TY - JOUR
T1 - Experimental discovery of a topological Weyl semimetal state in TaP
AU - Xu, Su Yang
AU - Belopolski, Ilya
AU - Sanchez, Daniel S.
AU - Zhang, Chenglong
AU - Chang, Guoqing
AU - Guo, Cheng
AU - Bian, Guang
AU - Yuan, Zhujun
AU - Lu, Hong
AU - Chang, Tay Rong
AU - Shibayev, Pavel P.
AU - Prokopovych, Mykhailo L.
AU - Alidoust, Nasser
AU - Zheng, Hao
AU - Lee, Chi Cheng
AU - Huang, Shin Ming
AU - Sankar, Raman
AU - Chou, Fangcheng
AU - Hsu, Chuang Han
AU - Jeng, Horng Tay
AU - Bansil, Arun
AU - Neupert, Titus
AU - Strocov, Vladimir N.
AU - Lin, Hsin
AU - Jia, Shuang
AU - Zahid Hasan, M.
N1 - Publisher Copyright:
© 2015 The Authors.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2015/11
Y1 - 2015/11
N2 - Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal's surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission.
AB - Weyl semimetals are expected to open up new horizons in physics and materials science because they provide the first realization of Weyl fermions and exhibit protected Fermi arc surface states. However, they had been found to be extremely rare in nature. Recently, a family of compounds, consisting of tantalum arsenide, tantalum phosphide (TaP), niobium arsenide, and niobium phosphide, was predicted as a Weyl semimetal candidates. We experimentally realize a Weyl semimetal state in TaP. Using photoemission spectroscopy, we directly observe the Weyl fermion cones and nodes in the bulk, and the Fermi arcs on the surface. Moreover, we find that the surface states show an unexpectedly rich structure, including both topological Fermi arcs and several topologically trivial closed contours in the vicinity of the Weyl points, which provides a promising platform to study the interplay between topological and trivial surface states on a Weyl semimetal's surface. We directly demonstrate the bulk-boundary correspondence and establish the topologically nontrivial nature of the Weyl semimetal state in TaP, by resolving the net number of chiral edge modes on a closed path that encloses the Weyl node. This also provides, for the first time, an experimentally practical approach to demonstrating a bulk Weyl fermion from a surface state dispersion measured in photoemission.
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U2 - 10.1126/sciadv.1501092
DO - 10.1126/sciadv.1501092
M3 - Article
AN - SCOPUS:85038359489
VL - 1
JO - Science advances
JF - Science advances
SN - 2375-2548
IS - 10
M1 - 1501092
ER -