Critical magnetic behavior and large magnetocaloric effect in Pr_0.67Ba_0.33MnO₃ perovskite manganite

We report results of critical magnetic behavior and magnetocaloric investigations of the perovskite manganite Pr_0.67Ba_0.33MnO₃. The compound exhibits a paramagnetic (PM) to ferromagnetic (FM) transition at the Curie temperature T_C, and significant negative magnetoresistance in a wide temperature range. To probe the magnetic interactions responsible for the magnetic transitions, we performed a critical exponent analysis in the vicinity of the FM–PM transition region. Magnetic entropy change ΔS_M was estimated from isothermal magnetization data. We have found a remarkable large value of |ΔS_M| around T_C's, of about 5.50 J/kg K for μ₀ΔH=4 T and a large relative cooling power (~225 J/kg). The analysis was done by using the modified Arrot plot (MAP) method. The values of the obtained critical exponents associated with this transition, β=0.366, γ=1.375 and δ=4.743 are close to those expected for the short range 3D Heisenberg model. The model was also confirmed by using |ΔS_M|∝(μ₀H)ⁿ, the field dependence of magnetic entropy change method. The large measured magnetocaloric effect is presumed to arise as a consequence of the sample preparation route