Indications for a metal-insulator transition in quasicrystalline i-AlPdRe

Abstract

We present indications for a metal-insulator transition in the icosahedral AlPdRe phase of high structural quality. We follow the conductivity through the transition and its dependence on temperature and magnetic field in a series of i-AlPdRe samples. Features typical for systems on both sides of the metal-insulator transition are found. Moreover, the variation of conductivity with temperature is very unusual with σ(T) varying like Tα (1 ⩽ α ⩽ 1.5) in a wide temperature range from 7 K to 700 K.

Covalency, semiconductor-like and thermoelectric properties of Al-based quasicrystals: icosahedral cluster solids

“…The electrical conductivities of AlPdRe icosahedral quasicrystals monotonically increase with increasing temperature. This temperature dependence is typical for Albased icosahedral quasicrystals since a few researchers have reported a similar tendency at high temperatures [35,36]. Seebeck coef®cients of the samples slightly increase with increasing temperature until they reach a broad maximum centering at 500 K. The peak value of the Seebeck coef®-cient of the Al 71 Pd 20 Re 9 sample is 189 mV/K.…”

Universal features in the electrical conductivity of icosahedral Al-transition-metal quasicrystals

“…The (T) curves of samples belonging to the second class can be then properly fitted in terms of power law functions of the form ⌬(T)ϳAT n (1/2рnр3/2), over a broad temperature range. 30,31 On the contrary, the (T) curve of samples belonging to the first class cannot be properly described in terms of monotonous functions, at least in the temperature region below the minimum position. 47 In addition, at very low temperatures, AlPdRe samples belonging to the second class exhibit negative curvatures which can be well fitted in terms of stretched exponential functions of the form ⌬(T)ϳ 0 exp͓Ϫ(T 0 /T) m ͔, with mϭ1/2 or 1/4.…”

Fermi surfaces and anomalous transport in quasicrystals

“…[30,31,32,36] [31,32] and ∼ 1.3 [33], for temperature range [400mK, 300K]. One recalls that in quasicrystals, the typical Debye temperature, which limits the "low temperature regime" estimated from specific heat measurements are typically ∝ 400 ∼ 500K.…”