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arXiv · 1901.04431

Probing and manipulating valley coherence of dark excitons in monolayer WSe$_2$

M. R. Molas·A. O. Slobodeniuk·T. Kazimierczuk·K. Nogajewski·M. Bartos·P. Kapuściński·K. Oreszczuk·K. Watanabe·T. Taniguchi·C. Faugeras·P. Kossacki·D. M. Basko·M. Potemski
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Abstract

Monolayers of semiconducting transition metal dichalcogenides are two-dimensional direct-gap systems which host tightly-bound excitons with an internal degree of freedom corresponding to the valley of the constituting carriers. Strong spin-orbit interaction and the resulting ordering of the spin-split subbands in the valence and conduction bands makes the lowest-lying excitons in WX$_2$ (X~being S or Se) spin-forbidden and optically dark. With polarization-resolved photoluminescence experiments performed on a WSe$_2$ monolayer encapsulated in a hexagonal boron nitride, we show how the intrinsic exchange interaction in combination with the applied in-plane and/or out-of-plane magnetic fields enables one to probe and manipulate the valley degree of freedom of the dark excitons.

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M. R. Molas, A. O. Slobodeniuk, T. Kazimierczuk, K. Nogajewski, M. Bartos, P. Kapuściński, K. Oreszczuk, K. Watanabe, T. Taniguchi, C. Faugeras, P. Kossacki, D. M. Basko, M. Potemski. 2019-01-14. Probing and manipulating valley coherence of dark excitons in monolayer WSe$_2$. https://doi.org/10.1103/physrevlett.123.096803

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