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Non-Hermitian dislocation modes: Stability and melting across exceptional points

Panigrahi, A and Moessner, R and Roy, B (2022) Non-Hermitian dislocation modes: Stability and melting across exceptional points. In: Physical Review B, 106 (4).

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Official URL: https://doi.org/10.1103/PhysRevB.106.L041302


The traditional bulk-boundary correspondence assuring robust gapless modes at the edges and surfaces of insulating and nodal topological materials gets masked in non-Hermitian (NH) systems by the skin effect, manifesting an accumulation of a macroscopic number of states near such interfaces. Here we show that dislocation lattice defects are immune to such skin effect or at most display a weak skin effect (depending on its relative orientation with the Burgers vector), and as such they support robust topological modes in the bulk of a NH system, specifically when the parent Hermitian phase features band inversion at a finite momentum. However, the dislocation modes gradually lose their support at their core when the system approaches an exceptional point, and finally melt into the boundary of the system across the NH band gap closing. We explicitly demonstrate these findings for a two-dimensional NH Chern insulator, thereby establishing that dislocation lattice defects can be instrumental to experimentally probe pristine NH topology.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright for this article belongs to the Authors.
Keywords: Crystal defects; Energy gap; Interface states; Skin effect, Band inversion; Burger vectors; Exceptional points; Feature bands; Finite momentum; Hermitians; Number of state; Phase features; Relative orientation; Topological materials, Topology
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 10 Aug 2022 05:46
Last Modified: 10 Aug 2022 05:46
URI: https://eprints.iisc.ac.in/id/eprint/75779

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