The magnetocaloric effect (MCE) is a common phenomenon in magnetic materials, and the essence of which is a thermal effect caused by the change of magnetic moment order under an adiabatic condition. A wide range of materials showing the first-order (FO)/second-order (SO) magnetic phase transitions (PT) exhibiting large/moderate magnetic entropy change (ΔS_M) has been reported 1-4. Among the magnetic materials, the perovskite manganites which shows FOPT/SOPT below room temperature (RT) finds importance in cryogenic technology for laboratory purpose and space technology and have been an interest for the researcher to study the MCE effect in the vicinity of magnetic PT 5-6.

In this paper, we present magnetic and MCE properties in Pr_0.52Sr_0.48MnO₃ (PSMO48) and Pr_0.52Sr_0.48MnO₃ (PSMO52) perovskite manganite. PSMO48 show a paramagnetic to ferromagnetic, a SOPT at Tc (Curie temperature)=258 K, while PSMO52 undergoes SOPT at T_c=224 K followed by a charge disordered ferromagnetic to A-type antiferromagnetic at T_N (Neel temperature)~ 139 K. PSMO52 shows irreversibility during the cooling and heating cycle in temperature-dependent magnetisation measurement, a signature of first-order phase transition at low temperature. Furthermore, ΔS_M has been calculated using the magnetic field (H)-dependent magnetisation (M) isotherms data using the Maxwell model. PSMO48 shows a trivial ΔS_M value ~ 4.7 J/kg K at H=8T (around T_c). PSMO52 showed a giant ΔS_M value of ~ 3.7 J/kg K (around T_c) and 4.2 J/kg K (around T_N) at H=8T. The simulation of ΔS_M carried out using the phenomenological Landau free energy Model shows good agreement with the experimental results as shown in Fig 1. The magnetotransport study of the samples shows a significant magnetoresistance in the vicinity of PT.

Acknowledgement:
This work is supported by UGC-DAE CSR, Indore, India (CSR-IC/CRS-89/2014-2018) granted to VD. AKS (Project fellow II) acknowledges UGC DAE CSR and MRF-MITM for fellowship.