Fast dynamics in glass-forming salol investigated by dielectric spectroscopy

TL;DR

This study uses dielectric spectroscopy up to 400 GHz to observe the high-frequency minimum in salol's glass transition, confirming predictions of mode-coupling theory and providing detailed critical dynamics analysis.

Contribution

First dielectric spectroscopy measurement of salol up to 400 GHz confirming the mode-coupling theory's critical scaling predictions.

Findings

Detection of the high-frequency minimum in dielectric spectra.

Spectral shape and temperature dependence match mode-coupling theory.

Critical temperature and exponents are consistent with previous studies.

Abstract

We analyze dielectric-loss spectra of glass forming salol extending up to 400 GHz allowing for the detection of the high-frequency minimum, where the fast critical dynamics predicted by the mode-coupling theory of the glass transition should prevail. Indeed, we find such a minimum which, moreover, well fulfills the critical scaling predicted by the theory. This includes the spectral shape of the minimum, the critical temperature dependence of the minimum frequency and amplitude, and the critical temperature dependence of the alpha-relaxation rate at high temperatures. The minimum exponents a and b leading to a system parameter lambda = 0.63 and the critical temperature Tc = 256 K are all in reasonable agreement with previous investigations of salol using different methods. Salol was one of the first materials where mode-coupling theory was tested and initial dielectric measurements were taken as an argument against the universal applicability of this theory.