Tunable Anomalous Andreev Reflection and Triplet Pairings in Spin Orbit Coupled Graphene

TL;DR

This paper theoretically investigates how Rashba spin-orbit interaction in graphene junctions enables tunable anomalous Andreev reflection and triplet pairings, revealing controllable spin-polarized transport phenomena.

Contribution

It introduces a model showing how RSO interaction induces equal-spin triplet pairings and anomalous Andreev reflection, which can be tuned via strain and Fermi level adjustments.

Findings

Spin-polarized subgap transport due to anomalous Andreev reflection

Direct link between Andreev reflection and triplet pairings

Experimental controllability through strain and Fermi level adjustments

Abstract

We theoretically study scattering process and superconducting triplet correlations in a graphene junction comprised of ferromagnet-RSO-superconductor in which RSO stands for a region with Rashba spin orbit interaction. Our results reveal spin-polarized subgap transport through the system due to an anomalous equal-spin Andreev reflection in addition to conventional back scatterings. We calculate equal- and opposite-spin pair correlations near the F-RSO interface and demonstrate direct link of the anomalous Andreev reflection and equal-spin pairings arised due to the proximity effect in the presence of RSO interaction. Moreover, we show that the amplitude of anomalous Andreev reflection, and thus the triplet pairings, are experimentally controllable when incorporating the influences of both tunable strain and Fermi level in the nonsuperconducting region. Our findings can be confirmed by a conductance spectroscopy experiment and provide better insights into the proximity-induced RSO coupling in graphene layers reported in recent experiments.