普林斯顿大学

摘要：

Twisted bilayer graphene (TBG) has shown two seemingly contradictory characters: (1) quantum-dot-like behavior in STM indicates localized electrons; (2) the transport experiments suggest the itinerant electrons. Two features can both be captured by a topological heavy-fermion model, in which the topological conduction electron bands couple to the local moments [1]. We study the local-moment physics and the Kondo effect in this model. We demonstrate that, at the integer fillings, the Kondo effect is irrelevant and the RKKY interactions stabilize long-range ordered states [2, 3]. However, at non-integer fillings, the Kondo effect is relevant [3, 4], and Kondo resonance appears in the single-particle spectrum. Based on the heavy-fermion model, we explore the transport properties of the TBG [5]. In addition, we demonstrate the critical role of f-electron spin, valley, and orbital fluctuations in inducing superconducting instability within the Kondo phase.

参考文献：

1. Z. Song, and B. A. Bernevig, Phy. Rev. Lett. 129, 047601 (2022).

2. H. Hu, B. A. Bernevig, and A. M. Tsvelik, Phys. Rev. Lett. 131, 026502 (2023). 3. G. Rai, et al., arXiv: 2309.08529 (2023).

4. H. Hu, et al., Phys. Rev. Lett. 131, 166501 (2023).

5. D. Calugaru, H. Hu, et al., arXiv:2402.14057 (2024).

报告人简介：

Dr. Haoyu Hu obtained his Ph.D. degree from Rice University in 2022 and then worked as a postdoctoral researcher at the Donosita International Physics Center. His research is centered around the study of the electron correlation effect and its interplay with band topology, with a particular emphasis on the kagome system and twisted bilayer graphene. Dr. Hu's work explores the novel correlation physics induced by the presence of topological flat bands.

联系人/邀请人：方辰（82649329）