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Long Ju Assistant Professor(Massachusetts Institute of Technology).docx
发布时间:2019-01-11 浏览:

报告人:Long Ju Assistant ProfessorMassachusetts Institute of Technology

报告题目:Probing Topological Valley Physics in Bilayer Graphene



报告内容简介Graphene has been a model solid state system where novel quantum phenomena emerge from the interplay between symmetry, band topology and reduced dimensionality. In particular, AB-stacked bilayer graphene has a unique bandstructure with an electrically tunable bandgap and a valley-dependent Berry phase. These features result in unusual electrical and optical properties, for which optical spectroscopy/microscopy are powerful characterization tools. In this talk, I will first show our experimental demonstration of the topological valley transport at AB/BA stacking domain walls in bilayer graphene. By combining near field infrared nanoscopy with low temperature electron transport, we showed that a 1D conducting channel exists at this structural domain wall, which can be attributed to the quantum valley Hall edge states in gapped bilayer graphene. Moreover, I will present our recent efforts on probing the excitons in bandgap-tuned bilayer graphene through advanced optical spectroscopy tools. I will show that due to the electron pseudospin and Berry curvature effects, these excitons obey distinct valley-dependent optical selection rules from that in conventional semiconductors and feature a large valley g-factor of 20 in magnetic field.

报告人简介:巨龙,2009年毕业于清华大学物理系,2009-2015年于美国加州大学伯克利分校攻读博士学位,2015-2018年在美国康奈尔大学做博士后研究。主要研究方向为双层石墨烯物理性质的外场操控,曾在NatureScienceNature NanotechnologyNature MaterialsNano Letters等著名期刊发表学术论文十余篇