Observation of Weyl nodes in TaAs

By B. Lv, N. Xu, H. Weng, Junzhang Ma, P. Richard, Xiaochun Huang, Lingxiao Zhao, Genfu Chen, C. Matt, F. Bisti and 7 more. Nature Physics, 2015

904 citations recorded by the source corpus.

Experiments show that TaAs is a three-dimensional topological Weyl semimetal. In 1929, H. Weyl proposed that the massless solution of the Dirac equation represents a pair of a new type of particles, the so-called Weyl fermions1. However, their existence in particle physics remains elusive after more than eight decades. Recently, significant advances in both topological insulators and topological semimetals have provided an alternative way to realize Weyl fermions in condensed matter, as an emergent phenomenon: when two non-degenerate bands in the three-dimensional momentum space cross in the vicinity of the Fermi energy (called Weyl nodes), the low-energy excitations behave exactly as Weyl fermions. Here we report the direct observation in TaAs of the long-sought-after Weyl nodes by performing bulk-sensitive soft X-ray angle-resolved photoemission spectroscopy measurements. The projected locations at the nodes on the (001) surface match well to the Fermi arcs, providing undisputable experimental evidence for the existence of Weyl fermionic quasiparticles in TaAs.

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

View Paper: https://www.semanticscholar.org/paper/4c188bc36e558b7245d94d322057bd670e8e4043

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. Ashvin Vishwanath
2. N. P. Armitage
3. E. Mele
4. Hsin Lin
5. Arun Bansil
6. Tanmoy Das
7. H. Weng
8. J. Venderbos

In Materials Chemistry

1. Ashvin Vishwanath
2. N. P. Armitage
3. E. Mele
4. Hsin Lin
5. Arun Bansil
6. Tanmoy Das
7. H. Weng
8. Z. Fang

Citations in the corpus

• Weyl and Dirac semimetals in three-dimensional solids (2017, methodology): “…as envisaged in (Halász and Balents, 2012; Murakami, 2007) reached fruition with the prediction and discovery of TaAs as a WSM (Huang et al., 2015a; Lv et al., 2015b,c; Weng et al., 2015a; Xu et al., 2015b) (and other members in this material class (Xu et al., 2016b, 2015a,c)), and the…”
• Colloquium : Topological band theory (2016, background): “(Huang et al. 2015; Weng et al. 2015; Xu, Belopolski, et al. 2015; Lv et al. 2015; Xu, Alidoust, et al. 2015; Yang, Liu, et al. 2015; Zhang et al. 2015)”
• Topological Semimetals from First Principles (2018, background): “A decisive advance came in 2015, when the observation of a T -invariant Weyl semimetal phase was reported in TaAs and related materials (94, 95, 96, 97, 98, 99) based on earlier theoretical predictions (7, 33).”
• Geometric phase from Aharonov–Bohm to Pancharatnam–Berry and beyond (2019, background): “determines the Chern class (89) of the bundle’s connection and provides details pertaining to the topological structure of the bundle such as the strength of singularities that it could be containing (90,91,92,93,94,95,96,97,98,99). 3. Geometric phase in optics There are two main types of geometric ”
• Direct optical detection of Weyl fermion chirality in a topological semimetal (2017, methodology): “The band structures, quasi-particle interferences, magneto-resistances measured by angle-resolved photoemission spectroscopy (ARPES)9,11–14, scanning tunnelling microscope33–35, and transport experiments17–19, respectively, are not sensitive to the chirality of WFs (see also Supplementary Informatio”
• Helicity protected ultrahigh mobility Weyl fermions in NbP (2015, background): “expected that the Weyl fermion transport in NbAs and NbP would notably differ from TaAs, because the W2-Weyl cones are highly anisotropic in k-space compared to the relatively isotropic W1-Weyl cones [1,5,6]. Intriguingly, the electron mobility of NbP (5106 cm2V-1s-1) [17] is one order of magnitude ”