Trigonal distortion in the honeycomb iridates: Proximity of zigzag and spiral phases in Na2IrO3
Trigonal distortion in the honeycomb iridates: Proximity of zigzag and spiral phases in Na2IrO3
复制标题
蜂窝状虹彩中的三角畸变：Na2IrO3 中之字形和螺旋相的接近性
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
H. Kee
中科院分区：
文献类型：
--
作者：
J. Rau;H. Kee
基塔耶夫蜂窝模型被认为是描述蜂窝iridates的一个有用的起点。然而，在Na2IrO3中看到的之字形排序和Li2IrO3中的磁跃迁提出了它们与Kitaev模型的联系以及这些磁态的微观起源的问题，因为它们的结构相似。本文研究了在纯近邻模型中氧八面体的三角畸变如何影响基塔耶夫自旋液体附近的磁相。利用经典分析和精确对角化相结合的方法，我们发现在铁磁基塔耶夫极限附近，少量的三角畸变，如在Na2IrO3中发现的那样，稳定了一个之形相位。减小畸变使之字形相向螺旋相不稳定，这可能与Li2IrO3有关。利用半经典自旋波计算，我们证明了这一机制与Na2IrO3中动力学结构因子的实验已知特征在质量上是一致的，并推测了对Li2IrO3的影响。
The Kitaev honeycomb model has been suggested as a useful starting point to describe the honeycomb iridates. However, the zigzag ordering seen in Na2IrO3 and the magnetic transition in Li2IrO3 have raised questions to their connection to the Kitaev model and to the microscopic origin of these magnetic states, given their structural similarities. Here we study how the magnetic phases near the Kitaev spin liquid are affected by the inclusion of trigonal distortion of the oxygen octahedra within a purely nearest neighbour model. Using a combination classical analysis and exact diagonalization we show that near the ferromagnetic Kitaev limit a small amount of trigonal distortion, as found in Na2IrO3, stabilizes a zigzag phase. Decreasing the distortion destabilizes the zigzag phase toward a spiral phase that may be relevant for Li2IrO3. Using semi-classical spin-wave calculations we show that this regime is qualitatively consistent with experimentally known features of the dynamical structure factor in Na2IrO3 and speculate on implications for Li2IrO3.