Observation of Chiral Fermions with a Large Topological Charge and and Associated Fermi-Arc Surface States in CoSi

Abstract

Topological semimetals materialize a new state of quantum matter where massless fermions protected by a specific crystal symmetry host exotic quantum phenomena. Distinct from well-known Dirac and Weyl fermions, structurally-chiral topological semimetals are predicted to host new types of massless fermions characterized by a large topological charge, whereas such exotic fermions are yet to be experimentally established. Here, by using angle-resolved photoemission spectroscopy, we experimentally demonstrate that a transition-metal silicide CoSi hosts two types of chiral topological fermions, spin-1 chiral fermion and double Weyl fermion, in the center and corner of the bulk Brillouin zone, respectively. Intriguingly, we found that the bulk Fermi surfaces are purely composed of the energy bands related to these fermions. We also find the surface states connecting the Fermi surfaces associated with these fermions, suggesting the existence of the predicted Fermi-arc surface states. Our result provides the first experimental evidence for the chiral topological fermions beyond Dirac and Weyl fermions in condensed-matter systems, and paves the pathway toward realizing exotic electronic properties associated with unconventional chiral fermions.

6 pages, 4 figures (paper proper) + 4 pages, 4 figures (supplemental material)

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Cited by in corpus (162)

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• Observation of Topological Photocurrents in the Chiral Weyl Semimetal RhSi
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• Weyl, Dirac and high-fold chiral fermions in topological quantum materials
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• Topological quantum materials from the viewpoint of chemistry
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• Topology and geometry under the nonlinear electromagnetic spotlight
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• Observation and control of maximal Chern numbers in a chiral topological semimetal
• A Charge-Density-Wave Topological Semimetal
• Topological triply-degenerate point with double Fermi arcs
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• Difference frequency generation in topological semimetals
• Linear and nonlinear optical responses in the chiral multifold semimetal RhSi
• Acoustic Higher-Order Weyl Semimetal with Bound Hinge States in the Continuum
• Observation of quadratic Weyl points and double-helicoid arcs
• Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa
• Crystal growth and quantum oscillations in the topological chiral semimetal CoSi
• Berry Curvature and Quantum Metric in $N$-band systems -- an Eigenprojector Approach
• Optical signatures of multifold fermions in the chiral topological semimetal CoSi
• Quasiparticle Interference Evidence of the Topological Fermi Arc States in Chiral Fermionic Semimetal CoSi
• Chiral fermion reversal in chiral crystals
• Linear optical conductivity of chiral multifold fermions
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• Observation of multiple types of topological fermions in PdBiSe
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• Kramers Nodal Line Metals
• Photoemission Spectroscopic Evidence for the Dirac Nodal Line in Monoclinic Semimetal SrAs${}_3$
• Direct observation of six-fold exotic fermions in topological semimetal PdSb${}_2$
• Single crystal growth and magnetoresistivity study of topological semimetal CoSi
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• Observation of sixfold degenerate fermions in PdSb${}_2$
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• Fully spin-polarized double-Weyl fermions with type-III dispersion in quasi-one dimensional materials X2RhF6 (X=K, Rb, Cs)
• Transmission and conductance across junctions of isotropic and anisotropic three-dimensional semimetals
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• Fermi surface, possible unconventional fermions, and unusually robust resistive critical fields in the chiral-structured superconductor AuBe
• Nodal Semimetals: A Survey on Optical Conductivity
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• Acoustic spin-1 Weyl semimetal
• Triple point fermions in ferroelectric GeTe
• Bulk-boundary correspondence in extended trimer Su-Schrieffer-Heeger model
• Symmetry protection and giant Fermi arcs from multifold fermions in binary, ternary, and quaternary compounds
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• Computing observables without eigenstates: applications to Bloch Hamiltonians
• Atomically Sharp Internal Interface in a Chiral Weyl Semimetal Nanowire
• Observation of gapless nodal-line states in NdSbTe
• Realization of Practical Eightfold Fermions and Fourfold van Hove Singularity in TaCo${}_2$Te${}_2$
• Collinear Rashba-Edelstein effect in non-magnetic chiral materials
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• Quantum oscillations and electronic structure in the large-Chern number topological chiral semimetal PtGa
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• Leveraging Electron-Phonon Interaction to Enhance Thermoelectric Power Factor in Graphene-Like Semimetals
• Quantum oscillations and electronic structures in large Chern number semimetal RhSn
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• Experimental and computational approaches to study the high temperature thermoelectric properties of novel topological semimetal CoSi
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• Anomalous in-gap edge states in two-dimensional pseudospin-1 Dirac insulators
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• Infrared fixed points of higher-spin fermions in topological semimetals
• Theory of Photocurrent and High-Harmonic Generation with Chiral Fermions
• Correlated interaction effects in three-dimensional semi-Dirac semimetal
• Magnon modes as a joint effect of surface ferromagnetism and spin-orbite coupling in CoSi chiral topological semimetal
• Preformed Cooper pairs in flat-band semimetals
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• On valley asymmetry in a topological interaction for quasi-particles
• Chiral separation effect for spin 3/2 fermions
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• Charge instability of topological Fermi arcs in chiral crystal CoSi
• High-chirality and multiquaternion Weyl nodes in hexagonal ReO${}_3$
• Floquet-Engineering Weyl Points and Linked Fermi Arcs from Straight Nodal Lines
• Collective plasmonic modes in the chiral multifold fermionic material CoSi
• Coalescence of Andreev bound states on the surface of a chiral topological semimetal
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• Broken Screw Rotational Symmetry in the Near-Surface Electronic Structure of $AB$-Stacked Crystals
• Symmetry-adapted models for multifold fermions with spin-orbit coupling
• Identification of chirality of chiral multifold fermions in anti-crystals
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• Anomalous Chiral Anomaly in Spin-1 Fermionic Systems
• Quantum Transport in Spin-1 Chiral Fermion: Self-Consistent Born Approximation
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