Spin-controlled superconductivity and tunable triplet correlations in graphene nanostructures

TL;DR

This paper demonstrates how spin-controlled superconductivity and tunable triplet correlations can be achieved in graphene nanostructures, enabling a graphene-based spin-triplet valve through proximity effects and parameter tuning.

Contribution

It introduces a microscopic self-consistent approach to control superconductivity and triplet correlations in graphene F/S/F nanostructures by tuning Fermi level and exchange field orientation.

Findings

Spin switching phenomena can be controlled by tuning Fermi level or exchange field angle.

Superconductivity can be turned on or off via spin or Fermi level adjustments.

Induced triplet correlations are tunable, enabling a spin-triplet valve.

Abstract

We study graphene ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures via a microscopic self-consistent Dirac Bogoliubov-de Gennes formalism. We show that as a result of proximity effects, experimentally accessible spin switching phenomena can occur as one tunes the Fermi level $\mu_F$ of the F regions or varies the angle $\theta$ between exchange field orientations. Superconductivity can then be switched on and off by varying either $\theta$ or $\mu_F$ (a spin-controlled superconducting graphene switch). The induced equal-spin triplet correlations in S can be controlled by tuning $\mu_F$, effectively making a graphene based two-dimensional spin-triplet valve.