Director switching dynamics of ferromagnetic nematic liquid crystals

TL;DR

This paper investigates the static and dynamic behavior of ferromagnetic nematic liquid crystals under magnetic fields, introducing a macroscopic model with a dissipative cross-coupling coefficient to explain experimental observations.

Contribution

It presents a detailed experimental and theoretical study of ferromagnetic nematic liquid crystals, highlighting the role of a dissipative cross-coupling coefficient in their dynamics.

Findings

The dissipative cross-coupling coefficient depends on material parameters.

The macroscopic model successfully explains the complex dynamics observed.

Theoretical results connect to microscopic aspects of the colloidal suspension.

Abstract

Successful realization of ferromagnetic nematic liquid crystals has opened up the possibility to experimentally study a completely new set of fundamental physical phenomena. In this contribution we present a detailed investigation of some aspects of the static response and the complex dynamics of ferromagnetic liquid crystals under the application of an external magnetic field. Experimental results are then compared with a macroscopic model. Dynamics of the director were measured by optical methods and analyzed in terms of a theoretical macroscopic model. A dissipative cross-coupling coefficient describing the dynamic coupling between the two system order parameters, the magnetization and the nematic director, is needed to explain the results. In this contribution we examine the dependency of this coefficient on material parameters and the saturation magnetization and the liquid crystal host. Despite the complexity of the system, the theoretical description allows for a proper interpretation of the results and is connected to several microscopic aspects of the colloidal suspension.