Study of magnetic and electrical properties of Pr0.65Ca0.25Ba0.1MnO3 manganite

Abstract

The magnetic properties and magnetocaloric effect (MCE) in Pr_0.65Ca_0.25Ba_0.1MnO₃ have been investigated supplemented by electrical data. X-ray diffraction shows that the sample crystallizes in the distorted orthorhombic system with the Pnma space group. Pr_0.65Ca_0.25Ba_0.1MnO₃ undergoes paramagnetic–ferromagnetic (PM–FM) phase transition at T_C ∼ 85 K. For a magnetic field change of 5 T, the maximum value of the magnetic entropy change (−ΔS^max_M) is estimated to be 4.4 J kg⁻¹ K⁻¹ around T_C with a large relative cooling power (RCP) value of 263.5 J kg⁻¹. While the modified Arrott plots suggested that the magnetic transition belongs to the second order phase transitions, the universal curves of the rescaled magnetic entropy (ΔS_M) proved the opposite. The electrical properties of Pr_0.65Ca_0.25Ba_0.1MnO₃ have been investigated using impedance spectroscopy techniques. The dc-resistivity (σ_dc) study shows the presence of semiconductor behavior. Ac-conductivity (σ_ac) analysis shows that the conductivity is governed by a hopping process. From the analysis of the alternating regime, the exponent s variation obtained is in good agreement with Mott theory. The impedance spectrum analysis reveals the presence of a relaxation phenomenon. Based on these analyzes, the sample can be modeled by an electrical equivalent circuit.