Observation of valence bond fluctuations in the spin-1/2 honeycomb lattice
Observation of valence bond fluctuations in the spin-1/2 honeycomb lattice
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自旋1/2蜂窝晶格中价键涨落的观察
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
M. Kenzelmann
中科院分区：
文献类型：
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作者：
C. Wessler;B. Roessli;Karl W. Kr¨amer;B. Delley;O. Waldmann;L. Keller;D. Cheptiakov;H. Braun;M. Kenzelmann
量子自旋液体是一种具有量子纠缠自旋相关性并在 T = 0 K 时避免磁性长程有序的材料。特别有趣的是二维蜂窝状自旋晶格，其中预测了大量奇异的量子自旋液体。在这里，我们通过实验研究了具有竞争性最近邻和次近邻相互作用的有效 S=1/2 海森堡蜂窝晶格。我们证明，YbBr$_3$ 避免了至少 T=100 mK 的有序度，并具有动态自旋-自旋相关函数，具有量子临界点附近量子自旋液体典型的宽连续谱散射。自旋谱的连续谱与理论预测的斑块型波动一致。我们的研究实验证明，即使没有基塔耶夫型相互作用，蜂窝晶格上也可以存在强量子涨落，并为量子自旋液体开辟了新的视角。
Quantum spin liquids are materials that feature quantum entangled spin correlations and avoid magnetic long-range order at T = 0 K. Particularly interesting are two-dimensional honeycomb spin lattices where a plethora of exotic quantum spin liquids have been predicted. Here, we experimentally study an effective S=1/2 Heisenberg honeycomb lattice with competing nearest and next-nearest neighbor interactions. We demonstrate that YbBr$_3$ avoids order down to at least T=100 mK and features a dynamic spin-spin correlation function with broad continuum scattering typical of quantum spin liquids near a quantum critical point. The continuum in the spin spectrum is consistent with plaquette type fluctuations predicted by theory. Our study is the experimental demonstration that strong quantum fluctuations can exist on the honeycomb lattice even in the absence of Kitaev-type interactions, and opens a new perspective on quantum spin liquids.