Dhahri Khadija, Dhahri N, Dhahri J, Taibi K, Hlil E K
Laboratoire de la Matière Condensée et des Nanosciences, Département de Physique, Faculté des Sciences, Université de Monastir Monastir 5019 Tunisia
Département SDM, FGMGP/USTHB 16311 Algeria.
RSC Adv. 2018 Jan 15;8(6):3099-3107. doi: 10.1039/c7ra12827d. eCollection 2018 Jan 12.
In the present work, we have studied the universal critical behavior in the perovskite-manganite compound LaCaPbMnAlSnO. Experimental results revealed that all samples exhibit a second-order magnetic phase transition. To study the critical behavior of the paramagnetic-ferromagnetic transition, various techniques such as modified Arrott plots, the Kouvel-Fisher method and critical isotherm analysis were used to determine the values of the Curie temperature , as well as the critical exponents (corresponding to the spontaneous magnetization), (corresponding to the initial susceptibility) and (corresponding to the critical magnetization isotherm). The critical exponent values for our sample are consistent with the prediction of the mean field model ( = 0.46, = 1.0, and = 2.94 at an average = 302.12 K), indicating that the magnetic interactions are long-range. The reliability of the critical exponent values was confirmed by the Widom scaling relation (WSR) and the universal scaling hypothesis. Moreover, to estimate the spontaneous magnetization of LaCaPbMnAlSnO perovskite, we used the magnetic entropy change (Δ ), obtained from isothermal magnetization. The results obtained through this approach are compared to those obtained from classical analysis using Arrott curves. An excellent agreement is found between this approach and the one obtained from the extrapolation of the Arrott curves.
在本工作中，我们研究了钙钛矿锰氧化物化合物LaCaPbMnAlSnO中的普遍临界行为。实验结果表明，所有样品均呈现二级磁相变。为了研究顺磁 - 铁磁转变的临界行为，我们使用了各种技术，如修正的阿罗特图、库维尔 - 费舍尔方法和临界等温线分析，以确定居里温度的值，以及临界指数（对应于自发磁化强度）、（对应于初始磁化率）和（对应于临界磁化等温线）。我们样品的临界指数值与平均场模型的预测一致（在平均 = 302.12 K时， = 0.46， = 1.0， = 2.94），这表明磁相互作用是长程的。临界指数值的可靠性通过维登标度关系（WSR）和通用标度假设得到了证实。此外，为了估计LaCaPbMnAlSnO钙钛矿的自发磁化强度，我们使用了从等温磁化获得的磁熵变（Δ）。通过这种方法获得的结果与使用阿罗特曲线进行经典分析得到的结果进行了比较。发现这种方法与从阿罗特曲线外推得到的方法之间有很好的一致性。
