Specific features of magnetic states of impurity iron ions in the perovskite La$_{0.75}$Sr$_{0.25}$Co$_{0.98}^{57}$Fe$_{0.02}$O$_{3}$

Single-phase polycrystalline La$_{0.75}$Sr$_{0.25}$Co$_{0.98}^{57}$Fe$_{0.02}$O$_{3}$ samples have been prepared by solidstate ceramic technology. The samples have the rhombohedral structure (space group R$\bar3$c). The studies of perovskite La$_{0.75}$Sr$_{0.25}$Co$_{0.98}^{57}$Fe$_{0.02}$O$_{3}$ by Mössbauer spectroscopy on impurity $^{57}$Fe nuclei in the temperature range of 5–293 K have revealed the existence of a superparamagnetic relaxation in the temperature range of 100–210 K. The parameters of hyperfine interactions (hyperfine magnetic fields, line shifts, and quadrupole shifts) and the anisotropy energy have been measured, and the frequencies of magnetic moment relaxation of iron ions have been estimated.