Fig. 7a. The magnetic transition it is not observed because it is below 400 K. Typically, two characteristic temperatures are defined in the ZFC-FC curves: TP-ZFC, which occurs at the maximum of the ZFC curves and is related to the blocking/freezing magnetic moment of the nanoparticles; and Tirr, which occurs at the temperature where the ZFC and FC curves overlap. Both ZFC curves of Fig.