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Dark Exciton Dynamics in Atomically Thin 2D Materials
posted by Department of Physics for HKU and Public
Event Type: Public Lecture/Forum/Seminar/Workshop/Conference/Symposium
Event Nature: Science & Technology

Event Details

PHYSICS SEMINAR
===============

Dark Exciton Dynamics in Atomically Thin 2D Materials

Speaker: Prof. Ermin Malic
(Department of Physics, Chalmers University of Technology)

Abstract:

Monolayers of semiconducting transition metal dichalcogenides (TMDs) build a new class of atomically thin two-dimensional materials. They exhibit a remarkably strong Coulomb interaction giving rise to the formation of tightly bound excitons. In addition to regular bright excitonic states, there is also a variety of dark states that cannot be accessed by light due to the required momentum-transfer or spin-flip.

To model the exciton physics in TMD monolayers, we apply a microscopic approach combining semiconductor Bloch equations with the Wannier equation providing access to time- and momentum-resolved optical response and the non-equilibrium dynamics in TMDs. In this talk, we review our recent work focusing on:
(i) Uncovering the full exciton landscape including bright as well as momentum- and/or spin-forbidden dark excitonic states [1].
(ii) Demonstrating signatures of dark excitonic states by probing the intra-excitonic 1s-2p transition directly after optical excitation and after exciton thermalization [2].
(iii) Activating momentum-forbidden dark excitonic states via efficient coupling with molecules suggesting a dark-exciton-based sensing mechanism for molecules [3].
(iv) Providing a fully quantum mechanical description of formation, thermalization, and photoemission of interlayer excitons in TMD-based heterostructures [4,5].

[1] E. Malic, M. Selig, M. Feierabend, S. Brem, D. Christiansen et al., Phys. Rev. Materials 2, 014002 (2018).
[2] G. Berghaeuser, P. Steinleitner, P. Merkl, R. Huber, A. Knorr, and E. Malic, arXiv: 1708.07725 (2017).
[3] M. Feierabend, G. Berghäuser, A. Knorr, E. Malic, Nature Commun. 8, 14776 (2017).
[4] M. Selig G. Berghaeuser, M. Richter, R. Bratschitsch, A. Knorr, E. Malic, 2D Mater. 5, 035017 (2018).
[5]S. Brem, G. Berghaeuser, M. Selig, E. Malic, Sci. Rep. 8, 8238 (2018).

Anyone interested is welcome to attend.

Coffee and tea will be served 20 minutes prior to the seminar.

Date/Time12/07/2018 16:00-17:00
VenueRm 522, 5/F, Chong Yuet Ming Physics Building, HKU
LanguageEnglish

Registration Instruction

Registration is not required.

Contact Information

Should you have any enquiries, please feel free to contact Ms. Eva Wong by email at physdept@hku.hk or by phone at 2859 2360 or by fax at 2559 9152.