“前沿卓越”讲坛：2022年重庆大学前沿院

量子材料与器件前沿讲座（十一）

时间：2022年8月30日 星期二09:30-12:30

地点：腾讯会议ID: 246-169-463

Ultrahigh transverse thermoelectric power factor

in flexible Weyl semimetal WTe₂

主讲人：潘瑜 博士

报告摘要：

Topological electronic structures lay the foundation for new functionalities and are crucial for various applications, including thermoelectric energy conversion. In the past few decades, many good longitudinal thermoelectric materials have been demonstrated to be topological insulators. In recent years, with the emergence of topological semimetals, the transverse thermoelectric effect, Nernst effect, has attracted renewed attention. Compared to longitudinal thermoelectric effect, the transverse thermoelectric effect facilitates module fabrication. Though well known for their interesting physical properties, the mechanical properties of topological materials have rarely received attention. With the increasing demand for flexible electronics, we explore the great potential of the van der Waals bonded Weyl semimetal WTe₂for flexible thermoelectric applications. In this talk, I will introduce the thermoelectric properties of flexible WTe₂single crystals. It is found that WTe₂single crystals have an ultrahigh Nernst power factor of ~3 Wm^-1K^-2, which outperforms the conventional Seebeck power factors of the state-of-the-art thermoelectric semiconductors by 2–3 orders of magnitude. A unique band structure that hosts compensated electrons and holes with extremely high mobilities is the primary mechanism for this huge Nernst power factor. Moreover, a large Ettingshausen signal of ~5 × 10^-5KA^-1m is observed at 23.1 K and 9 T. Inspired by this work, we expect the potential applications of topological materials for flexible micro-/nano-thermoelectric devices.

报告人简介：

潘瑜，现于德国马克思普朗克化学固体物理所从事博士后研究，其中两年为德国洪堡学者，合作导师为Claudia Felser教授。2013年本科毕业于华中科技大学材料科学与工程学院，2018年获清华大学工学博士学位，博士研究方向为Bi₂Te₃基合金的热电输运与性能优化，导师为李敬锋教授，期间于美国西北大学访学一年，导师为G. Jeffrey Snyder教授。目前主要研究方向为热电材料输运特性、半金属新材料物理输运性质、新材料单晶生长等。共发表SCI论文30篇，其中2篇入选ESI高被引论文；以第一/通讯作者身份发表论文10篇，其中Nat. Mater.1篇，Nat. Commun.1篇，Adv. Mater.2篇，Energy Environ. Sci.2篇，Adv. Funct. Mater.1篇。

Higher-order topology and its control via light

主讲人：许东辉 副教授

报告摘要：

Topological phases with higher-order topology, as an extension of previously well-known topological phases of matter, have drawn great research interest in various fields of physics in very recent years. Higher-order topological phases host anomalous gapless boundary states (e.g., corner states and hinges states) which go beyond the celebrated bulk-boundary correspondence, a guiding principle in topological matter. Higher-order topology had been identified in both bulk gapped and gapless systems yet restricted to crystal structures. In this talk, I will first give a brief overview of the first-order and higher-order topological phases of matter. Then I will present our recent works on higher-order topology in aperiodic quasicrystals where we discovered a new class of higher-order topological insulators protected by forbidden rotational symmetries in a crystal, such as eightfold or twelvefold rotation symmetries. Next, I will discuss our recent studies of the realization of higher-order topological phases in exciton condensate and twisted bilayer honeycomb magnets. Finally, I will talk about how to manipulate semimetals with higher-order topology by using circularly polarized light.

主讲人简介：

许东辉，副教授，2005年毕业于潍坊学院获学士学位，2008年毕业于兰州大学获硕士学位，2012年毕业于浙江大学获博士学位，2012-2016年先后在浙江大学、香港科技大学从事博士后研究工作，2016-2022年在湖北大学任副教授，2022年3月入职重庆大学。从事凝聚态理论研究，主要研究方向为：拓扑量子物态、非传统超导体和相互电子系统。在美国物理学会Physical Review Letters, Physical Review A/B期刊发表上述方向研究论文40余篇。

量子材料在磁场下的横向输运响应及其应用

主讲人：李小康 博士

报告摘要：

本报告将分两部分进行介绍，第一部分将介绍拓扑反铁磁体Mn₃X (X= Sn, Ge)（金属体系）中的反常横向输运响应如反常霍尔效应、反常能斯特效应、反常里纪-勒杜克效应等奇异现象的发现、内禀机制及关联应用。第二部分主要介绍绝缘体系中声子热霍尔效应（SrTiO₃, cuprates,α-RuCl₃）的一些最新进展及争论。

主讲人简介：

李小康，2016年6月本科毕业于华中师范大学国家理科人才培养基地（物理学）；2020年6月直博提前毕业于华中科技大学凝聚态物理，导师朱增伟教授；2018年10月至2019年9月在法国巴黎高等工业物理化学院（ESPCI）联合培养交流一年，导师Kamran Behnia教授；2020年6月至2022年7月获国家博士后创新人才支持计划资助在华中科技大学国家脉冲强磁场科学中心开展博士后研究工作。截止目前，在国际著名学术期刊上累计发表高水平学术论文14篇，其中唯一第一作者论文6篇：分别为Phys. Rev. Lett.2篇，Nat. Commun.1篇，Adv. Mater.1篇，SciPost Phys.1篇以及Phys. Rev. B（Letter）1篇；主持博新计划、博士后面上项目、湖北省博士后创新研究岗位等博士后基金三项；在APS March Meeting等国际学术会议上做口头邀请报告达4次。目前主要研究兴趣是：量子材料的奇异电、热、磁性质探索，声子热霍尔效应的机理探索，横向热电堆装置的顶层结构设计与新原理探索等。