Optical relaxation properties of magnetic fluids under externally magnetic fields

The relaxation behavior (including the rising and falling relaxation processes) of the transmitted light after the magnetic fluid thin films under longitudinal and transverse magnetic fields is investigated, respectively. The physical mechanisms of the two different relaxation processes are discussed. The experimental data of the rising and falling relaxation processes are fitted by using two exponential functions to achieve the rising and falling response times. The relationship between the response time and the strength of applied magnetic field, the concentration of magnetic fluid is studied experimentally. The modulation depth of the transmitted light is researched quantificationally and the deepest modulation depth is obtained with Sample 3 (with volume fraction of 5.62%) in our experiments. (C) 2011 Elsevier B.V. All rights reserved.