Ferromagnetism in armchair graphene nanoribbon

TL;DR

This paper demonstrates that electron-electron interactions induce ferromagnetism in armchair graphene nanoribbons, with magnetic properties tunable via carrier concentration, highlighting potential for nanoscale spintronics applications.

Contribution

It provides a combined analytical and numerical study showing the emergence of ferromagnetism due to electronic correlations in armchair graphene nanoribbons, emphasizing the role of boundary topology.

Findings

Electron-electron interactions induce ferromagnetism in nanoribbons.

Ferromagnetic state is tunable by carrier concentration.

The ferromagnetic state exhibits metallic conductivity.

Abstract

Due to the weak spin-orbit interaction and the peculiar relativistic dispersion in graphene, there are exciting proposals to build spin qubits in graphene nanoribbons with armchair boundaries. However, the mutual interactions between electrons are neglected in most studies so far and thus motivate us to investigate the role of electronic correlations in armchair graphene nanoribbon by both analytical and numerical methods. Here we show that the inclusion of mutual repulsions leads to drastic changes and the ground state turns ferromagnetic in a range of carrier concentrations. Our findings highlight the crucial importance of the electron-electron interaction and its subtle interplay with boundary topology in graphene nanoribbons. Furthermore, since the ferromagnetic properties sensitively depends on the carrier concentration, it can be manipulated at ease by electric gates. The resultant ferromagnetic state with metallic conductivity is not only surprising from an academic viewpoint, but also has potential applications in spintronics at nanoscale.