Study of magnetic and electrical properties of Pr 0.65 Ca 0.25 Ba 0.1 MnO 3 manganite.

The magnetic properties and magnetocaloric effect (MCE) in Pr 0.65 Ca 0.25 Ba 0.1 MnO 3 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 0.65 Ca 0.25 Ba 0.1 MnO 3 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 (-Δ S 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 (Δ S M ) proved the opposite. The electrical properties of Pr 0.65 Ca 0.25 Ba 0.1 MnO 3 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.