RT Journal Article
SR Electronic
T1 Discovery of a Weyl fermion semimetal and topological Fermi arcs
JF Science
JO Science
FD American Association for the Advancement of Science
SP 613
OP 617
DO 10.1126/science.aaa9297
VO 349
IS 6248
A1 Xu, Su-Yang
A1 Belopolski, Ilya
A1 Alidoust, Nasser
A1 Neupane, Madhab
A1 Bian, Guang
A1 Zhang, Chenglong
A1 Sankar, Raman
A1 Chang, Guoqing
A1 Yuan, Zhujun
A1 Lee, Chi-Cheng
A1 Huang, Shin-Ming
A1 Zheng, Hao
A1 Ma, Jie
A1 Sanchez, Daniel S.
A1 Wang, BaoKai
A1 Bansil, Arun
A1 Chou, Fangcheng
A1 Shibayev, Pavel P.
A1 Lin, Hsin
A1 Jia, Shuang
A1 Hasan, M. Zahid
YR 2015
UL http://science.sciencemag.org/content/349/6248/613.abstract
AB Weyl fermions—massless particles with half-integer spin—were once mistakenly thought to describe neutrinos. Although not yet observed among elementary particles, Weyl fermions may exist as collective excitations in so-called Weyl semimetals. These materials have an unusual band structure in which the linearly dispersing valence and conduction bands meet at discrete “Weyl points.” Xu et al. used photoemission spectroscopy to identify TaAs as a Weyl semimetal capable of hosting Weyl fermions. In a complementary study, Lu et al. detected the characteristic Weyl points in a photonic crystal. The observation of Weyl physics may enable the discovery of exotic fundamental phenomena.Science, this issue p. 613 and 622A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties. We report the experimental discovery of a Weyl semimetal, tantalum arsenide (TaAs). Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl fermion cones and Weyl nodes in the bulk of TaAs single crystals. We find that Fermi arcs terminate on the Weyl fermion nodes, consistent with their topological character. Our work opens the field for the experimental study of Weyl fermions in physics and materials science.