From a heuristic calculation of the leading order essential singularity in the distribution of Yang-Lee zeroes, we obtain new scaling relations near the ferromagnetic-Griffiths transition, including the prediction of a discontinuity on the analogue of the critical isotherm. We show that experimental data for the magnetization and heat capacity of ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3$ are consistent with these predictions, thus supporting its identification as a Griffiths ferromagnet.

• Received 20 March 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.137201