Twistronics has become a new alchemy of materials. By choosing atomically thin layers, stacking them and changing their relative angle, researchers can create electronic behavior absent from the original ingredients. Twisted graphene and transition metal dichalcogenides have already yielded superconductivity and fractional Chern insulators, states with fractionally charged excitations. One of physics’ most active frontiers now has a moon shot ambition: to design entirely new forms of quantum matter.
New families of twisted materials have repeatedly brought new rules for how electrons move and interact — a different Hamiltonian — and new kinds of quantum simulators. A research team’s recent Nature study of M-point twisting illustrates how changing the starting electronic structure opens different physics. Exploring other atomic architectures could therefore uncover quantum states and models that today’s familiar platforms cannot reach.
Now, in two back-to-back papers published in Science Sept. 24, an international collaboration provides both the building blocks and a guide to that vast search. The first maps the electronic structures and topology of nearly 9,000 two-dimensional entries, whether topological or not. The second identifies more than 1,600 candidates for twisting, with different electronic starting points that could enable entirely new kinds of quantum simulators.
“Every new family of twisted materials gives us a chance to ask a different question about quantum matter. We want to move beyond the few platforms we know and explore the enormous range of physics that other layers and other twists could make possible,” said B. Andrei Bernevig, a Princeton University professor of physics and co-author of both studies.
Each candidate for twisting was a crystal that had to be grown in its bulk compounds.
“Each compound asks for its own growth conditions, so we work through them one at a time. That is how a list of candidates becomes samples other groups can measure,” said Emilia Morosan, a professor of physics and astronomy at Rice University and co-author on the second paper.
The two studies are the work of a joint theoretical and experimental team that spans more than a dozen institutions. At Princeton are B. Andrei Bernevig (also DIPC and IKERBASQUE), Dumitru Călugăru (also the University of Oxford), Haoyu Hu (also the University of Science and Technology of China), Nicolas Regnault (also the Flatiron Institute and, the École normale supérieure and the French National Centre for Scientific Research in Paris), Grigorii Skorupskii, Jiaze Xie and Leslie M. Schoop; at the Donostia International Physics Center (also DIPC), Yi Jiang, Hanqi Pi, Garen Avedissian, Yongsong Wang, Miguel M. Ugeda (also IKERBASQUE) and Maia G. Vergniory (also the Université de Sherbrooke); at the University of the Basque Country, Urko Petralanda and Luis Elcoro; at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Angel Rubio (also the Flatiron Institute and the University of the Basque Country) and Lede Xian (also the Tsientang Institute for Advanced Study and the Songshan-Lake Materials Laboratory); at RWTH Aachen University, Dante M. Kennes (also the Max Planck Institute in Hamburg); at Sichuan Normal University, Qiaoling Xu (also the Tsientang Institute for Advanced Study); and at the University of Pennsylvania, Martin Claassen. The experimental work involves Peter Höhn, Vicky Haase and Claudia Felser at the Max Planck Institute for Chemical Physics of Solids in Dresden; Rose Albu Mustaf and Morosan at Rice; Jiacheng Zhu, Dongyang Yang, Zuhan Geng, Jie Shan and Kin Fai Mak at Cornell University, with Shan and Mak also at the Kavli Institute at Cornell for Nanoscale Science and Yang, Geng, Shan and Mak at the Max Planck Institute in Hamburg; and Abdelmajid Ouahchi, Soumyajit Samal and Dmitri K. Efetov at Ludwig Maximilian University of Munich, with Ouahchi also at the Technical University of Munich and Samal and Efetov at the Munich Center for Quantum Science and Technology.