Phase separation in Pr0.7Ca0.3MnO0.3:: a case of weak quenched disorder -: art. no. 195

Phase separation (PS) in manganites has been suggested to arise as a consequence of quenched disorder due to the size mismatch of the A-site cations in the perovskite lattice. In this paper, we have used single crystal x-ray and in-field neutron diffraction measurements to investigate PS in Pr0.7Ca0.3MnO3, a compound with weak quenched disorder. Above the charge/ordering transition, our measurements show CE-type clusters with a coherence length of similar to 20 Angstrom. At T-CE = 220 K the coherence length of the diffuse scattering diverges as a long-range ordered CE state is formed. Concurrently, the Huang scattering abruptly decreases at T-CE as the diffuse CE-type reflections develop into Bragg reflections, suggesting that the transition to the CE-state is of the disorder - order type. Our neutron measurements of the ferromagnetic (FM) and antiferromagnetic (AF) ordering in Pr0.7Ca0.3MnO3, show the presence of FM 200 Angstrom clusters coexisting with long range AF and FM phases. Application of field after zero-field-cooling leads to the reduction of the diffuse FM scattering. We argue that PS in this compound arises as a consequence of the Jahn-Teller strain from Mn3+ centres that act like quenched disorder.