ELECTRON-PHONON INTERACTION, LATTICE-DYNAMICS AND SUPERCONDUCTIVITY OF AN OXIDE SPINEL LITI2O4

The electron-phonon interaction of an oxide spinel LiTi2O4 is calculated on the basis of a realistic electronic band structure, which is obtained by the tight-binding model so as to reproduce the first-principles bands. The lattice dynamics of LiTi2O4 is studied by taking account of the effect of the electron-phonon interaction. Due to the characteristic dependences of the electron-phonon interaction on wavevectors and vibrational modes, a remarkable phonon frequency renormalization is found in the frequency range of 30-80 meV over a wide region of the Brillouin zone. By using the electron-phonon interaction and the renormalized phonon frequencies, the electron-phonon spectral function alpha2 F(omega) is calculated to provide a basis for understanding the superconductivity of LiTi2O4. The superconducting transition temperature, gap functions, tunneling spectra and other thermodynamic properties are studied by solving the Eliashberg equation. The calculated results are in good agreement with observations.