Studies of icosahedral AlPdRe quasicrystals across the metal–insulator transition

The metal–insulator transition (MIT) in icosahedral AlPdRe quasicrystals is investigated by studying changes in sample properties across the transition. The magnetoresistance (MR) the conductivity σ(T), and the magnetic susceptibility χ(T) have been studied. The MR results show that an MIT occurs for resistance ratios R [=ρ(4.2 K)/ρ(295 K)] of about 20–30. σ(0 K) is finite, and decreases over four orders of magnitude with increasing R. Besides the MR, the most prominent change in a studied property across the MIT is a change of slope of log σ(0) vs R. In contrast, no features in the resistivity from 1.5 to 300 K reveals an MIT. New results for χ(T,R) are presented. The diamagnetic χ decreases from the metallic to the insulating side, while on the insulating side χ(T,R) is almost independent of R. Although the MR indicates a disorder driven MIT, there is no support for this picture from the results for χ.