Criticality of an isotropic-to-smectic transition induced by anisotropic quenched disorder

TL;DR

This study investigates how anisotropic quenched disorder in nanoporous silicon alters the phase transition of liquid crystal 12CB from a discontinuous bulk isotropic-to-smectic transition to a continuous, short-range smectic state with coupled order parameters.

Contribution

It demonstrates that anisotropic quenched disorder changes the nature of the isotropic-to-smectic transition in 12CB, contrasting with isotropic disorder effects.

Findings

Transition becomes continuous under anisotropic disorder

Both orientational and translational orders follow the same power-law

Short-range smectic order emerges from paranematic phase

Abstract

We report combined optical birefringence and neutron scattering measurements on the liquid crystal 12CB nanoconfined in mesoporous silicon layers. This liquid crystal exhibits strong nematic-smectic coupling responsible for a discontinuous isotropic-to-smectic phase transition in the bulk state. Confined in porous silicon, 12CB is subjected to strong anisotropic quenched disorder: a short-ranged smectic state evolves out of a paranematic phase. This transformation appears continuous, losing its bulk first order character. This contrasts with previously reported observations on liquid crystals under isotropic quenched disorder. In the low temperature phase, both orientational and translational order parameters obey the same power-law.