Influence of ultrasonic frequency on field induced hysteresis phenomena observed in magnetic fluid

Kruti Shah - R. V. Upadhyay

P.D. Patel Institute of Applied Sciences, Charotar University of Science and Technology, CHARUSAT Campus, Changa 388 421, India

Abstract
Anisotropy of the ultrasonic propagation velocity for different frequencies in Mn-Zn magnetic fluid under uniform magnetic fields is studied experimentally. The change in ultrasonic velocity is due to the formation of a chain-like structure or clusters formation in magnetic fluids. Hysteresis is exhibited as the magnetic field is increased and then decreased. This behaviour is a function of the frequency of ultrasonic wave. These results suggest that the propagation velocity is related to a characteristic time of Brownian motion of magnetic particles. In this paper, we have given a theoretical approach to explain the experimental observations. The analysis indicates that the anisotropy behaviour is dominated by the grain-grain interaction, while hysteresis depends on the grain-field interaction. To confirm our model, we have fitted the hysteresis results obtained by earlier works and found them to agree well. Figs 3, Refs 9.