华中科技大学李小康团队研究了黑磷中准弹道声子的角度相关平面热霍尔效应。该项研究成果发表在2025年3月27日出版的《科学通报》上。

绝缘体中声子热霍尔效应的起源是一个持续争论的问题。元素非磁性固体（如黑磷（BP））中信号的大振幅要求一种不调用自旋自由度的最小机制。研究组表明，即使磁场、热流和热梯度位于同一平面内，纵向热流也会在BP中产生横向温度梯度。

声子平均自由程接近样品厚度。因此，点状对称破缺缺陷的散射不太可能起主要作用。研究组证明，当磁场平行于高对称性时，信号的角度依赖性可以映射到两个正弦分量的总和，每个分量都达到峰值。他们提出，非谐性可能起着重要作用，并认为磁场可以对与声子一起传播的电偶极波施加扭矩。

附：英文原文

Title: Angle-dependent planar thermal Hall effect by quasi-ballistic phonons in black phosphorus

Author: anonymous

Issue&Volume: 2025/03/27

Abstract: The origin of the phonon thermal Hall effect in insulators is a matter of ongoing debate. The large amplitude of the signal in an elemental non-magnetic solid, such as black phosphorus (BP), calls for a minimal mechanism not invoking the spin degree of freedom. Here, we show that a longitudinal heat flow generates a transverse temperature gradient in BP even when the magnetic field, the heat current and the thermal gradient lie in the same plane. The phonon mean-free-path is close to the sample thickness. Therefore, it is unlikely that scattering by point-like symmetry-breaking defects play a major role. We show that the angular dependence of the signal can be mapped to the sum of two sinusoidal components each peaking when the magnetic field is parallel to a high symmetry. We propose that anharmonicity may play a major role and argue that the magnetic field can exert a torque on electric dipolar waves traveling with phonons.

DOI: 10.1016/j.scib.2025.03.052

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927325003202