A regime in which particle-scale magnetic moments reverse thermally on the observation timescale, giving little quasistatic remanence despite internally ordered single-domain particles. Being single-domain is not sufficient: anisotropy barriers and measurement time determine whether reversal is rapid. A finite-frequency drive can still produce relaxation losses.
Thermally activated reorientation of a particle's internal magnetic moment across an anisotropy barrier. It differs from rotating the whole particle in a fluid. Its timescale can determine a measurement-dependent magnetic blocking temperature.
Articles by others on the same topic
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.