Anisotropic electron gas in a hyperbolic van der Waals material
- 1Centre for Nano Science and Technology, Fondazione Istituto Italiano di Tecnologia, Milano, Italy
Abstract
Electron gases in low-dimensional materials exhibit unusual optical and electronic phenomena arising from reduced dimensionality and enhanced interactions. While such states are typically engineered in quantum-confined systems and heterostructures, they rarely occur in naturally existing materials. Hyperbolic materials provide a unique platform where extreme lattice anisotropy can give rise to unconventional electronic states and electron-phonon interactions, yet experimental probes of their underlying electron dynamics remain limited. Here, we show that angle-resolved polarized Raman spectroscopy reveals anisotropic electron-phonon coupling in MoOCl2, a naturally occurring hyperbolic material whose optical response originates from a highly anisotropic electron gas. Pronounced polarization-dependent Fano line shapes reveal coherent coupling between optical phonons and an anisotropic electronic continuum. A microscopic model quantitatively reproduces the Raman spectra and identifies a distinct spectroscopic fingerprint of the anisotropic electron gas. Excitation-energy- and thickness-dependent measurements further reveal a tunable continuum with weak interlayer coupling. Our results establish Raman spectroscopy as a sensitive probe of electron-phonon interactions in naturally hyperbolic materials and anisotropic electron gases. Low-dimensional electron gases can give rise to unusual light-matter interactions, but naturally occurring examples are rare. Here, the authors show that Raman spectroscopy reveals a unique fingerprint of the strongly anisotropic electron gas in the hyperbolic material MoOCl2 through its interaction with lattice vibrations.
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BibTeX
@article{melchioni2026anisotropic,
title = {{Anisotropic electron gas in a hyperbolic van der Waals material}},
author = {Nicola Melchioni and Andrea Mancini and Antonio Ambrosio},
journal = {Communications Physics},
year = {2026},
month = aug,
doi = {10.1038/s42005-026-02802-5},
url = {https://doi.org/10.1038/s42005-026-02802-5},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Anisotropic electron gas in a hyperbolic van der Waals material
AU - Nicola Melchioni
AU - Andrea Mancini
AU - Antonio Ambrosio
PY - 2026
DA - 2026/08/10
JO - Communications Physics
DO - 10.1038/s42005-026-02802-5
UR - https://doi.org/10.1038/s42005-026-02802-5
AB - Electron gases in low-dimensional materials exhibit unusual optical and electronic phenomena arising from reduced dimensionality and enhanced interactions. While such states are typically engineered in quantum-confined systems and heterostructures, they rarely occur in naturally existing materials. Hyperbolic materials provide a unique platform where extreme lattice anisotropy can give rise to unconventional electronic states and electron-phonon interactions, yet experimental probes of their underlying electron dynamics remain limited. Here, we show that angle-resolved polarized Raman spectroscopy reveals anisotropic electron-phonon coupling in MoOCl2, a naturally occurring hyperbolic material whose optical response originates from a highly anisotropic electron gas. Pronounced polarization-dependent Fano line shapes reveal coherent coupling between optical phonons and an anisotropic electronic continuum. A microscopic model quantitatively reproduces the Raman spectra and identifies a distinct spectroscopic fingerprint of the anisotropic electron gas. Excitation-energy- and thickness-dependent measurements further reveal a tunable continuum with weak interlayer coupling. Our results establish Raman spectroscopy as a sensitive probe of electron-phonon interactions in naturally hyperbolic materials and anisotropic electron gases. Low-dimensional electron gases can give rise to unusual light-matter interactions, but naturally occurring examples are rare. Here, the authors show that Raman spectroscopy reveals a unique fingerprint of the strongly anisotropic electron gas in the hyperbolic material MoOCl2 through its interaction with lattice vibrations.
SN - 2399-3650
ER -