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arXiv · 2604.08382

Valley-controlled many-body exciton interactions in monolayer WSe$_2$ phototransistors

Daniel Vaquero·Cédric A. Cordero-Silis·Daniel Erkensten·Roberto Rosati·Martijn H. Takens·Kenji Watanabe·Takashi Taniguchi·Ermin Malic·Marcos H. D. Guimarães
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Abstract

Many-body exciton interactions shape the optoelectronic response of atomically-thin transition metal dichalcogenides, yet optical control of these interactions remains largely unexplored. To date, modulation of exciton-exciton interactions has primarily relied on electrical gating or van der Waals engineering. Here, we demonstrate all-optical control of many-body exciton interactions in monolayer WSe$_2$ via valley-selective excitation using polarization-resolved pulsed-laser photocurrent spectroscopy. Circular excitation selectively populates excitons in a single valley, whereas linear excitation populates both valleys, inducing a valley-dependent nonlinear photoresponse. We observe helicity-dependent exciton renormalization, alongside a two-fold enhancement of sublinear photocurrent scaling under circular excitation, reflecting single-valley population of interacting excitons. A microscopic model incorporating intervalley-exchange and exciton-exciton annihilation mediated by dark and bright exciton populations reproduces the nonlinear valley-selective response. These results establish the valley degree of freedom as an all-optical control parameter for tuning many-body excitonic effects and, exploring correlated exciton states and valleytronic applications in two-dimensional semiconductors.

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Daniel Vaquero, Cédric A. Cordero-Silis, Daniel Erkensten, Roberto Rosati, Martijn H. Takens, Kenji Watanabe, Takashi Taniguchi, Ermin Malic, Marcos H. D. Guimarães. 2026-04-09. Valley-controlled many-body exciton interactions in monolayer WSe$_2$ phototransistors. https://doi.org/10.1021/acs.nanolett.6c01091

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