Interplay between the Kagome flat band and the Dirac cone in porous graphitic networks

We have investigated the geometric and electronic structures of porous graphene consisting of triangular hydrocarbon molecules polymerized by oligoacene interconnects by density functional theory. The networks possess both Dirac cones and Kagome flat bands near the Fermi level of which electron filling is controllable by selecting appropriate oligoacene interconnects because the triangular units and interconnects are arranged in honeycomb and Kagome lattices, respectively. The partially filled Kagome band in the network with the shortest interconnects induces ferromagnetic spin ordering throughout the porous graphitic network with a magnetic moment of 1.00 μB/cell. For networks with longer interconnects, the sheet is a zero gap semiconductor with a Dirac cone at the Fermi level of which band width decreases with increasing length of the interconnect despite the network containing pentagonal rings.

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