Superparamagnetism

Superparamagnetism is a phenomenon observed in certain types of magnetic materials, particularly in very small ferromagnetic or ferrimagnetic particles. These particles typically range in size from a few nanometers to around a few tens of nanometers. In this size range, thermal fluctuations can overcome the magnetic anisotropy which normally stabilizes the magnetic moments of the particles. In a superparamagnetic state, the magnetic moments of these small particles can randomly flip direction under the influence of thermal energy.