Oxygen Isotope Fingerprints of Electron-Phonon Coupling in SrVO₃ Films

Transition metals exemplify correlated electronic systems, where electron-electron (𝑒−𝑒) scattering often results in a quadratic temperature dependence of the electrical resistivity, 𝜌⁡(𝑇) ∝𝑇2. In SrVO3 (SVO), a material with a 𝑉−3⁢d1 electronic configuration that ensures metallicity through narrow 3⁢𝑑−t2⁢𝑔 bands, a 𝜌⁡(𝑇) ∝𝑇2 dependence has been reported. While traditionally attributed to 𝑒−𝑒 scattering, recent studies suggest that electron-phonon (𝑒-ph) interactions may play a significant role. To unravel the influence of phonon interactions on carrier transport in SVO, we present a comparative study of the transport and optical properties of SVO films with partial substitution of 16O ions by their heavier isotope, 18O. Our findings reveal that 18O substitution induces a change in the slope of 𝑑⁢𝜌⁡(𝑇)/𝑑⁢𝑇 at nominal fixed carrier density, highlighting the dominant contribution of 𝑒-ph coupling over 𝑒−𝑒 scattering in determining 𝜌⁡(𝑇). Furthermore, it is found that the 18O substitution softens the phonon lattice and promotes a reduction in plasma frequency and an increase in the carrier effective mass. These results indicate that the 𝑒-ph coupling strength increases upon 18O substitution. Our findings suggest that 𝑒-ph interactions may surpass 𝑒−𝑒 scattering in governing the resistivity of metallic ionic lattices.