Characterization of the charge order to ferromagnetic crossover behavior in (LayPr1-y)0.5Ca0.5MnO3

We present structural and magnetization measurements in large-grain ceramic samples of the family (LayPr1-y)0.5Ca0.5MnO3 with y=0, 0.15, 0.3, 0.5, 0.7, 0.85 and 1.0. In this series, a change of the ionic radius in site A (rA) modifies the structural parameters, which strongly affect the physical properties of these compounds. While the Neel temperature remains essentially constant through the series, the ferromagnetic (FM) critical temperature (TC) decreases rapidly and the charge-order (CO) temperature (TCO) increases on decreasing y. The crossover of TC and TCO determines a critical tolerance factor (tc∼0.975) consistent with previous reports on other systems with the same Mn3+/Mn4+ ratio. For tolerance factors t near tc we observe coexistence of a FM and CO phases of varying degrees depending on y. For y=<0.15 we find no evidence of ferromagnetism