08/21
2023
Seminar
- Title题目 Different charge density waves in emerging kagome materials
- Speaker报告人 谭恒心（Weizmann Institute of Science）
- Date日期 2023年8月21日 10:30
- Venue地点 南楼6620
Abstract摘要
Kagome materials with corner-shared triangular sublattices are fascinating because of their unique crystal and electronic structures. In this talk, I will first introduce the charge density wave (CDW) orders in the intriguing kagome metals AV3Sb5 (A = K, Rb, Cs), where the Fermi surface nesting mechanism is believed to be critical for the formation of CDW. I will also show the sizable three-dimensionality of the CDW phase by quantum oscillation calculations. Then I will introduce the different CDW orders in a newly-discovered kagome metal ScV6Sn6. We propose that the √3×√3×2 CDW is the ground state and the experimentally observed √3×√3×3 CDW is a meta-stable phase, which is approved immediately by experiments. The short-ranged essence of the √3×√3×2 CDW and failure in competition with the long-ranged √3×√3×3 CDW prevent it from being observed in low temperatures. Unlike CDWs in AV3Sb5, CDWs in ScV6Sn6 are induced purely by the phonon softening mechanism, though two van Hove singularity close to the Fermi level contributes considerable Fermi surface nesting. At last, I will show our most recent predictions on the unexpected surface charge orders in the isomorphism kagome compounds RV6Sn6 (R = Y, rare earth elements) compounds in the absence of bulk charge instability. These predictions reveal the possible breakdown of the characteristic kagome band features of a kagome layer when exposed to the surface and call for special attention to surfaces terminated with kagome layers.
References
[1] Hengxin Tan, Yizhou Liu, Ziqiang Wang, Binghai Yan. Charge Density Waves and Electronic Properties of Superconducting Kagome Metals, Phys. Rev. Lett. 127, 046401 (2021).
[2] Hengxin Tan, Yongkang Li, Yizhou Liu, Daniel Kaplan, Ziqiang Wang, Binghai Yan. Emergent topological quantum orbits in the charge density wave phase of kagome metal CsV3Sb5, npj Quantum Mater. 8, 39 (2023).
[3] Hengxin Tan and Binghai Yan. Abundant lattice instability in kagome metal ScV6Sn6, Phys. Rev. Lett. 130, 266402 (2023).
个人简介：
Hengxin Tan, obtained his Bachelor's degree in applied physics in 2013 from the Dalian University of Technology. In September of the same year, he joined Prof. Wenhui Duan's research group at Tsinghua University and obtained the Doctor's degree in condensed matter physics in December of 2018. Before moving to the Weizmann Institute of Science in Israel, he joined Prof. Stuart Parkin's research group at the Max-Planck Institute for microstructure physics in Halle (Saale) in Germany for postdoc research. He has been working with Prof. Binghai Yan in Weizmann since the summer of 2020. During Hengxin Tan's Ph.D., he worked on ferroelectrics/multiferroics and transition metal oxides from theory. In his postdoc period, he works theoretically on topological materials. He is currently focusing on explaining and predicting charge density wave orders in kagome metals.
邀请人：
吴贤新 副研究员
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