Superparamagnetic state field-cooled magnetization

F.2. Field-Cooled and Zero-Field-Cooled Magnetizations and Susceptibility in the Superparamagnetic State at Low Field... 

F.2.2. Field-Cooled Magnetization (Mp ) Experiments F.2.3. Magnetization in the Superparamagnetic State... 

Let us recall the usual process. The sample is cooled at once without applied field from a temperature where all the particles are in the superparamagnetic state until the lowest temperature Afterward a field is applied and the measurement is performed increasing the temperature. In fact, if the magnetization in the superparamagnetic state has to be studied, the above condition on the initial temperature must be fulfilled. But if only Tg is of interest, it is sufficient that the magnetic moments m of the particles are frozen in random orientation at This can easily be checked from the zero field magnetization value, which must be equal to zero. 

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