The most energetically favorable configurations of hematite cube chains

TL;DR

This study explores the energetically optimal arrangements of cubic hematite particles in colloids under magnetic fields, revealing that stable configurations are mainly short chains with kink formations due to thermal fluctuations.

Contribution

It introduces a combined analytical, numerical, and molecular dynamics approach to identify stable hematite cube chain configurations and assesses their experimental observability.

Findings

Stable configurations are mainly short chains.

Long chains tend to have kinks due to thermal fluctuations.

Energetically favorable structures are observable only in short chains.

Abstract

Hematite at room temperature is a weak ferromagnetic material. Its permanent magnetization is three orders smaller than for magnetite. Thus, hematite colloids allow us to explore a different physical range of particle interaction parameters compared to ordinary ferromagnetic particle colloids. In this paper we investigate a colloid consisting of hematite particles with cubic shape. We search for energetically favorable structures in an external magnetic field with analytical and numerical methods and molecular dynamics simulations and analyze whether it is possible to observe them in experiments. We find that energetically favorable configurations are observable only for short chains. Longer chains usually contain kinks which are formed in the process of chain formation due to the interplay of energy and thermal fluctuations as an individual cube can be in one of two alignments with an equal probability.