Normal and Superconducting state of doped Strontium Titanate

Abstract

SrTiO is one of the most extensively studied perovskite oxides. Charge transport in the normal state and the origin of superconductivity are however still a source of debate in this material. In the first part of the talk, we present a combined theoretical and experimental study of specific heat and transport in the normal state, across a wide range of doping. On one hand, the Sommerfeld coefficients are consistent with a weakly correlated Fermi liquid across the entire doping range. On the other hand, combined with the T-square transport coefficient the Kadowaki-Woods scaling breaks down, implying an unusual mechanism for the T-square resistivity. Recent experimental work has led to new effort to understand the mechanism behind the most dilute superconducting semiconductor. In the second part of the talk, we consider the Bardeen-Pines interaction and explore how the instability in the superconducting channel is affected when the Fermi energy of the electrons is smaller than the characteristic phonon frequency.