LOW-TEMPERATURE ELECTRICAL-TRANSPORT IN ICOSAHEDRAL AL-RE-PD

Measurements of the electrical conductivity sigma(T) and magnetoconduc tivity Delta sigma(H) of icosahedral Al70Re10Pd20 and Al70Re8.6Pd21.4 quasicrystals at low temperatures and in high magnetic fields H are re ported. Below 0.2 K sigma of Al70Re10Pd20 varies as sigma(T) = sigma(0 )+aT(1/2) with sigma(0) = 30 Omega(-1)cm(-1) and a < 0. In agreement w ith expectations presuming a substantial Coulomb interaction, Delta si gma(H) is negative. For Al70Re8.6Pd21.4 sigma(T) decreases with decrea sing T and saturates at the level sigma(0) = 1.7 Omega(-1)cm(-1) below 0.1 K. In all measured magnetic fields up to 40 kOe, Delta sigma(H) i s negative below 1 K and remains temperature-independent at the lowest temperatures. The saturation of sigma(T) implies that in this materia l Coulomb interactions among itinerant electrons are negligible.