https://doi.org/10.1140/epjp/s13360-025-06798-9
Regular Article
Multiphonon interactions and anisotropic thermal transport in GaXCl (X = S, Se, Te) monolayers
1
Department of Physics, Shaoyang University, 422000, Shaoyang, China
2
Hunan International Intellectual Exchange and Cooperation Center, 410013, Changsha, China
a
4190@hnsyu.edu.cn
b
xinghualee@139.com
Received:
21
May
2025
Accepted:
27
August
2025
Published online:
10
September
2025
We investigate phonon thermal transport in GaXCl (X = S, Se, Te) monolayers using density functional theory combined with Boltzmann transport equation by considering three- and four-phonon scattering. Our results reveal that three-phonon scattering is not sufficient to describe the anharmonic scattering of GaXCl. Particularly under high-temperature conditions, four-phonon scattering significantly suppresses their thermal transport properties, decreasing by more than 50% compared to the three-phonon baseline. The strong four-phonon scattering stems from the presence of large bandgap and quasi-flat band. Furthermore, GaXCl exhibits thermal anisotropy, which is especially pronounced in GaSCl. The room-temperature thermal conductivity 
of GaSCl along the yy direction is 7.62 W/mK, while that along the xx direction 
is 2.97 W/mK, with an anisotropy ratio as high as 2.65. The thermal conductivity of GaXCl gradually decreases as the X atom transitions from S to Se to Te. Such reduction of thermal conductivity stems from synergistic effect of low group velocity and strong phonon anharmonic scattering. Our study comprehensively sheds light on the anisotropic phonon thermal transport behavior of GaXCl (X = S, Se, Te) monolayers and emphasizes the importance of multiphonon transport in lattice anharmonicity of two-dimensional materials.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjp/s13360-025-06798-9.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
