该研究团队提出了一种广泛适用的精确可解形式，用于描述Weyl半金属表面的原型特征。在这一框架中，共振表面态与体影响被统一处理，体现了表面与体之间的杂化共存现象。借助角分辨光谱学技术，研究人员能够解析地揭示从共振拓扑态光谱中获取的关于系统的普遍信息。
他们系统地发现了在表面体合并边界周围存在的非均匀和各向异性奇异响应，这一发现凸显了表面-体杂化在Weyl拓扑中的关键作用。此外，研究团队还讨论了扫描隧道光谱的响应特点。这一研究成果将为深入理解表面与体之间的耦合物理特性提供宝贵的见解，并有望指导对众多拓扑半金属材料中非平凡杂化现象的光谱研究。
据悉，拥有开弧表面态的Weyl半金属是三维拓扑量子物质中的显著代表。由于体边界对应性的存在，非平凡的表面与体之间的杂化现象不可避免，然而这一现象仍鲜为人知。光谱学在验证表面费米弧的存在方面有所局限，其光谱形状与能量-动量空间中杂化剖面的关系尚待深入研究。
附：英文原文
Title: Surface spectroscopy and surface–bulk hybridization of Weyl semimetals
Author: Zhang, Xiao-Xiao, Nagaosa, Naoto
Issue&Volume: 2024-3-21
Abstract: Weyl semimetal showing open-arc surface states is a prominent example of topological quantum matter in three dimensions. With the bulk-boundary correspondence present, nontrivial surface–bulk hybridization is inevitable but less understood. Spectroscopies have been often limited to verifying the existence of surface Fermi arcs, whereas its spectral shape related to the hybridization profile in energy–momentum space is not well studied. We present an exactly solvable formalism at the surface for a wide range of prototypical Weyl semimetals. The resonant surface state and the bulk influence coexist as a surface–bulk hybrid and are treated in a unified manner. Directly accessible to angle-resolved photoemission spectroscopy, we analytically reveal universal information about the system obtained from the spectroscopy of resonant topological states. We systematically find inhomogeneous and anisotropic singular responses around the surface–bulk merging borderline crossing Weyl points, highlighting its critical role in the Weyl topology. The response in scanning tunneling spectroscopy is also discussed. The results will provide much-needed insight into the surface–bulk-coupled physical properties and guide in-depth spectroscopic investigation of the nontrivial hybrid in many topological semimetal materials.
DOI: 10.1073/pnas.2313488121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2313488121