Room-temperature magnetocaloric performance in La0.57Nd0.1Sr0.23Ag0.1MnO3 manganite: a promising candidate for magnetic refrigeration

Abstract

The present paper presents an investigation of the structural, magnetic, magnetocaloric properties and critical behavior of La_0.57Nd_0.1Sr_0.23Ag_0.1MnO₃ (LNSAMO) perovskite manganite, synthesized via solid-state reaction. X-ray diffraction confirms a rhombohedral structure with minor impurity phases. The FTIR spectra confirmed the formation of the structure of rhombohedral perovskite. Magnetization measurements reveal a sharp ferromagnetic to paramagnetic transition at a Curie temperature T_c ≈ 318 K. In the paramagnetic regime, the inverse susceptibility obeys the Curie–Weiss law with a positive Weiss temperature close to T_c, indicative of strong ferromagnetic interactions. The magnetocaloric effect (MCE) was evaluated from isothermal magnetization curves using the Maxwell relation and Landau theory analysis, yielding a moderate maximum magnetic entropy change (−ΔS^max_M) and relative cooling power (RCP) under different magnetic fields. The nature of the magnetic phase transition was examined via Banerjee's criterion and universal curve, confirming its second-order character. Heat capacity measurements near T_c exhibit characteristic features consistent with a continuous magnetic phase transition. The critical behavior of the LNSAMO sample was analyzed using isothermal magnetization measurements near the transition temperature, employing methods such as the modified Arrott plot (MAP), Kouvel–Fisher (KF) technique, and critical isotherm analysis (CIA).