We studied the magnetic and phase transition properties of perovskite manganites \(\text {La}_{0.8}\text {Sr}_{0.2}\text {MnO}_{3}\) . A ferromagnetic-paramagnetic phase transition was confirmed at T \(_{C}\) =316 K by the measurement of the temperature-dependent magnetization M(T). Arrott plots show that this phase transition is of second order. Using the modified Arrott plots and Kouvel-Fisher method, the critical exponents are determined as \(\beta \) =0.594 for the spontaneous magnetization and \(\gamma \) =0.930 for the initial susceptibility, while \(\delta \) =2.660 obtained from the critical isotherm at T \(_{C}\) agrees well with that extracted from the Widom scaling relation. Within the long-range interaction framework, the decay exponent \(\sigma \approx 1.312\) in J(r) \(\sim \) r \(^{-(d+\sigma )}\) was evaluated. These results indicate that the phase transition of \(\text {La}_{0.8}\text {Sr}_{0.2}\text {MnO}_{3}\) belongs to a three-dimensional one-component system with long-range ferromagnetic interactions, close to a mean-field-like universality class. This work provides useful insight into the range of spin-spin interactions and critical behavior in doped manganites.
