Variable-range-hopping conductivity in polygrain samples of icosahedral Al–Re–Pd

Abstract

We further develop a model, based on an analogy with granular electronic conductors, which explains the nature of the variable-range-hopping conductivity in polygrain samples of icosahedral Al–Re–Pd with resistivity ratios of in an excess of ∼13. The electrical conductivity of the model is determined by intergranular tunnelling and electrostatic energy. In polygrain icosahedral Al–Re–Pd, pores and precipitates of secondary phases create the barriers. Depending on the barrier height and electrostatic disorder, either an insulating variable-range-hopping regime of an Efros–Shklovskii or Mott type with elastic co-tunnelling or a metallic regime typical of homogeneously disordered conductors is possible.

Keywords:

• granular electronic conductors
• quasicrystals
• tunnelling

Acknowledgements

This work was supported by the Russian Foundation for Basic Research (Grants 080201461-f and 090200147-f), the Russian Government Program “High School Development” (Grant RNP.2.1.1.5845) and the Göran Gustafsson foundation for nature sciences and medical research.