论文标题
单晶cu $ _3 $ Zn（oh）$ _ 6 $ fbr中分数激发的动态指纹
Dynamic fingerprint of fractionalized excitations in single-crystalline Cu$_3$Zn(OH)$_6$FBr
论文作者
论文摘要
量子自旋液体（QSL）代表了一类新的凝结物质状态，其特征是拓扑顺序的长期多体纠缠。难以捉摸的QSL状态最突出的特征是存在分数化旋转激发。受强量子波动的影响，kagome晶格上的自旋1/2抗磁磁系统是托管QSL基态的有前途的候选者，但结构上理想的实现很少见。在这里，我们报告了在单晶Cu $ _3 $ Zn（OH）$ _ 6 $ fbr上的拉曼散射，并确认理想的kagome结构一直降低到低温下，而没有任何晶格分解的偏振拉曼响应和第二种荷尔马人的测量值。此外，在低温下，拉曼散射揭示了Cu $ _3 $ _3 $ Zn（OH）$ _ 6 $ FBR中的旋转激发的连续性，与有序的Kagome Antiferromagnet Eucu $ _3 $（OH）$ _ 6 $ _ 6 $ cl $ cl $ _3 $相比，在有序的kagome抗fiferromagnet eucu $ _3 $中相比。这种磁性拉曼连续体，尤其是大量的低能单对旋子激发，是Cu $ _3 $ _3 $ Zn（OH）$ _ 6 $ fbr中分数化旋转激发的有力证据。
Quantum spin liquid (QSL) represents a new class of condensed matter states characterized by the long-range many-body entanglement of topological orders. The most prominent feature of the elusive QSL state is the existence of fractionalized spin excitations. Subject to the strong quantum fluctuations, the spin-1/2 antiferromagnetic system on a kagome lattice is the promising candidate for hosting a QSL ground state, but the structurally ideal realization is rare. Here, we report Raman scattering on the single crystalline Cu$_3$Zn(OH)$_6$FBr, and confirm that the ideal kagome structure remains down to low temperatures without any lattice distortion by the angle-resolved polarized Raman responses and second-harmonic-generation measurements. Furthermore, at low temperatures the Raman scattering reveals a continuum of the spin excitations in Cu$_3$Zn(OH)$_6$FBr, in contrast to the sharp magnon peak in the ordered kagome antiferromagnet EuCu$_3$(OH)$_6$Cl$_3$. Such magnetic Raman continuum, in particular, the substantial low-energy one-pair spinon excitation serves as strong evidence for fractionalized spin excitations in Cu$_3$Zn(OH)$_6$FBr.
