Tunable magnetism and spin-polarized electronic transport in graphene mediated by molecular functionalization of extended defects

Abstract

We use first-principles simulations to investigate the magnetic and the electronic transport properties of functionalized graphene layers upon the presence of extended linear defects (ELDs). We have considered electron-donor molecules, tetrathiafulvalene (TTF), lying on the graphene sites neighboring the ELD (TTF/ELD). Those molecules bond to the graphene sheet mediated by van der Waals interactions, giving rise to a net (molecule$\ensuremath{\rightarrow}$graphene) charge transfer. The $n$-type doping of graphene, as well as the molecule-graphene interaction, are strengthened by the presence of the ELD. There is a charge density accumulation on the C atoms along the defect sites, promoting the formation of magnetic states in TTF/ELD. We show that such a net magnetization can be modified through an external electric field (${E}_{\text{field}}$). Further electronic transport calculations reveal that the transmission coefficients exhibit a spin anisotropy which can be controlled by the ${E}_{\text{field}}$, and thus showing that TTF/ELD is a quite interesting system to realize tunable spin-polarized electronic currents on graphene.