / $s$- and d-wave superconductor junctions, where the proximity effect can be enhanced by the exchange field in contrast to common belief. It is shown that the resonant proximity effect originating from the exchange field strongly influences the tunneling conductance and density of states.Comment: 14 pages, 7 figures, submitted to Comptes Rendus de l'Acadeacute;mie des Sciences (Comptes Rendus Physique) Special Issue " Magnetism and Superconductivity Coexistence". Figures 4-7 are modified in v

Charge transport in 2DEG/s-wave superconductor junction with Dresselhaus-type spin–orbit coupling

“…Quantitatively, the effect of DSOC on the conductance gets weakened as the insulating barrier becomes high. These features are similar to those by the Rashba-type SOC in 2DEG/s-wave superconductor junction [14].…”

“…We use the wave function of linear combination of eigenfunction of the Hamiltonian and boundary conditions in Refs. [13,14] when we calculate the conductance.…”

Theory of tunneling conductance in normal metal/triplet superconductor junctions without inversion symmetry

“…The wave function follows the boundary conditions in Refs. [9,10]. Applying the BTK theory to our calculation, we can calculate the conductance [9].…”

Proximity effects and finite-quasiparticle-lifetime effects in normal metal/ferromagnetic semiconductor/superconductor structures

“…Andreev reflection (AR) [2] process plays an important role in the proximity effect. Proximity effects in ferromagnet (FM)/SC structures have recently attracted much attention in experimental and theoretical investigations [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The electron (hole) and the AR hole (electron) in FM have opposite spins and different Fermi momentum, interference between their wave functions causes the induced superconducting order parameter F(x) [21] to have a damped oscillation [22,23].…”