Anisotropic strain relaxation-induced directional ultrafast carrier dynamics in RuO<sub>2</sub> films.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40577474.
- Also identified by DOI 10.1126/sciadv.adw7125 and PMC identifier 12204164.
- Licence recorded as CC BY-NC.
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Abstract
Ultrafast light-matter interactions inspire potential functionalities in picosecond optoelectronic applications. However, achieving directional carrier dynamics in metals remains challenging due to strong carrier scattering within a multiband environment, typically expected for isotropic carrier relaxation. In this study, we demonstrate epitaxial RuO<sub>2</sub>/TiO<sub>2</sub> (110) heterostructures grown by hybrid molecular beam epitaxy to engineer polarization selectivity of ultrafast light-matter interactions via anisotropic strain engineering. Combining spectroscopic ellipsometry, x-ray absorption spectroscopy, and optical pump-probe spectroscopy, we revealed the strong anisotropic transient optoelectronic response at an excitation energy of 1.58 eV in strain-engineered RuO<sub>2</sub>/TiO<sub>2</sub> (110) heterostructures along both in-plane [001] and [1[Formula: see text] 0] crystallographic directions. Theoretical analysis identifies strain-induced modifications in band nesting as the underlying mechanism for enhanced anisotropic carrier relaxation observed at this excitation energy. These findings establish epitaxial strain engineering as a powerful tool for tuning anisotropic optoelectronic responses with near-infrared excitations in metallic systems, paving the way for next-generation polarization-sensitive ultrafast optoelectronic devices.