Fragile topologically flat band in the checkerboard antiferromagnetic monolayer FeSe

Abstract

By means of the first-principles calculations and magnetic topological quantum chemistry, we demonstrate that the low energy physics in the checkerboard antiferromagnetic (AFM) monolayer FeSe, very close to an AFM topological insulator that hosts robust edge states, can be well captured by a double-degenerate fragile topologically flat band just below the Fermi level. The Wilson loop calculations identify that such fragile topology is protected by the $S_{4z}$ symmetry, which gives rise to an AFM higher-order topological insulator that support the bound state with fractional charge $e/2$ at the sample corner. This is the first reported $S_{4z}$-protected fragile topological material, which provides a new platform to study the intriguing properties of magnetic fragile topological electronic states. Previous observations of the edge states and bound states in checkerboard AFM monolayer FeSe can also be well understood in our work.

References in corpus (52)

• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Topological Crystalline Insulators
• Quantized Electric Multipole Insulators
• Magnetic-field-induced quantized anomalous Hall effect in intrinsic magnetic topological insulator MnBi${}_2$Te${}_4$
• Higher-Order Topological Insulators
• Topological quantum chemistry
• Chern semi-metal and Quantized Anomalous Hall Effect in HgCr2Se4
• Topological Crystalline Insulators in the SnTe Material Class
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Topological axion states in magnetic insulator MnBi${}_2$Te${}_4$ with the quantized magnetoelectric effect
• Robust axion insulator and Chern insulator phases in a two-dimensional antiferromagnetic topological insulator
• Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films
• Observation of topological superconductivity on the surface of an iron-based superconductor
• Interface-induced superconductivity and strain-dependent spin density wave in FeSe/SrTiO3 thin films
• Antiferromagnetic topological insulators
• The space group classification of topological band insulators
• Dynamical Axion Field in Topological Magnetic Insulators
• High-throughput calculations of magnetic topological materials
• Hourglass Fermions
• Fragile Topology and Wannier Obstructions
• Higher-order Topology of Axion Insulator EuIn${}_2$As${}_2$
• Time-reversal-symmetry-broken quantum spin Hall effect
• Magnetic Topological Quantum Chemistry
• Topological nature of FeSe${}_{0.5}$Te${}_{0.5}$ superconductor
• Topology-Bounded Superfluid Weight In Twisted Bilayer Graphene
• Topological superconductivity on the surface of Fe-based superconductors
• Multiple topological states in iron-based superconductors
• Structure and Topology of Band Structures in the 1651 Magnetic Space Groups
• Wilson loop approach to fragile topology of split elementary band representations and topological crystalline insulators with time reversal symmetry
• Universal Approach to Magnetic Second-Order Topological Insulator
• Real Space Invariants: Twisted Bulk-Boundary Correspondence of Fragile Topology
• Topology of Disconnected Elementary Band Representations
• Experimental characterization of fragile topology in an acoustic metamaterial
• Disconnected Elementary Band Representations, Fragile Topology, and Wilson Loops as Topological Indices: An Example on the Triangular Lattice
• Fragile topology and flat-band superconductivity in the strong-coupling regime
• The Landau Level of Fragile Topology
• The study of magnetic topological semimetals by first principles calculations
• Fragile Topology Protected by Inversion Symmetry: Diagnosis, Bulk-Boundary Correspondence, and Wilson Loop
• Topological correspondence between magnetic space group representations
• Hofstadter Topology: Non-crystalline Topological Materials at High Flux
• The Axion Insulator as a Pump of Fragile Topology
• A topological look at the quantum spin Hall state
• Subdimensional topologies, indicators and higher order phases
• Delocalization Transition of Disordered Axion Insulator
• Edge states at nematic domain walls in FeSe films
• Higher-order topological insulators in a crisscross antiferromagnetic model

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• Higher-order topological phases in crystalline and non-crystalline systems: a review
• Sublattice-enriched tunability of bound states in second-order topological insulators and superconductors
• Orbital shift-induced boundary obstructed topological materials with a large energy gap
• Quantum spin Hall effect protected by spin U(1) quasisymmetry
• Spin-Dependent High-Order Topological Insulator and Two Types of Distinct Corner Modes in Monolayer FeSe/GdClO Heterostructure
• Fractional corner charges in threefold-symmetric two-dimensional materials with fragile topology
• Fragile topological phase on the triangular kagome lattice and its bulk-boundary correspondence
• Controllable magnetic anisotropy and ferroelasticity in superconducting FeSe monolayer with surface fluorine adsorption
• Symmetry-breaking-induced topology in FeSe
• Coexistence of d-Wave Altermagnetism and Topological States in Janus FeSeX (X = S, Te) Monolayers