报告题目：Pair density wave state in a monolayer high-Tc iron-based superconductor

报告时间：2023年9月15日（本周五）16:00

报告地点：鼓楼校区科技馆二楼报告厅

报  告 人：王健，北京大学

摘要：The pair density wave (PDW) is an extraordinary superconducting state where Cooper pairs carry nonzero momentum. Theoretically, the PDW order is hypothesized to play a fundamental role in high-temperature (high-Tc) cuprate superconductors, wherein experimental evidence of the PDW state has been reported. However, the evidence of PDW order is scarce in iron-based high-Tc superconductors and low dimensional superconductors. Here, using scanning tunneling microscopy/spectroscopy, we report the discovery of the PDW state in monolayer iron-based high-Tc Fe(Te,Se) films grown on SrTiO₃(001) substrates ^[1]. The PDW state with a period of λ ~ 3.6a_Fe (a_Fe  is the distance between neighboring Fe atoms) is observed at the domain walls by the spatial electronic modulations of the local density of states, superconducting coherence peak height and gap energy. Moreover, the π-phase shift boundaries of the PDW state are observed near the vortices of the induced secondary charge density wave state, further demonstrating that the PDW state at the domain wall is a primary state. The discovery of the primary PDW state in the monolayer Fe(Te,Se) film provides a low-dimensional platform to study the PDW state and its interplay with the topological electronic states and unconventional high-Tc superconductivity.

[1] Yanzhao Liu, Tianheng Wei, Guanyang He, Yi Zhang, Ziqiang Wang, and Jian Wang.Nature 618, 934-939 (2023).

报告人简介：王健博士是北京大学博雅特聘教授。2010年起在北大成立独立研究组，建立了极低温强磁场量子输运与分子束外延-扫描隧道显微镜联合实验室，围绕低维超导与拓扑材料的物性，在新奇量子物态与量子相变方面取得了一系列重要的原创性发现。代表性工作包括：1）在二维单晶超导体中发现，逼近绝对零温时，无序引起动力学临界指数在相变临界点发散，这种新的量子相变被称为量子格里菲斯奇异性，被认为是二维超导领域三个重要主题之一；2）在二维超导中证实存在玻色子主导的量子金属态；3）在单层铁基高温超导薄膜中直接观测到由非零动量库珀对形成的、超导序参量周期性调制的配对密度波态；4）在拓扑半金属表面调制出超导以及在二维高温超导薄膜中发现拓扑零能激发态；5）在拓扑材料中发现随磁场呈对数周期的新规律的量子振荡，以及在本征磁性拓扑材料器件中发现高陈数和高温陈绝缘体态等。上述成果得到了国内外学术界高度认可：在Science、Nature、Nature Physics等期刊发表学术论文120多篇，国内外学术会议上做邀请报告100多次；荣获马丁·伍德爵士中国科学奖（2015）、教育部长江特聘教授（2016）、教育部高校青年科学奖（2019）、全球华人物理和天文学会亚洲成就奖（2022）等。

主办：南京大学物理学院

联系人：奚啸翔，xxi@nju.edu.cn