Unveiling the Miniband Structure of Graphene Moiré Superlattices via Gate-Dependent Terahertz Photocurrent Spectroscopy
Moiré superlattices formed at the interface between stacked 2D atomic crystals offer limitless opportunities to design materials with widely tunable properties and engineer intriguing quantum phases of matter. However, despite progress, precise probing of the electronic states and tantalizingly complex band textures of these systems remain challenging. Here, we present gate-dependent terahertz photocurrent spectroscopy as a robust technique to detect, explore, and quantify intricate electronic properties in graphene moiré superlattices. Specifically, using terahertz light at different frequencies, we demonstrate distinct photocurrent regimes, evidencing the presence of avoided band crossings and tiny (∼1 to 20 meV) inversion-breaking global and local energy gaps in the miniband structure of minimally twisted graphene and hexagonal boron nitride heterostructures, key information that is inaccessible by conventional electrical or optical techniques. In the off-resonance regime, when the radiation energy is smaller than the gap values, enhanced zero-bias responsivities arise in the system due to the lower Fermi velocities and specific valley degeneracies of the charge carriers subjected to moiré superlattice potentials. In stark contrast, the above-gap excitations give rise to bulk photocurrents─intriguing optoelectronic responses related to the geometric Berry phase of the constituting electronic minibands. Besides their fundamental importance, these results place moiré superlattices as promising material platforms for advanced, sensitive, and low-noise terahertz detection applications.
Authors
- Daniel Vaquero (ORCID: https://orcid.org/0000-0001-7025-125X)
- W. Knap (ORCID: https://orcid.org/0000-0003-4537-8712)
- Yahya Moubarak Meziani (ORCID: https://orcid.org/0000-0001-5193-7993)
- Juan A. Delgado‐Notario (ORCID: https://orcid.org/0000-0001-9714-8180)
- Takashi Taniguchi (ORCID: https://orcid.org/0000-0002-1467-3105)
- Kenji Watanabe (ORCID: https://orcid.org/0000-0003-3701-8119)
- Jinluo Cheng (ORCID: https://orcid.org/0000-0003-4875-9342)
- J.E. Velázquez-Pérez (ORCID: https://orcid.org/0000-0002-6555-9871)
- Pablo Alonso‐González (ORCID: https://orcid.org/0000-0002-4597-9326)
- José M. Caridad (ORCID: https://orcid.org/0000-0001-8943-1170)
- Stephen R. Power (ORCID: https://orcid.org/0000-0003-4566-628X)
- M. Pino (ORCID: https://orcid.org/0000-0002-5758-8461)
Institutions
- Warsaw University of Technology (PL)
- Universidad de Oviedo (ES)
- University of Groningen (NL)
- Universidad de Salamanca (ES)
- Chinese Academy of Sciences (CN)
- National Institute for Materials Science (JP)
- Changchun Institute of Optics, Fine Mechanics and Physics (CN)
- Institute of High Pressure Physics (PL)
- Instituto de Física Fundamental (ES)
- Research Applications (United States) (US)
- Medical & Biological Laboratories (Japan) (JP)
- Excelencia in Education (US)
- University of Chinese Academy of Sciences (CN)
- Dublin City University (IE)
- Optica (US)
- Polish Academy of Sciences (PL)
Publication Details
- Journal
- ACS Nano
- Published
- 2025-07-21
- DOI
- https://doi.org/10.1021/acsnano.5c05306
- Citations
- 3
- Primary Topic
- Graphene research and applications
- Type
- article
- Field-Weighted Citation Impact
- 1.55
Funders
- Ministry of Education, Culture, Sports, Science and Technology
- Fundacja na rzecz Nauki Polskiej
- Irish Research Council
- Universidad de Salamanca
- Junta de Castilla y León
- Japan Society for the Promotion of Science
- European Regional Development Fund
- Agencia Estatal de Investigación
- Core Research for Evolutional Science and Technology
- European Social Fund
- HORIZON EUROPE European Research Council