Self-organized pseudo-graphene on grain boundaries in topological band insulators

Abstract

Semi-metals are characterized by nodal band structures that give rise to exotic electronic properties. The stability of Dirac semi-metals, such as graphene in two spatial dimensions (2D), requires the presence of lattice symmetries, while akin to the surface states of topological band insulators, Weyl semi-metals in three spatial dimensions (3D) are protected by band topology. Here we show that in the bulk of topological band insulators, self-organized topologically protected semi-metals can emerge along a grain boundary, a ubiquitous extended lattice defect in any crystalline material. In addition to experimentally accessible electronic transport measurements, these states exhibit valley anomaly in 2D influencing edge spin transport, whereas in 3D they appear as graphene-like states that may exhibit an odd-integer quantum Hall effect. The general mechanism underlying these novel semi-metals -- the hybridization of spinon modes bound to the grain boundary -- suggests that topological semi-metals can emerge in any topological material where lattice dislocations bind localized topological modes.

14 pages, 6 figures. Improved discussion compared to the earlier version

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Cited by in corpus (34)

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• The translational side of topological band insulators
• Global Phase Diagram of a Dirty Weyl Liquid and Emergent Superuniversality
• Hopf characterization of two-dimensional Floquet topological insulators
• Landau quantization, Aharonov-Bohm effect and two-dimensional pseudoharmonic quantum dot around a screw dislocation
• Wannier representation of Floquet topological states
• Subdimensional topologies, indicators and higher order phases
• Manipulation and braiding of Weyl nodes using symmetry-constrained phase transitions
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• Large-scale defects hidden inside a topological insulator grown onto a 2D substrate
• Flat Energy Bands within Antiphase and Twin Boundaries and at Open Edges in Topological Materials
• $\pi$-fluxes, semi-metals and flat bands in artificial materials
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• Robust one-dimensionality at twin-grain-boundaries in MoSe${}_2$
• Emergent metallicity at the grain boundaries of higher-order topological insulators
• Topological electronic structure of twin boundaries and twinning superlattices in the SnTe material class
• Grain-boundary topological superconductor
• Stability of Weyl node merging processes under symmetry constraints
• Selective branching, quenching, and converting of topological modes
• Dispersive nodal fermions along grain boundaries in Floquet topological crystals
• Anomalous wave-packet transport on boundaries of Floquet topological systems
• Designing atomic-scale resistive circuits in topological insulators through vacancy-induced localized modes
• Projected branes as platforms for crystalline, superconducting, and higher-order topological phases
• Intrinsic one-dimensional conducting channels in the Kondo insulator SmB6