Bhowal Sayantika, Ganguly Shreemoyee, Dasgupta Indra
School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
J Phys Condens Matter. 2019 May 8;31(18):185802. doi: 10.1088/1361-648X/ab048c. Epub 2019 Feb 5.
In the present paper, we have carried out a comparative first principles as well as model Hamiltonian study to understand the novel magnetism in 6H perovskite iridates BaIrTiO and BaTiIrO resulting from an unusual combination of geometrical as well as exchange frustration owing to their unique crystal geometry. Our model calculations corroborated with multipolar analysis provides a comprehensive understanding of the spin-orbit entangled [Formula: see text] pseudo-spin states in both materials. While, the [Formula: see text] character is quite robust in the former compound, it is found to be directly related to the nature of magnetism in the latter iridate. The identification of the relevant spin model for the ideal structure of BaIrTiO suggests that the Heisenberg exchange interaction dominates the Kitaev term favoring long range magnetic order in the system in line with the ab initio study while the other iridate BaTiIrO has the posibility to host novel spin-orbital singlet state with no resultant moment.
在本文中，我们进行了一项比较性的第一性原理以及模型哈密顿量研究，以理解6H钙钛矿铱酸盐BaIrTiO和BaTiIrO中由于其独特晶体几何结构导致的几何以及交换失稳的异常组合所产生的新型磁性。我们结合多极分析的模型计算对这两种材料中自旋轨道纠缠的[公式：见原文]赝自旋态提供了全面的理解。虽然，[公式：见原文]特征在前一种化合物中相当稳健，但发现它与后一种铱酸盐中的磁性本质直接相关。对于BaIrTiO理想结构的相关自旋模型的识别表明，海森堡交换相互作用主导了基塔耶夫项，有利于系统中的长程磁序，这与从头算研究一致，而另一种铱酸盐BaTiIrO有可能拥有没有净磁矩的新型自旋轨道单重态。
