We present nonlinear dielectric measurements of glass-forming glycerol and propylene carbonate applying electrical fields up to $671\mathrm{kV}/\mathrm{cm}$. 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.

• Received 10 August 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.107603