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Extended hot-electron model and current bistability in insulating a−YxSi1−x films

Le Hong Hoàng To1, Andrés M. Somoza2, Shamashis Sengupta1, Louis Dumoulin1, Laurent Bergé1, Stefanos Marnieros1, Claire Akiko Marrache-Kikuchi1,*, and Miguel Ortuño2,†

  • *Contact author: claire.marrache@universite-paris-saclay.fr
  • †Contact author: moo@um.es
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Phys. Rev. Research 8, 023360 – Published 30 June, 2026

DOI: https://doi.org/10.1103/kdd3-6zsh

Abstract

Electron-phonon interactions play a central role in determining charge and heat transport in condensed matter systems, but in disordered and low-dimensional materials, this coupling can be strongly suppressed, leading to nontrivial transport phenomena. One striking manifestation is the appearance of bistable current-voltage (I−V) characteristics, where an imbalance between electrical heating and electron-phonon cooling yields multiple nonequilibrium steady states. In this work, we experimentally investigate this phenomenon in amorphous a−YxSi1−x thin films, where disorder can be tuned by thermal annealing. We identify the critical disorder at which bistability emerges and characterize the associated jumps in nonlinear I−V curves. To interpret these results, we develop a microscopic derivation of the phenomenological hot-electron model and extend it by incorporating electric-field-assisted hopping and phonon-mediated intergrain transitions, allowing quantitative agreement with experimental data across different disorder regimes. Complementary numerical simulations confirm the robustness of our extended framework. Our combined experimental, analytical, and numerical results provide a comprehensive description of electron-phonon decoupling and its impact on transport in disordered systems, offering a platform for studying nonequilibrium phases.

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Phys. Rev. Research 8, 023360– Published 30 June, 2026
  • Received 1 October 2025
  • Accepted 11 May 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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