Suppression of the magnetic phase transition in manganites close to the metal-insulator crossover

We report the suppression of the ferromagnetic phase transition in La_1-xCaₓMnO₃ close to the localized-to-itinerant electronic transition, i.e., at x≈0.2 and x≈0.5. A new crossover temperature Tf can be defined for these compositions instead of TC. Unlike in common continuous magnetic phase transition the susceptibility does not diverge at Tf 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.