Asymmetric Coulomb Oscillation and Giant Anisotropic Magnetoresistance in Doped Graphene Nanojunctions

TL;DR

This paper investigates charge transport in doped graphene nanojunctions, revealing asymmetric Coulomb oscillations and giant anisotropic magnetoresistance, with potential applications in nanoscale spintronic logic devices.

Contribution

It demonstrates how substitutional doping of transition metals in graphene nanodots induces spin filtering and giant magnetoresistance, advancing spintronic device design.

Findings

Substitutional doping yields spin filtering with 700% magnetoresistance.

Doped nanodots exhibit asymmetric Coulomb oscillations.

Electric field strength increases with doping and reduced gap.

Abstract

We report here the charge transport behavior in graphene nanojunctions in which graphene nanodots, with relatively long relaxation time, are interfaced with ferromagnetic electrodes. Subsequently we explore the effect of substitutional doping of transition metal atoms in zigzag graphene nanodots (z-GNDs) on the charge transport under non-collinear magnetization. Only substitutional doping of transition metal atoms in z-GNDs at certain sites demonstrates the spin filtering effect with a large tunnelling magnetoresistance as high as 700%, making it actually suitable for spintronic applications. From the electrical field simulation around the junction area within the electrostatic physics model, we find that the value of electric field strength increases especially with doped graphene nanodots, as the gap between the gate electrode and tip axis is reduced from 3 nm to 1 nm. Our detailed analysis further suggests the onset of asymmetric Coulomb oscillations with varying amplitudes in graphene nanodots, on being doped with magnetic ions. Such kind of tunability in the electronic conductance can potentially be exploited in designing spintronic logic gates at nanoscale.