Novel Thermal Transport Phenomena in Quantum Materials

摘要：在固体中，电子不仅携带电荷，还携带热量和能量。电子的这种双重性质被证明是理解量子材料的有力工具。用热移动电子会产生电压或显示固体中的热传导。这些移动电子在磁场作用下可能进一步改变运动方向，导致横向电压和横向热传导。这些新的热输运性质是检测和探测强相关量子材料基态的重要步骤。该研究为研究强相关效应和拓扑之间的相互作用打开了大门，为未来的电子产品寻找新的量子相、新的拓扑相和新的多功能。该项目还提供了在该领域的科学和技术方面培养本科生和研究生的机会，预计在未来几年将有所增长。通过让本科生参与研究，让女性和少数族裔学生参与项目，并向更广泛的公众传播研究成果，该团队为公众带来了强相关材料的进展，并培养了对量子科学和凝聚态物理领域的兴奋、意识和兴趣。技术摘要：本研究项目旨在利用新型热输运特性研究强相关材料。结合强相关材料和拓扑量子材料的研究领域，研究小组将利用热电效应和热霍尔效应揭示最近观察到的强相关材料新现象的物理起源：(1)近藤绝缘体电阻率的量子振荡；(2)高温超导体未掺杂母化合物的莫特绝缘态存在较大的热霍尔效应；(3)铁基超导体的拓扑超导态。这些方向是凝聚态物理中长期存在的难题中令人兴奋的新进展。他们对电荷中性准粒子在强相互作用态中的作用有着同样的争论：是什么带来了这些有趣的现象：磁振子、声子和波格留波夫准粒子。研究任务将回答以下问题：(1)绝缘体中量子振荡的本质是什么？(2)是什么导致了近藤绝缘体中的类金属热输运？(3)为什么未掺杂铜的热流有霍尔信号？(4)铁基拓扑超导体中如何耦合量子反常涡？这些问题的答案揭示了强相互作用量子系统的基态。该研究还为探测强相关量子材料中的电荷中性准粒子提供了有效的方法，并揭示了这些材料系统的关键特性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract: In solids, electrons carry not only electrical charges but also heat and energy. This dual nature of electrons turns out to be a powerful tool to understand quantum materials. Moving the electrons with heat creates electrical voltages or reveals thermal conductions in the solids. These mobile electrons may further change the moving directions under a magnetic field, leading to transverse electrical voltages and transverse thermal conductions. These novel thermal transport properties are essential steps to detect and probe the ground state of strongly correlated quantum materials. The research brings the potential to open the door to study the interplay between strong-correlation effects and topology in the search for new quantum phases, novel topological phases, and new multi-functionalities for future electronics. The project also provides opportunities to train undergraduate and graduate students in the science and technology of this field anticipated to grow in the coming years. By involving undergraduates in research, integrating female and minority students in the projects, and communicating research to the broader public, the team brings the general public the advancements in strongly correlated materials and to develop excitement, awareness, and interest in the field of quantum science and condensed matter physics. Technical Abstract: The research project aims to investigate strongly correlated materials using novel thermal transport properties. Bridging the research fields of strongly correlated materials and topological quantum materials, the research team will use thermoelectric effect and thermal Hall effect to reveal the physical origin of recently observed novel phenomena of strongly correlated materials: (1) quantum oscillations in electrical resistivity of Kondo insulators; (2) large thermal Hall effects in Mott insulating state of the undoped parent compound of high-temperature superconductors, and (3) topological superconducting state in Fe-based superconductors. These directions are new exciting developments in long-standing puzzles in condensed matter physics. They share the same debate about the role of the charge-neutral quasiparticles in the strongly interacted states: what carries these interesting phenomena: magnon, phonon, and Bogoliubov quasiparticles. The research tasks will answer these questions: (1) What is the nature of the quantum oscillations in insulators? (2) What leads to the metal-like thermal transport in Kondo insulators? (3) Why are Hall signals of the heat flow in undoped cuprates? (4) How to couple to quantum anomalous vortices in Fe-based topological superconductors? The answers to these questions shed light on the ground state of the strongly interacted quantum systems. The research also leads to effective ways to probe charge-neutral quasiparticles in strongly correlated quantum materials and reveal the crucial characteristics in these material systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.