Superparamagnetism

Superparamagnetism is a form of magnetism. A superparamagnetic material has many small clusters of magnetic things in its structure, but they are not all pointed the same way, so the material is not magnetic by itself. If a magnetic field is applied to the material, then the clusters change direction to match the magnetic field and the material becomes magnetic. Superparamagnetism is like paramagnetism, except it can happen at near room temperature. It happens when materials are made up of very small parts (1-10 nm).

Superparamagnetism Media

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  Langevin function (red line), compared with \tanh\left(\frac{1}{3}x\right) (blue line).