Pseudospin Polarized Dual-Higher-Order Topology in Hydrogen-Substituted Graphdiyne

Tingfeng Zhang; Tianyi Hu; Yongqi Zhang; Zhengfei Wang

doi:10.1021/acs.nanolett.3c02684

Pseudospin Polarized Dual-Higher-Order Topology in Hydrogen-Substituted Graphdiyne

Nano Lett. 2023 Sep 13;23(17):8319-8325. doi: 10.1021/acs.nanolett.3c02684. Epub 2023 Aug 29.

Authors

Tingfeng Zhang¹, Tianyi Hu¹, Yongqi Zhang¹, Zhengfei Wang^{1

2}

Affiliations

¹ Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
² Hefei National Laboratory, University of Science and Technology of China, Hefei, Anhui 230088, China.

PMID: 37643363
DOI: 10.1021/acs.nanolett.3c02684

Abstract

Although the topological band theory is applicable to both Fermionic and bosonic systems, the same electronic and phononic topological phases are seldom reported in one natural material. In this work, we show the presence of a dual-higher-order topology in hydrogen-substituted graphdiyne (H-GDY) by first-principles calculations. The intriguing enantiomorphic flat-bands are realized in both electronic and phononic bands of H-GDY, which is confirmed to be an organic 2D second-order topological insulator (SOTI). Most importantly, we found that the topological corner states are pseudospin polarized in H-GDY, exhibiting a clockwise or counterclockwise texture perpendicular to the radial direction. Our results not only identify the existence of the dual-higher-order topology in covalent organic frameworks but also uncover a unique pseudospin polarization-coordinate locking relation, further extending the well-known spin-momentum locking relation in conventional topological insulators.

Keywords: dual-higher-order topology; enantiomorphic flat-bands; first-principles calculations; hydrogen-substituted graphdiyne; pseudospin polarization.