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Friday, September 21, 2018

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"Shining light on van der Waals materials"

"Shining light on van der Waals materials"

Fri, 09/21/2018 - 5:00pm
11M Conference Room – North West Corner
Hyunyong Choi
School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749, Korea

"Shining light on van der Waals materials"

In this talk, I will discuss how laser excitation can be used to manipulate the quantum degree of freedom in van der Waals materials. First part of this talk is about inversion-symmetry breaking in multi-layer transition metal dichalcogenides (TMD) and the associated non-local detection of valley-locked spin photocurrent in topological insulators (TI) using the characteristic spin-momentum locking [1]. In the second part, I will discuss the coherent exciton dynamics in group VII TMDs, where the broken in-plane symmetry plays a key role in observing the light-polarization-dependent phenomena [2,3]. Finally, I will show both intrinsic and extrinsic ways of manipulating the interaction dynamics between the surface and bulk states in TIs, where we have observed a strong Fano-like asymmetric response via optical-pump and terahertz (THz) probe spectroscopy. [4,5].


  • [1] Cha, S. et al. Nature Nanotechnology in press (2018).
  • [2] Sim, S. et al. Nature Communications 9, 351 (2018).
  • [3] Sim, S. et al. Nature Communications 7, 13569 (2016).
  • [4] Sim, S. et al. Nature Communications 6, 8814 (2015).
  • [5] In, C. et al. Nano Letters 18, 734 (2018).


About the speaker

Professor Hyunyong Choi received his B.S. degree in department of electrical and electronic engineering at Yonsei University in 2002. He did his M.S. and Ph.D. in department of electrical engineering and computer science at the University of Michigan, Ann Arbor (under Prof. Ted Norris) in 2004 and 2007, respectively, and postdocs at the Lawrence Berkeley National Laboratory until 2010. Since then, he has been working at Yonsei University as an Assistant Professor (2011.3-2015.8) and as an Associate Professor (2015.9-present).

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09/21/2018 - 5:00pm
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