Modification of the order of the magnetic phase transition in cobaltites without changing their crystal space group
Modification of the order of the magnetic phase transition in cobaltites without changing their crystal space group
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DOI：
10.1016/j.jallcom.2018.11.020
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发表时间：
2019-03-10
影响因子：
6.2
通讯作者：
Pramana, S. S.
中科院分区：
文献类型：
--
作者：
Law, J. Y.;Franco, V.;Pramana, S. S.
研究发现，GdBa_（1-x）Sr_xCo_（2-δ）具有反铁磁-铁磁（AFM-FM）和铁磁-顺磁（FM-PM）的连续磁转变，分别表现出逆磁热效应和常规磁热效应。在原始化合物（x = 0）中，其AFM-FM相变属于一级相变，FM-PM相变属于二级相变。尽管众所周知，钴酸盐的性质受到其氧含量和掺杂载体类型的高度影响，但在这项工作中，使用磁热分析的进一步评价（普适曲线法和利用磁熵变的磁场依赖性的定量判据）揭示了仅在x = 0.1的Sr掺杂下，一级AFM-FM相变转变为二级特征（尽管在室温下具有相同的空间群，并且掺杂剂载体的类型与x = 0相同），严重影响其热磁性质。此外，这两个MCE的峰值跨越的温度范围大于钴酸盐型材料所报道的温度范围，使其更接近室温应用。(C)2018爱思唯尔B. V.保留所有权利。
It has been found that GdBa1-xSrxCo2O6-delta can exhibit consecutive magnetic transitions: antiferromagnetic-ferromagnetic (AFM-FM) transition followed by ferromagnetic-paramagnetic transition (FM-PM), which give rise to a coexistence of inverse and conventional magnetocaloric effect (MCE), respectively. In the pristine compound (x = 0), its AFM-FM transition is shown to belong to a first-order phase transition and the FM-PM to a second-order type. Despite it is widely known that the properties of cobaltites are highly influenced by their oxygen content and type of doping carriers, in this work, further evaluation using magnetocaloric analysis (universal curve method and a quantitative criterion using magnetic field dependence of the magnetic entropy change) reveals that the first-order AFM-FM phase transition converts into a second-order character with just Sr doping of x = 0.1 (despite of having the same space group at room temperature and type of dopant carrier as x = 0), severely affecting its thermomagnetic properties. Moreover, the peaks of these two MCE span over a temperature range that is larger than those reported for cobaltite-type materials, making it closer to room temperature applications. (C) 2018 Elsevier B.V. All rights reserved.