Spin Excitations of a Proximate Kitaev Quantum Spin Liquid Realized in Cu2IrO3
Spin Excitations of a Proximate Kitaev Quantum Spin Liquid Realized in Cu2IrO3
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DOI：
10.1103/physrevx.9.031047
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发表时间：
2019-09
影响因子：
12.5
通讯作者：
S. Takahashi;Jiaming Wang;A. Arsenault;M. Abramchuk;F. Tafti;P. Singer;T. Imai
中科院分区：
文献类型：
--
作者：
S. Takahashi;Jiaming Wang;A. Arsenault;M. Abramchuk;F. Tafti;P. Singer;T. Imai
磁矩安排在一个蜂窝晶格的角落预测，形成一种新的物质状态，Kitaev量子自旋液体，键依赖伊辛相互作用之间的阻挫效应的影响下。一些层状蜂窝状铱酸盐和相关材料，如Na 2 IrO 3和α-RuCl 3，接近Kitaev量子自旋液体，但与不期望的反铁磁长程有序相关的玻色子自旋波激发掩盖了Kitaev哈密顿量的固有性质。在这里，我们使用铜核四极共振揭示了低能量自旋激发在近理想的蜂窝晶格的有效自旋S = 1/2的Ir网站在Cu 2 IrO 3。我们证明，不像Na 2 IrO 3，Ir自旋波动表现出没有证据的临界慢向磁长程有序在零外磁场。此外，低能量自旋激发谱由具有与伊辛相互作用相当的大激发间隙的模式主导，这是Kitaev量子自旋液体的Majorana费米子的预期签名。
Magnetic moments arranged at the corners of a honeycomb lattice are predicted to form a novel state of matter, Kitaev quantum spin liquid, under the influence of frustration effects between bond-dependent Ising interactions. Some layered honeycomb iridates and related materials, such as Na2IrO3 and α-RuCl3, are proximate to Kitaev quantum spin liquid, but bosonic spin-wave excitations associated with undesirable antiferromagnetic long-range order mask the inherent properties of Kitaev Hamiltonian. Here, we use Cu nuclear quadrupole resonance to uncover the low energy spin excitations in the nearly ideal honeycomb lattice of effective spin S = 1/2 at the Ir sites in Cu2IrO3. We demonstrate that, unlike Na2IrO3, Ir spin fluctuations exhibit no evidence for critical slowing down toward magnetic long range order in zero external magnetic field. Moreover, the low energy spin excitation spectrum is dominated by a mode that has a large excitation gap comparable to the Ising interactions, a signature expected for Majorana fermions of Kitaev quantum spin liquid.