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

摘要

We have observed conventional signature of exchange bias (EB), in form ofshift in field-cooled (FC) hysteresis loop, and training effect, inBiFe0.8Mn0.2O3 nanoparticles. From neutron diffraction, thermoremanentmagnetization and isothermoremanent magnetization measurements, thenanoparticles are found to be core-shell in nature, consisting of anantiferromagnetic (AFM) core, and a 2-dimensional diluted AFM (DAFF) shell witha net magnetization under a field. The analysis of the training effect datausing the Binek's model shows that the observed loop shift arises entirely dueto an interface exchange coupling between core and shell, and the intrinsiccontribution of the DAFF shell to the total loop shift is zero. A significantlyhigh value of EB field has been observed at room temperature. The present studyis useful to understand the origin of EB in other DAFF-based systems as well.