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arXiv · 1210.7590

Flat band electrons and interactions in rhombohedral trilayer graphene

Hao Wang·Jin-Hua Gao·Fu-Chun Zhang
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Abstract

Multilayer graphene systems with a rhombohedral stacking order harbor nearly flat bands in their single-particle spectrum. We propose ansatz states to describe the surface-localized states of flat band electrons. The absence of kinetic dispersion near the fermi level leaves the interaction as a dominate mechanism to govern the low energy physics of a low density electron system. We build up an effective lattice model in two interacting low-energy bands, where the full terms of the Coulomb interaction, including those long-range and off-diagonal parts, have been considered. The interaction matrix coefficients in the many-body Hamiltonian model are directly calculated for a trilayer system using orthonormal Wannier basis. We then present a flat-band projection to yield an interaction-only lattice model for flat band electrons. We find that this limited model might energetically favor a ferromagnetic quantum crystal under certain conditions.

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Hao Wang, Jin-Hua Gao, Fu-Chun Zhang. 2012-10-29. Flat band electrons and interactions in rhombohedral trilayer graphene. https://doi.org/10.1103/physrevb.87.155116

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