Stacking two-dimensional (2D) van der Waals (vdW) materials in a layered bulk structure provides an appealing platform for the emergence of exotic physical properties. As a vdW crystal with exceptional plasticity, InSe offers the opportunity to explore various effects arising from the coupling of its peculiar mechanical behaviors and other physical properties. Here, we employ neutron scattering techniques to investigate the correlations of plastic interlayer slip, lattice anharmonicity, and thermal transport in InSe crystals. Not only are the interlayer slip direction and magnitude well captured by shifts in the Bragg reflections, but we also observe a deviation from the expected Debye behaviour in the heat capacity and lattice thermal conductivity. Combining the experimental data with first-principles calculations, we tentatively attribute the observed evidence of strong phonon-phonon interactions to a combination of a large acoustic-optical frequency resonance and a nesting effect. These findings correlate the macroscopic plastic slip and the microscopic lattice dynamics, providing insights into the mechano-thermo coupling and modulation in 2D vdW materials.

在层状体结构中堆叠二维 (2D) 范德华 (vdW) 材料为奇异物理特性的出现提供了一个有吸引力的平台。作为一种具有卓越可塑性的 vdW 晶体，InSe 提供了探索其独特的机械行为和其他物理特性耦合产生的各种效应的机会。在这里，我们采用中子散射技术来研究 InSe 晶体中塑性层间滑移、晶格非和谐性和热传输的相关性。布拉格反射的变化不仅可以很好地捕获层间滑移方向和幅度，而且我们还观察到热容和晶格热导率与预期德拜行为的偏差。将实验数据与第一性原理计算相结合，我们暂时将观察到的强声子-声子相互作用的证据归因于大声光频率共振和嵌套效应的组合。这些发现将宏观塑性滑移与微观晶格动力学联系起来，为二维 vdW 材料中的力热耦合和调制提供了见解。