Magnetic and electronic phase crossovers in graphene nanoflakes

Abstract

Manipulation of intrinsic magnetic and electronic structures of graphene nanoflakes is of technological importance. Here we carry out systematic study of the magnetic and electronic phases, and its manipulation in graphene nanoflakes employing first-principles calculation. We illustrate the intricate shape and size dependence on the magnetic and electronic properties, and further investigate the effects of carrier doping, which could be tuned by gate voltage. A transition from nonmagnetic to magnetic phase is observed at a critical flake size for the flakes without sublattice imbalance, which we identify to be originated from the armchair defect at the junctions of two sublattices on the edge. Electron, or hole doping simultaneously influences the magnetic and electronic structures, and triggers phase changes. Beyond a critical doping, crossover from antiferromagnetic to ferromagnetic phase is observed for the flakes without sublattice imbalance, while suppression of magnetism, and a possible crossover from magnetic to nonmagnetic phase is observed for flakes with sublattice imbalance. Simultaneous to magnetic phase changes, a semiconductor to (half) metal transition is observed, upon carrier doping.

arXiv comment8 pages, 9 figures

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• Quantum interference assisted spin filtering in graphene nanoflakes
• Electrode effects on the observability of destructive quantum interference in single-molecule junctions
• Inducing and controlling magnetism in the honeycomb lattice through harmonic trapping potential
• Nature of magnetism and transport in BxCyNz thin films: The intriguing role of nitrogen defects in the electronic structure
• Fluorine Intercalated Graphene: Formation of a 2D Spin Lattice through Pseudoatomization
• Magnetic, charge, and transport properties of graphene nanoflakes
• Particle-hole symmetry broken solutions in graphene nanoribbons: a multi-orbital, mean-field perspective