Abstract:

　　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 review how the 1T-TaS2 was 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. Therefore, we conclude that the experimental observation of a pair of band edge resonance peaks on the Co atom provides further evidence that the monolayer 1T-TaSe2 is a charge insulator with gapless spinon excitations. In the rest of my talk, I will further introduce our latest study on the electronic density of states of a U(1) quantum spin liquid with spinon Fermi surface. 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.

[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 (Editor's Suggestion) in press.

[8] W.-Y. He and P. A. Lee, Phys. Rev. B (Editor's Suggestion) in press.

报告人简介：

　　贺文宇，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，赴麻省理工学院在Patrick A. Lee教授组担任博士研究员至2022年。2022年4月，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。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。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。