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Yi Chen, UC Berkeley, "Single-layer 1T-TaSe2: Mottness, local moments, and spin liquid behavior"

Date and Time
Location
Elings Hall Room 1605
Hosted By
Andrea Young
Yi Chen

Speaker

Yi Chen
Department of Physics
University of California, Berkeley

Bio

Yi Chen is currently a doctoral candidate in Mike Crommie’s group at UC Berkeley where he uses local electronic probes to study single-layer transition metal dichalcogenides. Yi received his BS from Peking University.

Abstract

Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as quantum spin liquids and unconventional superconductivity. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here I will discuss local electronic characterization of the single-layer Mott insulator 1T-TaSe2 via scanning tunneling microscopy/spectroscopy. Our combined experimental and theoretical study indicates that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by novel real-space orbital texture [1]. By placing single-layer 1T-TaSe2 onto a single-layer metal, we observe a strong Kondo resonance peak at the Fermi level, verifying the existence of local moments in this 2D Mott insulator [2]. Finally, STM dI/dV imaging at the Hubbard band edges of single-layer 1T-TaSe2 reveals a new incommensurate superstructure with a wavevector close to 2kF of a half-filled spinon band, indicating a possible formation of a spinon-induced density wave [2, 3].

[1] Y. Chen*, W. Ruan*, M. Wu*, S. Tang*, H. Ryu, H. Z. Tsai, R. Lee, S. Kahn, F. Liou, C. Jia, O. R. Albertini, H. Xiong, T. Jia, Z. Liu, J. A. Sobota, A. Y. Liu, J. E. Moore, Z.-X. Shen, S. G. Louie, S.-K. Mo, and M. F. Crommie, “Strong Correlations and Orbital Texture in Single-layer 1T-TaSe2”, Nature Physics (2020) doi: 10.1038/s41567-019-0744-9.

[2] W. Ruan*, Y. Chen*, S. Tang, J. Hwang, H. Z. Tsai, R. Lee, H. Ryu, S. Kahn, F. Liou, C. Jia, C. Hwang, F. Wang, P. A. Lee, Z.-X. Shen, S.-K. Mo, and M. F. Crommie, “Imaging Spinons in a Two-dimensional Quantum Spin Liquid”, Under review.

[3] W.-Y. He, X. Y. Xu, G. Chen, K. T. Law, and P. A. Lee, “Spinon Fermi Surface in a Cluster Mott Insulator Model on a Triangular Lattice and Possible Application to 1T-TaS2”, Phys. Rev. Lett. 121, 046401 (2018).

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