Disordered Magnetism at the Metal-Insulator Threshold in Nano-Graphite-Based Carbon Materials

The magnetism of activated carbon fibers composed of a disorder network of nanographites was investigated, where each nanographite has about 1 edge-inherited localized spin. The susceptibility, for samples situated around the metal-insulator threshold, shows a cusp around 4–7 K in addition to the presence of a field-cooling effect. These behaviors are explained in terms of disordered magnetism caused by random strengths of inter-nano-graphite antiferromagnetic interactions mediated by $\pi$-conduction carriers.