Chiral fermion reversal in chiral crystals

Li, Hang; Xu, Sheng; Rao, Zhicheng; Zhou, Liqin; Wang, Zhijun; Zhou, Shiming; Tian, Shangjie; Gao, Shangyu; Li, Jiajun; Huang, Yaobo; Lei, Hechang; Weng, Hongming; Sun, Yujuan; Xia, Tian‐Long; Qian, Tian; Ding, Hong

doi:10.1038/s41467-019-13435-4

Cited by 42 publications

(23 citation statements)

References 49 publications

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“…However, the experimental investigation of chirality-dependent phenomena, i.e., the emergence, observation, and manipulation of effects directly linked to the sign of the Chern number, remains largely unexplored. This requires chiral topological semimetals for which both enantiomers can be selectively synthesized so as to control the sign of the topological charge while keeping all other material properties unchanged 21 .…”

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confidence: 99%

Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa

et al. 2020

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It has recently been proposed that combining chirality with topological band theory results in a totally new class of fermions. Understanding how these unconventional quasiparticles propagate and interact remains largely unexplored so far. Here, we use scanning tunneling microscopy to visualize the electronic properties of the prototypical chiral topological semimetal PdGa. We reveal chiral quantum interference patterns of opposite spiraling directions for the two PdGa enantiomers, a direct manifestation of the change of sign of their Chern number. Additionally, we demonstrate that PdGa remains topologically non-trivial over a large energy range, experimentally detecting Fermi arcs in an energy window of more than 1.6 eV that is symmetrically centered around the Fermi level. These results are a consequence of the deep connection between chirality in real and reciprocal space in this class of materials, and, thereby, establish PdGa as an ideal topological chiral semimetal.

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confidence: 99%

Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa

et al. 2020

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“…We first consider RZT (class 1) structures using the ansatz of Equation (4). By minimising the total free energy F (i) with respect to Q 1 , it follows that:…”

Section: Landau-type Analysismentioning

confidence: 99%

“…Chirality is present throughout physics and often impacts or even dominates numerous important natural phenomena. For example, chiral symmetry plays an important role in the Standard Model of physics [4]. The functionalities of several essential components of biological cells rely heavily on chirality [3].…”

Section: Introductionmentioning

confidence: 99%

Multiple Twisted Chiral Nematic Structures in Cylindrical Confinement

et al. 2020

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In this article, we theoretically and numerically study the chirality and saddle-splay elastic constant (-enabled stability of multiple twist-like nematic liquid crystal (LC) structures in cylindrical confinement. We focus on the so-called radially z-twisted (RZT) and radially twisted (RT) configurations, which simultaneously exhibit twists in different spatial directions. We express the free energies of the structures in terms of dimensionless wave vectors, which characterise the structures and play the roles of order parameters. The impact of different confinement anchoring conditions is explored. A simple Landau-type analysis provides an insight into how different model parameters influence the stability of structures. We determine conditions for which the structures are stable in chiral and also nonchiral LCs. In particular, we find that the RZT structure could exhibit macroscopic chirality inversion upon varying the relevant parameters. This phenomenon could be exploited for the measurement of.

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“…A direct consequence of the 2D nonzero Chern number constrained by the no-go theorem is the appearance of surface Fermi arc states which connect the projections of Weyl points on the surface BZ 15,16 . The no-go theorem also applies to the recently discovered large Chern number Weyl points in the CoSi family materials [17][18][19][20][21][22] , i.e. the WPs at high symmetry points are paired and their projections on the surface BZ are connected by Fermi arcs as consequence of the no-go theorem.…”

Section: Introductionmentioning

confidence: 99%

Observation of a singular Weyl point surrounded by charged nodal walls in PtGa

Song

et al. 2021

Nat Commun

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Constrained by the Nielsen-Ninomiya no-go theorem, in all so-far experimentally determined Weyl semimetals (WSMs) the Weyl points (WPs) always appear in pairs in the momentum space with no exception. As a consequence, Fermi arcs occur on surfaces which connect the projections of the WPs with opposite chiral charges. However, this situation can be circumvented in the case of unpaired WP, without relevant surface Fermi arc connecting its surface projection, appearing singularly, while its Berry curvature field is absorbed by nontrivial charged nodal walls. Here, combining angle-resolved photoemission spectroscopy with density functional theory calculations, we show experimentally that a singular Weyl point emerges in PtGa at the center of the Brillouin zone (BZ), which is surrounded by closed Weyl nodal walls located at the BZ boundaries and there is no Fermi arc connecting its surface projection. Our results reveal that nontrivial band crossings of different dimensionalities can emerge concomitantly in condensed matter, while their coexistence ensures the net topological charge of different dimensional topological objects to be zero. Our observation extends the applicable range of the original Nielsen-Ninomiya no-go theorem which was derived from zero dimensional paired WPs with opposite chirality.

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Chiral fermion reversal in chiral crystals

Cited by 42 publications

References 49 publications

Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa

Handedness-dependent quasiparticle interference in the two enantiomers of the topological chiral semimetal PdGa

Multiple Twisted Chiral Nematic Structures in Cylindrical Confinement

Observation of a singular Weyl point surrounded by charged nodal walls in PtGa

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