TY - JOUR
T1 - Resistivity and magnetoresistivity near the metal-insulator and superconductor-insulator transition in granular Al-Ge
AU - Eytan, G.
AU - Zaken, E.
AU - Rosenbaum, R.
AU - McLachlan, D. S.
AU - Albers, A.
PY - 1994/6/1
Y1 - 1994/6/1
N2 - Granular Al-Ge films, just on the metallic side of the critical volume fraction φc (50.7% Al), are found to have critical fields in excess of 1.5T at 0.47 K due to the fine granular nature of the Al. In barely insulating films where φc - φ < 2.2% (φ is the volume fraction of aluminum), Josephson junction coupling dominates the behaviour below Tc. For 3.4% ≤ (φ - φ) ≤ 6.2%, the resistivity diverges strongly below Tc and a large negative magnetoresistivity (MR) is observed. This behaviour is explained in terms of quasiparticle tunnelling or alternatively by the Adkins charging model. The high negative MR is explained using a magnetic field-dependent superconducting energy gap. The normal resistivity in the insulating films obeys the hopping relation ρ = ρ0 exp(T0/T)x above Tc and also below Tc in a field of 3.45 T, which quenches all superconductivity in the Al below Tc = 1.61 K.
AB - Granular Al-Ge films, just on the metallic side of the critical volume fraction φc (50.7% Al), are found to have critical fields in excess of 1.5T at 0.47 K due to the fine granular nature of the Al. In barely insulating films where φc - φ < 2.2% (φ is the volume fraction of aluminum), Josephson junction coupling dominates the behaviour below Tc. For 3.4% ≤ (φ - φ) ≤ 6.2%, the resistivity diverges strongly below Tc and a large negative magnetoresistivity (MR) is observed. This behaviour is explained in terms of quasiparticle tunnelling or alternatively by the Adkins charging model. The high negative MR is explained using a magnetic field-dependent superconducting energy gap. The normal resistivity in the insulating films obeys the hopping relation ρ = ρ0 exp(T0/T)x above Tc and also below Tc in a field of 3.45 T, which quenches all superconductivity in the Al below Tc = 1.61 K.
UR - http://www.scopus.com/inward/record.url?scp=4243263910&partnerID=8YFLogxK
U2 - 10.1016/0378-4371(94)90379-4
DO - 10.1016/0378-4371(94)90379-4
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AN - SCOPUS:4243263910
SN - 0378-4371
VL - 207
SP - 240
EP - 244
JO - Physica A: Statistical Mechanics and its Applications
JF - Physica A: Statistical Mechanics and its Applications
IS - 1-3
ER -