Nonlocal Andreev Entanglements and Triplet Correlations in Graphene with Spin Orbit Coupling

TL;DR

This paper demonstrates how tunable Fermi levels and Rashba spin orbit coupling in graphene enable nonlocal Andreev reflection and equal spin triplet pairing, with potential applications in detecting entanglement in hybrid structures.

Contribution

It introduces a method to generate and analyze nonlocal Andreev reflection and triplet correlations in graphene with spin orbit coupling, revealing their relation and experimental signatures.

Findings

Anomalous nonlocal Andreev reflection occurs with tunable Fermi levels.

Equal spin triplet pairing is linked to crossed Andreev reflection.

Negative charge conductance observed at weak voltages.

Abstract

Using a wavefunction Dirac Bogoliubov-de Gennes method, we demonstrate that the tunable Fermi level of a graphene layer in the presence of Rashba spin orbit coupling (RSOC) allows for producing an anomalous nonlocal Andreev reflection and equal spin superconducting triplet pairing. We consider a graphene junction of a ferromagnet-RSOC-superconductor-ferromagnet configuration and study scattering processes, the appearance of spin triplet correlations, and charge conductance in this structure. We show that the anomalous crossed Andreev reflection is linked to the equal spin triplet pairing. Moreover, by calculating current cross-correlations, our results reveal that this phenomenon causes negative charge conductance at weak voltages and can be revealed in a spectroscopy experiment, and may provide a tool for detecting the entanglement of the equal spin superconducting pair correlations in hybrid structures.