Criteria for Directly Detecting Topological Fermi Arcs in Weyl Semimetals

The recent discovery of the first Weyl semimetal in TaAs provides the first observation of a Weyl fermion in nature and demonstrates a novel type of anomalous surface state, the Fermi arc. Like topological insulators, the bulk topological invariants of a Weyl semimetal are uniquely fixed by the surf...

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Published in:Physical review letters 2016-02, Vol.116 (6), p.066802-066802, Article 066802
Main Authors: Belopolski, Ilya, Xu, Su-Yang, Sanchez, Daniel S, Chang, Guoqing, Guo, Cheng, Neupane, Madhab, Zheng, Hao, Lee, Chi-Cheng, Huang, Shin-Ming, Bian, Guang, Alidoust, Nasser, Chang, Tay-Rong, Wang, BaoKai, Zhang, Xiao, Bansil, Arun, Jeng, Horng-Tay, Lin, Hsin, Jia, Shuang, Hasan, M Zahid
Format: Article
Language:English
Subjects:
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Band structure of solids
Bulk sampling
Insulators
Invariants
Material Science
MATERIALS SCIENCE
Mathematical analysis
Metalloids
Topology
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Summary:The recent discovery of the first Weyl semimetal in TaAs provides the first observation of a Weyl fermion in nature and demonstrates a novel type of anomalous surface state, the Fermi arc. Like topological insulators, the bulk topological invariants of a Weyl semimetal are uniquely fixed by the surface states of a bulk sample. Here we present a set of distinct conditions, accessible by angle-resolved photoemission spectroscopy (ARPES), each of which demonstrates topological Fermi arcs in a surface state band structure, with minimal reliance on calculation. We apply these results to TaAs and NbP. For the first time, we rigorously demonstrate a nonzero Chern number in TaAs by counting chiral edge modes on a closed loop. We further show that it is unreasonable to directly observe Fermi arcs in NbP by ARPES within available experimental resolution and spectral linewidth. Our results are general and apply to any new material to demonstrate a Weyl semimetal.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.116.066802