EXCHANGE INTERACTIONS IN FERROMAGNETIC CHROMIUM CHALCOGENIDE SPINELS
EXCHANGE INTERACTIONS IN FERROMAGNETIC CHROMIUM CHALCOGENIDE SPINELS
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DOI：
10.1103/physrev.151.367
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发表时间：
1966-01-01
期刊：
影响因子：
--
通讯作者：
LOPATIN, E
中科院分区：
文献类型：
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作者：
BALTZER, PK;WOJTOWICZ, PJ;LOPATIN, E
具有磁性离子的过渡金属尖晶石在八面体位置上一直是许多研究的主题。这种尖晶石的性质一直被发现是由反铁磁相互作用主导的。在本文中，我们描述了一组尖晶石的性质，其中铁磁相互作用被发现占主导地位。制备了CdCr2S4、CdCr2Se4、HgCr2S4和HgCr2Se4四种铁磁性化合物，居里温度分别为84.5，129.5，36.0和106K。除了HgCr2S4在25K以下变磁性外，所有这些材料在4.2K以下仍保持铁磁性这些材料的独特之处还在于，它们除了是铁磁体之外，还是良好的电绝缘体。提出了一种理论处理，它与居里温度的高温磁化率，并提供了一个确定的交换相互作用。六个最近邻相互作用处理的高温膨胀技术的拉什布鲁克和伍德，而30个更远的邻居相互作用内的Callen和Callen的两粒子团簇近似处理。数据的分析表明，在确定硫属尖晶石中观察到的磁序类型时，远邻相互作用起着非常重要的作用。
Transition-metal spinels with magnetic ions solely on the octahedral sites have been the subject of many investigations. The properties of such spinels had always been found to be dominated by antiferromagnetic interactions. In this paper we describe the properties of a group of spinels in which ferromagnetic interactions are found to predominate. The compounds Cd Cr 2 S 4, Cd Cr 2 Se 4, Hg Cr 2 S 4, and Hg Cr 2 Se 4 have been prepared and found to be ferromagnetic with Curie temperatures of 84.5, 129.5, 36.0, and 106 K, respectively. With the exception of Hg Cr 2 S 4, which becomes metamagnetic below 25 K, all these materials remain ferromagnetic down to 4.2 K. These materials are also unique in that they are good electrical insulators in addition to being ferromagnets. A theoretical treatment is presented which correlates the high-temperature susceptibility with the Curie temperature and which provides a determination of the exchange interactions. The six nearest-neighbor interactions are treated by the high-temperature expansion technique of Rush-brooke and Wood, while the 30 more-distant-neighbor interactions are treated within the two-particle-cluster approximation of Callen and Callen. The analysis of the data indicates that the distant-neighbor interactions play a very important role in the determination of the type of magnetic order observed in the chalcogenide spinels.