Complex competition between ferromagnetism and antiferromagnetism in the CMR manganites Pr1−x Ca x MnO3

Abstract

The systematic investigation of the magnetic susceptibility of the CMR manganites Pr1−x Ca x MnO3 versus temperature has been performed for 0.25 ≤ x ≤ 0.50. Due to the similar size of calcium and praseodymium, these results show the important role of the mixed valence of manganese upon the complex magnetic behaviour of these compounds. They demonstrate that the appearance of antiferromagnetism coincides with charge ordering, T N = T CO varying with x, from 250K for x = 0.50 to 225K for x = 0.35. A strong competition between ferromagnetism and antiferromagnetism is observed for 0.35 ≤ x 170 K) and going through canted antiferromagnetic or weak ferromagnetic states for intermediate temperatures (70 K < T < 170 K). For 0.25 ≤ x ≤ 0.30, a strong ferromagnetic state is observed for 95 K ≤ T ≤ 150 K, with a transition to a spin glass like state below 95–110 K.