Metal-insulator transition in perovskite oxides: A low-temperature perspective

A review is presented of recent experimental results of low temperature studies of composition driven metal-insulator transition in perovskite oxides of the ABO3 class. The evolution of physical properties like conductivity, tunnelling, density of states and magnetoconductivity has been studied at low temperatures (T 0. In this region the following important observations emerge. (1) It is possible to have a metallic state [σ(T = 0) = σ 0 ≠ 0] with σ 0/σ Mott ≪ 1 and dσ/dT > 0. (2) At T < 2 K the conductivity follows a power law σ ∼Tν , where the exponent can be related to the finite frequency response of a zero temperature phase transition. (3) The Coulomb interaction plays...