Conductance oscillation due to the geometrical resonance in FNS double junctions

TL;DR

This paper theoretically investigates conductance oscillations caused by geometrical resonance in ferromagnetic/nonmagnetic/superconductor double junctions, revealing how exchange fields influence the oscillation period and enabling spin polarization measurement.

Contribution

It introduces a theoretical analysis of conductance oscillations due to geometrical resonance in FNS double junctions, linking oscillation period to exchange field and spin polarization.

Findings

Conductance oscillates with bias voltage due to geometrical resonance.

The oscillation period is proportional to the square root of the exchange field.

Spin polarization can be inferred from conductance oscillation patterns.

Abstract

We theoretically analyzed the Andreev reflection in ferromagnetic metal/nonmagnetic metal/superconductor double junctions with special attention to the electron interference effect in the nonmagnetic metal layer. We showed that the conductance oscillates as a function of the bias voltage due to the geometrical resonance. We found that the exchange field, and therefore the spin polarization of the ferromagnetic metal can be determined from the period of the conductance oscillation, which is proportional to the square root of the exchange field.