Resonant transmission of normal electrons through Andreev states in ferromagnets

TL;DR

This paper predicts giant conductance oscillations in superconductor-ferromagnet-superconductor devices caused by resonant transmission through Andreev levels, enabling spectroscopy of these states.

Contribution

It introduces the concept of resonant transmission of normal electrons through Andreev states in ferromagnets and predicts giant conductance oscillations.

Findings

Giant oscillations of conductance are predicted.

Resonant transmission occurs near voltage 2h_0/e.

Bias voltage and phase difference affect conductance.

Abstract

Giant oscillations of the conductance of a superconductor - ferromagnet - superconductor Andreev interferometer are predicted. The effect is due to the resonant transmission of normal electrons through Andreev levels when the voltage $V$ applied to the ferromagnet is close to $2h_0/e$ ($h_0$ is the spin-dependant part of the electron energy). The effect of bias voltage and phase difference between the superconductors on the current and the differential conductance is presented. These efects allow a direct spectroscopy of Andreev levels in the ferromagnet.