Large magnetoresistance and relative cooling power in polycrystalline Pr 0.775 Sr 0.225 MnO 3 compound

The effect of the phase boundary of ferromagnetic metallic and ferromagnetic insulator state (FMM-FMI) on magnetotransport and magnetocaloric properties in the ${\mathrm{Pr}}_{0.775}{\mathrm{Sr}}_{0.225}{\mathrm{MnO}}_3$ compound has been described in this study. An enhancement of magnetoresistance (MR) has been observed in the ${\mathrm{Pr}}_{0.775}{\mathrm{Sr}}_{0.225}{\mathrm{MnO}}_3$ compound compared to the compounds, reside on both sides of the phase boundary (i.e. FMI and FMM phases for Sr doping 0.2 and 0.3 respectively in ${\mathrm{Pr}}_{1-x}{\mathrm{Sr}}_x{\mathrm{MnO}}_3$). Moreover, a large relative cooling power (RCP), an important parameter for utilization of magnetocaloric materials, has also been achieved in this compound. The large value of RCP has been attributed to the formation of ferromagnetic clusters, formed above the ferromagnetic ordering temperature $(T>T_C)$. On the other hand, enhancement of MR is achieved because of the suppression of enhanced phase fluctuations, arises due to the closeness of FMM-FMI phases.