Issue
EPL
Volume 84, Number 4, November 2008
Article Number 47009
Number of page(s) 6
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/84/47009
Published online 21 November 2008
EPL, 84 (2008) 47009
DOI: 10.1209/0295-5075/84/47009

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

Wanjun Jiang, XueZhi Zhou and Gwyn Williams

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

jiang@physics.umanitoba.ca

received 24 July 2008; accepted in final form 20 October 2008; published November 2008
published online 21 November 2008

Abstract
Detailed analyses of the temperature-dependent zero-field ac susceptibility of prototypical phase-separated (La1-yPry)0.7Ca0.3Mn16/18O3 , 0 $\leqslant$ y $\leqslant$ 1, reveal features consistent with the presence of a Griffiths-like phase (GP), viz, an inverse susceptibility $(\chi ^{-1})$ characterized by $\chi ^{-1}\propto (T-T_{{\rm C}}^{{\rm Rand}})^{1-\lambda}$ with $0.05\leqslant \lambda \leqslant 0.33$ as y decreases towards $y_{{\rm c}}$ $\leqslant$ 0.85. Beyond $y_{{\rm c}}$ = 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$\hbox{--} $linked percolation threshold is exceeded. The influence of electron-phonon coupling can also be seen through oxygen isotope effects.

PACS
75.40.Cx - Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.).
75.47.Lx - Manganites.
75.47.Gk - Colossal magnetoresistance.

© EPLA 2008