Title：Engineering topological electronics, photonics and optoelectronics based on two-dimensional van der Waals materials
Time：2022/10/19 (Wed.) 14:20
Place：Chee-Chun Leung Cosmology Hall 4F, NTU

Abstract:
Topology has been recognized to play an important role in providing novel routes to understanding and creating new quantum phases and phenomena in condensed matter physics. Recent advances in the development of two-dimensional (2D) atomic crystals from various van der Waals (vdW) materials have also simulated intense research efforts because of their unique properties for exploring the effects of different degrees of freedom on the quantum states of matter and their great promises for a wide range of technological applications. In this talk, I will describe our recent expeditions of engineering topological electronics, photonics, and optoelectronics based on 2D-vdW materials. For topological electronics, we develop valley-Hall transistors based on nanoscale strain-engineered single layer graphene [1] and discover a variety of new quantum phenomena associated with the topological electronic states in the presence of strain-induced giant pseudo-magnetic fields. In the case of topological photonics, we explore strong light-matter interactions in single-layer transition metal dichalcogenides (TMDs) with topological photons generated by optical and plasmonic vortices. [2,3] We will further describe how novel topological optoelectronic phenomena may be generated by applying spin-orbit coupling of light to the 2D-vdW materials and discuss potential technological applications of these topological electronics/photonic/optoelectronics.

References:
[1] “Nanoscale engineering of giant pseudo-magnetic fields, valley polarization and topological channels in strained graphene”, C.-C. Hsu, M. L. Teague, J.-Q. Wang, and N.-C. Yeh*, Science Advances 6, aat9488 (2020).
[2] “Dramatically enhanced valley-polarized emission of monolayer WS2 at room temperature with plasmonic Archimedes spiral nanostructures and gated control”, W.-H. Lin*, P. C. Wu, H. Akbari, G. R. Rossman, N.-C. Yeh*, and H. A. Atwater*, Advanced Materials 34 (3), 2104863 (2022).
[3] “Control of trion-to-exciton conversion in monolayer WS2 by orbital angular momentum of light”, R. Kesarwani, K. B. Simbulan, T.-D. Huang, Y.-F. Chiang, N.-C. Yeh*, Y.-W. Lan*, and T.-H. Lu*, Science Advances 8, eabm0100 (2022).