Observation of three-dimensional Heisenberg-like ferromagnetism in single crystal La_0.875Sr_0.125MnO₃

Abstract

We report measurements and analysis of the magnetic critical phenomena in a single crystal of La_0.875Sr_0.125MnO₃. The critical exponents associated with the ferromagnetic transition have been determined from ac susceptibility and dc magnetization data. Techniques like the Kouvel-Fischer plots, the modified Arrots plots, and the critical isotherm analysis were used for this purpose. The values of the exponents γ, β, and δ obtained are found to match very well with those predicted for the three-dimensional Heisenberg model. Our results are consistent with recent numerical calculations and suggest that though the double exchange interaction is driven by the motion of conduction electrons, the effective magnetic interaction near the transition is renormalized to a short range one.