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

The electron-phonon interaction of an oxide spinel LiTi2O4 is calculat ed on the basis of a realistic electronic band structure, which is obt ained by the tight-binding model so as to reproduce the first-principl es bands. The lattice dynamics of LiTi2O4 is studied by taking account of the effect of the electron-phonon interaction. Due to the characte ristic dependences of the electron-phonon interaction on wavevectors a nd vibrational modes, a remarkable phonon frequency renormalization is found in the frequency range of 30-80 meV over a wide region of the B rillouin zone. By using the electron-phonon interaction and the renorm alized phonon frequencies, the electron-phonon spectral function alpha 2 F(omega) is calculated to provide a basis for understanding the supe rconductivity of LiTi2O4. The superconducting transition temperature, gap functions, tunneling spectra and other thermodynamic properties ar e studied by solving the Eliashberg equation. The calculated results a re in good agreement with observations.