Observation of Weyl nodes in TaAs
Observation of Weyl nodes in TaAs
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TaAs 中 Weyl 节点的观察
DOI：
10.1038/nphys3426
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发表时间：
2015-09-01
期刊：
影响因子：
19.6
通讯作者：
Ding, H.
中科院分区：
文献类型：
--
作者：
Lv, B. Q.;Xu, N.;Ding, H.
1929年，H. Weyl提出狄拉克方程的无质量解代表了一对新型粒子，即所谓的Weyl费米子。然而，80多年后，它们在粒子物理学中的存在仍然难以捉摸。最近，拓扑绝缘体和拓扑半金属的重大进展为在凝聚态物质中实现Weyl费米子提供了另一种方法，作为一种突现现象：当三维动量空间中的两个非简并带在费米能量附近交叉（称为Weyl节点）时，低能激发的行为完全像Weyl费米子一样。在这里，我们报告了通过执行体敏感软x射线角度分辨光发射光谱测量，在TaAs中对长期追求的Weyl节点的直接观察。（001）表面上节点的投影位置与费米弧匹配良好，为TaAs中存在Weyl费米子准粒子提供了无可争议的实验证据。
In 1929, H. Weyl proposed that the massless solution of the Dirac equation represents a pair of a new type of particles, the so-called Weyl fermions1. However, their existence in particle physics remains elusive after more than eight decades. Recently, significant advances in both topological insulators and topological semimetals have provided an alternative way to realize Weyl fermions in condensed matter, as an emergent phenomenon: when two non-degenerate bands in the three-dimensional momentum space cross in the vicinity of the Fermi energy (called Weyl nodes), the low-energy excitations behave exactly as Weyl fermions. Here we report the direct observation in TaAs of the long-sought-after Weyl nodes by performing bulk-sensitive soft X-ray angle-resolved photoemission spectroscopy measurements. The projected locations at the nodes on the (001) surface match well to the Fermi arcs, providing undisputable experimental evidence for the existence of Weyl fermionic quasiparticles in TaAs.