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Add to Calendar 4/22/2019 12:00 pm 4/22/2019 America/Chicago Institute for Condensed Matter Theory Seminar: "Partial lattice defects in higher order topological insulators" DESCRIPTION:

Non-zero weak topological indices are thought to be a necessary condition to bind a single helical mode on lattice dislocations. In this work we show that higher-order topological insulators (HOTIs) can, in fact, host a single helical mode along screw or edge dislocations (including step edges) in the absence of weak topological indices. This helical mode is necessarily bound to a dislocation characterized by a fractional Burgers vector, macroscopically detected by the existence of a stacking fault. The robustness of a helical mode on a partial defect is demonstrated by an adiabatic transformation that restores translation symmetry in the stacking fault. We present two examples of HOTIs, one intrinsic and one extrinsic, that show helical modes at partial dislocations. Since partial defects and stacking faults are commonplace in bulk crystals, the existence of such helical modes can in principle significantly affect the expected conductivity in these materials.

Reference: https://arxiv.org/abs/1809.03518

\n\nSPEAKER: Jennifer Cano, Stony Brook University
190 ESB false

Institute for Condensed Matter Theory Seminar: "Partial lattice defects in higher order topological insulators"

Speaker Jennifer Cano, Stony Brook University
Date: 4/22/2019
Time: 12 p.m.
Location: 190 ESB
Sponsor: The Physics Department
Event Type: Seminar/Symposium
 

Non-zero weak topological indices are thought to be a necessary condition to bind a single helical mode on lattice dislocations. In this work we show that higher-order topological insulators (HOTIs) can, in fact, host a single helical mode along screw or edge dislocations (including step edges) in the absence of weak topological indices. This helical mode is necessarily bound to a dislocation characterized by a fractional Burgers vector, macroscopically detected by the existence of a stacking fault. The robustness of a helical mode on a partial defect is demonstrated by an adiabatic transformation that restores translation symmetry in the stacking fault. We present two examples of HOTIs, one intrinsic and one extrinsic, that show helical modes at partial dislocations. Since partial defects and stacking faults are commonplace in bulk crystals, the existence of such helical modes can in principle significantly affect the expected conductivity in these materials.

Reference: https://arxiv.org/abs/1809.03518

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