Xie L, Feng J H, Li R, He J Q
Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China.
School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Phys Rev Lett. 2020 Dec 11;125(24):245901. doi: 10.1103/PhysRevLett.125.245901.
We report a study of the anharmonic lattice dynamics in low lattice thermal conductivity (κ_{l}) material AgCrSe_{2} by many-body perturbation theory. We demonstrate surprisingly giant four-phonon scattering exclusive for the heat-carrying transverse acoustic phonons due to large quartic anharmonicity and nondispersive phonon band structure, which lead to four-phonon Fermi resonance and breaks the classical τ^{-1}∼ω^{m}T^{n} relation for phonon-phonon interactions. This strong resonant scattering extends over the Brillouin zone and substantially suppresses the thermal transport, even down to a low temperature of 100 K. The present results provide fundamental insights into the four-phonon resonant dynamics in the low-κ_{l} system with flat phonon dispersions, i.e., cuprous halides and skutterudites.
我们通过多体微扰理论报告了对低晶格热导率（κₗ）材料AgCrSe₂中非谐晶格动力学的一项研究。我们证明，由于大的四次非谐性和非色散声子能带结构，对于携带热量的横向声子存在惊人的巨大四声子散射，这导致了四声子费米共振，并打破了声子 - 声子相互作用的经典τ⁻¹∼ωᵐTⁿ关系。这种强共振散射扩展到布里渊区，并显著抑制热传输，甚至在低至100 K的低温下也是如此。目前的结果为具有平坦声子色散的低κₗ系统（即卤化亚铜和方钴矿）中的四声子共振动力学提供了基本见解。
