主讲人：贺文宇 研究员（上海科技大学）

题目：Quantum Spin Liquid Physics in 1T-TaS₂/TaSe₂

时间：2023年07月03日（周一）下午14：00

地点：理工楼1201报告厅

联系人：钟寅

报告摘要：

Quantum spin liquid phase has been a long sought exotic state of matter since 1980s. Recently, it was predicted that in the transition metal dichalcogenides 1T-TaS₂[1], the ground state of its Mott insulating phase is a U(1) quantum spin liquid with spinon Fermi surface [2]. In this talk, I will briefly review how the 1T-TaS₂was proposed as a quantum spin liquid candidate in 2017, and further introduce the recent studies on the related material: monolayer 1T-TaSe₂[3,4]. I will talk about the recent tunneling spectroscopy measurements on the Co atom embedded on the monolayer 1T-TaSe₂[5] and present our explanation to the pair of band edge resonance peaks observed in the experiment [6]. I will show that the spinon Kondo resonance on the magnetic impurity combined with the gauge field fluctuations in the spin liquid can give rise to a pair of band edge resonance peaks observed in the experiment. In the rest of my talk, I will further introduce our latest study of the magnetic field effects on the electronic density of states of a quantum spin liquid. I will talk about the Landau quantization signature of the spinon Fermi surface [7] and the anomalous Zeeman response [8] in the U(1) gapless quantum spin liquid. The connection between our theoretical simulations and a recent scanning tunneling spectroscopy measurement [9] will be presented.

[1] K. T. Law and P. A. Lee, Proc. Natl. Acad. Sci. (USA) 114, 6996 (2017).

[2] W.-Y. He, X. Y. Xu, G. Chen, K. T. Law, and P. A. Lee, Phys. Rev. Lett. 121, 046401 (2018).

[3] Y. Chen et al., Nat. Phys. 16, 218 (2020).

[4] W. Ruan et al., Nat. Phys. 17, 1154 (2021).

[5] Y. Chen*, W.-Y. He*, W. Ruan* et al., Nat. Phys. 18, 1335 (2022).

[6] W.-Y. He and P. A. Lee, Phys. Rev. B 105, 195156 (2022).

[7] W.-Y. He and P. A. Lee, Phys. Rev. B 107, 195155 (2023). Editor’s suggestion.

[8] W.-Y. He and P. A. Lee, Phys. Rev. B 107, 195156 (2023). Editor’s suggestion.

[9] C. J. Butler, M. Yoshida, T. Hanaguri, and Y. Iwasa, Phys. Rev. B 107, L161107 (2023).

个人简介：

贺文宇博士2013年本科毕业于北京师范大学物理学系，2018年博士毕业于香港科技大学物理学系，并在香港科技大学物理学系担任博士后研究员至2020年。随后，他赴麻省理工学院在Patrick A. Lee教授组担任博士研究员至2022年。在2022年四月，他加入上海科技大学物质科学与技术学院担任助理教授、研究员。贺文宇博士的研究领域集中在凝聚态物理，主要以二维过渡金属硫化物、双层有转角石墨烯和二维莫尔超晶格体系等二维量子材料为平台，研究其中出现的拓扑态、超导态和电子强关联效应。他的研究内容关注预言材料中的新物性和新物相，以及对实验中观测到的新现象提供物理解释。