Critical behavior of La$_{0.825}$Sr$_{0.175}$MnO$_{2.912}$ anion-deficient manganite in the magnetic phase transition region

For La _0.825 ³⁺ Sr _0.175 ² +Mn³⁺O _2.912 ²⁻ anion-deficient manganite, the specific magnetization, the dynamic magnetic susceptibility, and the heat capacity are investigated. This material is found to be an inhomogeneous ferromagnet below the Curie point T _C ≈ 122 K, which is much lower than the Curie point determined for the stoichiometric composition (T _C ≈ 268 K). An increase in magnetic field by two orders of magnitude leads to an increase in the Curie temperature by ΔT ≈ 12 K. The presence of oxygen vacancies leads to the frustration of a part, namely, V _fr ≈ 22%, of the indirect Mn³⁺-O-Mn³⁺ exchange interactions, but the spin glass state is not realized. The ferromagnetic matrix of the material under study is characterized by a scatter in the exchange interaction intensities. The heat capacity is found to exhibit an anomalous behavior. Based on the Banerjee magnetic criterion, it is established that the ferromagnet-paramagnet transition observed for La _0.825 ³⁺ Sr _0.175 ²⁺ Mn³⁺O _2.912 ²⁻ anion-deficient manganite is a second-order thermodynamic phase transition. The mechanism and origin of the critical behavior of the system under investigation are discussed.