Correlation between phase competition and the nucleation of a Griffiths-like phase in (LaPr_y)_0.7Ca_0.3Mn^16/18O₃

Department of Physics and Astronomy, University of Manitoba - Winnipeg, Manitoba, R3T 2N2 Canada

Corresponding author: jiang@physics.umanitoba.ca

Received: 24 July 2008
Accepted: 20 October 2008

Abstract

Detailed analyses of the temperature-dependent zero-field ac susceptibility of prototypical phase-separated (LaPr_y)_0.7Ca_0.3Mn^16/18O₃ , 0 y 1, reveal features consistent with the presence of a Griffiths-like phase (GP), viz, an inverse susceptibility characterized by with as y decreases towards 0.85. Beyond = 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-exchangelinked percolation threshold is exceeded. The influence of electron-phonon coupling can also be seen through oxygen isotope effects.