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Discovery of a Weyl fermion state with Fermi arcs in niobium arsenide

TitleDiscovery of a Weyl fermion state with Fermi arcs in niobium arsenide
Publication TypeJournal Article
Year of Publication2015
AuthorsXu, Su-Yang, Alidoust Nasser, Belopolski Ilya, Yuan Zhujun, Bian Guang, Chang Tay-Rong, Zheng Hao, Strocov Vladimir N., Sanchez Daniel S., Chang Guoqing, Zhang Chenglong, Mou Daixiang, Wu Yun, Huang Lunan, Lee Chi-Cheng, Huang Shin-Ming, Wang BaoKai, Bansil Arun, Jeng Horng-Tay, Neupert Titus, Kaminski Adam, Lin Hsin, Jia Shuang, and Hasan Zahid M.
JournalNature Physics
Date Published09/2015

Three types of fermions play a fundamental role in our understanding of nature: Dirac, Majorana and Weyl. Whereas Dirac fermions have been known for decades, the latter two have not been observed as any fundamental particle in high-energy physics, and have emerged as a much-sought-out treasure in condensed matter physics. A Weyl semimetal is a novel crystal whose low-energy electronic excitations behave as Weyl fermions. It has received worldwide interest and is believed to open the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, experimental research has been held back because Weyl semimetals are extremely rare in nature. Here, we present the experimental discovery of the Weyl semimetal state in an inversion-symmetry-breaking single-crystalline solid, niobium arsenide (NbAs). Utilizing the combination of soft X-ray and ultraviolet photoemission spectroscopy, we systematically study both the surface and bulk electronic structure of NbAs. We experimentally observe both the Weyl cones in the bulk and the Fermi arcs on the surface of this system. Our ARPES data, in agreement with our theoretical band structure calculations, identify the Weyl semimetal state in NbAs, which provides a real platform to test the potential of Weyltronics.


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