Magnetic heating effect of nanoparticles with different sizes and size distributions

We present a comparative study of dynamic and quasistatic magnetic properties of iron oxide nanoparticles. The heating effect in an ac field in the range 0-30 kA/m at 210 kHz was measured calorimetrically. In addition, a vibrating sample magnetometer was used for hysteresis and remanence curve measurements. Four samples were prepared by different wet-chemical precipitation methods. Their mean size and composition (magnetite vs. maghemite) was investigated by X-ray diffraction. We show that the quasistatic and dynamic properties can be interpreted on the common basis of a lognormal size distribution.