Topological nodal-line fermions in spin-orbit metal PbTaSe2

By G. Bian, Tay-Rong Chang, R. Sankar, Su-Yang Xu, Hao Zheng, Titus Neupert, Ching-Kai Chiu, Shin-Ming Huang, G. Chang, I. Belopolski and 14 more. Nature Communications, 2016

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Topological semimetals can support one-dimensional Fermi lines or zero-dimensional Weyl points in momentum space, where the valence and conduction bands touch. While the degeneracy points in Weyl semimetals are robust against any perturbation that preserves translational symmetry, nodal lines require protection by additional crystalline symmetries such as mirror reflection. Here we report, based on a systematic theoretical study and a detailed experimental characterization, the existence of topological nodal-line states in the non-centrosymmetric compound PbTaSe2 with strong spin-orbit coupling. Remarkably, the spin-orbit nodal lines in PbTaSe2 are not only protected by the reflection symmetry but also characterized by an integer topological invariant. Our detailed angle-resolved photoemission measurements, first-principles simulations and theoretical topological analysis illustrate the physical mechanism underlying the formation of the topological nodal-line states and associated surface states for the first time, thus paving the way towards exploring the exotic properties of the topological nodal-line fermions in condensed matter systems. Nodal-line shaped bands appearing near the Fermi level host unique properties in topological matter, which has yet to be confirmed in real materials. Here, the authors report the existence of topological nodal-line states in the non-centrosymmetric single-crystalline spin-orbit semimetal PbTaSe2.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/e7dafa666ba73b1aba08e5242affa676377062a2

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Citations in the corpus

Unconventional mass enhancement around the Dirac nodal loop in ZrSiS (2017, background): “In non-centrosymmetric PbTaSe 2 , strong spin-orbit coupling leads to the creation of nodal rings which have been conﬁrmed by angle-resolved photoemission spectroscopy (ARPES) [10] while in PtSn 4 , ARPES has revealed a Dirac nodal arc structure that has been attributed to surface states [9].”
Observation of Topological Nodal Fermion Semimetal Phase in ZrSiS (2016, neutral): “Multiple types of nontrivial topological metallic states have been proposed for Dirac materials such as the Weyl semimetal 14–19, 25– 27 , Dirac semimetal 6, PbTaSe 2 has recently been reported as a material with Dirac line nodes 28 .”
Experimental discovery of nodal chains (2017, neutral): “[24] Guang Bian, Tay-Rong Chang, Raman Sankar, Su-Yang Xu, Hao Zheng, Titus Neupert, Ching-Kai Chiu, ShinMing Huang, Guoqing Chang, Ilya Belopolski, et al.”
Weyl and Dirac semimetals in three-dimensional solids (2017, background): “They may have been observed in ZrSiS (Neupane et al., 2016; Schoop et al., 2016), PbTaSe2 (Bian et al., 2016a), HfSiS (Takane et al., 2016), and TlTaSe2 (Bian et al., 2016b) via ARPES.”