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arXiv · 2102.11850

Anomalous Electrodynamics and Quantum Geometry in the Dirac-Harper model for a Graphene Bilayer

Abigail Timmel·E. J. Mele
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Abstract

Graphene bilayers with layer antisymmetric strains are studied using the Dirac-Harper model for a pair of single layer Dirac Hamiltonians coupled by a one-dimensional moir\'e-periodic interlayer tunneling amplitude. This model hosts low energy, nearly dispersionless bands near charge neutrality that support anomalous polarizations of its charge multipole distributions. These are analyzed introducing a generalized Berry curvature that encodes the field-induced dynamics of multipole fields allowed in a chiral medium with time reversal symmetry. The formulation identifies a reciprocity relation between responses to layer-symmetric and layer-antisymmetric in-plane electric fields and reveals momentum-space quantum oscillations produced by a spatial pattern of band inversions on the moir\'e scale.

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Abigail Timmel, E. J. Mele. 2021-02-23. Anomalous Electrodynamics and Quantum Geometry in the Dirac-Harper model for a Graphene Bilayer. https://doi.org/10.1103/physrevb.104.075419

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