第9回物理工学科教室談話会[Prof. Hiroyuki Nakamura・12/25(月)16:45～]

講　師：Prof. Hiroyuki Nakamura
所　属：Department of Physics, University of Arkansas, Fayetteville, USA
題　目：Shedding light on excitons in atomically thin materials
日　時：2023 年 12 月 25 日（月）16:45～
Date and Time：December 25, 2023 (Monday) 16:45-
場　所：工 6 号館 3 階セミナー室 A（対面のみ）
Place ：Seminar Room A, 3rd floor, Engineering Bldg.6（in-person only）

Abstract:
Exciton has gained a considerable interest as a quasiparticle to realize emergent physics as well as to enable future quantum photonic technologies. In this talk, I will first show the ultrafast dynamics of excitons in a Van der Waals heterostructure [1,2] (WSe2/graphene), directly observed in the momentum space by using the time-and-angle resolved photoelectron spectroscopy (trARPES). Next, I will share our recent work that focused on exciton-induced nonlinearity in atomically thin materials. Through a second-harmonic generation (SHG) spectroscopy in biaxially-strained monolayer MoX2 (X=S,Se), we observe unusual SHG signal that violates the conventional symmetry expected from the nonlinear Χ(2) tensor, which only emerges at an excitonic resonance [3].

[1] H. Nakamura et al., Phys. Rev. B 101, 165103 (2020).
[2] S. Dong et al., Nature Commun. 14, 5057 (2023).
[3] S. Puri, S. Patel, and H. Nakamura, in preparation.

紹介教員：木村 剛 教授（物理工学専攻）、長谷川 達生 教授（物理工学専攻）