Surface Instabilities and Magnetic Soft Matter

  title={Surface Instabilities and Magnetic Soft Matter},
  author={C. Gollwitzer and M. Krekhova and Guenter Lattermann and I. Rehberg and R. Richter},
  journal={Soft Matter},
We report on the formation of surface instabilities in a layer of thermoreversible ferrogel when exposed to a vertical magnetic field. Both static and time dependent magnetic fields are employed. Under variations of temperature, the viscoelastic properties of our soft magnetic matter can be tuned. Stress relaxation experiments unveil a stretched exponential scaling of the shear modulus, with an exponent of β = 1/3. The resulting magnetic threshold for the formation of Rosensweig-cusps is… Expand
Surface Instabilities of Ferrofluids
We report on recent progress in understanding the formation of surface protuberances on a planar layer of ferrofluid in a magnetic field oriented normally to the surface. This normal field orExpand
Meniscus of a ferrofluid around a vertical cylindrical wire carrying electric current.
The classical model that neglects interface tension yields significant deviations from the experimental profiles in the parameter range studied, which can be modeled by the equilibrium of magnetic, gravitational, and interface tension forces. Expand
Retarding the growth of the Rosensweig instability unveils a new scaling regime.
Using a highly viscous magnetic fluid, the dynamics in the aftermath of the Rosensweig instability can be slowed down by more than 2000 times. In this way we expand the regime where the growth rateExpand
Modeling and finite element simulation of the magneto-mechanical behavior of ferrogels
Abstract In our previous study (see Ref. Attaran et al. (in press) [1] ) we formulated a continuum model for ferrogels considering them as multicomponent materials. In the present work a reducedExpand
Enhanced rheological properties of dilute suspensions of magnetic nanoparticles in a concentrated amphiphilic surfactant solution
We present an experimental study of the magnetorheological response of dilute suspensions of magnetic nanoparticles in concentrated amphiphilic surfactant solutions. Low particle content (<0.4% v/v)Expand
Effect of Medium Oil on Magnetorheology of Soft Carbonyl Iron Particles
A magnetorheological (MR) fluid, suspension of soft magnetic carbonyl iron (CI) dispersed in a mixture medium of grease and kerosene, was prepared, focusing on controlling the medium viscosity forExpand
Tunable mechanical characteristics of a novel soft magnetic entangled metallic wire material
This article proposes a novel soft magnetic entangled metallic wire material(SM-EMWM) for the first time, and describes the manufacturing and quasi-static tests of its samples produced from softExpand
Magnetorheology of Snowman-Like Anisotropic Microparticle Added Carbonyl Iron Suspension
The improvement of the magnetorheological (MR) performance of a carbonyl iron (CI)-based MR fluid was assessed by adding nonmagnetic anisotropic snowman-like polymethyl methacrylate (PMMA) particlesExpand
The role of structural anisotropy in the magnetooptical response of an organoferrogel with mobile magnetic nanoparticles.
It is demonstrated that the presence of the gel network restricts the magnetooptical response of the ferrogel, and the optical response in structurally anisotropic gels becomes orientation-dependent, revealing an intricate interplay between the gel mesh and the MNPs. Expand
Magnetorheology: materials and application
As one of the most important field-responsive intelligent and smart soft matter materials, magnetorheological (MR) fluids, consisting of magneto-responsive magnetizable particles suspended inExpand


Surface waves in ferrofluids under vertical magnetic field
Abstract:We present here new experimental results about the waves at the horizontal free surface of a magnetic fluid submitted to a normal magnetic field. The waves are generated by a smallExpand
Two-dimensional solitons on the surface of magnetic fluids.
The radioscopic measurements of the soliton's surface profile suggest that locking on the wavelength defined by the nonmonotonic dispersion curve is instrumental in its stabilization. Expand
The normal field instability under side-wall effects: comparison of experiments and computations
We consider a single spike of ferrofluid, arising in a small cylindrical container, when a vertically oriented magnetic field is applied. The height of the spike as well as the surface topography isExpand
The surface topography of a magnetic fluid: a quantitative comparison between experiment and numerical simulation
The normal field instability in magnetic liquids is investigated experimentally by means of a radioscopic technique which allows a precise measurement of the surface topography. The dependence of theExpand
The interfacial stability of a ferromagnetic fluid
A normal magnetic field has a destabilizing influence on a flat interface between a magnetizable and a non-magnetic fluid. Stabilizing influences are provided by interfacial tension and gravity ifExpand
Measuring the deformation of a ferrogel sphere in a homogeneous magnetic field.
By comparing the elongation along the field to the contraction perpendicular to it, Poisson's ratio of the gel is calculated, which shows the magnitude of the elongations is compared to the theoretical predictions for elastic spheres in homogeneous fields. Expand
Surface Waves and Rosensweig Instability in Isotropic Ferrogels
Summary We derive the dispersion relation of surface waves for isotropic magnetic gels in the presence of an external magnetic field normal to the free surface. Above a critical field strengthExpand
Pattern and wave number selection in magnetic fluids.
  • R. Friedrichs, A. Engel
  • Physics, Medicine
  • Physical review. E, Statistical, nonlinear, and soft matter physics
  • 2001
The formation of patterns of peaks on the free surface of a magnetic fluid subject to a magnetic field normal to the undisturbed interface is investigated theoretically. The relative stability ofExpand
Magnetic properties of dense ferrofluids: an influence of interparticle correlations.
  • A. Ivanov, O. Kuznetsova
  • Physics, Medicine
  • Physical review. E, Statistical, nonlinear, and soft matter physics
  • 2001
A statistical model has been developed describing the magnetostatic properties of dense ferrocolloids and the dielectric properties of polar fluids and the effective field is calculated as a function of the Langevin magnetization. Expand
Pattern formation in ferrogels : analysis of the Rosensweig instability using the energy method
We present a nonlinear description of the Rosensweig instability in isotropic magnetic gels based on the energy minimizing method used by Gailitis to describe the Rosensweig instability in typicalExpand