Observation of thermally activated glassiness and memory dip in a-NbSi insulating thin films

TL;DR

This study reports the observation of thermally activated glassy behavior and persistent memory effects in amorphous NbSi insulating thin films, revealing unique electronic relaxation dynamics that extend up to room temperature.

Contribution

It is the first to demonstrate thermally activated glassiness and long-lasting memory dips in amorphous NbSi films, contrasting with previously studied disordered insulators.

Findings

Memory dip persists up to room temperature

Conductance relaxations show temperature-dependent dynamics

Glass-like behavior observed in amorphous NbSi films

Abstract

We present electrical conductance measurements on amorphous NbSi insulating thin films. These films display out-of equilibrium electronic features that are markedly different from what has been reported so far in disordered insulators. Like in the most studied systems (indium oxide and granular Al films), a slow relaxation of the conductance is observed after a quench to liquid helium temperature which gives rise to the growth of a memory dip in MOSFET devices. But unlike in these systems, this memory dip and the related conductance relaxations are still visible up to room temperature, with clear signatures of a temperature dependent dynamics.