Eur. Phys. J. B 65, 5-19 (2008)
https://doi.org/10.1140/epjb/e2008-00317-4

Coexistence of anomalous field effect and mesoscopic conductance fluctuations in granular aluminium

Institut Néel, CNRS & Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France

Corresponding author: ^a julien.delahaye@grenoble.cnrs.fr

Received: 18 March 2008
Revised: 18 June 2008
Published online: 1 August 2008

Abstract

We perform electrical field effect measurements at 4 K on insulating granular aluminium thin films. When the samples size is reduced below 100 μm, reproducible and stable conductance fluctuations are seen as a function of the gate voltage. Our results suggest that these fluctuations reflect the incomplete self-averaging of largely distributed microscopic resistances. We also study the anomalous field effect (conductance dip) already known to exist in large samples and its slow relaxation in the presence of the conductance fluctuations. Within our measurements accuracy, the two phenomena appear to be independent of each other, like two additive contributions to the conductance. We discuss the possible physical meaning of this independence and in particular whether or not this observation is in favor of an electron glass interpretation of slow conductance anomaly relaxations.