best365平台“博约学术论坛”系列报告第119期   
  (2016年第9期)

Title：Quantum oscillation in narrow-gap topological insulators
报告人：张龙（北京大学）
时   间：4月28日（周四）上午10：00
地   点：中心教学楼610
ABSTRACT
The canonical understanding of quantum oscillation in metals is challenged by the observation of de Haas-van Alphen effect in an insulator, SmB6 [Tan et al, Science 349, 287 (2015)]. Based on a two-band model with inverted band structure, we show that the periodically narrowing hybridization gap in magnetic fields can induce the oscillation of low-energy density of states in the bulk, which is observable provided that the activation energy is small and comparable to the Landau level spacing. Its temperature dependence strongly deviates from the Lifshitz-Kosevich theory. The nontrivial band topology manifests itself as a nonzero Berry phase in the oscillation pattern, which crosses over to a trivial Berry phase by increasing the temperature or the magnetic field. Further predictions to experiments are also proposed.
Curriculum Vitae
北京大学量子材料中心博士后，清华大学基础科学实验班本科，高等研究院博士毕业。研究方向为凝聚态理论，包括高温超导理论、量子磁性理论以及拓扑绝缘体理论。在PRL和PR.B等国际一流刊物发表论文多篇。

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