论文标题
非线性少坚元和交换Delafossite近端量子自旋液体的哈密顿量
Non-linear magnons and exchange Hamiltonians of delafossite proximate quantum spin liquids
论文作者
论文摘要
量子自旋液体（QSL）是具有远距离纠缠和外来准颗粒的物质的理论状态。但是，它们通常揭示了定量理论，从而使他们的基本阶段神秘而妨碍了识别实验性QSL状态的努力。在这里，我们研究三角晶格共鸣债券QSL候选材料kybse $ _2 $和naybse $ _2 $。我们使用非弹性中子散射，并使用非线性自旋波理论来测量其1/3高原阶段的镁模式，其中定量理论是可行的。我们还使用高温系列扩展，适合Kybse $ _2 $热容量。两种kybse $ _2 $拟合在不确定性内产生相同的磁性汉密尔顿人，证实了先前的估计，并显示海森伯格$ j_2/j_1 $成为这些材料的准确模型。最重要的是，比较kybse $ _2 $和naybse $ _2 $表明，较小的$ a $ a $ a $ a $^+$ ion具有较大的$ j_2/j_1 $比率。但是，施加到KYBSE $ _2 $的静水压力增加了订购温度（与密度功能理论计算一致的结果），表明压力降低了$ j_2/j_1 $。这些结果表明，元素表和静液压压力如何以受控的方式调整$ ybse $ _2 $材料。
Quantum spin liquids (QSL) are theoretical states of matter with long-range entanglement and exotic quasiparticles. However, they generally elude quantitative theory, rendering their underlying phases mysterious and hampering efforts to identify experimental QSL states. Here we study triangular lattice resonating valence bond QSL candidate materials KYbSe$_2$ and NaYbSe$_2$. We measure the magnon modes in their 1/3 plateau phase, where quantitative theory is tractable, using inelastic neutron scattering and fit them using nonlinear spin wave theory. We also fit the KYbSe$_2$ heat capacity using high temperature series expansion. Both KYbSe$_2$ fits yield the same magnetic Hamiltonian to within uncertainty, confirming previous estimates and showing the Heisenberg $J_2/J_1$ to be an accurate model for these materials. Most importantly, comparing KYbSe$_2$ and NaYbSe$_2$ shows that smaller $A$-site Na$^+$ ion has a larger $J_2/J_1$ ratio. However, hydrostatic pressure applied to KYbSe$_2$ increases the ordering temperature (a result consistent with density functional theory calculations), indicating that pressure decreases $J_2/J_1$. These results show how periodic table and hydrostatic pressure can tune the $A$YbSe$_2$ materials in a controlled way.
