Slow relaxation of conductance of amorphous hopping insulators

We perform electrical field effect measurements at 4 K on insulating granular aluminium thin films. When the samples size is reduced below 100µm, 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 conductance 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.

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“…Last, we would like to mention that an extrinsic type of scenario has been recently suggested for indium-oxide films [22].…”

Section: Arxiv:08032764v2 [Cond-matdis-nn] 8 Sep 2008mentioning

confidence: 88%

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

Delahaye

Grenet

2008

Eur. Phys. J. B

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“…Ref. [110] suggests that the slow relaxing modes are not (as was assumed above) an intrinsic part of the electronic system, but rather, atomic configurations which change over time and interact with the electronic configuration. Ref.…”

Section: Anomalous Field Effect and Two-dip Experiments -Qualitatimentioning

confidence: 96%

Electron Glass Dynamics

Amir

Oreg

Imry

2011

Annu. Rev. Condens. Matter Phys.

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Examples of glasses are abundant, yet it remains one of the phases of matter whose understanding is very elusive. In recent years, remarkable experiments have been performed on the dynamical aspects of glasses. Electron glasses offer a particularly good example of the 'trademarks' of glassy behavior, such as aging and slow relaxations. In this work we review the experimental literature on electron glasses, as well as the local mean-field theoretical framework put forward in recent years to understand some of these results. We also present novel theoretical results explaining the periodic aging experiment.Comment: Invited review to appear in Annual Review of Condensed Matter Physic

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“…In previous studies [16,17,22,23,26,[29][30][31][32][33][34] the glassy behavior of hopping insulators was investigated [14]. It turns out that the conductance of many materials showing glassy behavior possesses a stronger temperature dependence close to the Arrhenius law, n ≈ 1 [8][9][10].…”

Section: Field Confinementmentioning

confidence: 99%

“…A general mechanism for the non-equilibrium relaxation of conductance, similar to the one used for the interpretation of the experimental data for a dielectric constant in glasses [5,15], can be described as following [16,17]. Electronic DOS decreases due to interaction of fluctuators with electrons in localized states (see interaction of electron with local fluctuator shown in Fig.…”

Section: Glassy Behaviormentioning

confidence: 99%