Evidence for Variable Range Hopping Conductivity in the Ordered Quasicrystal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">i</mml:mi></mml:math>-AlPdRe

Abstract

We show that the conductivity of the quasicrystal $i$-AlPdRe follows a Mott's variable range hopping conduction law $\ensuremath{\sigma}(T)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}{\ensuremath{\sigma}}_{0}\mathrm{exp}\ensuremath{-}({T}_{0}/T{)}^{1/4}$ 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 ${T}_{0}\ensuremath{\sim}1$ $\mathrm{mK}$, which is an indication of a large localization length $\ensuremath{\xi}$, 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.