Superconductivity in SrTiO3: Dielectric Function Method for Non-Parabolic Bands
The dielectric function method for superconductivity has been applied to SrTiO3 accounting for the non-parabolic dispersion of charge carriers in the conduction band and for the dispersion of optical phonons based on density functional theory calculations. The obtained critical temperatures of the superconducting phase transition in SrTiO3 are in agreement with experiments in the density range n ∼ 5 × 1018 to 5 × 1020cm− 3. The dielectric function method predicts also the sign of the anomalous isotope effect in strontium titanate, in line with recent observations.