Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session W70: Topology and Correlation: Magnetism, Superconductivity, and Flat Bands
3:00 PM–5:24 PM,
Thursday, March 17, 2022
Room: Hyatt Regency Hotel -Jackson Park B
Chair: Matthew Brahlek, Oak Ridge National Laboratory
Abstract: W70.00001 : Tunable topological states with and without flat bands in semiconductor heterostructures*
3:00 PM–3:36 PM
We discuss two mechanisms by which topology, the quantum anomalous Hall (QAH) effect, can emerge in these systems.
First, QAH can arise in TMD homobilayers at small relative twist angles due to interaction effects in the presence of flat topological bands. In [arXiv:2106.11954], we derive a "magic angle" condition for twisted TMD homobilayers (similar to in bilayer graphene), at which the first moire bands are almost exactly flat, well separated from other bands, and topological.
Second, we present a new mechanism by which topology can emerge even without flat bands [arXiv:2109.13909]. Our theory explains the recent experimental observation of a QAH state in AB-stacked MoTe2/WSe2 tuned by displacement field [arXiv:2107.01796]. Our mechanism shows that QAH can emerge quite generically in these systems. We predict that the QAH state is a mostly intervalley-coherent state, with only a small valley polarization.
*I acknowledge funding from the Simons Foundation through a Simons Investigator Award to Liang Fu and Senthil Todadri.
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