Strongly Correlated Chern Insulators in Magic-Angle Twisted Bilayer Graphene
ORAL
Abstract
Most topological electronic phases appear in systems with weak electron-electron interactions, making instances where topological phases emerge only as a result of strong interactions rare. The discovery of flat electronic bands with topological character in magic-angle twisted bilayer graphene (MATBG) has created a unique opportunity to search for new strongly correlated topological phases. I will describe the use of a novel local spectroscopic technique using a scanning tunneling microscope (STM) to detect a sequence of topological insulators in MATBG with Chern numbers C = ±1, ±2, ±3 near v = ±3, ±2, ±1 electrons per moiré unit cell respectively, which are stabilized by modest magnetic fields [1]. One of these phases (C = +1) was previously observed when the sublattice symmetry of MATBG was intentionally broken by a hexagonal boron nitride (hBN) substrate, with interactions playing a secondary role [2]. We demonstrate that strong electron-electron interactions alone can produce not only the previously observed phase, but also new Chern insulating phases in MATBG by breaking time-reversal symmetry [1, 3].
[1] K. P. Nuckolls et al. arXiv:2007.03810
[2] M. Serlin, et al. Science 367, 900-903 (2020).
[3] B. Lian, et al. arXiv:2009.13530
[1] K. P. Nuckolls et al. arXiv:2007.03810
[2] M. Serlin, et al. Science 367, 900-903 (2020).
[3] B. Lian, et al. arXiv:2009.13530
*Supported by the Moore Foundation and the DOE
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Presenters
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Kevin Nuckolls
- Princeton University
- Joseph Henry Laboratories & Department of Physics, Princeton University