Despite increased interest in thermal Hall measurements for the analysis of insulating quantum materials, there remains large uncertainty in such measurements due to contact misalignment. In this paper we propose that sample geometry and uncertain boundary conditions may account for uncertainty in the measurement of $D_{xy}$ or $κ_{xy}$ as well. By running simple simulations in an open source finite-element solver, we demonstrate that measured $D_{xy}$ in a thermal Hall bar can be changed by a factor of order unity in samples with similar width and length. This geometric corrective factor depends on the distinction between uniform heat flow and constant temperature boundary couplings to a bath. Sample geometry and boundary conditions can be accounted for through simulation or by using rectangular samples to make thermal Hall measurements more reliable and reproducible when the amplitude of $κ_{xy}$ is important. Finally, we propose a contactless optical method for measuring $D_{xy}$ which is insensitive to the longitudinal diffusivity pollution caused by contact misalignment.
Frequency-Dependent Photothermal Measurement of Transverse Thermal Diffusivity of Organic Semiconductors
我们已经使用了光热技术，其中斩波光加热的前表面的一个小的（~ 1 mm 2）样品和斩波频率依赖性的热辐射从背面测量与液氮冷却的红外探测器。在我们的系统中，样品直接放置在杜瓦瓶内的检测器前面。因为检测器对在样品周围或通过样品泄漏的一些入射光也敏感，所以对与斩波光正交的检测器信号进行测量。结果呈现为层状晶体的半导体6，13-双（三异丙基甲硅烷基乙炔基）并五苯（TIPS-PN）和纸的纤维素纳米原纤维涂覆有半导体聚（3，4-乙烯-二氧噻吩）：聚（苯乙烯-磺酸盐）（NFC-PEDOT）。对于NFC-PEDOT，我们已经发现，横向扩散率，小于面内值，与厚度成反比，这表明纸的纹理随厚度而变化。对于TIPS-pn，我们已经发现，层间扩散率是一个数量级大于面内值，与以前的估计一致，这表明低频光学声子，大概与TIPS侧群中的振动，携带大部分的热量。
Thermal Hall resistivity and transverse entropy production in a phonon gas
Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology（华中科技大学物理学院）；CPHT, CNRS, École polytechnique, Institut Polytechnique de Paris（巴黎理工学院）；Laboratoire de Physique et d’Étude de Matériaux (CNRS) ESPCI Paris, PSL Research University（巴黎高等物理化工大学）
Magnetic field induced modulation of heat transport in CrPS$_4$ probed by TaIrTe$_4$ transverse Seebeck thermometry
University of Groningen（格罗宁根大学）；Cavendish Laboratory, University of Cambridge（剑桥大学卡文迪许实验室）；School of Physics and Astronomy, University of Leeds（利兹大学物理与天文学院）
