Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/118373
Title: Effects of interactions, structure formation, and polydispersity on the dynamic magnetic susceptibility and magnetic relaxation of ferrofluids
Authors: Ivanov, A. O.
Camp, P. J.
Issue Date: 2022
Citation: Ivanov A. O. Effects of interactions, structure formation, and polydispersity on the dynamic magnetic susceptibility and magnetic relaxation of ferrofluids / A. O. Ivanov, P. J. Camp // Journal of Molecular Liquids. — 2022. — Vol. 356. — 119034.
Abstract: Linear response theory relates the decay of equilibrium magnetisation fluctuations in a ferrofluid to the frequency-dependent response of the magnetisation to a weak ac external magnetic field. The characteristic relaxation times are strongly affected by interactions between the constituent particles. Similarly, the relaxation of an initially magnetised system towards equilibrium in zero field occurs on a range of timescales depending on the structure of the initial state, and the interactions between the particles. In this work, ferrofluids are modelled as colloidal suspensions of spherical particles carrying point dipole moments, and undergoing Brownian motion. Recent theoretical and simulation work on the relaxation and linear response of these model ferrofluids is reviewed, and the effects of interactions, structure formation, and polydispersity on the characteristic time scales are outlined. It is shown that: (i) in monodisperse ferrofluids, the timescale characterising the collective response to weak fields increases with increasing interaction strength and/or concentration; (ii) in monodisperse ferrofluids, the initial, short-time decay is independent of interaction strength, but the asymptotic relaxation time is the same as that characterising the collective response to weak fields; (iii) in the strong-interaction regime, the formation of self-assembled chains and rings introduces additional timescales that vary by orders of magnitude; and (iv) in polydisperse ferrofluids, the instantaneous magnetic relaxation time of each fraction varies in a complex way due to the role of interactions. © 2022 The Authors
Keywords: BROWNIAN DYNAMICS SIMULATIONS
DYNAMIC MAGNETIC SUSCEPTIBILITY
FERROFLUIDS
FOKKER–PLANCK-BROWN EQUATION
BROWNIAN MOVEMENT
FOKKER PLANCK EQUATION
MAGNETIC RELAXATION
MAGNETIC SUSCEPTIBILITY
MAGNETIZATION
NANOMAGNETICS
RELAXATION TIME
SUSPENSIONS (FLUIDS)
BROWNIAN DYNAMIC SIMULATIONS
DYNAMIC MAGNETIC SUSCEPTIBILITY
FOKKER PLANCK
FOKKE–PLANCK-BROWN EQUATION
INTERACTION STRENGTH
INTERACTION STRUCTURES
LINEAR-RESPONSE THEORY
MONO-DISPERSE FERROFLUIDS
STRUCTURE FORMATIONS
TIME-SCALES
MAGNETIC FLUIDS
URI: http://hdl.handle.net/10995/118373
Access: info:eu-repo/semantics/openAccess
SCOPUS ID: 85127487602
DOI: 10.1016/j.molliq.2022.119034
metadata.dc.description.sponsorship: Ministry of Education and Science of the Russian Federation, Minobrnauka; Ural Federal University, UrFU
A.O.I. gratefully acknowledges research funding from the Ministry of Science and Higher Education of the Russian Federation (Ural Federal University project within the Priority 2030 Program).
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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