Fractional Corner Charge of Sodium Chloride

Abstract

Recent developments in higher-order topological phases have elucidated on the relationship between nontrivial multipole moments in the bulk and the emergence of fractionally quantized charges at the boundary. Here, we put on the table a proposal of the three-dimensional octupole insulator with fractionally quantized corner charges $\pm e/8$: sodium chloride, commonly known as table salt. The fractional quantization of the corner charge is unaffected by the quantum fluctuation of the electric charge per ion, as we demonstrate explicitly with ab initio calculations. We further show that the electrostatic signature of the fractional charge is well-preserved even when the ideal crystal is sprinkled with defects, and provide a systematic analysis on how the corner charge contribution could be isolated from the electric-field corrections originating from realistic surface relaxation. Our results suggest that the observation of corner charges from quantized multipole moments in solids might be around the corner.

arXiv comment14 pages, 7 figures

References in corpus (39)

• Topological Insulators
• Topological insulators and superconductors
• Advances in atomic force microscopy
• Quantized Electric Multipole Insulators
• Higher-Order Topological 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
• Topolectrical circuit realization of topological corner modes
• Reflection symmetric second-order topological insulators and superconductors
• Observation of a phononic quadrupole topological insulator
• Higher-order topological insulators and semimetals on the breathing Kagome and pyrochlore lattices
• Demonstration of a quantized microwave quadrupole insulator with topologically protected corner states
• Quantization of fractional corner charge in $C_n$-symmetric higher-order topological crystalline insulators
• Photonic quadrupole topological phases
• Higher-order bulk-boundary correspondence for topological crystalline phases
• Acoustic realization of quadrupole topological insulators
• Higher-Order Topological Insulators in Quasicrystals
• A fractional corner anomaly reveals higher-order topology
• Higher-order topological insulators protected by inversion and rotoinversion symmetries
• Observation of an acoustic octupole topological insulator
• An anomalous higher-order topological insulator
• Rotation Anomaly and Topological Crystalline Insulators
• Many-Body Electric Multipole Operators in Extended Systems
• Many-Body Order Parameters for Multipoles in Solids
• Quadrupole Topological Photonic Crystals
• Fractional corner charges in spin-orbit coupled crystals
• Connecting higher-order topological insulators to lower-dimensional topological insulators
• Scanning Quantum Dot Microscopy
• Shift insulators: rotation-protected two-dimensional topological crystalline insulators
• Investigating Atomic Contrast in Atomic Force Microscopy and Kelvin Probe Force Microscopy on Ionic Systems using Functionalized Tips
• Difficulties in operator-based formulation of the bulk quadrupole moment
• Topological Mirror Insulators in One Dimension
• Bulk-corner correspondence of time-reversal symmetric insulators: deduplicating real-space invariants
• Corner charge and bulk multipole moment in periodic systems
• Higher-Order Entanglement and Many-Body Invariants for Higher-Order Topological Phases
• Bulk-and-edge to corner correspondence
• Quadrupole moments, edge polarizations, and corner charges in the Wannier representation
• Higher-Order Topological Crystalline Insulating Phase and Quantized Hinge Charge in Topological Electride Apatite
• Electric field sensing with a scanning fiber-coupled quantum dot

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• Universal higher-order bulk-boundary correspondence of triple nodal points
• Fractional hinge and corner charges in various crystal shapes with cubic symmetry
• Protected Gapless Edge States In Trivial Topology
• Topologically localized insulators
• Additive rule of real and reciprocal space topologies at disclinations
• Recipe for higher-order topology on the triangular lattice
• Many-Body Quadrupolar Sum Rule for Higher-Order Topological Insulator