Evidence for Variable Range Hopping Conductivity in the Ordered Quasicrystali-AlPdRe

We show that the conductivity of the quasicrystal i-AlPdRe follows a Mott's variable range hopping conduction law σ(T)0ex0ex=0ex0exσ₀exp-(T₀/T)1/4 in the temperature range 20--600mK. The i-AlPdRe phase thus behaves like disordered insulators at very low temperature. We find a very low activation term T₀~1 mK, which is an indication of a large localization length ξ, 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.