dorsal/arxiv
View SchemaStrain-Driven "Sinusoidal" Valley Control of Hybridized $\Gamma -\mathrm{K}$ Excitons
| Authors | Yingtong Zhu, Kang Lan, Shiling Li, Ning Hao, Ping Zhang, Jiyong Fu |
|---|---|
| Categories | |
| ArXiv ID | 2601.09030vv1 |
| URL | https://arxiv.org/abs/2601.09030 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
The photoluminescence (PL) of momentum-indirect $\rm \Gamma- K$ excitons in monolayer WS$_2$ under biaxial strain was recently observed by Blundo et al. [Phys. Rev. Lett. 129, 067402 (2022)], yet its microscopic origin remains elusive. Here we develop a unified framework that reproduces the measured PL and reveals its fundamental excitonic mechanism. We reveal that: (i) the PL originates from genuinely hybridized direct-indirect excitonic eigenstates, rather than nominally mixed species with fixed dominant character; (ii) the direct exciton converts into the indirect one via a previously unrecognized two-step pathway -- exchange-interaction-driven exciton transfer followed by a spin flip; and (iii) a higher-energy indirect exciton, absent from prior studies, acts as a crucial intermediate mediating this conversion. Beyond explaining experiment, our theory predicts a striking strain-driven "sinusoidal'' valley response, furnishing a continuously tunable valley dial that far exceeds binary control schemes. This unified picture of strain-engineered direct-indirect exciton dynamics introduces a new paradigm for manipulating long-lived valley degrees of freedom, opening a pathway toward programmable valley pseudospin engineering and next-generation valleytronic quantum technologies.
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"abstract": "The photoluminescence (PL) of momentum-indirect $\\rm \\Gamma- K$ excitons in monolayer WS$_2$ under biaxial strain was recently observed by Blundo et al. [Phys. Rev. Lett. 129, 067402 (2022)], yet its microscopic origin remains elusive. Here we develop a unified framework that reproduces the measured PL and reveals its fundamental excitonic mechanism. We reveal that: (i) the PL originates from genuinely hybridized direct-indirect excitonic eigenstates, rather than nominally mixed species with fixed dominant character; (ii) the direct exciton converts into the indirect one via a previously unrecognized two-step pathway -- exchange-interaction-driven exciton transfer followed by a spin flip; and (iii) a higher-energy indirect exciton, absent from prior studies, acts as a crucial intermediate mediating this conversion. Beyond explaining experiment, our theory predicts a striking strain-driven \"sinusoidal\u0027\u0027 valley response, furnishing a continuously tunable valley dial that far exceeds binary control schemes. This unified picture of strain-engineered direct-indirect exciton dynamics introduces a new paradigm for manipulating long-lived valley degrees of freedom, opening a pathway toward programmable valley pseudospin engineering and next-generation valleytronic quantum technologies.",
"arxiv_id": "2601.09030",
"authors": [
"Yingtong Zhu",
"Kang Lan",
"Shiling Li",
"Ning Hao",
"Ping Zhang",
"Jiyong Fu"
],
"categories": [
"cond-mat.mes-hall"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "Strain-Driven \"Sinusoidal\" Valley Control of Hybridized $\\Gamma -\\mathrm{K}$ Excitons",
"url": "https://arxiv.org/abs/2601.09030",
"version": "v1"
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