Abstract
Topological Dirac and Weyl semimetals not only host quasiparticles analogous to the elementary fermionic particles in high-energy physics, but also have a non-trivial band topology manifested by gapless surface states, which induce exotic surface Fermi arcs1,2. Recent advances suggest new types of topological semimetal, in which spatial symmetries protect gapless electronic excitations without high-energy analogues3,4,5,6,7,8,9,10,11. Here, using angle-resolved photoemission spectroscopy, we observe triply degenerate nodal points near the Fermi level of tungsten carbide with space group \(P\bar{6}m2\) (no. 187), in which the low-energy quasiparticles are described as three-component fermions distinct from Dirac and Weyl fermions. We further observe topological surface states, whose constant-energy contours constitute pairs of ‘Fermi arcs’ connecting to the surface projections of the triply degenerate nodal points, proving the non-trivial topology of the newly identified semimetal state.
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References
Wan, X., Turner, A. M., Vishwanath, A. & Savrasov, S. Y. Topological semimetal and Fermi-arc surface states in the electronic structure of pyrochlore iridates. Phys. Rev. B 83, 205101 (2011).
Wang, Z. et al. Dirac semimetal and topological phase transitions in A3Bi (A = Na, K, Rb). Phys. Rev. B 85, 195320 (2012).
Wieder, B. J., Kim, Y., Rappe, A. M. & Kane, C. L. Double Dirac semimetals in three dimensions. Phys. Rev. Lett. 116, 186402 (2016).
Bradlyn, B. et al. Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals. Science 353, 558 (2016).
Heikkilä, T. T. & Volovik, G. E. Nexus and Dirac lines in topological materials. New J. Phys. 17, 093019 (2015).
Weng, H., Fang, C., Fang, Z. & Dai, X. Topological semimetals with triply degenerate nodal points in θ-phase tantalum nitride. Phys. Rev. B 93, 241202 (2016).
Zhu, Z., Winkler, G. W., Wu, Q., Li, J. & Soluyanov, A. A. Triple point topological metals. Phys. Rev. X 6, 031003 (2016).
Weng, H., Fang, C., Fang, Z. & Dai, X. Coexistence of Weyl fermion and massless triply degenerate nodal points. Phys. Rev. B 94, 165201 (2016).
Chang, G. et al. Nexus fermions in topological symmorphic crystalline metals. Sci. Rep. 7, 1688 (2017).
Chang, G. et al. Unconventional Chiral Fermions and Large Topological Fermi Arcs in RhSi. Phys. Rev. Lett. 119, 206401 (2017).
Tang, P., Zhou, Q. & Zhang, S. C. Multiple types of topological fermions in transition metal silicides. Phys. Rev. Lett. 119, 206402 (2017).
Castro Neto, A. H., Guinea, F., Peres, N. M. R., Novoselov, K. S. & Geim, A. K. The electronic properties of graphene. Rev. Mod. Phys. 81, 109–162 (2009).
Fu, L. & Kane, C. L. Superconducting proximity effect and majorana fermions at the surface of a topological insulator. Phys. Rev. Lett. 100, 096407 (2008).
Fang, Z. et al. The anomalous Hall effect and magnetic monopoles in momentum space. Science 302, 92–95 (2003).
Weng, H. M., Fang, C., Fang, Z., Bernevig, B. A. & Dai, X. Weyl semimetal phase in noncentrosymmetric transition-metal monophosphides. Phys. Rev. X 5, 011029 (2015).
Huang, S.-M. et al. A Weyl fermion semimetal with surface Fermi arcs in the transition metal monopnictide TaAs class. Nat. Commun. 6, 7373 (2015).
Soluyanov, A. A. et al. Type-II Weyl semimetals. Nature 527, 495–498 (2015).
Chang, G. et al. Kramers–Weyl fermions. Preprint at https://arxiv.org/abs/1611.07925 (2016).
Liu, Z. K. et al. Discovery of a three-dimensional topological Dirac semimetal Na3Bi. Science 343, 864–867 (2014).
Lv, B. Q. et al. Experimental discovery of Weyl semimetal TaAs. Phys. Rev. X 5, 031013 (2015).
Xu, S. Y. et al. Discovery of a Weyl fermion semimetal and topological Fermi arcs. Science 349, 613–617 (2016).
Lv, B. Q. et al. Observation of Weyl nodes in TaAs. Nat. Phys. 11, 724–727 (2015).
Yang, L. X. et al. Weyl semimetal phase in the non-centrosymmetric compound TaAs. Nat. Phys. 11, 728–732 (2015).
Xu, S.-Y. et al. Observation of Fermi arc surface states in a topological metal. Science 347, 294–298 (2015).
Potter, A. C., Kimchi, I. & Vishwanath, A. Quantum oscillations from surface Fermi arcs in Weyl and Dirac semimetals. Nat. Commun. 5, 5161 (2014).
Kargarian, M., Randeria, M. & Lu, Y.-M. Are the surface Fermi arcs in Dirac semimetals topologically protected? Proc. Natl Acad. Sci. USA 113, 8648–8652 (2016).
Fang, C., Lu, L., Liu, J. & Fu, L. Topological semimetals with helicoid surface states. Nat. Phys. 12, 936–941 (2016).
Lv, B. Q. et al. Observation of three-component fermions in the topological semimetal molybdenum phosphide. Nature 546, 627–631 (2016).
Shekhar, C. et al. Extremely high conductivity observed in the unconventional triple point fermion material MoP. Preprint at https://arxiv.org/abs/1703.03736 (2017).
He, J. B. et al. Magnetotransport properties of the triply degenerate node topological semimetal tungsten carbide. Phys. Rev. B 95, 195165 (2017).
Xiong, J. et al. Evidence for the chiral anomaly in the Dirac semimetal Na3Bi. Science 350, 413–416 (2015).
Huang, X. et al. Observation of the chiral-anomaly-induced negative magnetoresistance in 3D Weyl semimetal TaAs. Phys. Rev. X 5, 031023 (2015).
Strocov, V. N. et al. Three-dimensional electron realm in VSe2 by soft X-ray photoelectron spectroscopy: origin of charge-density waves. Phys. Rev. Lett. 109, 086401 (2012).
Shoenberg, D. Magnetic Oscillations in Metals (Cambridge Univ. Press, Cambridge, 1984).
Kane, C. L. & Mele, E. J. Z 2 topological order and the quantum spin Hall effect. Phys. Rev. Lett. 95, 146802 (2005).
Fu, L., Kane, C. L. & Mele, E. J. Topological insulators in three dimensions. Phys. Rev. Lett. 98, 106803 (2007).
Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).
Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996).
Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).
Marzari, N. & Vanderbilt, D. Maximally localized generalized Wannier functions for composite energy bands. Phys. Rev. B 56, 12847 (1997).
Acknowl1edgements
We acknowledge G. Li for valuable discussion. This work was supported by the Ministry of Science and Technology of China (2016YFA0300600, 2016YFA0401000, 2016YFA0302400, 2015CB921300, 2013CB921700, 2016YFA0202301 and 2016YFA0300300), the National Natural Science Foundation of China (11622435, 11474340, 11422428, 11674369, 11234014, 11404175, 61725107 and 11674371) and the Chinese Academy of Sciences (XDB07000000 and XDB06). Y.-B.H. acknowledges funding from the CAS Pioneer Hundred Talents Program (type C). A portion of this work performed at the National High Magnetic Field Laboratory, Tallahassee, USA, is supported by the National Science Foundation Cooperative Agreement DMR-1157490 and the State of Florida.
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H.D. and T.Q. conceived the ARPES experiments; J.-Z.M. and T.Q. performed ARPES measurements with the assistance of B.-Q.L., L.-Y.K., X.G., L.-Y.R. and Y.-B.H.; Y.-F.X. and H.-M.W. performed ab initio calculations; J.-B.H., D.C., W.-L.Z. and G.-F.C. synthesized the single crystals; S.Z., D.C., C.-Y.X., E.S.C. and G.-F.C. performed quantum oscillation measurements; J.-Z.M., T.Q. and H.D. analysed the experimental data; J.-Z.M., Y.-F.X., T.Q. and J.-B.H. plotted the figures; X.D. discussed the experimental and calculated data; Y.S., J.-Z.M., Y.-L.W. and H.-J.G. performed STM experiments. T.Q., C.F., H.-M.W., H.D., J.-Z.M. and P.R. wrote the manuscript.
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Ma, JZ., He, JB., Xu, YF. et al. Three-component fermions with surface Fermi arcs in tungsten carbide. Nature Phys 14, 349–354 (2018). https://doi.org/10.1038/s41567-017-0021-8
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DOI: https://doi.org/10.1038/s41567-017-0021-8
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