Magnetic-Field-Induced Darkening of Bright Excitons in a MoWSe2 Monolayer Alloy
Abstract
Magnetic fields are widely used to brighten spin-forbidden dark excitons, but the inverse effect on an optically bright exciton has remained largely unexplored. We demonstrate the complementary phenomenon of magnetic-field-induced darkening of a bright exciton in Mo0.68W0.32Se2. At 4.2 K, an in-plane magnetic field up to 25 T activates a dark-exciton line 14.2±1.3 meV below the bright exciton while suppressing the bright-exciton emission by about 85\%. A bright-dark mixing model quantitatively captures the coupled energy and intensity evolution with an effective in-plane g factor of |g∥|=5.2±0.2. Alloying is crucial to the effect, as it brings the system close to the bright-dark crossover, where a small bright-dark splitting is combined with unusually strong in-plane magnetic coupling. This places the system in a regime where field-induced level repulsion raises the bright-like branch and strongly depletes its thermal population. These results identify a general route to magnetic control of exciton populations through engineering of the bright-dark hierarchy.
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BibTeX
@misc{olkowskapucko2026magneticfieldinduced,
title = {{Magnetic-Field-Induced Darkening of Bright Excitons in a MoWSe$_2$ Monolayer Alloy}},
author = {Katarzyna Olkowska-Pucko and Artur O. Slobodeniuk and Mehdi Arfaoui and Elena Blundo and Natalia Zawadzka and Łucja Kipczak and Jan Szpakowski and Diana Vaclavkova and Dipankar Jana and Piotr Kapuściński and Kenji Watanabe and Takashi Taniguchi and Clement Faugeras and Marek Potemski and Adam Babiński and Antonio Polimeni and Maciej R. Molas},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27469},
eprint = {2610.27469},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27469},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Magnetic-Field-Induced Darkening of Bright Excitons in a MoWSe_2 Monolayer Alloy
AU - Katarzyna Olkowska-Pucko
AU - Artur O. Slobodeniuk
AU - Mehdi Arfaoui
AU - Elena Blundo
AU - Natalia Zawadzka
AU - Łucja Kipczak
AU - Jan Szpakowski
AU - Diana Vaclavkova
AU - Dipankar Jana
AU - Piotr Kapuściński
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Clement Faugeras
AU - Marek Potemski
AU - Adam Babiński
AU - Antonio Polimeni
AU - Maciej R. Molas
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.27469
UR - https://arxiv.org/abs/2610.27469
AB - Magnetic fields are widely used to brighten spin-forbidden dark excitons, but the inverse effect on an optically bright exciton has remained largely unexplored. We demonstrate the complementary phenomenon of magnetic-field-induced darkening of a bright exciton in Mo_0.68W_0.32Se_2. At 4.2 K, an in-plane magnetic field up to 25 T activates a dark-exciton line 14.2±1.3 meV below the bright exciton while suppressing the bright-exciton emission by about 85\%. A bright-dark mixing model quantitatively captures the coupled energy and intensity evolution with an effective in-plane g factor of |g_∥|=5.2±0.2. Alloying is crucial to the effect, as it brings the system close to the bright-dark crossover, where a small bright-dark splitting is combined with unusually strong in-plane magnetic coupling. This places the system in a regime where field-induced level repulsion raises the bright-like branch and strongly depletes its thermal population. These results identify a general route to magnetic control of exciton populations through engineering of the bright-dark hierarchy.
ER -