Dynamics of the Destruction and Rebuilding of a Dipole Gap in Glasses

TL;DR

This paper investigates how a strong electric bias affects the dielectric properties of glasses at millikelvin temperatures, revealing long-lasting changes due to non-adiabatic tunneling state dynamics and interactions.

Contribution

It introduces a model combining relaxational processes and non-adiabatic tunneling effects to explain dielectric constant changes in glasses after bias application.

Findings

Dielectric constant increases and decays logarithmically after bias

Non-adiabatic driving causes long-lasting dielectric changes

TS interactions dominate relaxation below 50 mK

Abstract

After a strong electric bias field was applied to a glass sample at temperatures in the millikelvin range its AC-dielectric constant increases and then decays logarithmically with time. For the polyester glass mylar we have observed the relaxation of the dielectric constant back to its initial value for several temperatures and histories of the bias field. Starting from the dipole gap theory we have developed a model suggesting that the change of the dielectric constant after transient application of a bias field is only partly due to relaxational processes. In addition, non-adiabatic driving of tunneling states (TSs) by applied electric fields causes long lasting changes in the dielectric constant. Moreover, our observations indicate that at temperatures below 50 mK the relaxation of TSs is caused primarily by interactions between TSs.