Mesoscopic Ferromagnet/Superconductor Junctions and the Proximity Effect

TL;DR

This study investigates electrical transport in mesoscopic ferromagnet/superconductor junctions, revealing interface-dependent effects influenced by magnetic fields, with findings fitting a modified Blonder-Tinkham-Klapwijk model.

Contribution

It provides new insights into the interface effects and temperature dependence in ferromagnet/superconductor junctions, extending the understanding of proximity effects in mesoscopic systems.

Findings

No significant proximity effect in ferromagnet alone.

Strong temperature, field, and bias dependence at the interface.

Temperature dependence fits a modified Blonder-Tinkham-Klapwijk theory.

Abstract

We have measured the electrical transport of submicron ferromagnets (Ni) in contact with a mesoscopic superconductor (Al) for a range of interface resistances. In the geometry measured, the interface and the ferromagnet are measured separately. The ferromagnet itself shows no appreciable superconducting proximity effect, but the ferromagnet/superconductor interface exhibits strong temperature, field and current bias dependences. These effects are dependent on the local magnetic field distribution near the interface arising from the ferromagnet. We find that the temperature dependences may be fit to a modified version of the Blonder-Tinkham-Klapwijk theory for normal-superconductor transport.