Chiral Dirac fermion in a collinear antiferromagnet

Abstract

In a Dirac semimetal, the massless Dirac fermion has zero chirality, leading to surface states connected adiabatically to a topologically trivial surface state as well as vanishing anomalous Hall effect (AHE). Recently, it is predicted that in the nonrelativistic limit of certain collinear antiferromagnets, there exists a type of chiral Dirac-like fermion, whose dispersion manifests four-fold degenerate crossing points formed by spin-degenerate linear bands, with topologically protected Fermi arcs. Such unconventional chiral fermion, protected by a hidden SU(2) symmetry in the hierarchy of an enhanced crystallographic group, namely spin space group, is not experimentally verified yet. Here, by angle-resolved photoemission spectroscopy measurements, we reveal the surface origin of the electron pocket at the Fermi surface in collinear antiferromagnet CoNb3S6. Combining with neutron diffraction and first-principles calculations, we suggest a multidomain collinear AFM configuration, rendering the the existence of the Fermi-arc surface states induced by chiral Dirac-like fermions. Our work provides spectral evidence of the chiral Dirac-like fermion caused by particular spin symmetry in CoNb3S6, paving an avenue for exploring new emergent phenomena in antiferromagnets with unconventional quasiparticle excitations.

19 pages, 4 figures

References in corpus (16)

• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Classification of stable three-dimensional Dirac semimetals with nontrivial topology
• New classes of chiral topological nodes with non-contractible surface Fermi arcs in CoSi
• Layer Hall effect in a 2D topological Axion antiferromagnet
• Spin-group symmetry in magnetic materials with negligible spin-orbit coupling
• Spontaneous topological Hall effect induced by non-coplanar antiferromagnetic order in intercalated van der Waals materials
• Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators
• Giant anomalous Hall effect in quasi-two-dimensional layered antiferromagnet Co${}_{1/3}$NbS${}_2$
• Crystal growth and quantum oscillations in the topological chiral semimetal CoSi
• Quasiparticle Interference Evidence of the Topological Fermi Arc States in Chiral Fermionic Semimetal CoSi
• Magnetic ground state of the Kitaev Na${}_2$Co${}_2$TeO${}_6$ spin liquid candidate
• Large anomalous Hall effect induced by weak ferromagnetism in the noncentrosymmetric antiferromagnet $\mathrm{Co}{\mathrm{Nb}}_3{\mathrm{S}}_6$
• Network of topological nodal planes, multifold degeneracies, and Weyl points in CoSi
• Chiral Dirac-like fermion in spin-orbit-free antiferromagnetic semimetals
• Role of intercalated Cobalt in the electronic structure of Co${}_{1/3}$NbS${}_2$
• Visualizing the out-of-plane electronic dispersions in an intercalated transition metal dichalcogenide

Cited by in corpus (12)

• Observation of plaid-like spin splitting in a noncoplanar antiferromagnet
• Enumeration and representation theory of spin space groups
• Enumeration of spin-space groups: Towards a complete description of symmetries of magnetic orders
• Observation of Spin Splitting in Room-Temperature Metallic Antiferromagnet CrSb
• Symmetry invariants and classes of quasiparticles in magnetically ordered systems having weak spin-orbit coupling
• Gapped nodal planes drive a large topological Nernst effect in a chiral lattice antiferromagnet
• Crossover from relativistic to non-relativistic net magnetization for MnTe altermagnet candidate
• Crystalline electric field excitations in Weyl semimetal \textit{R}AlSi (\textit{R} = Ce, Pr and Nd)
• Topological Charge Quadrupole Protected by Spin-Orbit U(1) Quasi-Symmetry in Antiferromagnet NdBiPt
• Physical properties of RhGe and CoGe single crystals synthesized under high pressure
• Double-$Q$ chiral stripe order in the anomalous Hall antiferromagnet CoNb${}_3$S${}_6$
• Discovery of Van Hove Singularities: Electronic Fingerprints of 3Q Magnetic Order in a van der Waals Quantum Magnet