论文标题

非磁性晶体中的单对Weyl点

Single Pair of Weyl Points in Nonmagnetic Crystals

论文作者

Wang, Xiaotian, Zhou, Feng, Zhang, Zeying, Wu, Weikang, Yu, Zhi-Ming, Yang, Shengyuan A.

论文摘要

对于与手性拓扑电荷相关的效果的研究,需要最小的拓扑半学状态,即只有一对Weyl点。到目前为止,对此类状态的搜索集中在磁性刺激系统上。在这里,我们发现非磁性无旋转系统可以托管一类单重 - 韦尔点(SP-WP)状态,在该状态下,两个Weyl点位于两个高对称时间反转不变的动量。我们确定了32个托管此类状态的候选空间组,我们表明SP-WP状态中每个Weyl点的手性电荷必须是一个均匀的整数。除了达到最少的数字外,SP-WP状态中的Weyl点在动量空间中远距离分开,从而使每个单个点的物理学都更好地暴露出来。较大的分离与均匀的拓扑电荷相结合,导致表面延伸的表面循环,在表面布里鲁因区域圆环上具有不可扣除的绕组拓扑,这与常规的Weyl半含量不同。我们在两种混凝土材料TLBO $ _2 $和KNIIO $ _6 $的声子光谱中确认我们的建议。我们的发现适用于广泛的系统,包括电子,声音和各种人造系统。它为搜索理想平台学习手性颗粒提供了新的方向。

Topological semimetal states having the minimal number, i.e., only a single pair, of Weyl points are desirable for the study of effects associated with chiral topological charges. So far, the search for such states is focused on magnetic spinful systems. Here, we find that nonmagnetic spinless systems can host a class of single-pair-Weyl-point (SP-WP) states, where the two Weyl points are located at two high-symmetry time-reversal-invariant momenta. We identify 32 candidate space groups that host such states, and we show that the chiral charge of each Weyl point in the SP-WP state must be an even integer. Besides achieving the minimal number, Weyl points in SP-WP states are far separated in momentum space, making the physics of each individual point better exposed. The large separation combined with the even topological charge lead to extended surface Fermi loops with a non-contractible winding topology on the surface Brillouin zone torus, distinct from conventional Weyl semimetals. We confirm our proposal in the phonon spectra of two concrete materials TlBO$_2$ and KNiIO$_6$. Our finding applies to a wide range of systems, including electronic, phononic, and various artificial systems. It offers a new direction for the search of ideal platforms to study chiral particles.

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