H-T diagrams of Ln(1-x)Ca(x)MnO(3) (x = 1/2, 1/3) in pulsed fields up to 50 T

Well characterized Ln(1-x)Ca(x)MnO(3) manganites (Ln=La, Pr, Nd, Sm) with x = 1/2 and x = 1/3 have been investigated by magnetization measurements in pulsed magnetic fields up to 50 T. Using such high fields all the CO phase boundaries were identified in the temperature range 4-300 K. The transition fields at 4.2 K have been determined in a series of polycrystalline sample s with x = 1/2 and different effective bandwidths. They vary from H-c = 8 T for La to approximate to 30 T for Sm. In this article we have focused on s elected H-T phase diagrams. In particular, the results on Pr1/2Ca1/2MnO3, w ith the ideal 1:1 electron/hole ratio, are compared with Pr2/3Ca1/3MnO3 whe re the carrier concentration has been significantly reduced. The observed a nomalies in the H-c (T) curves are discussed in the light on neutron diffra ction data. (C) 1999 American Institute of Physics. [S0021-8979(99)36108-9] .