https://doi.org/10.1140/epjb/s10051-025-00941-2
Regular Article - Solid State and Materials
Plasmon-sound hybridization in ionic crystals
Institut für Theoretische Physik, Universität Frankfurt, Max-von-Laue Straße 1, 60438, Frankfurt, Hesse, Germany
a
rueckriegel@itp.uni-frankfurt.de
Received:
24
January
2025
Accepted:
27
April
2025
Published online:
13
May
2025
We study the hybridization between plasmons, phonons, and electronic sound in ionic crystals using the Debye model, where the ionic background is modeled as a homogeneous, isotropic, elastic medium. We explicitly obtain the energies and the damping of the hybrid plasmon-sound modes in the hydrodynamic regime and calculate the corresponding dynamic structure factor. We find that with increasing viscosity, a plasmon-like mode quickly decays into a broad, incoherent background, while a phonon-like mode with linear dispersion remains rather sharp. The quantitative behavior of the hybridized collective modes depends on the ratio of the electronic and the ionic plasma frequencies. We also show that the direct Coulomb interaction between the ions is essential to obtain a collective sound mode with linear dispersion.
© The Author(s) 2025
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