论文标题
KagoméHeisenberg量子旋转液体候选ycu $ _3 $（oh）$ _ {6.5} $ br $ _ {2.5} $的热运输
Heat transport of the kagomé Heisenberg quantum spin liquid candidate YCu$_3$(OH)$_{6.5}$Br$_{2.5}$: localized magnetic excitations and spin gap
论文作者
论文摘要
Spin-1/2KagoméHeisenberg抗铁磁铁通常被认为是实现量子自旋液态的最有希望的二维模型之一。以前的实验努力几乎仅仅是一种原型材料，即Herbertsmithite Zncu $ _3 $（oh）$ _ 6 $ Cl $ _2 $，不幸的是，这遭受了由磁性障碍引起的臭名昭著的孤儿旋转问题。在这里，我们求助于ycu $ _3 $（oh）$ _ {6.5} $ br $ _ {2.5} $，最近被公认为是由孤儿旋转免费的全球含有全球含有的kagomécu$^{2+} $ lattice的托管，因此可以从孤儿旋转，因此可以使用本质上的液体量化量化的液体量化物质，从而更可行的系统。我们的高分辨率低温导热率测量结果消失了$κ/t $（$ t \ rightArrow 0 $）的小剩余线性项，因此显然排除了流动的无间隙费米子激发。声子的异常散射随温度呈指数增长，表明热激活的声子旋转散射，因此与$ \ Mathbb {z} _2 $ Quantum Spin液态液态状态一致。此外，对磁场对热导率的影响的分析揭示了自旋间隙的场闭合，而激发仍在定位。
The spin-1/2 kagomé Heisenberg antiferromagnet is generally accepted as one of the most promising two-dimensional models to realize a quantum spin liquid state. Previous experimental efforts were almost exclusively on only one archetypal material, the herbertsmithite ZnCu$_3$(OH)$_6$Cl$_2$, which unfortunately suffers from the notorious orphan spins problem caused by magnetic disorders. Here we turn to YCu$_3$(OH)$_{6.5}$Br$_{2.5}$, recently recognized as another host of a globally undistorted kagomé Cu$^{2+}$ lattice free from the orphan spins, thus a more feasible system for studying the intrinsic kagomé quantum spin liquid physics. Our high-resolution low-temperature thermal conductivity measurements yield a vanishing small residual linear term of $κ/T$ ($T\rightarrow 0$), and thus clearly rule out itinerant gapless fermionic excitations. Unusual scattering of phonons grows exponentially with temperature, suggesting thermally activated phonon-spin scattering and hence a gapped magnetic excitation, consistent with a $\mathbb{Z}_2$ quantum spin liquid ground state. Additionally, the analysis of magnetic field impact on the thermal conductivity reveals a field closing of the spin gap, while the excitations remain localized.
