Preparation, characterization and magnetic studies of Bi_0.5 X_0.5(X=Ca,Sr)MnO_3 nanoparticles

TL;DR

This study synthesizes Bi_0.5 X_0.5 (X=Ca,Sr)MnO_3 nanoparticles via a polymer-assisted sol-gel method, characterizes their structure and magnetic properties, and finds that charge ordering is robust in these nanomanganites.

Contribution

It demonstrates the synthesis and detailed characterization of Bi-based nanomanganites, revealing their persistent charge ordering unlike other rare-earth manganites.

Findings

Nanoparticles are 5-7 nm in size with single-phase structure.

Charge ordering remains stable in Bi-based nanomanganites.

High magnetic fields are required to melt the charge order.

Abstract

Nanoparticles (dia ~ 5 - 7 nm) of Bi_0.5 X_0.5(X=Ca,Sr)MnO_3 are prepared by polymer assisted sol-gel method and characterized by various physico-chemical techniques. X-ray diffraction gives evidence for single phasic nature of the materials as well as their structures. Mono dispersed to a large extent, isolated nanoparticles are seen in the transmission electron micrographs. High resolution electron microscopy shows the crystalline nature of the nanoparticles. Superconducting quantum interferometer based magnetic measurements from 10 K to 300 K show that these nanomanganites retain the charge ordering (CO) nature unlike Pr and Nd based nanomanganites. The CO in Bi based manganites is thus found to be very robust consistent with the observation that magnetic field of the order of 130 T are necessary to melt the CO in these compounds. These results are supported by electron magnetic resonance measurements.