A.Tschöpe: Field induced rotational motion of ferromagnetic nanorods in a viscoelastic matrix
Description
The magneto-elastic coupling between particles and matrix which determines the physical properties of magnetic hybrid materials is influenced by numerous factors.
The objective of the present project is to systematically investigate the impact of these factors using the example of the rotational motion of ferromagnetic nanoparticles in viscoelastic hydrogels and to derive suitable quantitative models. Starting point is the characterization of the single particle behavior in the limit of low particle volume fraction. We use uniaxial ferromagnetic single domain nickel nanorods as model particles. The optical anisotropy of these nanorods allows to measure particle rotation by means of optical transmission of linearly polarized light at a particle volume fraction as low as 10-6. These highly diluted systems are predestinated to study the influence of physical/chemical particle-matrix interaction, finite magnetic anisotropy and deviations from the linear elastic behavior of the matrix deformation at large rotation angles. Changes in the rotational motion, induced by increasing volume fraction and/or the magnetic moments of the nanorods as well as field-induced aggregation of the magnetic particles are analyzed with respect to the concomitant dipolar and elastic interactions. Finally, the dynamics of nanoparticle rotation in time-dependent magnetic fields is investigated and related to the local viscoelastic properties of the matrix.
Transmission electron micrograph of ferromagnetic nickel nanorods.
Project Manager
Dr. Andreas Tschöpe, Universität des Saarlandes
Staff
Kerstin Birster, Universität des Saarlandes
Micha Gratz, Universität des Saarlandes
Christoph Schopphoven, Universität des Saarlandes
Grant period
2013 -
Publications
[1] Bender, P.; Krämer, F.; Tschöpe, A.; Birringer, R. (2015) „Influence of dipolar interactions on the angular-dependent coercivity of nickel nanocylinders“ J. Phys. D: Appl. Phys. 48 , 145003
[2] Bender, P.; Tschöpe, A.; Birringer, R. (2014) „Magnetization measurements reveal the local shear stiffness of hydrogels probed by ferromagnetic nanorods“ J. Magn. Magn. Mater. 372 , 187 - 194
[3] Roeder, L.; Bender, P.; Kundt, M.; Tschöpe, A.; Schmidt, A. M. (2015) „Magnetic and geometric anisotropy in particle-crosslinked ferrohydrogels“ Physical Chemistry Chemical Physics 17, 2 , 1290 - 1298
[4] Tschöpe, A.; Kirster, K.; Trapp, B.; Bender, P.; Birringer, R. (2014) „Nanoscale rheometry of viscoelastic soft matter by oscillating field magneto-optical transmission using ferromagnetic nanorod colloidal probes“ J. Appl. Phys. 116 , 184305
[5] Remmer, H.; Dieckhoff, J.; Tschöpe, A.; Roeben, E.; Schmidt, A.M.; Ludwig, F. (2015) „Dynamics of CoFe2O4 Single-Core Nanoparticles in Viscoelastic Media“ Physics Procedia
Contact
Universität des Saarlandes
Fachrichtung 7.3 - Technische Physik
Gebäude D2 2
Postfach 15 11 50
D-66041 Saarbrücken