DOE OSTI · 3387208
Two-component exciton condensates in an electron–hole bilayer
Abstract
Macroscopic quantum coherence emerges when bosons condense into a Bose–Einstein condensate (BEC). Excitons are a long-sought solid-state route to high-temperature BECs with strong interactions, electrical tunability and potentially multicomponent spinor order, but conclusive evidence for equilibrium condensation has remained elusive. Here we report evidence for two-component exciton BECs in MoSe 2 /hBN/WSe 2 electron–hole bilayers by probing the spin–valley susceptibility of constituent electrons and holes. This heterostructure hosts equilibrium exciton fluids with four spin–valley flavours. Magneto-optical spectroscopy in a dilution refrigerator reveals three exciton condensate phases with distinct flavour polarizations. At zero magnetic field, the many-body ground state is a coherent superposition of two condensed intravalley exciton flavours. Under a magnetic field, the intravalley exciton condensate first switches to a two-component intervalley condensate through a first-order quantum phase transition at a weak critical field and then turns into a fully polarized single-component condensate at high fields. The condensate signatures form a dome in density–temperature space, persisting up to approximately 1.8 K. Our results establish van der Waals electron–hole bilayers as a versatile platform for strongly interacting, multicomponent exciton BECs.
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Qi, Ruishi [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0009000013051104), Li, Qize [University of California, Berkeley, CA (United States)] (ORCID:0009000123520370), Nie, Jiahui [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Xia, Ruichen [University of California, Berkeley, CA (United States)], Kim, Haleem [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:000000032073029X), Lim, Hyungbin [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Xie, Jingxu [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0009000096912474), Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105), Watanabe, Kenji (ORCID:0000000337018119), Crommie, Michael F. [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)] (ORCID:0000000182463444), MacDonald, Allan H. [Univ. of Texas, Austin, TX (United States)] (ORCID:0000000335613379), Wang, Feng [University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Kavli Energy NanoScience Institute, Berkeley, CA (United States)] (ORCID:0000000183696194). 2026-06-10. Two-component exciton condensates in an electron–hole bilayer. https://doi.org/10.1038/s41586-026-10636-y
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