Origin of the Griffiths phase and correlation with the magnetic phase transition in the nanocrystalline manganiteLa0.4(Ca0.5Sr0.5)0.6MnO3

Abstract

In this paper, a detailed comprehensive magnetic study on the origin of the Griffiths phase (GP) in the nanocrystalline ${\mathrm{La}}_{0.4}{({\mathrm{Ca}}_{0.5}{\mathrm{Sr}}_{0.5})}_{0.6}{\mathrm{MnO}}_{3}$ compound has been presented. The system exhibits a ferromagnetic (FM)-like transition around ${T}_{\mathrm{C}}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}$ 274 K. Interestingly, above ${T}_{\mathrm{C}}$, the state is not pure paramagnetic, but a short-range FM interaction or GP is observed and the interaction persists up to the Griffiths transition temperature, ${T}_{G}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}$ 350 K. The detailed investigation of isothermal magnetization and the magnetocaloric effect along with its theoretical analysis have been employed besides the conventional magnetic measurements to probe the GP. Disorder in the system is introduced via increasing an A-site cationic size mismatch along with an additional defect originated owing to the particle size reduction. The disorder-induced magnetic phase transition has also been analyzed by critical analysis. A correlation between the unusual critical parameters with the GP has been furnished.