Magnetic Nanoparticles in a Nematic Channel: A One-Dimensional Study

TL;DR

This study explores the behavior of magnetic nanoparticles in nematic media through one-dimensional models, revealing how magneto-nematic interactions influence domain structures and stability, supported by numerical and analytical results.

Contribution

It introduces a hierarchy of one-dimensional models incorporating nematic, magnetic, and coupling energies, providing new insights into polydomain formation and stability in magneto-nematic systems.

Findings

Polydomains with distinct magnetization states are observed at weak to moderate coupling.

Lowering temperature stabilizes polydomain structures.

Increasing magneto-nematic coupling destabilizes polydomain configurations.

Abstract

We study a ferromagnetic suspension or a suspension of magnetic nanoparticles in an anisotropic nematic medium, in three different one-dimensional variational settings, ordered in terms of increasing complexity. The three models are featured by a nematic energy, a magnetic energy and a magneto-nematic coupling energy and the experimentally observed patterns are modelled as local or global energy minimizers. We numerically observe polydomains with distinct states of magnetization for weak to moderate magneto-nematic coupling in our models. We demonstrate that these polydomains are stabilised by lowering the temperature (as in Mertelj et al., 2013) and that the polydomain structures lose stability as the magneto-nematic coupling increases. Some exact solutions for prototypical situations are also obtained.