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Honeycomb-shaped structures made of carbon atoms, known as graphene, can conduct electric current without resistance when twisted against each other. Credit: Uni Innsbruck |
In the search for novel types of superconductors – phases of matter that conduct electric current without loss – scientists are investigating materials that consist of multiple layers. A team led by theoretical physicist Mathias Scheurer has studied in detail the properties of a system of three twisted graphene layers and gained important insights into its properties.
Since the first successful fabrication of a two-dimensional structure of carbon atoms about 20 years ago, graphene has fascinated scientists. A few years ago, researchers discovered that two layers of graphene, slightly twisted against each other, can conduct electric current without loss. In recent years, this discovery has prompted scientists to explore such layered materials in greater detail. A recent notable example is mirror-symmetric twisted trilayer graphene, where three layers of graphene are stacked with alternating twist angles. It is the first moiré system that can both be efficiently tuned with a perpendicular electric field and was demonstrated experimentally to exhibit robust superconductivity, alongside various other phases. “This establishes trilayer graphene as an exciting platform for complex many-body physics, but the nature of the observed interaction-induced insulators, semi-metals, and superconductivity remains unknown”, says Mathias Scheurer from the Department of Theoretical Physics of the University of Innsbruck.