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

Abstract

The magnetic properties and magnetocaloric effect (MCE) in Pr0.65Ca0.25Ba0.1MnO3 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. Pr0.65Ca0.25Ba0.1MnO3 undergoes paramagnetic-ferromagnetic (PM-FM) phase transition at TC ∼ 85 K. For a magnetic field change of 5 T, the maximum value of the magnetic entropy change (-ΔSmaxM) is estimated to be 4.4 J kg-1 K-1 around TC 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 (ΔSM) proved the opposite. The electrical properties of Pr0.65Ca0.25Ba0.1MnO3 have been investigated using impedance spectroscopy techniques. The dc-resistivity (σdc) study shows the presence of semiconductor behavior. Ac-conductivity (σac) 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.