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Excitonic-Superconducting Coexistence and Emergent Nematic Superconductivity Driven by Spontaneous Symmetry Breaking

Fei Yang1,*, Ruigang Li2,*, Junwei Liu1,†, and Binghai Yan3,4,‡

  • *These authors contributed equally to this work.
  • †Contact author: liuj@ust.hk
  • ‡Contact author: binghai.yan@psu.edu
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Phys. Rev. Lett. 137, 206001 – Published 12 November, 2026

DOI: https://doi.org/10.1103/fnnn-n593

Abstract

Excitonic insulating (EI) and superconducting (SC) orders are generally regarded as mutually exclusive electronic instabilities. Within a self-consistent microscopic theory, we study electronic systems hosting an EI phase in the presence of SC pairing and show that an intrinsic mismatch between electron and hole Fermi surfaces fundamentally reshapes this competition. This mismatch stabilizes Fulde-Ferrell-Larkin-Ovchinnikov-like electron-hole pairing and drives spontaneous symmetry breaking of the EI state. The resulting symmetry breaking reconstructs the pairing phase space for SC and EI state, such that different regions of the Fermi surface complementarily support either EI or SC correlations, leading to a natural coexistence of the two orders. Notably, the emergent SC state consequently breaks rotational symmetry and develops intrinsic nematic superconductivity, even in the absence of explicit symmetry-breaking fields (such as magnetic fields, spin-orbit coupling, or bare band-structure anisotropy). Our results suggest that candidate materials such as monolayer 1T′−MoTe2 and the square-net semimetal NaAlSi may provide promising platforms for observing this phenomenon. More broadly, these findings reveal a unique mechanism by which competing many-body orders generate electronic nematicity, suggesting a broader route toward spontaneous anisotropic electronic states in correlated quantum materials.

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Phys. Rev. Lett. 137, 206001– Published 12 November, 2026
  • Received 1 June 2026
  • Accepted 27 October 2026
Article part of CHORUS
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