Sub-gap conductance in ferromagnetic-superconducting mesoscopic structures

TL;DR

This paper investigates how sub-gap conductance in ferromagnetic mesoscopic structures is affected by tunnel junction resistance ratios and exchange fields, revealing peak splitting and shifts in conductance features.

Contribution

It demonstrates the impact of exchange fields on sub-gap conductance behavior, including peak splitting and shifting in ferromagnetic-superconducting mesoscopic systems.

Findings

Peak splitting occurs due to exchange fields at low resistance ratios.

Zero-bias conductance peaks shift to finite voltages with exchange fields.

Conductance behavior depends critically on the ratio of tunnel junction resistances.

Abstract

We study the sub-gap conductance of a ferromagnetic mesoscopic region attached to a ferromagnetic and a superconducting electrode by means of tunnel junctions. In the absence of the exchange field, the ratio $r= \gamma / \epsilon_T$ of the two tunnel junction resistances determines the behaviour of the sub-gap conductance which possesses a zero-bias peak for $r\gg 1$ and for $r\ll 1$ a peak at finite voltage. We show that the inclusion of the exchange field leads to a peak splitting for $r\ll 1$, while it shifts the zero-bias anomaly to finite voltages for $r\gg 1$.