A NOVEL BARRIER MODEL FOR FLUCTUATION-INDUCED TUNNELING IN HIGHLY CONDUCTIVE POLYACETYLENE

A reexamination of the model of fluctuation-induced tunnelling for Naarmann polyacetylene shows that its proper application leads to much more reasonable barrier parameters than obtained in recently published work. The remaining serious inconsistencies can be removed by assuming an inhomogeneous distribution of dopants. According to Kivelson and Heeger, in higher doped regions the Peierls distortion may be suppressed. These 'metallic' regions are separated by other regions where the commensurate gap still exists. The corresponding small effective mass determines tunnelling through the gap in these regions. This model yields quite reasonable barrier parameters for fresh samples and also allows an explanation of the anisotropy and ageing behaviour. © 1990.