Local spectroscopic study of moiré band flattening and correlated gaps in magic-angle twisted bilayer graphene

Hyunjin Kim; Youngjoon Choi; Cyprian Lewandowski; Yang Peng; Alex R Thomson; Kenji Watanabe; Takashi Taniguchi; Jason F. Alicea; Stevan Nadj-Perge

Local spectroscopic study of moiré band flattening and correlated gaps in magic-angle twisted bilayer graphene

ORAL

Abstract

Magic angle (~1.1°) twisted bilayer graphene (TBG) shows a wide range of correlated electronic states that originate from the flat moiré bands. Scanning tunneling spectroscopy experiments on TBG near the magic angle observed, a large separation between van Hove singularities and finite Dirac velocities signaling relatively large bandwidth that is not compatible with the continuum model expectations. While these previous measurements highlight the presence of electronic interactions, their impact on the band structure is still unclear. Here, we report scanning tunneling spectroscopy measurements of TBG across the area where the twist angle slowly changes from non-magic to magic-angle value. By systematically following the evolution of the moiré electronic bands, we study doping dependent band deformations. Surprisingly, we discover interaction-driven band flattening that can be also related to gap opening near half-filling. Our results provide crucial insights into the robustness of half-filling correlated phases.

March 17, 2021, 4:24 PM – March 17, 2021, 4:36 PM

Presenters

Hyunjin Kim

Caltech, Department of Physics, California Institute of Technology

Authors

Hyunjin Kim

Caltech, Department of Physics, California Institute of Technology
Youngjoon Choi

Caltech, Department of Physics, California Institute of Technology
Cyprian Lewandowski

Department of Physics, California Institute of Technology, California Institute of Technology, Caltech
Yang Peng

Department of Physics and Astronomy, California State University, Northridge, USA, Caltech, California State University, Northridge
Alex R Thomson

Caltech, Department of Physics, California Institute of Technology
Kenji Watanabe

National Institute for Materials Science, National Institute for Materials Science, Japan, National Institure for Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, NIMS, National Institute of Materials Science, National Institute for Materials Science (NIMS), Research Center for Functional Materials, National Institute for Materials Science, National Institute for Materials Science,1-1 Namiki, National Institute of Material Science, National Institute for Materials Science, Tsukuba, Japan, Research Center for Functional Materials, NIMS, National Institute of Materials Science, Tsukuba, Japan, National Institude for Materials Science, National Institute for Materials Science, Tsukuba, Ibaraki, Japan, Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials, NIMS - Japan, National Institute for Materials Science ,Japan, National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan, National Institute for Material Science, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science Japan, NIMS Tsukuba, National Institute for Materials Science, Research Center for Functional Materials, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Materials Science: Namiki, Tsukuba, Ibaraki, JP, National Institue for Material Science, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan, Materials, NIMS, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, National In, Research Center for Functional Materials, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, International Center for Materials nanoarchtectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, NIMS Suguba, NIMS, Tsukuba, Japan, National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan, National institute of material science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, Advanced Materials Laboratory, NIMS, Research Center for Functional Materials, National Institute for Materials Science, Ibaraki, Japan, National Institute for Materials Science, Research Center for Functional Materials, National Institute of Material Science, Japan, Tsukuba, National Institute for Materials Science
Takashi Taniguchi

National Institute for Materials Science, National Institute for Materials Science, Japan, National Institure for Materials Science, Advanced Materials Laboratory, National Institute for Materials Science, NIMS, National Institute of Materials Science, National Institute for Materials Science (NIMS), International Center for Materials Nanoarchitectonics, National Institute for Materials Science, National Institute for Materials Science,1-1 Namiki, National Institute of Material Science, National Institute for Materials Science, Tsukuba, Japan, International Center for Materials Nanoarchitectonics, NIMS, Research Center for Functional Materials, National Institute for Materials Science, National Institute of Materials Science, Tsukuba, Japan, National Institude for Materials Science, International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044, Japan, International Center for Materials Nanoarchitectonics, National Institute for Materials, NIMS - Japan, National Institute for Materials Science ,Japan, National Institute for Materials Science, Tsukuba, 305-0044, Ibaraki, Japan, National Institute for Material Science, National Institute for Material Science, 1-1 Namiki, Tsukuba 305-0044, Japan, National Institute for Material Science Japan, 8International Center for Materials Nanoarchitectonics, NIMS Tsukuba, National Institute for Materials Science: Namiki, Tsukuba, Ibaraki, JP, National Institue for Material Science, National Institute for Materials Science,1-1 Namiki, Tsukuba, 305-0044, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan, Research Center for Functional Materials, National In, Research Center for Functional Materials, Japan, Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, International Center for Material Nanoarchitectonics, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, NIMS Suguba, NIMS, Tsukuba, Japan, National Cheng Kung University, National Institute for Materials Science, Namiki 1-1, Tsukuba, 305-0044, Ibaraki, Japan, National institute of material science, Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan, Advanced Materials Laboratory, NIMS, National Institute for Materials Science, International Center for Materials Nanoarchitectonics, National Institute of Material Science, Japan, Tsukuba, National Institute for Materials Science
Jason F. Alicea

Caltech, Department of Physics, California Institute of Technology, Department of Physics and Institute for Quantum Information and Matter; Walter Burke Institute for Theoretical Physics, California Institute of Technology
Stevan Nadj-Perge

Caltech, Watson Laboratory of Applied Physics, California Institute of Technology, Physics, California Institute of Technology