Geometric and electronic structures of two-dimensional networks of fused C₃₆ fullerenes

We theoretically designed layered materials with nanometer thickness by assembling C₃₆ fullerenes with D_6h symmetry based on first-principles total-energy calculations within the framework of density functional theory. Our calculations show three possible network topologies derived from fused C₃₆ fullerenes depending on the lateral lattice constant, possessing both static and kinetic stabilities. The electronic structures of these materials are semiconducting or metallic depending on their network topologies. We found small dispersion bands near the fundamental gap of the semiconducting systems, resulting from the segmentation of the π network or the strained bonds of four-fold coordinated C atoms. By injecting holes into the valence bands under a normal electric field, C₃₆ sheets exhibit spin polarization with a magnetic moment of approximately 2 μ_B/nm². (author)