Metal-insulator transition in perovskite oxides: tunneling experiments

Raychaudhuri, A. K. ; Rajeev, K. P. ; Srikanth, H. ; Gayathri, N. (1995) Metal-insulator transition in perovskite oxides: tunneling experiments Physical Review B: Condensed Matter and Materials Physics, 51 (12). pp. 7421-7428. ISSN 0163-1829

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In this paper we have investigated the composition-driven metal-insulator (MI) transitions in two ABO3 classes of perovskite oxides (LaNixCo1−xO3 and NaxTayW1−yO3) in the composition range close to the critical region by using the tunneling technique. Two types of junctions (point-contact and planar) have been used for the investigation covering the temperature range 0.4 K<T<4.2 K. We find that in both classes of materials the junction conductance G(V) [=dI/dV] decreases near the zero-bias region as the MI transition is approached. However, there is a fairly strong thermal-smearing effect near the zero-bias region for ||V||<10kBT/e. $G(V)- has been found to follow a power law of the type G(V)=G0(1+{||V||/V}n) with V=const and with n=0.5 for samples in the weak-localization region. However, as the critical region of the MI transition is approached G0→0 and n→1. We also find that for samples lying in the weak-localization region Δ=eV has a well-defined dependence on σ0, the zero-temperature conductivity. The observed behavior can be explained either as a manifestation of depletion of density of states at the Fermi level as the MI transition is approached or as a manifestation of strong inelastic scattering in the junction region.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:42694
Deposited On:06 Jun 2011 06:03
Last Modified:06 Jun 2011 06:03

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