Slow Conductance Relaxation in Insulating Granular Al: Evidence for Screening Effects

Abstract

It is shown that the conductance relaxations observed in electrical field effect measurements on granular Al films are the sum of two contributions. One is sensitive to gate voltage changes and gives the already reported anomalous electrical field effect. The other one is independent of the gate voltage history and starts when the films are cooled down to low temperature. Their relative amplitude is strongly thickness dependent which demonstrates the existence of a finite screening length in our insulating films and allows its quantitative estimate (about 10nm at 4K). This metallic-like screening should be taken into account in the electron glass models of disordered insulators.

References in corpus (8)

• Mean field theory for the three-dimensional Coulomb glass
• Heterogeneous dynamics of the three dimensional Coulomb glass out of equilibrium
• Relaxation dynamics in quantum electron-glasses
• Slow conductance relaxations; Distinguishing the Electron Glass from extrinsic mechanisms
• Manifestation of ageing in the low temperature conductance of disordered insulators
• The Electron-Glass in samples approaching the Mesoscopic regime
• Coexistence of anomalous field effect and mesoscopic conductance fluctuations in granular aluminium
• Conductance relaxation in the Electron-Glass; Microwaves versus infra-red response