We analytically compute the scanning tunneling microscopy (STM) signatures of integer-filled correlated ground states of the magic angle twisted bilayer graphene (TBG) narrow bands. After experimentally validating the strong-coupling approach at ±4 electrons/moir\'e unit cell, we consider the spatial features of the STM signal for 14 different many-body correlated states and assess the possibility of Kekul\'e distortion (KD) emerging at the graphene lattice scale. Remarkably, we find that coupling the two opposite graphene valleys in the intervalley-coherent (IVC) TBG insulators does not always result in KD. As an example, we show that the Kramers IVC state and its nonchiral U(4) rotations do not exhibit any KD, while the time-reversal-symmetric IVC state does. Our results, obtained over a large range of energies and model parameters, show that the STM signal and Chern number of a state can be used to uniquely determine the nature of the TBG ground state.
@article{arxiv.2110.15300,
title = {Spectroscopy of Twisted Bilayer Graphene Correlated Insulators},
author = {Dumitru Călugăru and Nicolas Regnault and Myungchul Oh and Kevin P. Nuckolls and Dillon Wong and Ryan L. Lee and Ali Yazdani and Oskar Vafek and B. Andrei Bernevig},
journal= {arXiv preprint arXiv:2110.15300},
year = {2022}
}
Comments
8+80 pages, 2+65 figures. New version matches the published version