Critical fluctuations and random-anisotropy glass transition in nematic elastomers

TL;DR

This study uses deuterium NMR to investigate local nematic ordering in polydomain nematic elastomers, revealing a continuous transition and critical fluctuations that suggest quenched impurities can alter the nature of phase transitions.

Contribution

It provides experimental evidence that quenched disorder induces a continuous transition in nematic elastomers, contrary to the expected first-order transition.

Findings

Order parameter emerges via a continuous phase transition.

Local director fluctuations grow critically around the transition.

Evidence supports quenched impurities changing transition order as per Aizenman-Wehr theorem.

Abstract

We carry out a detailed deuterium NMR study of local nematic ordering in polydomain nematic elastomers. This system has a close analogy to the random-anisotropy spin glass. We find that, in spite of the quadrupolar nematic symmetry in 3-dimensions requiring a first-order transition, the order parameter in the quenched ``nematic glass'' emerges via a continuous phase transition. In addition, by a careful analysis of the NMR line shape, we deduce that the local director fluctuations grow in a critical manner around the transition point. This could be the experimental evidence for the Aizenman-Wehr theorem about the quenched impurities changing the order of discontinuous transition.