Ulta-slow relaxation in discontinuous-film based electron glasses

TL;DR

This study investigates the extremely slow relaxation dynamics in discontinuous 2D electron glass films composed of nano-grains, revealing a temperature-dependent slowdown and conductance fluctuations linked to weak electrical connectivity.

Contribution

It demonstrates the unique slow relaxation behavior below a characteristic temperature and connects it to the dilute current-carrying network in discontinuous films, offering new insights into electron glass physics.

Findings

Relaxation dynamics slow dramatically below T* (10-50K).

Conductance fluctuations appear in millimeter-sized samples below T*.

System sluggishness is linked to weakly connected regions in the film.

Abstract

We present field effect measurements on discontinuous 2D thin films which are composed of a sub monolayer of nano-grains of Au, Ni, Ag or Al. Like other electron glasses these systems exhibit slow conductance relaxation and memory effects. However, unlike other systems, the discontinuous films exhibit a dramatic slowing down of the dynamics below a characteristic temperature $T^*$. $T^*$ is typically between 10-50K and is sample dependent. For $T<T^*$ the sample exhibits a few other peculiar features such as repeatable conductance fluctuations in millimeter size samples. We suggest that the enhanced system sluggishness is related to the current carrying network becoming very dilute in discontinuous films so that the system contains many parts which are electrically very weakly connected and the transport is dominated by very few weak links. This enables studying the glassy properties of the sample as it transitions from a macroscopic sample to a mesocopic sample, hence, the results provide new insight on the underlying physics of electron glasses.