Figure 6: The dependence of the absorption lines derivatives, 𝑑 𝜒 / 𝑑 𝐻 d 𝑐 , on dc magnetic field 𝐻 d c for two samples of type D. The plot made by dashed line relates to magnetic nanoparticles, which in the course of filling the pores of the porous glass were subjected to an external magnetic field of a permanent magnet ( 𝐵 s a t 0 . 5  T). It was not the case for the plot made by continuous line.