How superconductivity arises: New insights from moiré materials
- Mateo Cardinal
- 8 minutes ago
- 2 min read
How exactly unconventional superconductivity arises is one of the central questions of modern solid-state physics. A new study published in the scientific journal Nature provides crucial insights into this question.
For the first time, an international research team was able to demonstrate a direct microscopic connection between a strongly correlated normal state and superconductivity in so-called moiré materials. In the long term, these findings could contribute to the development of new quantum materials and superconductors for future quantum technologies.
Professor Giorgio Sangiovanni from the Institute of Theoretical Physics and Astrophysics at Julius-Maximilians-Universität Würzburg (JMU) was involved in the study. His research is part of the Cluster of Excellence ctd.qmat - Complexity, Topology and Dynamics in Quantum Matter - at JMU and the Technical University of Dresden.
Novel quantum states and unconventional superconductivity
Moiré materials consist of atomically thin crystal layers that are stacked with a slight twist relative to each other.
This minimal twist fundamentally changes the behavior of the electrons: their mobility decreases, while their mutual interactions dominate. This gives rise to novel quantum states such as correlated insulators, magnetism, and unconventional superconductivity.
Until now, however, it was unclear exactly how superconductivity develops from these strongly correlated initial states. To clarify this, the researchers combined high-precision experiments using scanning tunneling microscopy with theoretical models. This enabled them to study twisted graphene systems, which allow particularly precise control over electronic interactions and symmetries.
The theoretical analysis of the data was carried out in close cooperation with partner institutions from Princeton, San Sebastián, Frankfurt and Hamburg at Professor Sangiovanni's chair.
New quantum materials and superconductors for future quantum technologies
The key finding: the superconductivity observed does not arise from an ordinary metal, but from an already strongly correlated state with broken symmetry.
Particularly noteworthy was the detection of a spiral-shaped order of the so-called “valley” degree of freedom. In addition, the researchers observed several energy gaps whose behavior varies with temperature and magnetic field – a clear indication of the close connection between the normal state and superconductivity.
The results provide a new physical understanding of how unconventional and possibly also high-temperature superconductivity arises. In the long term, the findings could contribute to the targeted development of new quantum materials and superconductors for future quantum technologies.
Reference Resolving intervalley gaps and many-body resonances in moiré superconductors
Hyunjin Kim, Gautam Rai, Lorenzo Crippa, Dumitru Călugăru, Haoyu Hu, Youngjoon Choi, Lingyuan Kong, Eli Baum, Yiran Zhang, Ludwig Holleis, Kenji Watanabe, Takashi Taniguchi, Andrea F. Young, B. Andrei Bernevig, Roser Valentí, Giorgio Sangiovanni, Tim Wehling & Stevan Nadj-Perge
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