Quantum Anomalous Hall Effect of Twisted Bilayer Graphene/Hexagonal Boron Nitride Double-Moiré Structures
ORAL
Abstract
Twisted bilayer graphene (tBG) nearly aligned with a hexagonal boron nitride (hBN) substrate hosts two moiré patterns and sometimes shows quantum anomalous Hall effects (QAHE). The influence of hBN on low-energy states in tBG has normally been approximated by a spatially uniform sublattice-asymmetric potential, in spite of the fact that moiré periodic terms in the Hamiltonian are estimated to be equally large. I will present a study of the QAHE of tBG/hBN trilayers using a double-moiré model. I will first identify a series of twist-angle pairs at which the two moiré patterns are commensurate, allowing moiré band theory to be applied, and then illustrate the significant effect of rigid in-plane hBN translation on the moiré band structures and Chern numbers. Using this information, I will discuss the anomalous Hall properties of general tBG/hBN trilayers in two regimes: i) when the twist-angle pair is close to a commensurate point, so that a supermoiré pattern arises between the two patterns; ii) when the twist-angle pair is far from a commensurate point, creating a disorder-like effect. Finally, I will suggest a number of possible experiments that could verify the proposed critical role of the G/hBN moiré pattern.
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Presenters
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Jingtian Shi
University of Texas at Austin
Authors
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Jingtian Shi
University of Texas at Austin
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Jihang Zhu
University of Texas at Austin, Department of Physics, University of Texas at Austin, University of Texas, Austin
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Allan MacDonald
Physics, University of Texas at Austin, Physics Department, University of Texas at Austin, University of Texas at Austin, Department of physics, University of Texas at Austin, Department of Physics, University of Texas at Austin, University of Texas, Austin