The question of intrinsic origin of the metal-insulator transition in i-AlPdRe quasicrystal

Abstract

The icosahedral (i-) AlPdRe is the most resistive quasicrystalline alloy discovered so far. Resistivities (ρ) of 1Ωcm at 4K and correlated resistance ratios (RRR = ρ4K /ρ300K ) of more than 200 are observed in polycrystalline samples. These values are two orders of magnitude larger than for the isomorphous i-AlPdMn phase. We discuss here the controversial microscopic origin of the i-AlPdRe alloy electrical specificity. It has been proposed that the high resistivity values are due to extrinsic parameters, such as secondary phases or oxygen contamination. From comprehensive measurements and data from the literature including electronic transport correlated with micro structural and micro chemical analysis, we show that on the contrary there is mounting evidence in support of an origin intrinsic to the i-phase. Similarly to the other quasicrystalline alloys, the electrical resistivity of the i-AlPdRe samples depends critically on minute changes in the structural quality and chemical composition. The low resistivity in i-AlPdRe single-grains compared to polycrystaline samples can be explained by difference in chemical composition, heterogeneity and thermal treatment.

Sub-diffusive electronic states in octagonal tiling

“…Experimental investigations have indicated that the conduction properties of many stable quasicrystals (AlCuFe, AlPdMn, AlPdRe, ...) are unusual and differ strongly from those of simple inter-metallic alloys [1][2][3]. In particular their conductivity increases with static defects density and when temperature increases.…”

On Modified Mott (Т–1/4) Law in the Conductivity of Quasicrystals

“…To resolve this issue, we used the data available in the literature for Al-Pd-Re materials, monocrystalline with σ 0 ∼ 176 (Ω cm) -1 [14] and amorphous with σ 0 ∼ 1470 (Ω cm) -1 [15], i.e., for dense materials morphologically different from polycrystals [1][2][3][4][5]. The corresponding curves are shown in Figs.…”

“…After thirty years of intensive research, variable range hopping (VRH) conductivity has become the focus of violent polemics about the intrinsic and nonintrinsic properties of quasicrystals [1][2][3][4][5][6]. This is not accidental.…”

Chemical Bonding and Physical Properties in Quasicrystals and Their Related Approximant Phases: Known Facts and Current Perspectives

“…Table 4. Chemical trends in the low-temperature electrical resistivity ( ) and the electrical resistivity ratio (R) defined as R = (4 K)/ (300 K) of Al-based i-QCs [57,[69][70][71][72][73][74][75]. The electrical resistivity trends illustrated in Table 4 may arise from the relativistic contraction of the s and p states relative to the d and f ones, which lowers the orbital energies of the former and screens the nucleus effective charge, so that the outer d electrons experience a lesser binding, hence displaying a larger spatial extent.…”