Imaging Magic-Angle Twisted Bilayer Graphene: Part III
ORAL
Abstract
Magic-angle twisted bilayer graphene (MATBG) hosts many correlated ground states, including correlated insulating, superconducting, and magnetic phases [1]. Theoretical studies have predicted an intense energetic competition among several candidate ground states in MATBG, but it appears to be very difficult to differentiate among them without spatially resolved experiments [2, 3]. Fortunately, scanning tunneling microscopy (STM) has the capability to access key microscopic observables predicted by theory that are crucial for understanding the origin of these phases. In this final talk in a series of three presentations, I will discuss how we combine STM imaging experiments with a unified symmetry-based analysis framework to extract quantitative information about gapped phases in MATBG. In large-scale imaging experiments, we identify universal real-space features that are shared across devices, and identify more subtle features that are highly sample-dependent. This approach allows us to directly compare candidate ground states to our experimental observations, which we use to distinguish the nature of the insulating phases near v = +-2 in MATBG, ruling out leading theoretical contenders for these states on the basis of symmetry.
*This work was primarily supported by the Gordon and Betty Moore Foundation's EPiQS initiative grants GBMF9469 and DOE-BES grant DE-FG02-07ER4641.
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Publication: [1] Y. Cao et al. Nature 556, 43-50, 80-84 (2018).
[2] D. Calugaru et al. Phys. Rev. Lett. 129, 117602 (2022).
[3] J. P. Hong et al. Phys. Rev. Lett. 129, 147001 (2022).
Presenters
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Kevin P Nuckolls
- Princeton University