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Electron glass effects in amorphous NbSi films

by J. Delahaye, T. Grenet, C. A Marrache-Kikuchi, V. Humbert, L. Bergé, L. Dumoulin

Submission summary

As Contributors: Julien Delahaye
Arxiv Link: (pdf)
Date accepted: 2020-04-07
Date submitted: 2020-03-18
Submitted by: Delahaye, Julien
Submitted to: SciPost Physics
Discipline: Physics
Subject area: Condensed Matter Physics - Experiment
Approach: Experimental


We report on non equilibrium field effect in insulating amorphous NbSi thin films having different Nb contents and thicknesses. The hallmark of an electron glass, namely the logarithmic growth of a memory dip in conductance versus gate voltage curves, is observed in all the films after a cooling from room temperature to 4.2 K. A very rich phenomenology is demonstrated. While the memory dip width is found to strongly vary with the film parameters, as was also observed in amorphous indium oxide films, screening lengths and temperature dependence of the dynamics are closer to what is observed in granular Al films. Our results demonstrate that the differentiation between continuous and discontinuous systems is not relevant to understand the discrepancies reported between various systems in the electron glass features. We suggest instead that they are not of fundamental nature and stem from differences in the protocols used and in the electrical inhomogeneity length scales within each material.

Ontology / Topics

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Thin films

Published as SciPost Phys. 8, 056 (2020)

Author comments upon resubmission

Here is our latest version of the article which takes into account the referees remarks. See also our response to referee reports.

List of changes

- Section 1 (Introduction): last sentence of paragraph 3 (added): "...but with a transition temperature much smaller than the mean field prediction."
- Section 4: middle of paragraph 2 (added): "Note that according to this interpretation the penetration length introduced earlier is nothing else than the screening length of the system."
- Section 4: end of paragraph 3 (replacement): "All these findings suggest that a material specific long range electrical inhomogeneity may explain why the penetration length is larger in InOx than in granular Al and NbSi films."
- Section 4: end of paragraph 4 (added): "These controversial results emphasize that the physical origin of the penetration
length, and especially of the large values observed in InOx films, remains an open and debated issue. Screening length determination by other means than gate voltage induced conductance relaxations would be very helpful in order to confirm our interpretation."
We have also improve the resolution of the Figures.

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