A-site Randomness Effect on Structural and Physical Properties of Ba-based Perovskite Manganites

TL;DR

This study investigates how A-site randomness in Ba-based perovskite manganites affects their structure and magnetic properties, revealing a transition to magnetic glassy states and complex magnetization behaviors due to ionic size heterogeneity.

Contribution

It provides new insights into the effects of A-site disorder on the structural and magnetic properties of Ba-based manganites, highlighting the emergence of magnetic glassy states.

Findings

A-site disordered Ba-based manganites have a primitive cubic structure.

Magnetic glassy states dominate as the ground state in disordered samples.

Multi-step magnetization and resistivity changes are observed in Pr$_{0.5}$Ba$_{0.5}$MnO$_{3}$.

Abstract

The discovery of novel structural and physical properties in the $A$-site ordered manganite $R$BaMn$_{2}$O$_{6}$ ($R$ = Y and rare earth elements) has demanded new comprehension about perovskite manganese oxides. In the present study, the $A$-site disordered form, $R_{0.5}$Ba$_{0.5}$MnO$_{3}$, has been investigated and compared with both $R$BaMn$_{2}$O$_{6}$ and $R_{0.5}A_{0.5}$MnO$_{3}$ ($A$: Sr, Ca) in the structures and electromagnetic properties. $R_{0.5}$Ba$_{0.5}$MnO$_{3}$ has a primitive cubic perovskite cell in the structure and magnetic glassy states are dominant as its ground state, in contrast to the ordinary disordered $R_{0.5}A_{0.5}$MnO$_{3}$ ($A$: Sr, Ca). In Pr-compounds with various degrees of Pr/Ba randomness at the $A$-sites, the $A$-site disorder gradually suppresses both ferromagnetic and A-type antiferromagnetic transitions and finally leads to a magnetic glassy state in Pr$_{0.5}$Ba$_{0.5}$MnO$_{3}$. A peculiar behavior, multi-step magnetization and resistivity change, has been observed in Pr$_{0.5}$Ba$_{0.5}$MnO$_{3}$. These properties could be closely related to any spatial heterogeneity caused by the random distribution of Ba$^{2 +}$ and $R^{3 +}$ with much different ionic radius.