ArXiv · 2025
Souvik Sasmal (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Ryan Muzzio (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Ahmed Khalifa (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Paulina Majchrzak (Department of Applied Physics, Stanford University, Stanford, CA, USA), Alfred J. H. Jones (Department of Physics and Astronomy, Aarhus University, Aarhus C, Denmark), I-Hsuan Kao (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Kenji Watanabe (Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan), Takashi Taniguchi (Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan), Simranjeet Singh (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Eli Rotenberg (Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA), Aaron Bostwick (Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA), Chris Jozwiak (Advanced Light Source, E. O. Lawrence Berkeley National Laboratory, Berkeley, CA, USA), Søren Ulstrup (Department of Physics and Astronomy, Aarhus University, Aarhus C, Denmark), Shubhayu Chatterjee (Department of Physics, Carnegie Mellon University, Pittsburgh, USA), Jyoti Katoch (Department of Physics, Carnegie Mellon University, Pittsburgh, USA)
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.
