报告题目:Pair density wave state in a monolayer high-Tc iron-based superconductor
报告人：王健 教授（北京大学）
报告时间：2023年6月25日（周日）上午 10:00
报告地点：#腾讯会议：508-426-736
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 PDW order has not been experimentally observed in iron-based superconductors, another high-Tc superconductor family. 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 ~ 3.6aFe (aFe 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, 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 interplay between the correlated electronic states and unconventional Cooper pairing in high-Tc superconductors.
[1] Yanzhao Liu, Tianheng Wei, Guanyang He, Yi Zhang, Ziqiang Wang, and Jian Wang. arXiv:2209.04592 (2022). Nature in press.
报告人：王健，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）在二维高温超导中发现由玻色子主导的量子金属态，这一发现被认为结束了多年来是否存在玻色金属态的争议；3）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；4）在拓扑材料中发现随磁场呈对数周期的量子振荡，被称为凝聚态体系量子振荡研究历史上发现的第三种规律的量子振荡；5）在本征磁性拓扑材料中发现高陈数和高温量子反常霍尔效应，突破了之前量子反常霍尔效应陈数为1以及低工作温度的禁锢；等等。上述成果得到了国内外学术界高度认可：在Science、Nature 等期刊发表论文120多篇；荣获马丁·伍德爵士中国科学奖、教育部高校青年科学奖、全球华人物理与天文学会亚洲成就奖等。