Special CMP Seminar: Shining light on van der Waals materials: symmetry and topology
| Date/Time: | Friday, 16 Nov 2018 from 9:30 am to 10:20 am |
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| Location: | Zaffarano A401 |
| Phone: | 515-294-7377 |
| Channel: | College of Liberal Arts and Sciences |
| Actions: | Download iCal/vCal | Email Reminder |
This talk is all about the "symmetry" and "topology". A key connector is Berry phase, which is easily parameterized as the quantum degrees of freedom (DoF) in van der Waals (vdW) materials. Followed by a brief introduction, focus will be made on the following exceptional observations when the vdW systems are taken out of equilibrium by optical excitation. (i) The spin-valley locking in vdW can be unlocked by circularly polarized optical excitation in the heterostructures of transition metal dichalcogenides (TMD) and topological insulators (TI) [1]. (ii) Broken in-plane symmetry in TMD enables to observe the excitonic quantum coherence, manifested by the quantum beats and optical Stark effect [2,3]. (iii) Symmetry protected Dirac surface in 3D TI provides extrinsic means for observing and exploiting the quansiparticle Fano interference [4,5].
References
[1] Cha, S. et al. Nature Nanotechnology 13, 910 (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).
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).