Evolution from non-Griffiths phase to Griffiths phase: Giant enhancement of magnetoresistance in nanocrystalline (La0.4Y0.6)0.7Ca0.3MnO3 compound

The particle size driven modification of the non-Griffiths phase to Griffiths phase in (La0.4Y0.6)0.7Ca0.3MnO3 (LYCMO) compound have been presented here. In the nanocrystal, the decreased lattice distortions together with the quenched disorder arising from the ionic size mismatch of the different A-site ions are the possible reason for the occurrence of Griffiths phase. On the other hand, though in the bulk compound quenched disorder is present but the higher distortions enhance the effective antiferromagnetic superexchange interactions and may be the probable reason for the non-Griffiths phase which is identified by the upturn of the inverse susceptibility versus temperature plot from the Curie-Weiss line. An enhancement of Colossal magnetoresistance (CMR) in the minimal surface disorder nanoparticle (∼120nm) has been observed. The study shows that for LYCMO compound, the enhancement of CMR in 120 nm nanoparticle is due to the conversion from non-Griffiths phase to Griffiths phase.