Anomalous polarization-dependent transport in nanoscale double-barrier superconductor/ferromagnet/superconductor junctions

TL;DR

This paper investigates the unique polarization-dependent transport phenomena in nanoscale superconductor/ferromagnet/superconductor junctions, revealing unexpected resistance behaviors influenced by magnetic alignment and interface effects.

Contribution

It introduces a spin-dependent interface scattering model to explain anomalous resistance behavior in SFFS junctions, highlighting the impact of magnetic configuration on transport.

Findings

Resistance shows re-entrant behavior with temperature.

Antiparallel magnetization yields higher resistance than parallel at low temperatures.

Transport properties are highly sensitive to interfacial parameters.

Abstract

We study the transport properties of nanoscale superconducting (S) devices in which two superconducting electrodes are bridged by two parallel ferromagnetic (F) wires, forming an SFFS junction with a separation between the two wires less than the superconducting coherence length. This allows crossed Andreev reflection to take place. We find that the resistance as a function of temperature exhibits behavior reminiscent of the re-entrant effect and, at low temperatures and excitation energies below the superconducting gap, the resistance corresponding to antiparallel alignment of the magnetization of the ferromagnetic wires is higher than that of parallel alignment, in contrast to the behavior expected from crossed Andreev reflection. We present a model based on spin-dependent interface scattering that explains this surprising result and demonstrates the sensitivity of the junction transport properties to interfacial parameters.