Metal-insulator transition in perovskite oxides: Tunneling experiments

Raychaudhuri, AK and Rajeev, KP and Srikanth, H and Gayathri, N (1995) Metal-insulator transition in perovskite oxides: Tunneling experiments. In: Physical Review B: Condensed Matter, 51 (12). pp. 7421-7428.

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Abstract

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 ?=eV* has a well-defined dependence on ?0, 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:	Journal Article
Publication:	Physical Review B: Condensed Matter
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	01 Jun 2011 05:50
Last Modified:	01 Jun 2011 05:50
URI:	http://eprints.iisc.ac.in/id/eprint/38097

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