Microstructure and magnetic properties of magnetic fluids consisting of shifted dipole particles under the influence of an external magnetic field

Abstract

Articles you may be interested inTheory of magnetic fluid heating with an alternating magnetic field with temperature dependent materials properties for self-regulated heating J. Appl. Phys. 105, 07B324 (2009) We investigate the structure of a recently proposed magnetic fluid consisting of shifted dipolar (SD) particles in an externally applied magnetic field via computer simulations. For standard dipolar fluids the applied magnetic field usually enhances the dipole-dipole correlations and facilitates chain formation whereas in the present system the effect of an external field can result in a break-up of clusters. We thoroughly investigate the origin of this phenomenon through analyzing first the ground states of the SD-particle systems as a function of an applied field. In a second step we quantify the microstructure of these systems as functions of the shift parameter, the effective interaction parameter, and the applied magnetic field strength. We conclude the paper by showing that with the proper choice of parameters, it is possible to create a system of SD-particles with highly interacting magnetic particles, whose initial susceptibility is below the Langevin susceptibility, and which remains spatially isotropic even in a very strong external magnetic field. © 2013 AIP Publishing LLC.

Active dipole clusters: From helical motion to fission

“…Our results can be verified for colloidal Janus parti-cles which a strong dipole moment along their symmetry axis. At vanishing self-propulsion these particles have been considered quite a lot in the context of ferrogels and ferrofluids [17][18][19][20][21]52]. Dipolar self-propelled particles have been prepared recently by Baraban and coworkers [53,54] and aggregation into clusters has indeed been observed [55].…”

Fission and fusion scenarios for magnetic microswimmer clusters

“…An important example for the former are magnetic dipole moments which enable to actuate and control the swimming path by an external magnetic field [13][14][15][16][17][18][19][20][21]. In the absence of swimming, the structure of two-dimensional [22,23] and three-dimensional [24,25] dipole clusters has been explored recently, but the impact of activity on a swimmer cluster has been rarely studied [19,26]. Recent simulation studies [27,28] have revealed that the mean cluster size crucially depends on the strength of the selfpropulsion speed.…”

“…This has important consequences for the interactions between swimmers and give rise to qualitatively different fission and fusion scenarios which we classify for small particle clusters. In detail, we study the spontaneous fission processes for two chosen types of clusters, linear chains and rings, representing the ground state of magnetic dipoles [22,25]. While linear chains remain stable for pullers and neutral swimmers they are split in the case of pushers.…”

Interplay between particle microstructure, network topology and sample shape in magnetic gels -- A molecular dynamics simulation study

“…in Refs. [37][38][39][40]. Once a configuration of magnetic particles is obtained, in the second step, the desired sample shape is cut from the ferrofluid.…”

“…The analysis is performed in analogy to Refs. [40,41]. Two magnetic particles are taken to be part of the same cluster if their distance is smaller 3.…”