• 
  Argyriou, D.N.; Ruett, U.; Adams, C.P.; Lynn, J.W.; Mitchell, J.F.: Phase separation in Pr_0.7Ca_0.3MnO_0.3: a case of weak quenched disorder. New Journal of Physics 6 (2004), p. 195/1-15
  http://www.njp.org/

10.1088/1367-2630/6/1/195

Abstract:
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 ~20 Å. At TCE = 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 TCE 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 Å 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.