Transition to a quasi-insulating state in quasi-crystalline AlPdRe

We present results about electronic properties of quasi-crystalline AlPdRe samples, assumed to be on each side of the metal-insulator transition. The structural quality and the chemical composition are investigated by X-ray d iffraction, scanning electron microscopy and microprobe analysis. Conductiv ity is reported. The density of states (DOS) at the Fermi level is probed b y specific heat and diamagnetic susceptibility measurements, and the energy dependence around the Fermi level by scanning tunneling spectroscopy. The DOS at the Fermi level and the preopening of a correlation gap confirm the proximity to the metal-insulator transition, as indicated by the conductivi ty. The transition towards an insulating state could be related to local co mpositional fluctuations. (C) 1999 Elsevier Science B.V. All rights reserve d.