近日，以色列魏茨曼科学研究所的E.Zeldov及其研究团队取得一项新进展。经过不懈努力，他们实现范德华半金属中低温磁热电冷却的证明和成像。相关研究成果已于2024年3月8日在国际知名学术期刊《自然—物理学》上发表。
该研究团队成功开发出纳米级低温成像技术，用于研究磁热电效应，并在液氦温度下，验证了剥离的WTe2 Weyl半金属薄片展现出的绝对冷却和Ettingshausen效应。相较于块状材料，冷却效果在磁场和器件尺寸影响下呈现出非单调的特性。
进一步的研究揭示，该介观半金属器件的磁热电模型中，冷却效率与诱导温度分布受到样品几何形状、电子-空穴复合长度、磁场强度以及薄片和衬底导热系数等多重因素的相互作用影响。这些重要发现为微观热电冷却技术的直接集成，以及范德华器件温度景观工程的实现，开辟了崭新的道路。
据悉，在低温下实现可行的热电冷却对于电子和量子材料的应用具有重要的基础和技术意义。与传统的全局冷却相比，设备内温度控制可以提供更有效和精确的热环境管理。通过施加电流和垂直磁场，在样品的一侧产生电子-空穴对而产生冷却，并由于它们在另一侧的复合而产生加热，这就是众所周知的Ettingshausen效应。
附：英文原文
Title: Demonstration and imaging of cryogenic magneto-thermoelectric cooling in a van der Waals semimetal
Author: Vlkl, T., Aharon-Steinberg, A., Holder, T., Alpern, E., Banu, N., Pariari, A. K., Myasoedov, Y., Huber, M. E., Hcker, M., Zeldov, E.
Issue&Volume: 2024-03-08
Abstract: Attaining viable thermoelectric cooling at cryogenic temperatures is of considerable fundamental and technological interest for electronics and quantum materials applications. In-device temperature control can provide more efficient and precise thermal environment management compared with conventional global cooling. The application of a current and perpendicular magnetic field gives rise to cooling by generating electron–hole pairs on one side of the sample and to heating due to their recombination on the opposite side, which is known as the Ettingshausen effect. Here we develop nanoscale cryogenic imaging of the magneto-thermoelectric effect and demonstrate absolute cooling and an Ettingshausen effect in exfoliated WTe2 Weyl semimetal flakes at liquid He temperatures. In contrast to bulk materials, the cooling is non-monotonic with respect to the magnetic field and device size. Our model of magneto-thermoelectricity in mesoscopic semimetal devices shows that the cooling efficiency and the induced temperature profiles are governed by the interplay between sample geometry, electron–hole recombination length, magnetic field, and flake and substrate heat conductivities. The observations open the way for the direct integration of microscopic thermoelectric cooling and for temperature landscape engineering in van der Waals devices.
DOI: 10.1038/s41567-024-02417-z
Source: https://www.nature.com/articles/s41567-024-02417-z