Second-order topological insulator in Bilayer borophene

Abstract

As the novel topological states, the higher-order topological insulators have attracted great attentions in the past years. However, their realizations in realistic materials, in particular in two dimensional systems, remains the big challenge due to the lack of adequate candidates. Here, based on the first-principle calculation and tight-binding model simulations, we identify the currently \emph{existing} bilayer ${\alpha }_5$-phase borophenes as the two-dimensional second-order topological insulators, protected by the $C_2$-rotational symmetry. The formation of interlayer B-B covalent bonds, stabilizing the bilayer borophenes and opening the large direct bulk gaps ($\sim 0.55-0.62$ eV) at Fermi level, plays the key roles. The second-order topology is characterized by the bulk quantized quadrupole momentum. Our results enriches the candidates for the second-order topological insulators, and also provide a way to study topological states in borophenes.

9 Pages, 7 figures

References in corpus (23)

• The electronic properties of graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Topological Crystalline Insulators
• Electric Multipole Moments, Topological Multipole Moment Pumping, and Chiral Hinge States in Crystalline Insulators
• $(d-2)$-dimensional edge states of rotation symmetry protected topological states
• Reflection symmetric second-order topological insulators and superconductors
• Higher-order topological insulators and semimetals on the breathing Kagome and pyrochlore lattices
• Novel Topological Phase with Zero Berry Curvature
• Review of borophene and its potential applications
• Prediction of Near-Room-Temperature Quantum Anomalous Hall Effect on Honeycomb Materials
• Building Blocks of Topological Quantum Chemistry: Elementary Band Representations
• Liganded Xene as a Prototype of Two-Dimensional Stiefel-Whitney Insulators
• $PT$ Symmetric Real Dirac Fermions and Semimetals
• $C_n$-symmetric higher-order topological crystalline insulators in atomically thin transition-metal dichalcogenides
• General invariance and equilibrium conditions for lattice dynamics in 1D, 2D, and 3D materials
• Second Order Topological Insulator State in Hexagonal Lattices and its Abundant Material Candidates
• A Higher-Order Topological Insulator Phase in a Modulated Haldane Model
• Ferroelectric higher-order topological insulator in two dimensions
• Second-order and real Chern topological insulator in twisted bilayer $\alpha$-graphyne
• Abundance of second order topology in $C_3$ symmetric two-dimensional insulators
• High-spin orbital interactions across van der Waals gaps controlling the interlayer ferromagnetism in van der Waals ferromagnets
• Takagi Topological Insulator on the Honeycomb Lattice

Cited by in corpus (3)

• Engineering Two-Dimensional Hybrid-Order Topological Insulators via Trilayer Coupling
• Structural dependence of quantum transport properties on topological nodal-line semimetal bilayer borophene
• Magnetically tuned topological phase in graphene nanoribbon heterojunctions