Hyperhoneycomb Iridate β-Li2IrO3 as a Platform for Kitaev Magnetism
Hyperhoneycomb Iridate β-Li2IrO3 as a Platform for Kitaev Magnetism
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DOI：
10.1103/physrevlett.114.077202
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发表时间：
2015-02-19
影响因子：
8.6
通讯作者：
Takagi, H.
中科院分区：
文献类型：
--
作者：
Takayama, T.;Kato, A.;Takagi, H.
一个配合物氧化铱β - li2iro3在超蜂窝结构中结晶，这是蜂窝晶格的三维类似物，并且发现它是一个J(eff) = 1/2矩的自旋轨道莫特绝缘体。Ir离子通过Ir- o -2-Ir键平面与相邻的三个Ir离子相连，这很可能在J(eff) = 1/2矩之间产生依赖键的铁磁相互作用，这是具有自旋液体基态的Kitaev模型的重要组成部分。磁化率chi(T)的温度依赖性确实证实了J(eff) = 1/2矩之间的主要铁磁相互作用，显示出与+40 K相似的正居里-魏斯温度theta（CW）。在T-c = 38 K时观察到具有非常小熵变的磁序，可能与J(eff) = 1/2矩的非线性排列有关。当磁场作用于有序态时，在3t以上产生一个大于0.35 mu(B)/Ir的大力矩，这是一个基本极化的J(eff) = 1/2态。我们认为，接近铁磁性和大波动的存在证明了超蜂窝β - li2iro3的基态位于基塔耶夫自旋液体的附近。
A complex iridium oxide beta-Li2IrO3 crystallizes in a hyperhoneycomb structure, a three-dimensional analogue of honeycomb lattice, and is found to be a spin-orbital Mott insulator with J(eff) = 1/2 moment. Ir ions are connected to the three neighboring Ir ions via Ir-O-2-Ir bonding planes, which very likely gives rise to bond-dependent ferromagnetic interactions between the J(eff) = 1/2 moments, an essential ingredient of Kitaev model with a spin liquid ground state. Dominant ferromagnetic interaction between J(eff) = 1/2 moments is indeed confirmed by the temperature dependence of magnetic susceptibility chi(T) which shows a positive Curie-Weiss temperature theta(CW) similar to +40 K. A magnetic ordering with a very small entropy change, likely associated with a noncollinear arrangement of J(eff) = 1/2 moments, is observed at T-c = 38 K. With the application of magnetic field to the ordered state, a large moment of more than 0.35 mu(B)/Ir is induced above 3 T, a substantially polarized J(eff) = 1/2 state. We argue that the close proximity to ferromagnetism and the presence of large fluctuations evidence that the ground state of hyperhoneycomb beta-Li2IrO3 is located in close proximity of a Kitaev spin liquid.