北京大学量子材料科学中心学术报告视频-- Long Ju

图|Long Ju

题目：Probing Topological Valley Physics in Bilayer Graphene

报告人： Long Ju

单位：麻省理工学院

时间：2019年1月8日

地点：北京大学

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报告摘要

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 charecterization 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 ID conducting channel exists at this structural domain wall, which can be attributed to the quantum valley Hall edge states in gapped bilayer grephene. 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.

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个人简介

Long Ju, 2005年毕业于清华大学物理系，2015年在加州大学伯克利分校取得物理学博士学位，2015年至2019年于康奈尔大学从事博士后研究，2019年1月正式入职麻省理工学院物理系任助理教授；其研究方向为新型二维材料机器异质结的基础物性研究。

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