3rd International Conference on Magnetism and Magnetic Materials
MIREA— Russian Technological University, Russia
Title: Macroscopic dynamics of ferrofluids
Biography: Victor V Sokolov
Ferrofluids (magnetic fluids, magnetic nanofluids) are ultrastable colloidal suspensions of magnetic nanoparticles in non-polar and polar carrier liquids. The most striking feature of a ferrofluid is that it is a liquid with strong magnetic properties. The macroscopic dynamics of ferrofluids remains a subject of interest. Here we concentrate mainly on the two limiting cases. One corresponds to the assumption about equilibrium magnetization of ferrofluids i.e., under dynamic perturbations of the ferrofluids, the relaxation time of a magnetic field strength to its equilibrium value is infinitely small. Another limiting case corresponds to the assumption of frozen-in magnetization. The relaxation time of a magnetic field strength to its equilibrium value is infinitely large. The physical grounds for introducing this limiting case were descriptions of dynamic processes, in particular, ultrasound propagation in ferrofluids. The obtained expression for the velocity of fast magnetosonic waves describes the existing experimental data on the anisotropy of ultrasound wave propagation in ferrofluids. The previous theories could not describe the propagation of ultrasound waves in magnetic fluid under external magnetic field. The prediction concerning the existence of new waves, namely slow magnetosonic wave and Alfvén-type wave in ferrofluids seems very important and requires an experimental verification. We believe these waves would prove a most prolific area of experimental research.