Second-order magnetic critical points at finite magnetic fields: Revisiting Arrott plots
Second-order magnetic critical points at finite magnetic fields: Revisiting Arrott plots
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DOI：
10.1103/physrevb.93.224429
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发表时间：
2016-06-27
影响因子：
3.7
通讯作者：
Curiale, J.
中科院分区：
文献类型：
--
作者：
Bustingorry, S.;Pomiro, F.;Curiale, J.
所谓的Arrott图，其包括绘制H/M对M-2，其中H为施加的磁场，M为磁化强度，用于提取二阶磁相变中的有价值的信息。此外，人们普遍认为，阿罗特图中的负斜率指示一级磁转变。这被称为Banerjee标准。因此，零场转变温度T* 被报告为特征一阶转变温度。通过仔细分析用于研究一阶磁跃迁的平均场朗道模型，我们在这项工作中表明，T* 实际上对应于三个一阶线相交的三相点。更重要的是，该分析揭示了在有限磁场（T-c，+/- H-c）下存在两个对称的二阶临界点。然后，我们表明，修改后的Arrott图可以用来获得这些二阶临界点的信息。为了支持这一想法，我们分析实验数据的La 2/3Ca 1/3 MnO 3和讨论的位置的三相点和二阶临界点的估计。
The so-called Arrott plot, which consists in plotting H/M against M-2, with H the applied magnetic field and M the magnetization, is used to extract valuable information in second-order magnetic phase transitions. Besides, it is widely accepted that a negative slope in the Arrott plot is indicative of a first-order magnetic transition. This is known as the Banerjee criterion. In consequence, the zero-field transition temperature T* is reported as the characteristic first-order transition temperature. By carefully analyzing the mean-field Landau model used for studying first-order magnetic transitions, we show in this work that T* corresponds in fact to a triple point where three first-order lines meet. More importantly, this analysis reveals the existence of two symmetrical second-order critical points at finite magnetic field (T-c,+/- H-c). We then show that a modified Arrott plot can be used to obtain information about these second-order critical points. To support this idea we analyze experimental data on La2/3Ca1/3MnO3 and discuss an estimate for the location of the triple point and the second-order critical points.