journal article·2025Open access

Electronic confinement induced quantum dot behavior in magic-angle twisted bilayer graphene

Bhaskar Ghawri, Pablo Bastante, Kenji Watanabe, Takashi Taniguchi, Michel Calame, Mickael L. Perrin, Jian Zhang

Nanoscale· Volume 17· Issue 7

Abstract

Magic-angle twisted bilayer graphene (TBLG) has emerged as a versatile platform to explore correlated electron phases driven primarily by low-energy flat bands in moiré superlattices. While techniques for controlling the twist angle between graphene layers have spurred rapid experimental progress, understanding the effects of doping inhomogeneity on electronic transport in correlated electron systems remains challenging. In this work, we investigate the interplay of confinement and doping inhomogeneity on the electrical transport properties of TBLG by leveraging device dimensions and twist angles. We show that reducing device dimensions can magnify disorder potentials caused by doping inhomogeneity, resulting in pronounced carrier confinement. This phenomenon is evident in charge transport measurements, where the Coulomb blockade effect is observed. Temperature-dependent measurements reveal a large variation in the activation gap across the device. These findings highlight the critical role of doping inhomogeneity in TBLG and its significant impact on the transport properties of the system.
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Research context

OpenAlex topics: Graphene research and applications · Quantum and electron transport phenomena · Molecular Junctions and Nanostructures

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

Affiliations

Transport at Nanoscale Interfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049, Madrid, Spain

Research Center for Electronic and Optical Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan

Department of Physics, University of Basel, 4056 Basel, Switzerland

Swiss Nanoscience Institute, University of Basel, 4056 Basel, Switzerland

Department of Information Technology and Electrical Engineering, ETH Zurich, 8092 Zurich, Switzerland

Quantum Center, ETH Zürich, 8093 Zürich, Switzerland

Max Planck Institute of Microstructure Physics, Weinberg 2, Halle 06120, Germany

Funding

Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung · Ministerio de Ciencia e Innovación · H2020 Future and Emerging Technologies · Staatssekretariat für Bildung, Forschung und Innovation · Japan Society for the Promotion of Science · Ministry of Education, Culture, Sports, Science and Technology

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