Plasmon-driven exciton formation in a non-equilibrium Fermi liquid
Abstract
Collective modes in Fermi liquids are usually regarded as dissipation channels that relax electronic excitations through Landau damping. Whether such modes can instead mediate the formation of correlated electronic states under non-equilibrium conditions remains an open question. Here we show that, under optical photo-doping, a bulk plasmon can drive correlated inter-band transfer within a transient electronic continuum. Using time- and angle-resolved photoemission spectroscopy (Tr-ARPES) on EuCdAs supported by electronic structure calculations, we observe that at high excitation density, plasmons transfer energy from a weakly dispersing bulk band into unoccupied surface states. This bulk-to-surface redistribution stabilizes a long-lived, energy-localized spectral feature consistent with a Mahan exciton. Our results uncover a non-equilibrium regime of Fermi-liquid physics in which collective modes do not merely dissipate energy, but also stabilize correlated bound states.
Cite
@article{arxiv.2603.10108,
title = {Plasmon-driven exciton formation in a non-equilibrium Fermi liquid},
author = {Rishi Acharya and Eli Gerber and Nina Bielinski and Hannah E. Aguirre and Younsik Kim and Camille Bernal-Choban and Gaurav Tenkila and Suhas Sheikh and Pranav Mahaadev and Faren Hoveyda-Marashi and Subhajit Roychowdhury and Chandra Shekhar and Claudia Felser and Peter Abbamonte and Benjamin J. Wieder and Fahad Mahmood},
journal= {arXiv preprint arXiv:2603.10108},
year = {2026}
}
Comments
Main Text (including End Matter and references) and Supplementary Materials (11 + 26 pages, 6 + 13 figures, 0 + 3 tables)