Quantum corrections to the conductivity in a perovskite oxide: a low-temperature study of LaNi1−xCoxO3(0≤x≤0.75)

Rajeev, K. P. ; Raychaudhuri, A. K. (1992) Quantum corrections to the conductivity in a perovskite oxide: a low-temperature study of LaNi1−xCoxO3(0≤x≤0.75) Physical Review B: Condensed Matter and Materials Physics, 46 (3). pp. 1309-1320. ISSN 0163-1829

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Official URL: http://prb.aps.org/abstract/PRB/v46/i3/p1309_1

Related URL: http://dx.doi.org/10.1103/PhysRevB.46.1309

Abstract

In this paper we propose to study the evolution of the quantum corrections to the conductivity in an oxide system as we approach the metal-insulator (M-I) transition from the metallic side. We report here the measurement of the low-temperature (0.1 K<T<100 K) electrical conductivity of the perovskite-structure oxide system LaNi1−x CoxO3 (0≤x≤0.75). LaNiO3 is a metal and LaCoO3 is an insulator. The system is metallic for x≤0.65. For all x, at low temperatures, the conductivity (σ) rises with temperature (T). Below 2 K, σ follows a power-law behavior, σ(T)=σ(0)+αTm. For samples in the metallic regime, away from the metal-insulator transition (x≤0.4), m≊0.3-0.4. As the transition is approached [i.e., σ(0)→0], m increases rapidly; and at the transition [σ(0)=0, xc≊0.65], m≊1. On the insulating side (x>0.65), m takes on large values and σ(0)=0. We explain the temperature dependence of σ(T), for T<2 K, on the metallic side (x≤0.4), as arising predominantly from electron-electron interactions, taking into account the diffusion-channel contribution (which gives m=0.5) as well as the Cooper-channel contribution. In this regime, the correction to conductivity, δσ(T), is a small fraction of σ(T). However, as the M-I transition is approached (x→xc), δσ(T) starts to dominate σ(T) and the above theories fail to explain the observed σ(T).

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