# Tunnelling studies on sodium tungsten bronzes near the metal-insulator transition

Srikanth, H and Raychaudhuri, AK (1993) Tunnelling studies on sodium tungsten bronzes near the metal-insulator transition. In: Journal of Physics: Condensed Matter, 5 (44). L551-L558.

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## Abstract

We present measurements of tunnelling conductances (at T = 4.2 K) of point contact and planar junctions formed on sodium tungsten bronze single crystals as the carrier concentration is changed through the metal-insulaor (MI)transition. We find Ihat the junction conductance is $\alpha |V|^{1/2}$ on the melallic side, and that as the MI transifion is qproached, the voltage dependence becames deeper and changes to a linear dependence $(\alpha |V|)$ in the critical reson. We interpret this observed behaviour as being due to evolution of short-range screened Coulomb interactions (giving rise to a square-root cusp in the density of states) in the disordered metallic phase into an Efros-Shklovskii-type Coulomb gap in the insulating phase. The possibility of breakdown of normal Fermi-liquid-like behaviour in the critical region is discussed.

Item Type: Journal Article Copyright of this article belongs to Institute of Physics. Division of Physical & Mathematical Sciences > Physics 08 Jul 2008 06 Jan 2011 08:17 http://eprints.iisc.ernet.in/id/eprint/14850