论文标题
沙漏电荷 - 三个Weyl Phonon
Hourglass Charge-Three Weyl Phonons
论文作者
论文摘要
具有非线性色散的非常规的Weyl点具有较高的拓扑电荷$ | {\ cal {c}} |> 1 $，并且在其边界处有多个受拓扑保护的费米弧状态。作为一种新颖的拓扑状态，它一直引起广泛的关注。但是，即使理论上已经提出了十多年，但尚未用$ | {\ cal {c}} | = 3 $进行$ | {\ cal {c}} | = 3 $的非常规的Weyl点。在这项工作中，基于第一原理的计算和理论分析，我们预测现有材料$ \rmα$ -liio $ _3 $是这个非常规的Weyl点的第一个现实示例。特别是，在$ \rmα$ -liio $ _3 $的声子光谱中，由$ {\ cal {c}}} = - 3 $的两个Weyl点，由时间反向对称性连接，出现在一个小型型带的颈部交叉点上，导致了两个小时的Graglass Charge-3 Hourglass Charge-3 Weyl Phonons。揭示了对称性保护和相关的新型三重和六倍 - 螺旋表面弧形圆形电荷-3 Weyl Phonons的态。我们的结果发现了$ \rmα$ -liio $ _3 $的隐藏拓扑特征，还表明声子光谱是探索非常规拓扑状态的绝佳平台。
Unconventional Weyl point with nonlinear dispersion features higher topological charge $|{\cal{C}}|>1$ and multiple topologically protected Fermi arc states at its boundary. As a novel topological state, it has been attracting widespread attention. However, the unconventional Weyl point with $|{\cal{C}}|=3$ has not yet been reported in realistic materials, even though it has been theoretically proposed for more than a decade. In this work, based on first-principles calculations and theoretical analysis, we predict the existing material, $\rmα$-LiIO$_3$ as the first realistic example with this unconventional Weyl point. Particularly, in the phonon spectra of $\rmα$-LiIO$_3$, two Weyl points with ${\cal{C}}=-3$, connected by time-reversal symmetry, appear at the neck crossing-point of a hourglass-type band, leading to two hourglass charge-3 Weyl phonons. The symmetry protection and the associated novel triple- and sextuple-helicoid surface arc states of the hourglass charge-3 Weyl phonons are revealed. Our results uncover a hidden topological character of $\rmα$-LiIO$_3$ and also show that the phonon spectra is a great platform for exploring unconventional topological states.
