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arXiv · 1911.05244

Spin-Triplet Excitonic Insulator: The Case of Graphone

Zeyu Jiang·Wenkai Lou·Yu Liu·Yuanchang Li·Haifeng Song·Kai Chang·Wenhui Duan·Shengbai Zhang
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Abstract

While various excitonic insulators have been studied in the literature, due to the perceived too-small spin splitting, spin-triplet excitonic insulator is rare. In two-dimensional systems such as a graphone, however, it is possible, as revealed by first-principles calculations coupled with Bethe-Salpeter equation. The critical temperature, given by an effective Hamiltonian, is 11.5 K. While detecting excitonic insulators is still a daunting challenge, the condensation of triplet excitons will result in spin superfluidity, which can be directly measured by a transport experiment. Nonlocal dielectric screening also leads to an unexpected phenomenon, namely, an indirect-to-direct transition crossover between single-particle band and exciton dispersion in graphone, which offers yet another test by experiment.

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Zeyu Jiang, Wenkai Lou, Yu Liu, Yuanchang Li, Haifeng Song, Kai Chang, Wenhui Duan, Shengbai Zhang. 2020-03-31. Spin-Triplet Excitonic Insulator: The Case of Graphone. https://doi.org/10.1103/physrevlett.124.166401

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