Raman study of electron-phonon coupling in thin films of the spinel oxide superconductor LiTi2O4

We performed a Raman scattering study of thin films of ${\mathrm{LiTi}}_{2}{\mathrm{O}}_{4}$ spinel oxide superconductor. We detected four out of five Raman active modes, with frequencies in good accordance with our first-principles calculations. Three ${\mathrm{T}}_{2g}$ modes show a Fano lineshape from 5 K to 295 K, which suggests an electron-phonon coupling in ${\mathrm{LiTi}}_{2}{\mathrm{O}}_{4}$. Interestingly, the electron-phonon coupling shows an anomaly across the negative to positive magnetoresistance transition at 50 K, which may be due to the onset of other competing orders. The strength of the electron-phonon interaction estimated from the Allen's formula and the observed lineshape parameters suggest that the three ${\mathrm{T}}_{2g}$ modes at 0 momentum are not sufficient to drive superconductivity.