Anomalous increase in nematic-isotropic transition temperature in dimer molecules induced by magnetic field

TL;DR

This study demonstrates a significant increase in the nematic-isotropic transition temperature of liquid crystalline dimers under a strong magnetic field, revealing a novel magnetic field-induced enhancement of nematic order.

Contribution

It reports the first observation of a magnetic field-induced increase in transition temperature in liquid crystal dimers, suggesting a new mechanism involving bend angle reduction.

Findings

Transition temperature increased by up to 15K at 22T magnetic field.

Magnetic field likely decreases the bend angle in spacers, enhancing nematic order.

Unprecedented magnetic field effect on nematic-isotropic transition in dimers.

Abstract

We have determined the nematic-isotropic transition temperature as a function of applied magnetic field in three different thermotropic liquid crystalline dimers. These molecules are comprised of two rigid calamitic moieties joined end to end by flexible spacers with odd numbers of methylene groups. They show an unprecedented magnetic field enhancement of nematic order in that the transition temperature is increased by up to 15K when subjected to 22T magnetic field. The increase is conjectured to be caused by a magnetic field-induced decrease of the average bend angle in the aliphatic spacers connecting the rigid mesogenic units of the dimers.