Critical phenomena and estimation of the spontaneous magnetization from a mean field analysis of the magnetic entropy change in La0.65Eu0.05Sr0.3Mn0.95Cr0.05O3

摘要

We have studied the magnetic and magnetocaloric properties of the La0.65Eu0.05Sr0.3Mn0.95Cr0.05O3 manganite prepared by using a soft chemical method (Pechini method). This compound presents a single magnetic transition from ferromagnetic (FM) to paramagnetic (PM) phase at T-C = 338 K. To investigate the nature of the magnetic phase transition, found to be of second-order, a detailed critical exponent study has been performed by dc-magnetization M (H,T) measurements around the Curie temperature T-C. Modified Arrott plot method has been adopted to study the critical behavior of the compound around its transition region. The values deduced for the critical exponents beta, gamma and delta are close to the theoretical prediction of the mean-field model, indicating that the magnetic interactions are long-range. Moreover, we have investigated the validity and usefulness of the theoretical modeling in our compound La0.65Eu0.05Sr0.3Mn0.95Cr0.05O3 based on the mean-field analysis of the magnetic entropy change (-Delta S-M) versus the magnetization data. Results obtained through this approach are compared to those obtained from extrapolation of the Arrott curves. An excellent agreement is found between the experimental (-Delta S-M) and the one estimated by Landau theory. (C) 2015 Elsevier Ltd. All rights reserved.