We report the suppression of the ferromagnetic phase transition in ${\mathrm{La}}_{1-x}{\mathrm{Ca}}_x\mathrm{Mn}{\mathrm{O}}_3$ close to the localized-to-itinerant electronic transition, i.e., at $x\approx 0.2$ and $x\approx 0.5$. A new crossover temperature $T_f$ can be defined for these compositions instead of $T_{\mathrm{C}}$. Unlike in common continuous magnetic phase transition the susceptibility does not diverge at $T_f$ and a spontaneous magnetization cannot be defined below it. We propose that the proximity to the doping-induced metal-insulator transition breaks up the electronic/magnetic homogeneity of the system and explains these effects.

• Received 31 August 2004

DOI:https://doi.org/10.1103/PhysRevB.70.172410