Electrical, magneto-, and optical conductivity of quasicrystals in the Al-Re-Pd system

Measurements of the electrical conductivity sigma(T) and magnetoconductivity Delta sigma(H) of icosahedral Al70Re10Pd20 and Al70Re8.6Pd21.4 quasicrystals at low temperatures and in high magnetic fields H are reported. 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. The conductivity decreases with increasing magnetic field. For Al70Re8.6Pd21.4 sigma(T) decreases with decreasing T and saturates at the level sigma(0) = 1.7 Omega(-1) cm(-1) below 0.1 K. In magnetic fields up to 40 kOe, Delta sigma(H) is negative below 1 K and sigma(T,H) remains temperature-independent at the lowest temperatures. The optical conductivity sigma(omega) is obtained from reflectivity data in the frequency range between 15 and 10(5) cm(-1). The main contributions to sigma(omega) are a broad absorption signal centered at about 0.1 eV and a sizable peak with its maximum at 2.6 eV.