Helical topological edge states in a quadrupole phase

Liu, Feng, Deng, Hai-Yao ORCID: https://orcid.org/0000-0001-6065-483X and Wakabayashi, Katsunori 2019. Helical topological edge states in a quadrupole phase. Physical Review Letters 122 (8) , 086804. 10.1103/PhysRevLett.122.086804

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Abstract

A topological electric quadrupole is a recently proposed concept that extends the theory of electric polarization of crystals to higher orders. Such a quadrupole phase supports topological states localized on both edges and corners. In this work, we show that in a quadrupole phase of a honeycomb lattice, topological helical edge states and pseudospin-polarized corner states appear by making use of a pseudospin degree of freedom related to point group symmetry. Furthermore, we argue that a general condition for the emergence of helical edge states in a (pseudo)spinful quadrupole phase is the existence of either mirror or time-reversal symmetry. Our results offer a way of generating topological helical edge states without spin-orbital couplings.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	0031-9007
Date of First Compliant Deposit:	20 January 2020
Last Modified:	04 May 2023 04:08
URI:	https://orca.cardiff.ac.uk/id/eprint/128132

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