Role of electron-phonon interaction in lattice dynamics and superconductivity of oxide spinel LiTi₂O₄

The lattice dynamics of an oxide spinel LiTi₂O₄ is studied by taking account of the electron-phonon (EP) interaction derived on the basis of the realistic tight-binding bands fitted to the first-principles bands. Due to the characteristic dependences of the EP interaction on wavevectors and vibrational modes, a remarkable frequency renormalization of the O vibrational modes, which hybridize with the Ti vibrational modes, is obtained over a wide region of the Brillouin zone. The overall features of the calculated phonon density of states are in agreement with those observed by the inelastic neutron scattering measurements. By using the EP interaction and the renormalized phonon frequencies we have calculated the EP spectral function α²F(ω). The superconducting transition temperature, gap function, and tunneling spectra are calculated by solving the Éliashberg equation. The results agree well with the observations.