Does a ferromagnet with spin-dependent masses produce a spin-filtering effect in a ferromagnetic/insulator/superconductor junction?

Abstract

We analyze charge transport through a ballistic ferromagnet/insulator/superconductor junction by means of the Bogoliubov-de Gennes equations. We take into account the possibility that ferromagnetism in the first electrode may be driven by a mass renormalization of oppositely polarized carriers, i.e. by a spin bandwidth asymmetry, rather than by a rigid splitting of up-and down-spin electron bands as in a standard Stoner ferromagnet. By evaluating the averaged charge conductance for both an s- and a $d_{x^2-y^2}$-wave order parameter for the S side, we show that the mass mismatch in the ferromagnetic electrode may mimic a spin active barrier. Indeed, in the $s$-wave case we show that under suitable conditions the spin dependent conductance of minority carriers below the energy gap ${\Delta }_0$ can be larger than for majority carriers, and lower above ${\Delta }_0$. On the other hand, for a d_{x^2-y^2}-wave superconductor similar spin-dependent effects give rise to an asymmetric peak splitting in the conductance. These results suggest that the junction may work as a spin-filtering device.

7 pages, 5 figures

References in corpus (4)

• The BCS-like gap in superconductor SmFeAsO_0.85F_0.15
• Theory of Andreev reflection in junctions with iron-based High-$T_c$ superconductors
• Tunneling conductance in Superconductor/Ferromagnet junctions: a self consistent approach
• Proximity effect in ferromagnet-superconductor hybrid structures: role of the pairing symmetry

Cited by in corpus (4)

• Josephson effect in S/F/S junctions: spin bandwidth asymmetry vs. Stoner exchange
• Charge and spin transport through a ferromagnet/insulator/unconventional superconductor junction
• Spin and charge transport in ferromagnet-superconductor-ferromagnet heterostructures: Stoner versus spin mass mismatch mechanism
• Ferromagnetic features on zero-bias conductance peaks in ferromagnet/insulator/superconductor junction