The symmetry-broken correlated states in twisted double bilayer graphene (TDBG) can be tuned via several external knobs, including twist angle, displacement field, and carrier density. However, a direct, momentum-resolved characterization of how these parameters reshape the flat-band structure remains limited. In this study, we employ micro focused angle-resolved photoemission spectroscopy to investigate the flat-band dispersion of TDBG at a twist angle of 1.6, systematically varying the displacement field and carrier density via electrostatic gating. We directly observe multiple flat moir'e minibands near charge neutrality, including a flat remote valence band residing below the low-energy flat-band manifold. Furthermore, the dominant Coulomb repulsive energy over the flat- band bandwidth suggests favorable conditions for the emergence of interaction-driven correlated phenomena in TDBG. These findings establish that the formation and evolution of flat bands in TDBG arises from the interplay between the electron filling and the displacement field.
@article{arxiv.2510.19632,
title = {Direct visualization of gate-tunable flat bands in twisted double bilayer graphene},
author = {Souvik Sasmal and Ryan Muzzio and Ahmed Khalifa and Paulina Majchrzak and Alfred J. H. Jones and I-Hsuan Kao and Kenji Watanabe and Takashi Taniguchi and Simranjeet Singh and Eli Rotenberg and Aaron Bostwick and Chris Jozwiak and Søren Ulstrup and Shubhayu Chatterjee and Jyoti Katoch},
journal= {arXiv preprint arXiv:2510.19632},
year = {2025}
}