The correlation between superparamagnetic blocking temperatures and peak temperatures obtained from ac magnetization measurements

We study the correlation between the superparamagnetic blocking temperature TB and the peak positions Tp observed in ac magnetization measurements for nanoparticles of different classes of magnetic materials. In general, Tp=α+βTB . The parameters α and β are different for the in-phase (χ') and out-of-phase (χ") components and depend on the width σv of the log-normal volume distribution and the class of magnetic material (ferromagnetic/antiferromagnetic). Consequently, knowledge of both α and β is required if the anisotropy energy barrier KV and the attempt time To are to be reliably obtained from an analysis based solely on the peak positions