A second-order topological insulator (SOTI) in d spatial dimensions features topologically protected gapless states at its (d-2)-dimensional boundary at the intersection of two crystal faces, but is gapped otherwise. As a novel topological state, it has been attracting great interest, but it remains a challenge to identify a realistic SOTI material in two dimensions (2D). Here, based on combined first-principles calculations and theoretical analysis, we reveal the already experimentally synthesized 2D material graphdiyne as the first realistic example of a 2D SOTI, with topologically protected 0D corner states. The role of crystalline symmetry, the robustness against symmetry breaking, and the possible experimental characterization are discussed. Our results uncover a hidden topological character of graphdiyne and promote it as a concrete material platform for exploring the intriguing physics of higher-order topological phases.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1103/PhysRevLett.123.256402 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Prediction and observation of topological modes in fractal nonlinear optics.
Light Sci Appl
January 2025
Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, and Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel.
This item from the News and Views (N&V) category aims to provide a summary of theoretical and experimental results recently published in ref. , which demonstrates the creation of corner modes in nonlinear optical waveguides of the higher-order topological insulator (HOTI) type. Actually, these are second-order HOTIs, in which the transverse dimension of the topologically protected edge modes is smaller than the bulk dimension (it is 2, in the case of optical waveguide) by 2, implying zero dimension of the protected modes, which are actually realized as corner or defect ones.
View Article and Find Full Text PDFThermodynamic Perturbation Theory for Charged Branched Polymers.
J Chem Theory Comput
December 2024
Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry Chinese Academy of Sciences, Beijing 100190, PR China.
Classical density functional theory (DFT) provides a versatile framework to study the polymers with complex topological structure. Generally, a classical DFT describes the excess Helmholtz free energy of nonbonded chain connectivity due to excluded-volume effects and electrostatic correlations using the first-order thermodynamic perturbation theory (referred to as DFT-TPT1). Beyond first-order perturbation, the second-order TPT (TPT2) captures not only the correlations between neighboring monomers but also the interactions within three consecutive monomers, playing a crucial role in describing the polymer topology.
View Article and Find Full Text PDFDisorder-induced phase transitions in a two-dimensional magnetic topological insulator system.
J Phys Condens Matter
December 2024
School of Physics and Technology, University of Jinan, Jinan, Shandong 250022, People's Republic of China.
We investigate the phase diagram of a two-dimensional magnetic topological system in the parameter space of uncorrelated Anderson disorder and Zeeman splitting energy. In the absence of disorder, the system undergoes the phases of higher-order topological insulators (HOTIs), Chern insulators (CIs) with Chern numbers = 2 and = 1, and band insulators successively with enhancing Zeeman energy. The phase boundary separating these phases is found to be strongly deformed by the disorder, which leads to several topological Anderson insulators.
View Article and Find Full Text PDFAn On-Chip Second-Order Elastic Topological Insulator for Demultiplexing Out-of-Plane and In-Plane Corner Modes.
Adv Sci (Weinh)
December 2024
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, 999077, China.
Second-order elastic topological insulators (SETIs) with tightly localized corner states present a promising avenue for manipulating elastic waves in lower dimensions. However, existing SETIs typically support corner states of only a single mode, either out-of-plane or in-plane. In this work, an on-chip SETI that simultaneously hosts both high-frequency out-of-plane and in-plane corner states at ≈0.
View Article and Find Full Text PDFMeasuring topological invariants for higher-order exceptional points in quantum three-mode systems.
Nat Commun
November 2024
Fujian Key Laboratory of Quantum Information and Quantum Optics, College of Physics and Information Engineering, Fuzhou University, Fuzhou, China.
Owing to the presence of exceptional points (EPs), non-Hermitian (NH) systems can display intriguing topological phenomena without Hermitian analogs. However, experimental characterizations of exceptional topological invariants have been restricted to second-order EPs (EP2s) in classical or semiclassical systems. We here propose an NH multi-mode system with higher-order EPs, each of which is underlain by a multifold-degenerate multipartite entangled eigenstate.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!