Characterisation of the magnetic response of nanoscale magnetic filaments in applied fields

Autor(en)

Deniz Mostarac, Pedro A. Sánchez, Sofia Kantorovich

Abstrakt

Incorporating magnetic nanoparticles (MNPs) within permanently crosslinked polymer-like structures opens up the possibility for synthesis of complex, highly magneto-responsive systems. Among such structures are chains of prealigned magnetic (ferro- or super-paramagnetic) monomers, permanently crosslinked by means of macromolecules, which we refer to as magnetic filaments (MFs). In this paper, using molecular dynamics simulations, we encompass filament synthesis scenarios, with a compact set of easily tuneable computational models, where we consider two distinct crosslinking approaches, for both ferromagnetic and super-paramagnetic monomers. We characterise the equilibrium structure, correlations and magnetic properties of MFs in static magnetic fields. Calculations show that MFs with ferromagnetic MNPs in crosslinking scenarios where the dipole moment orientations are decoupled from the filament backbone, have similar properties to MFs with super-paramagnetic monomers. At the same time, magnetic properties of MFs with ferromagnetic MNPs are more dependent on the crosslinking approach than they are for ones with super-paramagnetic monomers. Our results show that, in a strong applied field, MFs with super-paramagnetic MNPs have similar magnetic properties to ferromagnetic ones, while exhibiting higher susceptibility in low fields. We find that MFs with super-paramagnetic MNPs have a tendency to bend the backbone locally rather than to fully stretch along the field. We explain this behaviour by supplementing Flory theory with an explicit dipole–dipole interaction potential, with which we can take in to account folded filament configurations. It turns out that the entropy gain obtained through bending compensates an insignificant loss in dipolar energy for the filament lengths considered in the manuscript.

Organisation(en)

Forschungsplattform MMM Mathematics-Magnetism-Materials, Computergestützte Physik und Physik der Weichen Materie

Externe Organisation(en)

Ural Federal University, Wolfgang Pauli Institute (WPI) Vienna

Journal

Nanoscale

Band

12

Seiten

13933-13947

Anzahl der Seiten

15

ISSN

2040-3364

DOI

https://doi.org/10.1039/D0NR01646B

Publikationsdatum

05-2020

Peer-reviewed

Ja

ÖFOS 2012

103023 Polymerphysik, 103017 Magnetismus, 103029 Statistische Physik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/e27ae247-c73b-442a-9e90-71881ec62af3