Graphene single electron transistor as a spin sensor for magnetic adsorbates

TL;DR

This paper investigates how the spin state of magnetic adsorbates affects the electronic transport in a graphene quantum dot, proposing it as an effective spin sensor for magnetic centers.

Contribution

It introduces a detailed model of electron transport in graphene quantum dots with magnetic adsorbates, highlighting their potential as sensitive spin detection devices.

Findings

Graphene dots can detect the spin state of magnetic adsorbates.

Transport mechanisms include tuning addition energy, tunneling rate, and magnetoresistive effects.

Graphene is optimal for sensing small numbers of magnetic centers.

Abstract

We study single electron transport through a graphene quantum dot with magnetic adsorbates. We focus on the relation between the spin order of the adsorbates and the linear conductance of the device. The electronic structure of the graphene dot with magnetic adsorbates is modeled through numerical diagonalization of a tight-binding model with an exchange potential. We consider several mechanisms by which the adsorbate magnetic state can influence transport in a single electron transistor: by tuning the addition energy, by changing the tunneling rate and, in the case of spin polarized electrodes, through magnetoresistive effects. Whereas the first mechanism is always present, the others require that the electrode has either an energy or spin dependent density of states. We find that graphene dots are optimal systems to detect the spin state of a few magnetic centers.