Noise Characteristics of the Optical Response of Ferrofluids to a Magnetic Field

The noise generated by different ferrofluid samples when probed by the fiber-optic method has been investigated. It is shown that switching on a magnetic field significantly increases the noise, which is presumably related to fluctuations accompanying the process of aggregate formation. The dependences of the rms noise on the field strength and probe-light intensity have been experimentally determined. A slow decrease in the rms noise after switching off the magnetic field has been found, which indicates relaxation of the aggregates formed by the field.