Electronic transport in polycrystalline samples of icosahedral phases

Resumo

The low-temperature electronic transport in polycrystals of quasicrystalline phases with an icosahedral structure has been analyzed within the model of the granular electronic system. In this model, the grains (drops) of a metallic icosahedral phase are surrounded by extended defects and grain boundaries, which create an insulating environment. The electron transport in this model is determined by the size quantization of electronic states inside metallic grains, by intergranular tunneling, and by electrostatic barriers. Depending on the temperature and structural state of the system, the hopping conductivity with variable lengths of jumps in the Efros–Shklovskii or Mott regime is observed with predominantly elastic cotunneling. In the case of strong intergranular coupling, the system passes into the metallic regime with the exponential temperature dependence of the electrical conductivity.