Weyl points created by a three-dimensional flat band

Abstract

Following the discovery of topological insulators (TIs), topological Dirac/Weyl semimetal has attracted much recent interest. A prevailing mechanism for the formation of Weyl points is by breaking time-reversal symmetry (TRS) or spatial inversion symmetry of a Dirac point. Here we demonstrate a generic formation mechanism for Weyl points by breaking TRS of a three-dimensional (3D) TI featured with highly degenerate 3D flat bands (FBs). It is in direct contrast to the conventional view that breaking TRS of a 2D/3D TI leads to a Chern insulator exhibiting quantum anomalous Hall effect. Based on a tight-binding model of pyrochlore lattice, we show that this unusual 3D-FB-enabled Weyl state may contain only a minimum of two Weyl points. Furthermore, using first-principles calculations, we identify this Weyl state in a real material Sn${}_2$Nb${}_2$O${}_7$. The main features of the resulting Weyl points are analyzed with respect to symmetry, topological invariant and surface state. Our finding sheds new light on our fundamental understanding of topological physics and significantly extends the scope of Weyl semimetals to attract immediate experimental interest.

References in corpus (35)

• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Maximally-localized generalized Wannier functions for composite energy bands
• Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator
• Wannier90: A Tool for Obtaining Maximally-Localised Wannier Functions
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Discovery of a Weyl Fermion Semimetal and Topological Fermi Arcs
• WannierTools: An open-source software package for novel topological materials
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Topological Materials: Weyl Semimetals
• Chern semi-metal and Quantized Anomalous Hall Effect in HgCr2Se4
• High temperature fractional quantum Hall states
• Fractional quantum Hall states at zero magnetic field
• Observation of Weyl nodes in TaAs
• Bismuthene on a SiC Substrate: A Candidate for a New High-Temperature Quantum Spin Hall Paradigm
• Nearly-flat bands with nontrivial topology
• Topological insulator on the kagome lattice
• Flat bands and Wigner crystallization in the honeycomb optical lattice
• Quantum Anomalous Hall Effect in 2D Organic Topological Insulators
• Epitaxial growth of large-gap quantum spin Hall insulator on semiconductor surface
• Exotic electronic states in the world of flat bands: from theory to material
• The $p_{x,y}$-orbital counterpart of graphene: cold atoms in the honeycomb optical lattice
• Three-dimensional Topological Insulators on the Pyrochlore Lattice
• $Z_Q$ Topological Invariants for Polyacetylene, Kagome and Pyrochlore lattices
• Proposed realization of itinerant ferromagnetism in optical lattices
• Topology and Interactions in a Frustrated Slab: Tuning from Weyl Semimetals to C > 1 Fractional Chern Insulators
• Topological Insulators from Spontaneous Symmetry Breaking Induced by Electron Correlation on Pyrochlore Lattices
• Superconductivity in repulsively interacting fermions on a diamond chain: flat-band induced pairing
• Kinetic ferromagnetism on a kagome lattice
• Stability of ferromagnetism in the Hubbard model on the kagomé lattice
• Spin Hall effect in the kagome lattice with Rashba spin-orbit interaction
• Magnetic field effects on two-dimensional Kagome lattices
• Quantum spin Hall effect and spin-charge separation in a kagome lattice

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• Non-volatile Electric Control of Magnetic and Topological Properties of MnBi2Te4 Thin Films
• Optical properties of two dimensional Dirac Weyl materials with a flatband
• Optical Signature of Flat Bands in Topological Hourglass Semimetal Nb3SiTe6
• Trends in Bandgap of Epitaxial $\text{A}$${}_2$$\text{B}$${}_2$O${}_7$ ($\text{A}$ = Sn, Pb; $\text{B}$ = Nb, Ta) Films Fabricated by Pulsed Laser Deposition
• Accessing quasi-flat $\text{f}$-bands to harvest large Berry curvature in NdGaSi