Structural correlations in La0.7Pb0.3(Mn1-xFex)O-3 manganites as probed by small-angle and polarized neutron diffraction

Small-to-medium-angle neutron diffraction as well as a full neutron polarization study of CMR manganites of general formula La0.7Pb0.3(Mn1-xFex)O-3, from x = 0 up to x = 0.2, reveal the presence of nanometre-sized magnetic domains having characteristic dimensions about one order of magnitude smaller than the crystal grain sizes. The role played by such entities as main drivers of the magnetic ordering transition is established here by analysis of the diffraction data. The model employed is then validated from data derived from polarized neutron diffraction. The latter also provides a direct insight into the presence of antiferromagnetic regions that arise as a consequence of competing interactions brought about by Fe substitution on the Mn site. The results are finally discussed within the context of recent findings on related materials.