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Title: Multiple percolation tunneling staircase in metal-semiconductor nanoparticle composites

Multiple percolation transitions are observed in a binary system of RuO{sub 2}-CaCu{sub 3}Ti{sub 4}O{sub 12} metal-semiconductor nanoparticle composites near percolation thresholds. Apart from a classical percolation transition, associated with the appearance of a continuous conductance path through RuO{sub 2} metal oxide nanoparticles, at least two additional tunneling percolation transitions are detected in this composite system. Such behavior is consistent with the recently emerged picture of a quantum conductivity staircase, which predicts several percolation tunneling thresholds in a system with a hierarchy of local tunneling conductance, due to various degrees of proximity of adjacent conducting particles distributed in an insulating matrix. Here, we investigate a different type of percolation tunneling staircase, associated with a more complex conductive and insulating particle microstructure of two types of non-spherical constituents. As tunneling is strongly temperature dependent, we use variable temperature measurements to emphasize the hierarchical nature of consecutive tunneling transitions. The critical exponents corresponding to specific tunneling percolation thresholds are found to be nonuniversal and temperature dependent.
Authors:
; ;  [1]
  1. Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201 (United States)
Publication Date:
OSTI Identifier:
22310671
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CALCIUM COMPOUNDS; COPPER COMPOUNDS; METALS; MICROSTRUCTURE; NANOPARTICLES; RUTHENIUM OXIDES; SEMICONDUCTOR MATERIALS; SPHERICAL CONFIGURATION; TEMPERATURE DEPENDENCE; TEMPERATURE MEASUREMENT; TITANATES; TUNNEL EFFECT