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Electronic properties and superconductivity of amorphous Si 1‐ x Au x alloys near the metal‐insulator transition
Author(s) -
Fischer J.,
v. Löhneysen H.
Publication year - 1993
Publication title -
annalen der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.009
H-Index - 68
eISSN - 1521-3889
pISSN - 0003-3804
DOI - 10.1002/andp.19935050705
Subject(s) - condensed matter physics , superconductivity , metastability , materials science , electrical resistivity and conductivity , amorphous solid , fermi level , annealing (glass) , density of states , metal–insulator transition , transition temperature , anomaly (physics) , metal , physics , crystallography , electron , metallurgy , chemistry , quantum mechanics
We report on specific‐heat and resistivity measurements on quench‐condensed Si 1‐x Au x films for 0.11 ⩽ x 0.36 in the temperature range 0.35 K ⩽ T ⩽ 6 K. A distinct increase of the specificheat derived electronic density of states at the Fermi level is observed at x b ≈ 0.2, i.e., in the vicinity of the metal‐insulator transition occurring for our samples at x c = 0.16. This suggests a different type of bonding between Au and Si for x < x b and x > x b . 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.