Abstract
Graphene quantum dots with the high edge-to-area ratio have possibly substantial spin polarized edge states, which theoretically can generate fascinating magnetic properties. The magnetism of well-defined graphene quantum dots is relevant with both fundamental physics and potential applications in spintronics. In this article, we report the intrinsic magnetism of graphene quantum dots. Our graphene quantum dots with the average diameter of ca. 2.04 nm show the purely Curie-like paramagnetism with the local moment of 1.2 μB at 2 K. It is proposed that the magnetic moment of graphene quantum dots may mainly origin from the residual zigzag edges passivated by hydroxyl groups. The ratio of nonmagnetic graphene quantum dots is approximately 6/7, with most of the magnetic edge states suppressed by edge defects and/or edge reconstruction arising from the high-temperature annealing. Our study experimentally unveils the intrinsic magnetism of graphene quantum dots.
Highlights
Graphene quantum dots (GQDs) with a tiny size of only several nanometers present extraordinary properties due to quantum confinement[1] and edge effects,[2] which attract a great deal of interest lately in the fields of bio-imaging, sensors, catalysis, photovoltaic devices, supercapacitors, etc.[3]
We report the intrinsic magnetism of GQDs with mostly pristine edges and nearly perfect basal plane
The morphologies of GQDs were investigated by transmission electron microscopy (TEM) and atomic force microscope (AFM)
Summary
Graphene quantum dots (GQDs) with a tiny size of only several nanometers present extraordinary properties due to quantum confinement[1] and edge effects,[2] which attract a great deal of interest lately in the fields of bio-imaging, sensors, catalysis, photovoltaic devices, supercapacitors, etc.[3]. To unveil the edge states magnetism in GQDs, experimental investigation on the magnetism of intrinsic GQDs is of great significance and highly anticipated.[11,12]. The magnetism of GQDs may mainly origin from the residual edge states passivated by hydroxyl groups
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