Dual origin of defect magnetism in graphene and its reversible switching by molecular doping

TL;DR

This paper demonstrates that defect-induced magnetism in graphene, originating from both vacancies and adatoms, can be reversibly controlled through molecular doping, advancing potential spintronics applications.

Contribution

It reveals the dual origin of vacancy magnetism and shows how adatom magnetism in graphene can be switched via doping, providing new control mechanisms for magnetic properties.

Findings

Adatom magnetism in graphene is itinerant and controllable by doping.

Vacancy magnetism has a dual origin: itinerant and broken bonds.

Magnetic response can be modulated by the electric field effect.

Abstract

A possibility to control magnetic properties by using electric fields is one of the most desirable characteristics for spintronics applications. Finding a suitable material remains an elusive goal, with only a few candidates found so far. Graphene is one of them and offers a hope due to its weak spin-orbit interaction, the ability to control electronic properties by the electric field effect and the possibility to introduce paramagnetic centres such as vacancies and adatoms. Here we show that adatoms magnetism in graphene is itinerant and can be controlled by doping, so that magnetic moments can be switched on and off. The much-discussed vacancy magnetism is found to have a dual origin, with two approximately equal contributions: one coming from the same itinerant magnetism and the other due to broken bonds. Our work suggests that magnetic response of graphene can be controlled by the field effect, similar to its transport and optical properties, and that spin diffusion length can be significantly enhanced above a certain carrier density.