Effect of CePO4 on structural, magnetic and optical properties of ceria nanoparticles

We report an intrinsic dilute ferromagnetism in CeO2 nanoparticles prepared by a green synthesis route where Artocarpus Heterophyllus leaf extract is used as a bioreducing agent. PO43- ions from leaf extract lock oxygen vacancy derived Ce3+ ions as CePO4 at surface of the CeO(2 )nanoparticles. The observed ferromagnetic behavior is strongly influenced by the distribution of frustrated Ce3+ ions at surface which has been attributed to the RKKY (Ruderman-Kittel-Kasuya-Yosida) type indirect exchange interaction of the spins. A giant redshift (similar to 0.3 eV) in the optical bandgap with decrease in particle size indicates the presence of a spin polaron formed by the interaction between heavy fermion & charge carrier electrons in the system. The concept of locking the surface spins by phosphate ions may open up new possibilities for manipulation of the spin polarized charge carriers in future spintronics researches.