Coexisting tuneable fractions of glassy and equilibrium long-range-order phases in manganites

TL;DR

This study demonstrates that in certain manganites, the proportions of glassy and equilibrium phases can be continuously tuned by specific temperature and magnetic field protocols, revealing complex phase coexistence behavior.

Contribution

It shows that phase fractions in manganites can be controlled through tailored protocols, highlighting the coexistence of homogeneous equilibrium and glassy phases at low temperatures.

Findings

Phase fractions are tunable via field-temperature protocols.

Different materials exhibit opposite low-temperature phase transitions.

Path-dependent states involve coexistence of equilibrium and supercooled phases.

Abstract

Antiferromagnetic-insulating(AF-I) and the ferromagnetic-metallic(FM-M) phases coexist in various half-doped manganites over a range of temperature and magnetic field, and this is often believed to be an essential ingredient to their colossal magnetoresistence. We present magnetization and resistivity measurements on Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) and Pr(0.5)Sr(0.5)MnO(3) showing that the fraction of the two coexisting phases at low-temperature in any specified measuring field H, can be continuously controlled by following designed protocols traversing field-temperature space; for both materials the FM-M fraction rises under similar cooling paths. Constant-field temperature variations however show that the former sample undergoes a 1st order transition from AF-I to FM-M with decreasing T, while the latter undergoes the reverse transition. We suggest that the observed path-dependent phase-separated states result from the low-T equilibrium phase coexisting with supercooled glass-like high temperature phase, where the low-T equilibrium phases are actually homogeneous FM-M and AF-I phases respectively for the two materials.