Critical magnetic behavior and large magnetocaloric effect in Pr0.67Ba0.33MnO3 perovskite manganite

We report results of critical magnetic behavior and magnetocaloric investigations of the perovskite manganite Pr0.67Ba0.33MnO3. The compound exhibits a paramagnetic (PM) to ferromagnetic (FM) transition at the Curie temperature TC, 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 ΔSM was estimated from isothermal magnetization data. We have found a remarkable large value of |ΔSM| around TC'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 |ΔSM|∝(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.