Institute for Theoretical Solid State Physics, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
Dresden Center for Computational Materials Science (DCMS), TU Dresden, 01062 Dresden, Germany.
Phys Rev Lett. 2018 Nov 9;121(19):197203. doi: 10.1103/PhysRevLett.121.197203.
Very recently a quantum liquid was reported to form in H_{3}LiIr_{2}O_{6}, an iridate proposed to be a close realization of the Kitaev honeycomb model. To test this assertion we perform detailed quantum chemistry calculations to determine the magnetic interactions between Ir moments. We find that weakly bond dependent ferromagnetic Kitaev exchange dominates over other couplings, but still is substantially lower than in Na_{2}IrO_{3}. This reduction is caused by the peculiar position of the interlayer species: removing hydrogen cations next to a Ir_{2}O_{2} plaquette increases the Kitaev exchange by more than a factor of 3 on the corresponding Ir─Ir link. Consequently, any lack of hydrogen order will have a drastic effect on the magnetic interactions and strongly promote spin disordering.
最近有报道称，在 H_{3}LiIr_{2}O_{6}中形成了一种量子液体，该化合物被认为是 Kitaev 蜂窝模型的一个紧密实现。为了验证这一说法，我们进行了详细的量子化学计算，以确定 Ir 磁矩之间的磁相互作用。我们发现，弱键相关的铁磁 Kitaev 交换占主导地位，但仍远低于 Na_{2}IrO_{3}。这种降低是由层间物种的特殊位置引起的：在 Ir_{2}O_{2} 平面附近去除氢离子，会使相应的 Ir─Ir 键上的 Kitaev 交换增加超过 3 倍。因此，任何缺乏氢序的情况都会对磁相互作用产生剧烈影响，并强烈促进自旋无序。
