Magnetic properties of compacted 50 nm CaMnO3-δ (CMO) nanoparticles have been investigated. Measurements of ac-susceptibility exhibit upon cooling two magnetic transitions at T∼270 K accompanied by a small spontaneous magnetic moment and a para-antiferromagnetic (AFM) transition at TN ∼120 K, observed previously in bulk CMO. Asymmetric magnetization hysteresis loops observed in applied magnetic fields H≤90 kOe are attributed to an exchange coupling between the antiferromagnetic core and the ferromagnetic (FM) shell of the CMO nanoparticles. This work provides the observation of exchange bias effect in manganite nanoparticles with inverted AFM-core-FM-shell structure, as compared to the typical FM-core-AFM-shell. Effects of surface and exchange anisotropy are also discussed.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 7 Feb 2008|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics