Excitron-Induced Pair Fluctuations Reveal Superconductivity in the Electron Gas

Yasutami Takada

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arXiv · 2608.08498

Excitron-Induced Pair Fluctuations Reveal Superconductivity in the Electron Gas

Yasutami Takada

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Abstract

Understanding how superconductivity can emerge in dilute electronic systems remains a central challenge in condensed matter physics. By performing first-principles calculations of the electron self-energy \Sigma(k,iw_n) in the low-density three-dimensional electron gas, we identify a sharp divergence at r_s ~ 8 and T ~ 10^{-4}E_ F, signaling a second-order phase transition. This critical behavior originates from one-dimensional superconducting fluctuations mediated by virtual excitations of an excitron---a quasi-1D electronic composite formed by an electron and longitudinal electron-hole pairs. Although the superconducting mechanism itself is plasmon-mediated, the excitron channel provides a unique window into its fluctuation dynamics. Near the transition, we observe a pseudogap and a linear-in-T inverse electron lifetime, reminiscent of phenomena in high-T_c materials. These results reveal an unexpected route by which plasmon-driven superconductivity manifests in the dilute 3D electron gas through quasi-1D excitron dynamics.

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Yasutami Takada. 2026-08-09. Excitron-Induced Pair Fluctuations Reveal Superconductivity in the Electron Gas. https://arxiv.org/abs/2608.08498

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