Charge order suppression and antiferromagnetic to ferromagnetic switch over in Pr_0.5Ca_0.5MnO_3 nanowires

TL;DR

This study demonstrates that nanowires of Pr_0.5Ca_0.5MnO_3 suppress charge order and switch from antiferromagnetic to ferromagnetic states at lower temperatures, contrasting with bulk behavior.

Contribution

It introduces a low-temperature hydrothermal synthesis method for Pr_0.5Ca_0.5MnO_3 nanowires and reveals their distinct magnetic phase transitions.

Findings

Charge order is suppressed in nanowires.

A ferromagnetic transition appears at ~105 K.

Antiferromagnetic and charge order transitions are absent in nanowires.

Abstract

We have prepared crystalline nanowires (diameter ~ 50 nm, length ~ a few microns) of the charge ordering manganite Pr_0.5Ca_0.5Mn_O3 using a low reaction temperature hydrothermal method and characterized them using X-ray diffraction, transmission electron microscopy, SQUID magnetometry and electron magnetic resonance measurements. While the bulk sample shows a charge ordering transition at 245 K and an antiferromagnetic transition at 175 K, SQUID magnetometry and electron magnetic resonance experiments reveal that in the nanowires phase, a ferromagnetic transition occurs at ~ 105 K. Further, the antiferromagnetic transition disappears and the charge ordering transition is suppressed. This result is particularly significant since the charge order in Pr_0.5Ca_0.5MnO_3 is known to be very robust, magnetic fields as high as 27 T being needed to melt it.