Correlation Between Phase Competition and the Nucleation of a Griffiths Phase in (La1-yPry)0.7Ca0.3Mn16/18O3

TL;DR

This study investigates how phase competition influences the nucleation of a Griffiths phase in (La1-yPry)0.7Ca0.3Mn16/18O3, revealing a composition-dependent Griffiths phase suppressed beyond a critical y value.

Contribution

It establishes a correlation between phase competition and Griffiths phase nucleation, providing a phase diagram and highlighting the role of disorder and electron-phonon coupling.

Findings

Griffiths phase characterized by power-law inverse susceptibility for y < 0.85

Griffiths phase suppressed beyond critical composition y = 0.85

Disorder linked to phase-separated antiferromagnetic and ferromagnetic components

Abstract

Detailed analyses of the temperature-dependent zero field ac susceptibility of prototypical phase-separated (La1-yPry)0.7Ca0.3Mn16/18O3, 0 < y < 1, reveal features consistent with the presence of a Griffiths phase (GP), viz., an inverse susceptibility characterized by power law with 0.05 < lamda < 0.33 as y decreases towards yc < 0.85. Beyond yc = 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; in particular, it shows that the disorder relevant for the establishment of such a phase is linked closely to the relative volume fractions of the phase separated antiferromagnetic and ferromagnetic components, even when the recently estimated double exchange (DE) linked percolation threshold is exceeded. The influence of electron-phonon coupling can also be seen through oxygen isotope effects.