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Evidence of excitonic insulators

An excitonic insulator is a state of matter characterised by the spontaneous proliferation of excitons, i.e. electron-hole pairs held together by Coulomb interactions, that at low temperatures can give rise to a coherent condensate. Predicted in the 1960s by Walter Kohn, this state of matter has long eluded experimental validation in crystalline materials. Researchers at UNIMORE and CNR in Modena have decided to take up this challenge and since a few years have been searching for realistic candidates through analytical calculations and large scale simulations on supercomputing clusters, supported by the prestigious "PRIN" funding programme of the Ministry for University and Research.

This experience, condensed in scientific papers that appeared on high-impact journals like Nature Nanotechnology, Nature Communications and PNAS, has highlighted a particularly promising class of materials: transition metal dichalcogenides, which can be exfoliated down to atomically thin layers. Intrigued by such discoveries at UNIMORE and CNR, experimental scientists at the Washington University have investigated one of these materials, a single layer of WTe2. With the theoretical support by Prof. Elisa Molinari at FIM and other theoreticians at CNR and Tor Vergata, these experiments have shown the first evidence of an excitonic insulator.

These results, now published in Nature Physics together with analogous data from Princeton University, have drawn considerable attention from the scientific community, opening an exciting new field of research.

Reference: Sun, B., Zhao, W., Palomaki, T. et al. Evidence for equilibrium exciton condensation in monolayer WTe2. Nat. Phys. (2021). https://doi.org/10.1038/s41567-021-01427-5.

[Ultimo aggiornamento: 14/01/2022 12:45:01]