Exchange Bias in BiFe_{0.8}Mn_{0.2}O_3 Nanoparticles with an Antiferromagnetic Core and a Diluted Antiferromagnetic Shell

TL;DR

This study investigates exchange bias in BiFe0.8Mn0.2O3 nanoparticles with an antiferromagnetic core and a diluted antiferromagnetic shell, revealing interface exchange coupling as the main cause of the observed magnetic shift.

Contribution

It demonstrates that the exchange bias in these nanoparticles originates from interface coupling, with the DAFF shell's intrinsic contribution being negligible, and provides insights into EB in DAFF-based systems.

Findings

Exchange bias observed at room temperature.

Interface exchange coupling causes the loop shift.

High exchange bias field value measured at room temperature.

Abstract

We have observed conventional signature of exchange bias (EB), in form of shift in field-cooled (FC) hysteresis loop, and training effect, in BiFe0.8Mn0.2O3 nanoparticles. From neutron diffraction, thermoremanent magnetization and isothermoremanent magnetization measurements, the nanoparticles are found to be core-shell in nature, consisting of an antiferromagnetic (AFM) core, and a 2-dimensional diluted AFM (DAFF) shell with a net magnetization under a field. The analysis of the training effect data using the Binek's model shows that the observed loop shift arises entirely due to an interface exchange coupling between core and shell, and the intrinsic contribution of the DAFF shell to the total loop shift is zero. A significantly high value of EB field has been observed at room temperature. The present study is useful to understand the origin of EB in other DAFF-based systems as well.