Two-dimensional ferroelectric crystal with temperature-invariant ultralow thermal conductivity
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912200653799424 |
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| author | Zhou, Wenjie Liu, Shi |
| author_facet | Zhou, Wenjie Liu, Shi |
| contents | We report the discovery of temperature-invariant ultralow thermal conductivity ($κ$) in monolayer $β'$-In$_2$Se$_3$, a two-dimensional ferroelectric crystal with in-plane polarization. Using a combination of generalized Wigner transport equation theory and machine-learning-assisted molecular dynamics simulations, we reveal that the balance between particle-like phonon propagating and wave-like tunneling transport mechanisms results in a propagating-tunneling-invariant (PTI) ultralow thermal conductivity of approximately 0.6 W/mK (comparable to that of glass) over a broad temperature range ($150<T<800$~K). This behavior stems from intrinsic strong lattice anharmonicity driven by ferroelectric dipolar fluctuations, eliminating the need for extrinsic structural modifications. In contrast, the $α$-In$_2$Se$_3$~monolayer, which shares the same stoichiometry, exhibits a conventional temperature-dependent thermal conductivity, $κ(T) \propto T^{-1}$, typical of simple crystals. Furthermore, we demonstrate that the anharmonicity in $β'$-In$_2$Se$_3$~can be precisely modulated by an external electric field, enabling on-demand control of thermal transport properties, including modifying the temperature scaling behavior of heat conductivity and achieving a large thermal switching ratio of $\approx$2.5. These findings provide fundamental insights into the interplay between field-tunable lattice anharmonicity, phonon dynamics, and thermal transport mechanisms. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2501_09990 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Two-dimensional ferroelectric crystal with temperature-invariant ultralow thermal conductivity Zhou, Wenjie Liu, Shi Materials Science We report the discovery of temperature-invariant ultralow thermal conductivity ($κ$) in monolayer $β'$-In$_2$Se$_3$, a two-dimensional ferroelectric crystal with in-plane polarization. Using a combination of generalized Wigner transport equation theory and machine-learning-assisted molecular dynamics simulations, we reveal that the balance between particle-like phonon propagating and wave-like tunneling transport mechanisms results in a propagating-tunneling-invariant (PTI) ultralow thermal conductivity of approximately 0.6 W/mK (comparable to that of glass) over a broad temperature range ($150<T<800$~K). This behavior stems from intrinsic strong lattice anharmonicity driven by ferroelectric dipolar fluctuations, eliminating the need for extrinsic structural modifications. In contrast, the $α$-In$_2$Se$_3$~monolayer, which shares the same stoichiometry, exhibits a conventional temperature-dependent thermal conductivity, $κ(T) \propto T^{-1}$, typical of simple crystals. Furthermore, we demonstrate that the anharmonicity in $β'$-In$_2$Se$_3$~can be precisely modulated by an external electric field, enabling on-demand control of thermal transport properties, including modifying the temperature scaling behavior of heat conductivity and achieving a large thermal switching ratio of $\approx$2.5. These findings provide fundamental insights into the interplay between field-tunable lattice anharmonicity, phonon dynamics, and thermal transport mechanisms. |
| title | Two-dimensional ferroelectric crystal with temperature-invariant ultralow thermal conductivity |
| topic | Materials Science |
| url | https://arxiv.org/abs/2501.09990 |