Non-Equilibrium Magnetization of a Dilute Suspension of Magnetic Particles

2009 ◽  
Vol 152-153 ◽  
pp. 167-170 ◽  
Author(s):  
Alexander Tyatyushkin
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Heat Generation ◽  
Applied Magnetic Field ◽  
Single Particle ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Equilibrium Magnetization ◽  
Dilute Suspension ◽  
Generation Power

A suspension of magnetic particles in a viscous liquid magnetized in an alternating uniform magnetic field is theoretically studied. The suspension is regarded as so dilute that interaction of a single particle with the applied magnetic field can be considered without taking into account the influence of other particles. The complex magnetic susceptibility of the suspension is found as a function of the frequency of the applied magnetic field. The heat generation power density averaged over the period of the oscillations is calculated.

Non-Equilibrium Magnetization of a Dilute Suspension of Brownian Magnetic Particles

2012 ◽  
Vol 190 ◽  
pp. 657-660 ◽  
Author(s):  
Alexander Tyatyushkin
Keyword(s):  
Magnetic Field ◽  
Heat Generation ◽  
Applied Magnetic Field ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Inertial Effects ◽  
Equilibrium Magnetization ◽  
Dilute Suspension ◽  
Generation Power ◽  
Non Equilibrium

The influence of the inertial effects on the non-equilibrium magnetization of a suspensionof Brownian magnetic particles in a viscous liquid in a varying uniform magnetic field is theoreticallystudied. Themagnetization of the suspension is calculated. The heat generation power density is foundas a function of the frequency of the applied magnetic field.

ASTROID CURVES FOR A SYNTHETIC ANTIFERROMAGNETIC STACK IN AN APPLIED MAGNETIC FIELD

2009 ◽  
Vol 23 (20n21) ◽  
pp. 4021-4040
Author(s):  
D. M. FORRESTER ◽  
E. KOVACS ◽  
K. E. KÜRTEN ◽  
F. V. KUSMARTSEV
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Single Particle ◽  
Material Properties ◽  
Magnetic Particles ◽  
Particle System ◽  
Energy Landscape ◽  
Metastable States ◽  
Field Plane ◽  
The Magnetic Field

The interaction of two magnetic particles separated by an interlayer is illustrated through the "astroid" curves that represent regions in the magnetic field plane where different numbers of minima associated with stable or metastable states may exist. For a single particle, we describe the astroid curves of the Stoner-Wohlfarth model. The case of two particles is then examined and found to be much more complicated. The energy landscape of the two-particle system contains ferromagnetic, antiferromagnetic and canting states that emerge in response to the level of applied magnetic field. Because of this, up to four energy minima can exist in the system, depending upon the strength of the magnetic field and the material properties of the particles.

scholarly journals Magnetic Field-Dependent Reversal Effect of the Electromagnet- Induced Normal Stress of Magnetorheological Materials

2020 ◽  
Vol 1 (4) ◽  
pp. 1 ◽  
Author(s):  
Taixiang Liu ◽  
Yangguang Xu ◽  
Ke Yang ◽  
Lianghong Yan ◽  
Beicong Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mechanical Properties ◽  
Normal Stress ◽  
Applied Magnetic Field ◽  
Smart Materials ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Reversal Effect ◽  
Field Dependent

Magnetorheological (MR) materials are a type of magnetoactive smart materials, whose physical or mechanical properties can be altered by applying a magnetic field. In usual, MR materials can be prepared by mixing magnetic particles into non-magnetic matrices. In this work, the electromagnet-induced (or non-uniform magnetic field-induced) normal stress of MR materials is studied. It shows that the stress does not vary monotonically along with the enhancement of the applied magnetic field. There exists a field-dependent reversal effect of the variation of the stress. The reversal effect is thought resulting from that the ratio of interparticle repellent of parallel magnetic particles to the particle-electromagnet attraction gets enlarged along with the enhancement of the field.

Modeling Magneto-Active Elastomer Composites Using the Finite Element Method

2014 ◽  
Author(s):  
Robert Sheridan ◽  
Carrie Tedesco ◽  
Paris von Lockette ◽  
Mary Frecker
Keyword(s):  
Magnetic Field ◽  
Boundary Conditions ◽  
Applied Magnetic Field ◽  
Applied Field ◽  
Barium Ferrite ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Magnetic Interactions ◽  
Pdms Substrate ◽  
Fixed Boundary

Magneto-active elastomers (MAE) are a new branch of smart materials that consist of hard-magnetic particles such as barium ferrite in an elastomer matrix. Under the application of a uniform magnetic field, the MAE material undergoes large deformation as the material bends due to magnetic torques acting on the distribution of hard-magnetic particles. This behavior demonstrates the potential of MAEs to act as remote actuators. MAEs vary from magnetorheological elastomers (MRE) which use soft-magnetic iron particles in place of the hard-magnetic particles and they are driven by magnetic interactions between particles. In this work, MAEs were fabricated using 30% v/v 325 mesh M-type barium ferrite (BaM) particles in Dow Corning HS II silicone elastomers. Prior to curing, the samples were placed in a uniform (∼2 Tesla) magnetic field to align the magnetic particles and produce a magnetization oriented in the direction of the applied magnetic field. The specimens were bonded to a passive poldymethylsiloxane (PDMS) substrate to form a two-segment accordion structure where the MAEs with magnetization, M, were placed in opposing orientations a prescribed distance apart. The application of a uniform magnetic field perpendicular to the magnetization of the undeformed MAEs would result in a bend (on the PDMS) that is dependent upon the orientation of the magnetic particles and the direction of the applied field. This behavior of the composite structure highlights the ability of the MAE material to perform work. Experimental testing of the MAEs used a two-segment accordion structure with fixed boundary-conditions on both ends of the PDMS substrate and a uniform magnetic field was applied to the structure. The resulting deformation roughly represented either a mountain or valley fold (dependent upon the orientation of the applied field). The resulting axial force was observed and compared to computational simulations which utilized numerical techniques to develop approximate solutions. This procedure was repeated with a prescribed displacement on one of the two fixed boundary conditions to induce bending prior to the application of a uniform magnetic field. Results show a decrease in magnetic work potential with increases in the aforementioned prescribed displacement; results also show an increase in magnetic work potential with increases in the applied magnetic field.

scholarly journals Tunable Adhesion of a Bio-Inspired Micropillar Arrayed Surface Actuated by a Magnetic Field

2018 ◽  
Vol 86 (1) ◽  
Author(s):  
Xingji Li ◽  
Zhilong Peng ◽  
Yazheng Yang ◽  
Shaohua Chen
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Rotation Angle ◽  
Adhesion Force ◽  
Practical Applications ◽  
Section Shape ◽  
Theoretical Predictions ◽  
Large Elastic Deformation ◽  
The Difference

Bio-inspired functional surfaces attract many research interests due to the promising applications. In this paper, tunable adhesion of a bio-inspired micropillar arrayed surface actuated by a magnetic field is investigated theoretically in order to disclose the mechanical mechanism of changeable adhesion and the influencing factors. Each polydimethylsiloxane (PDMS) micropillar reinforced by uniformly distributed magnetic particles is assumed to be a cantilever beam. The beam's large elastic deformation is obtained under an externally magnetic field. Specially, the rotation angle of the pillar's end is predicted, which shows an essential effect on the changeable adhesion of the micropillar arrayed surface. The larger the strength of the applied magnetic field, the larger the rotation angle of the pillar's end will be, yielding a decreasing adhesion force of the micropillar arrayed surface. The difference of adhesion force tuned by the applied magnetic field can be a few orders of magnitude, which leads to controllable adhesion of such a micropillar arrayed surface. Influences of each pillar's cross section shape, size, intervals between neighboring pillars, and the distribution pattern on the adhesion force are further analyzed. The theoretical predictions are qualitatively well consistent with the experimental measurements. The present theoretical results should be helpful not only for the understanding of mechanical mechanism of tunable adhesion of micropillar arrayed surface under a magnetic field but also for further precise and optimal design of such an adhesion-controllable bio-inspired surface in future practical applications.

Investigation of Magnetorheological Suspensions by Optical Methods

2009 ◽  
Vol 152-153 ◽  
pp. 151-154
Author(s):  
L.V. Nikitin ◽  
D.N. Kudryavcev ◽  
I.V. Shashkov ◽  
A.P. Kazakov
Keyword(s):  
Magnetic Field ◽  
Composite Materials ◽  
Uniform Magnetic Field ◽  
Magnetic Particles ◽  
Raw Materials ◽  
Optical Methods ◽  
Magnetic Clusters ◽  
Liquid Polymer ◽  
Synthetic Rubber ◽  
Magnetorheological Suspensions

In this work we studied magnetorheological suspensions, which are produced by dispersion of magnetic particles in liquid polymer matrix, based on natural and synthetic rubber. Such suspensions are the raw materials for creation of new high-elastic magneto-controlled composite materials (magnitoelastics[1-4]). Processes of aggregation and structurization of magnetic particles in suspension are also examined. We discovered that motion of magnetic clusters in oligomer solution has interrupted character. Such behavior can be explained by interaction of magnetic clusters moving in not uniform magnetic field with polymer net fragments. Evaluation of polymer net’s elastic properties was calculated.

scholarly journals Nonsaturating large magnetoresistance in semimetals

2018 ◽  
Vol 115 (42) ◽  
pp. 10570-10575 ◽  
Author(s):  
Ian A. Leahy ◽  
Yu-Ping Lin ◽  
Peter E. Siegfried ◽  
Andrew C. Treglia ◽  
Justin C. W. Song ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Transport Properties ◽  
Applied Magnetic Field ◽  
Charge Compensation ◽  
Linear Dispersion ◽  
Dominant Mechanism ◽  
Temperature Dependences ◽  
Topological Semimetals ◽  
Different Origins

The rapidly expanding class of quantum materials known as topological semimetals (TSMs) displays unique transport properties, including a striking dependence of resistivity on applied magnetic field, that are of great interest for both scientific and technological reasons. So far, many possible sources of extraordinarily large nonsaturating magnetoresistance have been proposed. However, experimental signatures that can identify or discern the dominant mechanism and connect to available theories are scarce. Here we present the magnetic susceptibility (χ), the tangent of the Hall angle (tan⁡θH), along with magnetoresistance in four different nonmagnetic semimetals with high mobilities, NbP, TaP, NbSb2, and TaSb2, all of which exhibit nonsaturating large magnetoresistance (MR). We find that the distinctly different temperature dependences, χ(T), and the values of tan⁡θH in phosphides and antimonates serve as empirical criteria to sort the MR from different origins: NbP and TaP are uncompensated semimetals with linear dispersion, in which the nonsaturating magnetoresistance arises due to guiding center motion, while NbSb2 and TaSb2 are compensated semimetals, with a magnetoresistance emerging from nearly perfect charge compensation of two quadratic bands. Our results illustrate how a combination of magnetotransport and susceptibility measurements may be used to categorize the increasingly ubiquitous nonsaturating large magnetoresistance in TSMs.

scholarly journals Quantifying the motion of magnetic particles in excised tissue: Effect of particle properties and applied magnetic field

2015 ◽  
Vol 393 ◽  
pp. 243-252 ◽  
Author(s):  
Sandip Kulkarni ◽  
Bharath Ramaswamy ◽  
Emily Horton ◽  
Sruthi Gangapuram ◽  
Alek Nacev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Magnetic Particles ◽  
Particle Properties ◽  
Excised Tissue ◽  
Tissue Effect
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