Signature of Magnetic Phase Separation in the Ground State of   Pr1-xCaxMnO3
  Neutron scattering has been used to investigate the evolution of the long- and short-range charge-ordered (CO), ferromagnetic (FM), and antiferromagnetic (AF) correlations in single crystals of Pr1-xCaxMnO3. The existence and population of spin clusters as refected by short-range correlations are found to drastically depend on the doping (x) and temperature (T). Concentrated spin clusters coexist with long-range canted AF order in a wide temperature range in x = 0.3 while clusters do not appear in x = 0.4 crystal. In contrast, both CO and AF order parameters in the x = 0.35 crystal show a precipitous decrease below ~ 35 K where spin clusters form. These results provide direct evidence of magnetic phase separation and indicate that there is a critical doping x_c (close to x = 0.35) that divides the phase-separated site-centered from the homogeneous bond-centered or charge-disproportionated CO ground state. 
Hao Sha, F. Ye, Pengcheng Dai, J. A. Fernandez-Baca, D. Mesa, J. W.   Lynn, Y. Tomioka, Y. Tokura, Jiandi Zhang