Ferromagnetic Liquid Thin Films Under Applied Field

TL;DR

This paper explores the theoretical and experimental possibilities of ferromagnetic liquid thin films, analyzing their shape and magnetization behavior under applied magnetic fields, highlighting differences from paramagnetic films.

Contribution

It provides the first detailed calculations and simulations of ferromagnetic liquid droplet shapes and magnetization textures in thin films under weak magnetic fields.

Findings

Ferromagnetic liquid droplets elongate and develop domain walls under applied fields.

Magnetization textures are coupled with droplet shape deformation.

Distinct behavior from paramagnetic thin films is observed.

Abstract

Theoretical calculations, computer simulations and experiments indicate the possible existence of a ferromagnetic liquid state, although definitive experimental evidence is lacking. Should such a state exist, demagnetization effects would force a nontrivial magnetization texture. Since liquid droplets are deformable, the droplet shape is coupled with the magnetization texture. In a thin-film geometry in zero applied field, the droplet has a circular shape and a rotating magnetization texture with a point vortex at the center. We calculate the elongation and magnetization texture of such ferromagnetic thin film liquid droplet confined between two parallel plates under a weak applied magnetic field. The vortex stretches into a domain wall and exchange forces break the reflection symmetry. This behavior contrasts qualitatively and quantitatively with the elongation of paramagnetic thin films.