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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Complex Fluids and Colloids II (joint session CPP/DY)
CPP 24.5: Vortrag
Dienstag, 13. März 2018, 10:30–10:45, C 264
Influence of rotating magnetic field on magnetic fluids with different viscosities — •Anastasia Storozhenko1, Ralf Stannarius2, Alexey Eremin2, Torsten Trittel2, and Igor Aref'ev3 — 1Southwest State University, 305040 Kursk, Russia — 2Otto von Guericke University Magdeburg, 39016 Magdeburg, Germany — 3Ivanovo Power Engineering University, 153003, Ivanovo, Russia
In an external rotating magnetic field, the magnetization of magnetic nanoparticles follows the field direction with a certain phase lag, which results in a macroscopic torque. We investigated experimentally the dependence of the torque density on the strength and frequency of the magnetic field, as well as on the viscosity of magnetic fluid.
The torque density increases with the square of the field strength; this can be explained by well-known expressions. At the same time, the magnetization direction changes slower than the external magnetic field due to the relaxation of magnetic nanoparticles. The dependence of the torque on frequency is thus complex and depends on the viscosity of magnetic fluid. We find a growth of the torque with rotation rate of the field, followed by a decay at higher rates. The torque maximum shifts with changing viscosity. This phenomenon can be related to the balance of Neel and Debye relaxation times.
This study was funded by DFG within SPP 1681, Project STA 425/36 and a DAAD Stipendium.