SEARCH

SEARCH BY CITATION

Keywords:

  • Amorphous metals;
  • Electronic density of states;
  • Metal-insulator transition;
  • Superconductivity

Abstract

We report on specific-heat and resistivity measurements on quench-condensed Si1-xAux films for 0.11 ⩽ x 0.36 in the temperature range 0.35 KT ⩽ 6 K. A distinct increase of the specificheat derived electronic density of states at the Fermi level is observed at xb ≈ 0.2, i.e., in the vicinity of the metal-insulator transition occurring for our samples at xc = 0.16. This suggests a different type of bonding between Au and Si for x < xb and x > xb. While resistive transitions to superconductivity are observed for x⩾0.21, the absence of a specific-heat anomaly at the transition points to filamentary superconductivity except for × = 0.35 where a sizable anomaly is seen. The difference in various electronic properties between differently prepared samples of these metastable alloys, in particular the influence of different preparation and annealing temperatures is emphasized. It is suggested that these differences are caused by incipient phase separation in the room-temperature prepared samples.