Dipolar particles trapped in a cylindrical pore

¹ Université de Lorraine, Laboratoire de Physique et Chimie Théoriques, LPCT, UMR CNRS 7019 1 Boulevard Arago, 57070 Metz, France
² Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN Villeneuve d'Ascq, France

^(a) E-mail: rene.messina@univ-lorraine.fr (corresponding author)

Received: 7 December 2022
Accepted: 3 March 2023

Abstract

A salient effect of strong confinement, especially when quasi one-dimensional, is to drastically alter the phase behavior and concomitantly the physico-chemical properties of a substance encountered in the bulk. The ground state phase diagram of dipolar hard spheres of diameter d as a function of the pore opening , with D being the cylinder diameter of the confining pore, is investigated theoretically. Whereas finding the densest configurations with hard spheres would be a purely geometrical problem, the situation becomes much more intricate with long-ranged anisotropic interactions. As a major finding, long pores prohibit chain undulation (helicity) and wall-contact–free (floating) linear chain bundles emerge. These results shed light on recent experimental observations with magnetic colloids in microtubes. Applications in other fields are discussed as well.