Low temperature studies on normal perovskite oxides: role of correlation and disorder

Abstract

In this report we discuss the main results of low temperature transport and tunneling measurements in correlated metallic oxides belonging to the ABO₃ class. Electron-electron interaction in these metallic oxides gives rise to a T^½ term in the conductivity (ϐ) below 10 K. The tunneling conductance shows a characteristic cusp. In these materials the metallic state [ϐ(T=0)≠0] is retained for ϐ(T=0)<ϐ_Mott and dϐ/dT>0. Near the critical region of the metal-insulator transition we find that the conductivity ϐ(T) varies as ϐ₀+αT^m. However, away from the transition, m=½ and as ϐ_Mott, m→1/3 or 1/2.5 depending on the strength of magnetic scattering. But very close to the transition (ϐ₀«_Mott), m→1.