Experimental Evidence of Local Magnetic Moments at Edges of n-Layer Graphenes and Graphite

Abstract

Ferromagnetism in graphite/graphenes is attractive for fundamental science and potential applications in carbon-based magnetism and spintronics. In this work, we show that magnetic particle inspection can be miniaturized to detect local magnetic moments with a high spatial resolution of ∼1.0 nm using scanning electron microscopy. A metal nanowire and adjacent nanogap can be found at the edges of graphenes and graphite for atoms with magnetic moments (Fe, Co, Ni, Mn, Pd, Al), whereas no similar characteristics are found for diamagnetic metals (Au, Ag). By investigating these features under an external magnetic field and at different temperatures, we discuss possible mechanisms and propose that intrinsic ferromagnets exist and form a one-dimensional array at the edges of graphenes and graphite. Meanwhile, the size of individual magnets (<4.8 Å), orientation, magnitude (∼0.45 μB per carbon edge atom) of magnetic moments, and their Curie temperature (>95 °C) are obtained, which are novel and interesting.