Critical behavior and long-range ferromagnetic order in perovskite manganite Nd _0.55 Sr _0.45 MnO ₃

Abstract

The critical behavior of perovskite manganite Nd0.55Sr0.45MnO3 has been investigated based on the static magnetization measurement around the paramagnetic-ferromagnetic transition temperature 273 K. A large critical exponent and a small one have been obtained by calculating the magnetic-field dependence of the magnetic-entropy change and the Widom scaling relation. These critical exponents not only obey the scaling hypothesis, but also corroborate the results obtained from the Kouvel-Fisher method. In comparison with the values given by standard models, these obtained exponents are very close to those expected from the mean-field model ( and ) and its magnetic-coupling type belongs to nearly long-range interaction. We suggest that the A-site spin disorder and localized magnetic phase competition are the main reasons for the actual critical exponents to show a slight deviation from the theoretical model.