Instituto de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970 Porto Alegre, Brazil.
J Phys Condens Matter. 2012 Jun 27;24(25):256005. doi: 10.1088/0953-8984/24/25/256005. Epub 2012 May 28.
We propose a three-dimensional model to describe magnetic interactions in a class of tantalite compounds of compositions A(x)A'(1-x)Ta(2)O(6), with A,A' = Fe, Co or Ni. Due to the quasi-two-dimensional nature of the magnetism in these compounds, experimental data have been previously interpreted using two-dimensional models. These are anisotropic Heisenberg models or Ising models and include competing exchange interactions from different neighbors. Taking into account all the relevant exchange terms, which include interplane interactions, we show that the latter allows us to understand the various low-temperature magnetic phases observed by neutron diffraction in this family of compounds. This is done by studying the eigenvalues of the exchange-interaction matrix in wavevector space for different sets of coupling parameters, of which those relative to in-plane interactions have been obtained from high-temperature series analysis of the magnetic susceptibility. This approach is rather general and the model presented here is directly applicable to isostructural compounds like ASb(2)O(6).
我们提出了一个三维模型来描述 A(x)A'(1-x)Ta(2)O(6)（其中 A,A'=Fe,Co 或 Ni）类钽铁矿化合物中的磁相互作用。由于这些化合物中磁性质的准二维性质，以前的实验数据使用二维模型进行了解释。这些模型是各向异性的海森堡模型或伊辛模型，并包括来自不同近邻的竞争交换相互作用。考虑到所有相关的交换项，包括层间相互作用，我们表明后者允许我们理解在该化合物系列的中子衍射中观察到的各种低温磁相。这是通过在波矢空间中研究交换相互作用矩阵的本征值来实现的，对于不同的耦合参数集，我们通过对磁性磁化率的高温级数分析获得了与面内相互作用相关的那些参数。这种方法相当通用，并且这里提出的模型可以直接应用于具有同构结构的化合物，如 ASb(2)O(6)。
