Heat generation by an alternating magnetic field of low frequency in a ferrofluid: The dependence of energy dissipation on temperature

The heating of cobalt ferrite hydrocarbon magnetic fluids in an alternating magnetic field is studied at frequencies 22 kHz and 44 kHz. The magnetization curves of fluids and powders extracted from colloids are measured in fields up to 10 kOe. Complex magnetic susceptibilities are measured for these magnetic fluids in the range of 20Hz to 2MHz at two temperatures. A non-monotonic temperature dependence of heat generation is found for these fluids in the range of 10°C to 120°C. The temperature dependence of the carrier liquid viscosity is suggested as a main reason of this.