Aging Effects Across the Metal-Insulator Transition in Two Dimensions

TL;DR

This study investigates aging effects in the conductivity relaxations of a two-dimensional electron system in silicon, revealing a transition in glassy behavior at the metal-insulator transition and highlighting differences in relaxation dynamics across phases.

Contribution

It provides new insights into the nature of glassy phases and aging phenomena across the metal-insulator transition in two-dimensional systems.

Findings

Full aging observed in the insulating regime

Significant departures from full aging on the metallic side

Relaxation amplitude peaks below the MIT and is suppressed in the insulator

Abstract

Aging effects in the relaxations of conductivity of a two-dimensional electron system in Si have been studied as a function of carrier density. They reveal an abrupt change in the nature of the glassy phase at the metal-insulator transition (MIT): (a) while full aging is observed in the insulating regime, there are significant departures from full aging on the metallic side of the MIT, before the glassy phase disappears completely at a higher density $n_g$; (b) the amplitude of the relaxations peaks just below the MIT, and it is strongly suppressed in the insulating phase. Other aspects of aging, including large non-Gaussian noise and similarities to spin glasses, also have been discussed.