Formation of Wigner crystals in conducting polymer nanowires

TL;DR

This study provides experimental evidence for the formation of one-dimensional Wigner crystals in polypyrrole nanowires, demonstrating long-range electron interactions and characteristic electrical behaviors at low temperatures.

Contribution

First experimental observation of 1D Wigner crystal formation in conducting polymer nanowires, revealing new insights into electron interactions in disordered 1D systems.

Findings

Presence of a temperature-dependent energy gap

Power-law current-voltage behavior indicative of 1D Wigner crystals

Switching to a high-conductivity state above a threshold voltage

Abstract

The search for theoretically predicted Wigner crystal in one-dimensional (1D) wires of structurally disordered materials exhibiting properties of charge-density-waves have remained unsuccessful. Based on the results of a low temperature conductivity study we report here formation of such 1D Wigner crystal (1DWC) in polypyrrole nanowires having low electron densities. The current-voltage characteristics of all the nanowires show a 'gap' that decreases rapidly as the temperature is increased - confirming the existence of long-range electron-electron interaction in the nanowires. The measured current show power-law dependence on voltage and temperature as expected in 1DWC. A switching transition to highly conducting state has been observed above a threshold voltage, which can be tuned by changing the diameters of the nanowires and the temperature. Negative differential resistance and enhancement of noise has been observed above the threshold as expected.