Perfect Coulomb drag and exciton transport in an excitonic insulator.
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| Title: | Perfect Coulomb drag and exciton transport in an excitonic insulator. |
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| Authors: | Qi, Ruishi, Joe, Andrew Y., Zhang, Zuocheng, Xie, Jingxu, Feng, Qixin, Lu, Zheyu, Wang, Ziyu, Taniguchi, Takashi, Watanabe, Kenji, Tongay, Sefaattin, Wang, Feng |
| Source: | Science. 4/18/2025, Vol. 388 Issue 6744, p278-283. 6p. |
| Subjects: | Coulomb excitation, Exciton theory, Electron-hole droplets, Electron gas, Heterostructures, Counterflows (Fluid dynamics), Optical spectroscopy |
| Abstract: | Strongly coupled electron-hole bilayers can host quantum states of interlayer excitons, such as high-temperature exciton condensates at zero magnetic field. This state is predicted to feature perfect Coulomb drag, where a current in one layer is accompanied by an equal but opposite current in the other. We used an optical technique to probe the electrical transport of correlated electron-hole bilayers based on MoSe2/hBN/WSe2 heterostructures. We observed perfect Coulomb drag in the excitonic insulator phase at low temperatures; the counterflow resistance of interlayer excitons remained finite. These results indicate the formation of an exciton gas that does not condense into a superfluid. Our work demonstrates that dynamic optical spectroscopy provides a powerful tool for probing exciton transport behavior in correlated electron-hole fluids. Editor's summary: A pair of two-dimensional (2D) systems, one featuring electron carriers and the other hole carriers, separated by a thin insulating layer can host correlated interlayer excitons. Such excitons are predicted to exhibit superfluidity, as well as the so-called perfect Coulomb drag, in which the current in one layer causes an equal but opposite current in the other layer. Two studies have now observed nearly perfect drag at low temperatures in heterostructures consisting of molybdenum diselenide and tungsten diselenide layers separated by hexagonal boron nitride. Nguyen et al. used transport measurements, whereas Qi et al. relied on an optical technique. The studies enable further exploration of exciton transport in such heterostructures, including searching for superfluidity. —Jelena Stajic [ABSTRACT FROM AUTHOR] |
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| Database: | Psychology and Behavioral Sciences Collection |
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| Abstract: | Strongly coupled electron-hole bilayers can host quantum states of interlayer excitons, such as high-temperature exciton condensates at zero magnetic field. This state is predicted to feature perfect Coulomb drag, where a current in one layer is accompanied by an equal but opposite current in the other. We used an optical technique to probe the electrical transport of correlated electron-hole bilayers based on MoSe2/hBN/WSe2 heterostructures. We observed perfect Coulomb drag in the excitonic insulator phase at low temperatures; the counterflow resistance of interlayer excitons remained finite. These results indicate the formation of an exciton gas that does not condense into a superfluid. Our work demonstrates that dynamic optical spectroscopy provides a powerful tool for probing exciton transport behavior in correlated electron-hole fluids. Editor's summary: A pair of two-dimensional (2D) systems, one featuring electron carriers and the other hole carriers, separated by a thin insulating layer can host correlated interlayer excitons. Such excitons are predicted to exhibit superfluidity, as well as the so-called perfect Coulomb drag, in which the current in one layer causes an equal but opposite current in the other layer. Two studies have now observed nearly perfect drag at low temperatures in heterostructures consisting of molybdenum diselenide and tungsten diselenide layers separated by hexagonal boron nitride. Nguyen et al. used transport measurements, whereas Qi et al. relied on an optical technique. The studies enable further exploration of exciton transport in such heterostructures, including searching for superfluidity. —Jelena Stajic [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00368075 |
| DOI: | 10.1126/science.adl1839 |
