Determination of characteristic relaxation times and their significance in glassy disordered insulators

TL;DR

This paper critically examines the field effect method for measuring relaxation times in glassy disordered insulators, revealing limitations and emphasizing the need for more comprehensive experiments to accurately understand their slow dynamics.

Contribution

It demonstrates that the commonly used characteristic relaxation times are often artifacts of the experimental procedure and not intrinsic properties of the systems.

Findings

In slow systems, the procedure fails to measure intrinsic relaxation times.

In lightly doped indium oxide, qualitative dynamics can be inferred but not precise relaxation times.

More complete experiments are necessary for accurate characterization of glassy dynamics.

Abstract

We revisit the field effect procedure used to characterise the slow dynamics of glassy Anderson insulators. It is shown that in the slowest systems the procedure fails and the "characteristic" time values extracted are not intrinsic but determined by the experimental procedure itself. In other cases (like lightly doped indium oxide) qualitative indications about the dynamics might be obtained, however the times extracted cannot be seen as characteristic relaxation times of the system in any simple manner, and more complete experiments are necessary. Implications regarding the effect of carrier concentration on the emergence of glassiness are briefly outlined.