Anomalous Magnetic Aftereffect of a Frozen Magnetic Fluid

Published

January 1, 2004

Author(s)

S Taketomi, R V. Drew, Robert D. Shull

Abstract

A very stably dispersed magnetic fluid (MF) was zero-field-cooled from room temperature of 5 K followed by the application of a magnetic field of 2.86 MA/m for 300 seconds. After the field was removed (t = 0), its residual magnetization M was measured as a function of time t for 80000 s. After measurement, the MF sample was heated to room temperature, and the experiment was repeated after zero-field cooling to 5K and again applying and removing the 2.86 MA/m field. We performed the same experiment several times, and obtained a different M t curve each time. With each cycle, the average M (at t = 0) increased and the M t curve converged to a universal curve. In the early cycles experiments, M surprisingly increased with t during the later stages of the experiment. From the different experiments, it was concluded that the isolated surfactant molecules in the MF solvent played an important role. We propose a model wherein the magnetic colloids from closed magnetic flux circuits by forming collective micelle structures with temperature decrease. After application and removal of the field at 5 K, the micelles in the frozen MK break spontaneously, leading to and increase in the residual magnetization.

Citation

IEEE Transactions on Magnetics

Volume

40

Issue

No. 4

Pub Type

Journals

Keywords

anomalous, magnetic fluid (MF), magnetic flux, micelle structures, residual magnetization

Citation

Taketomi, S. , Drew, R. and Shull, R. (2004), Anomalous Magnetic Aftereffect of a Frozen Magnetic Fluid, IEEE Transactions on Magnetics (Accessed October 11, 2025)