We show that the conductivity of the quasicrystal $i$-AlPdRe follows a Mott's variable range hopping conduction law $\sigma \left(T\right)={\sigma }_0\exp -(T_0/T{)}^{1/4}$ in the temperature range $20–600\mathrm{mK}$. The $i$-AlPdRe phase thus behaves like disordered insulators at very low temperature. We find a very low activation term $T_0\sim 1$ $\mathrm{mK}$, which is an indication of a large localization length $\xi$, in accordance with the vicinity to the metal-insulator transition. This is the first time that a pure Mott's law is observed at very low temperature in a structurally ordered compound made of metallic elements.

• Received 20 July 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.4204