论文标题
手性立方晶体中的两倍四倍的四倍
Twofold quadruple Weyl nodes in chiral cubic crystals
论文作者
论文摘要
常规的Weyl节点是带有单位单极电荷的双重带交叉点，可以在凝结物质系统中存在，并保护翻译对称性。非常规的Weyl节点是携带大于1的量化单极电荷的双重/多胎横梁，它们的存在需要保护附加的晶体对称性。关于非常规Weyl节点的研究已经非常全面，例如C = 2/c = 3的Chern数量的双重Weyl节点和C = 4的四倍/六翼淋巴结。然而，在本文中，我们提出了一个具有C = 4的新发现的两倍非常规Weyl节点，该节点可以存在于任何具有整数旋转的手性立方系统中。这种两倍的四倍体weyl节点具有沿[111]方向的立方条带分散，并且在考虑自旋轨道耦合后将演变成四倍的四倍Weyl节点。在本文中，我们耗尽所有可能的手性立方空间组和相应的K点，它们可以具有双重四倍的Weyl节点。我们还提出了一系列的Lairsi-Type材料，它们在电子系统和声子光谱中都具有双重四倍的Weyl节点。
Conventional Weyl nodes are twofold band crossings that carry a unit monopole charge, which can exist in condensed matter systems with the protection of translation symmetry. Unconventional Weyl nodes are twofold/multifold band crossings carrying a quantized monopole charge larger than one, and their existence needs the protection of additional crystalline symmetries. Studies on unconventional Weyl nodes are already very comprehensive, such as twofold Weyl nodes with Chern number of C=2/C=3 and fourfold/sixfoldWeyl nodes with C=4. Yet in this paper, we propose a newfound twofold unconventional Weyl node with C=4, which can exist in any chiral cubic systems with integer spin. Such kind of twofold quadruple Weyl node has a cubic band dispersion along [111] direction and will evolve into a fourfold quadruple Weyl node after considering spin-orbit coupling. In this paper, we exhaust all the possible chiral cubic space groups and corresponding k-points, which can have twofold quadruple Weyl nodes. We also propose a series of LaIrSi-type materials that both have twofold quadruple Weyl nodes in electronic systems and the phonon spectra.
