Nonlinear dielectric response at the excess wing of glass-forming liquids

TL;DR

This study investigates the nonlinear dielectric response of glass-forming liquids glycerol and propylene carbonate at high fields, revealing no nonlinear behavior in the excess wing region despite strong effects in alpha-relaxation.

Contribution

First to measure nonlinear dielectric response in the excess wing region of glass formers, showing a surprising absence of nonlinearity in this regime.

Findings

No nonlinear dielectric response observed in the excess wing.

Strong nonlinear effects detected in alpha-relaxation.

Results challenge existing theories on excess wing behavior.

Abstract

We present nonlinear dielectric measurements of glass-forming glycerol and propylene carbonate applying electrical fields up to 671 kV/cm. The measurements extend to sufficiently high frequencies to allow for the investigation of the nonlinear behavior in the regime of the so-far mysterious excess wing, showing up in the loss spectra of many glass formers as a second power law at high frequencies. Surprisingly, we find a complete lack of nonlinear behavior in the excess wing, in marked contrast to the alpha-relaxation where, in agreement with previous reports, a strong increase of dielectric constant and loss is found.