Open Access

A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a “cascade” of spontaneous symmetry-breaking transitions, sparking interest in the potential relationship between symmetry breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking. Here, we show how atomically resolved scanning tunneling microscopy can be used as a fingerprint of symmetry-breaking order. By analyzing the pattern of sublattice polarization and “Kekulé” distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the “Kramers intervalley coherent state,” which theoretical work predicts to be the ground state at even integer fillings, shows a Kekulé distortion which emerges only in a magnetic field.

  • Received 30 November 2021
  • Revised 20 August 2022
  • Accepted 25 August 2022

DOI:https://doi.org/10.1103/PhysRevLett.129.147001

© 2022 American Physical Society

Condensed Matter, Materials & Applied Physics

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