Instability of insulator state towards nanocrystallinity in (La0.5Y0.5)0.7Ca0.3MnO3 compound: Enhancement of low field magnetoresistance

The present study shows the modification of the insulator state to metallic state with reduction of particle size in (La0.5Y0.5)0.7Ca0.3MnO3 compound by magnetotransport measurements. The decrease in the activation energy as well as increase in the effective density of states near Fermi level is observed with particle size reduction. This modification leads to the decrease in the resistivity in the nanoparticle in the low-temperature regime (T<150K). On the other hand, the temperature dependent dc susceptibility data shows the evolution of the non-Griffiths phase to Griffiths phase with reduction of particle size in the temperature range 100K