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Abstract: The ABC-stacked N-layer-graphene family of two-dimensional electron systemsis described at low energies by two remarkably flat bands with Bloch statesthat have strongly momentum-dependent phase differences between carbonpi-orbital amplitudes on different layers, and large associated momentum spaceBerry phases. These properties are most easily understood using a simplifiedmodel with only nearest-neighbor inter-layer hopping which leads to gaplesssemiconductor electronic structure, with p^N dispersion in both conduction andvalence bands. We report on a study of the electronic band structures oftrilayers which uses ab initio density functional theory and k*p theory to fitthe parameters of a pi-band tight-binding model. We find that when remoteinterlayer hopping is retained, the triple Dirac point of the simplified modelis split into three single Dirac points located along the three KM directions.External potential differences between top and bottom layers are stronglyscreened by charge transfer within the trilayer, but still open an energy gapat overall neutrality.



Autor: Fan Zhang, Bhagawan Sahu, Hongki Min, Allan H. MacDonald

Fuente: https://arxiv.org/







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