Type-II Dirac Nodal Lines in double-kagome-layered CsV${}_8$Sb${}_{12}$

Abstract

Lorentz-violating type-II Dirac nodal line semimetals (DNLSs), hosting curves of band degeneracy formed by two dispersion branches with the same sign of slope, represent a novel states of matter. While being studied extensively in theory, convincing experimental evidences of type-II DNLSs remain elusive. Recently, Vanadium-based kagome materials have emerged as a fertile ground to study the interplay between lattice symmetry and band topology. In this work, we study the low-energy band structure of double-kagome-layered CsV${}_8$Sb${}_{12}$ and identify it as a scarce type-II DNLS protected by mirror symmetry. We have observed multiple DNLs consisting of type-II Dirac cones close to or almost at the Fermi level via angle-resolved photoemission spectroscopy (ARPES). First-principle analyses show that spin-orbit coupling only opens a small gap, resulting effectively gapless ARPES spectra, yet generating large spin Berry curvature. These type-II DNLs, together with the interaction between a low-energy van Hove singularity and quasi-1D band as we observed in the same material, suggest CsV${}_8$Sb${}_{12}$ as an ideal platform for exploring novel transport properties such as chiral anomaly, the Klein tunneling and fractional quantum Hall effect.

arXiv comment10 pages, 4 figures

References in corpus (28)

• Weyl and Dirac Semimetals in Three Dimensional Solids
• WannierTools: An open-source software package for novel topological materials
• Type-II Weyl Semimetals
• Maximally-localized Wannier functions for entangled energy bands
• Titanic Magnetoresistance in WTe2
• High temperature fractional quantum Hall states
• Extremely large magnetoresistance and ultrahigh mobility in the topological Weyl semimetal NbP
• Fractional quantum Hall states at zero magnetic field
• CsV${}_3$Sb${}_5$: a ${\mathbb{Z}}_2$ topological kagome metal with a superconducting ground state
• Nearly-flat bands with nontrivial topology
• Topological nodal line semimetals
• Discovery of unconventional chiral charge order in kagome superconductor KV3Sb5
• Roton pair density wave and unconventional strong-coupling superconductivity in a topological kagome metal
• Time-reversal symmetry-breaking charge order in a kagome superconductor
• Concurrence of anomalous Hall effect and charge density wave in a superconducting topological kagome metal
• Chiral flux phase in the Kagome superconductor AV${}_3$Sb${}_5$
• Magnetic breakdown and Klein tunneling in a type-II Weyl semimetal
• Intrinsic nature of chiral charge order in the kagome superconductor RbV3Sb5
• Symmetry Demanded Topological Nodal-line Materials
• Multiple Energy Scales and Anisotropic Energy Gap in the Charge-Density-Wave Phase of Kagome Superconductor CsV3Sb5
• Absence of local moments in the kagome metal KV3Sb5 as determined by muon spin spectroscopy
• Emergence of new van Hove singularities in the charge density wave state of a topological kagome metal RbV3Sb5
• No observation of chiral flux current in the topological kagome metal CsV${}_3$Sb${}_5$
• Momentum-space structure of surface states in a topological semimetal with a nexus point of Dirac lines
• Type-I and type-II Nodal Lines Coexistence in the Antiferromagnetic monolayer CrAs${}_2$
• Structures and physical properties of V-based kagome metals CsV${}_6$Sb${}_6$ and CsV${}_8$Sb${}_{12}$
• Discovery of two families of VSb-based compounds with V-kagome lattice
• Type-II topological metals