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

Julien Delahaye (1) , Jean Honoré , Thierry Grenet (1)

1 NEEL - MagSup - Magnétisme et Supraconductivité

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.

Mots clés: Electron glass; Disordered insulators; Granular Aluminium

Domaines: Systèmes désordonnés et réseaux de neurones [cond-mat.dis-nn]

Julien Delahaye, Jean Honoré, Thierry Grenet. Slow Conductance Relaxation in Insulating Granular Al: Evidence for Screening Effects.. Physical Review Letters, 2011, 106, pp.186602. ⟨10.1103/PhysRevLett.106.186602⟩. ⟨hal-00600700⟩