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arXiv · 2608.30164

Coexisting Large and Small Polarons in Photoexcited CeO$_2$

Valentina Mazzotti·Eleonora Spurio·Nicolas Delnour·Michael Hilke·Kirk H. Bevan·Alexander Shluger·Paola Luches·David G. Cooke
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Abstract

Time-resolved terahertz (THz) spectroscopy is used to probe polaron formation in CeO$_2$. The ultrafast THz photoconductivity is dominated by contributions from large hole and small electron polarons. Delocalized large hole polarons are formed on a $820 \pm 50$ fs time scale and are of Fr\"ohlich type, with optical conductivity well described by a simple Drude model and a transient hole mobility of $100$ cm$^2$/Vs. Small electron polarons form via localized coupling to Ce lattice sites, revealed by reduction in the lattice Born effective charge causing a transient phonon softening. These results establish the dual polaron nature of CeO$_2$ and provide a basis for understanding charge transfer dynamics in metal oxide photocatalysts.

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Valentina Mazzotti, Eleonora Spurio, Nicolas Delnour, Michael Hilke, Kirk H. Bevan, Alexander Shluger, Paola Luches, David G. Cooke. 2026-08-31. Coexisting Large and Small Polarons in Photoexcited CeO$_2$. https://arxiv.org/abs/2608.30164

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