Correlation between phase competition and the nucleation of a Griffiths-like phase in (La1-yPry)0.7Ca0.3Mn16/18O3

Detailed analyses of the temperature-dependent zero-field ac susceptibility of prototypical phase-separated (La1-yPry)(0.7)(Ca0.3MnO3)-O-16/18, 0 <= y <= 1, reveal features consistent with the presence of a Gri.ths-like phase ( GP), viz, an inverse susceptibility (chi(-1)) characterized by chi(-1)proportional to (T - T-C(Rand))(1-lambda) with 0.05 <= lambda <= 0.33 as y decreases towards y(c) <= 0.85. Beyond y(c) = 0.85, the GP is suppressed. These data, combined with previous neutron diffraction measurements, enable a phase diagram summarizing the evolution of the GP with composition to be constructed for this system; this phase diagram demonstrates the novel result that the disorder relevant for the establishment of such a phase in this system is linked closely to the relative volume fractions of the phase-separated antiferromagnetic and ferromagnetic components, even when the recently estimated double-exchange-linked percolation threshold is exceeded. The influence of electronphonon coupling can also be seen through oxygen isotope effects. Copyright (c) EPLA, 2008