Crossover critical behavior and magnetic entropy change of La_0.7Ba_0.1Ca_0.1Sr_0.1MnO₃: A comparison between wet-mixing and sol-gel synthesis methods

We have investigated the effect of synthesis method on critical behavior and magnetic entropy change of La_0.7Ba_0.1Ca_0.1Sr_0.1MnO₃. The samples were prepared using the wet-mixing (WM) and sol-gel (SG) methods. The Curie temperature (T_C) was approximately 316 and 330 K for the WM and SG samples, respectively. The estimated critical exponents (β, γ, and δ) were close to the mean-field theory for the WM samples, whereas the exponent values for the SG sample were close to the tricritical mean-field model. The difference in the estimated critical exponents obtained from the same sample is known as a crossover phenomenon. The maximum magnetic entropy change (−ΔS_M) under an applied magnetic field at 5 T was estimated at 3.16 and 4.89 J.kg⁻¹.K⁻¹ for the WM and SG samples, respectively. The synthesis method strongly affected physical properties and universality class, which can be explained by changes in the structural parameter and by grain size reduction.