Spectroscopic features of the parent phase of magic-angle twisted bilayer graphene*

Recent experiments on magic-angle twisted bilayer graphene (MATBG) have shown various intriguing low-temperature electronic phases induced by filling of the moiré flat bands [1][2]. These phases, including correlated insulator and superconducting phases, are derived from a high-temperature “parent phase,” which is currently not well understood. Previously, there have been scanning tunneling microscopy and spectroscopy (STM/STS) measurements of this parent phase that have shown signatures of strong electronic correlations [3]. In this talk, we report on new, higher resolution STM/STS studies of this phase. Our experimental results reveal new distinct filling-dependent spectroscopic features that reflect key information on the nature of many-body correlations in MATBG. We have found that these features can be compared to a model of strongly interacting electrons in the flat bands allowing us to determine the microscopic origin of these features as well as extract an estimate of the strength of electronic correlation in MATBG.

[1] Y. Cao et al. Nature 556, 43-50 (2018)
[2] M. Yankowitz et al. Science 363, 1059-1064 (2019)
[3] Y. Xie et al. Nature 572, 101-105 (2019)