Slow conductance relaxations: Distinguishing the electron glass from extrinsic mechanisms

Slow conductance relaxations are observable in many condensed-matter systems. These are sometimes described as manifestations of a glassy phase. The underlying mechanisms responsible for the slow dynamics are often due to structural changes which modify the potential landscape experienced by the charge carriers and thus are reflected in the conductance. Sluggish conductance dynamics may however originate from the interplay between electron-electron interactions and quenched disorder. Examples for both scenarios and the experimental features that should help to distinguish between them are shown and discussed. In particular, it is suggested that the "memory dip" observable through field-effect measurements is a characteristic signature of the inherent electron glass provided it obeys certain conditions.