1
|
Bake A, Zhang Q, Ho CS, Causer GL, Zhao W, Yue Z, Nguyen A, Akhgar G, Karel J, Mitchell D, Pastuovic Z, Lewis R, Cole JH, Nancarrow M, Valanoor N, Wang X, Cortie D. Top-down patterning of topological surface and edge states using a focused ion beam. Nat Commun 2023; 14:1693. [PMID: 36973266 PMCID: PMC10042877 DOI: 10.1038/s41467-023-37102-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 02/27/2023] [Indexed: 03/29/2023] Open
Abstract
AbstractThe conducting boundary states of topological insulators appear at an interface where the characteristic invariant ℤ2 switches from 1 to 0. These states offer prospects for quantum electronics; however, a method is needed to spatially-control ℤ2 to pattern conducting channels. It is shown that modifying Sb2Te3 single-crystal surfaces with an ion beam switches the topological insulator into an amorphous state exhibiting negligible bulk and surface conductivity. This is attributed to a transition from ℤ2 = 1 → ℤ2 = 0 at a threshold disorder strength. This observation is supported by density functional theory and model Hamiltonian calculations. Here we show that this ion-beam treatment allows for inverse lithography to pattern arrays of topological surfaces, edges and corners which are the building blocks of topological electronics.
Collapse
|
2
|
Xu H, Xi H, Gao YC. Hexagonal Zr 3X (X = Al, Ga, In) Metals: High Dynamic Stability, Nodal Loop, and Perfect Nodal Surface States. Front Chem 2020; 8:608398. [PMID: 33330404 PMCID: PMC7710705 DOI: 10.3389/fchem.2020.608398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Accepted: 09/30/2020] [Indexed: 11/25/2022] Open
Abstract
In recent years, topological semimetals/metals, including nodal point, nodal line, and nodal surface semimetals/metals, have been studied extensively because of their potential applications in spintronics and quantum computers. In this study, we predict a family of materials, Zr3X (X = Al, Ga, In), hosting the nodal loop and nodal surface states in the absence of spin–orbit coupling. Remarkably, the energy variation of the nodal loop and nodal surface states in Zr3X are very small, and these topological signatures lie very close to the Fermi level. When the effect of spin–orbit coupling is considered, the nodal loop and nodal surface states exhibit small energy gaps (<25 and 35 meV, respectively) that are suitable observables that reflect the spin-orbit coupling response of these topological signatures and can be detected in experiments. Moreover, these compounds are dynamically stable, and they consequently form potential material platforms to study nodal loop and nodal surface semimetals.
Collapse
Affiliation(s)
- Heju Xu
- College of Science, North China University of Science and Technology, Tangshan, China
| | - Hailong Xi
- College of Science, North China University of Science and Technology, Tangshan, China
| | - Yong-Chun Gao
- College of Science, North China University of Science and Technology, Tangshan, China
| |
Collapse
|
3
|
Xiao D, Ruan Q, Bao DL, Luo Y, Huang C, Tang S, Shen J, Cheng C, Chu PK. Effects of Ion Energy and Density on the Plasma Etching-Induced Surface Area, Edge Electrical Field, and Multivacancies in MoSe 2 Nanosheets for Enhancement of the Hydrogen Evolution Reaction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2001470. [PMID: 32463594 DOI: 10.1002/smll.202001470] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/24/2020] [Accepted: 04/24/2020] [Indexed: 05/12/2023]
Abstract
Plasma functionalization can increase the efficiency of MoSe2 in the hydrogen evolution reaction (HER) by providing multiple species but the interactions between the plasma and catalyst are not well understood. In this work, the effects of the ion energy and plasma density on the catalytic properties of MoSe2 nanosheets are studied. The through-holes resulting from plasma etching and multi-vacancies induced by plasma-induced damage enhance the HER efficiency as exemplified by a small overpotential of 148 mV at 10 mA cm-2 and Tafel slope of 51.6 mV dec-1 after the plasma treatment using a power of 20 W. The interactions between the plasma and catalyst during etching and vacancies generation are evaluated by plasma simulation. Finite element and first-principles density functional theory calculations are also conducted and the results are consistent with the experimental results, indicating that the improved HER catalytic activity stems from the enhanced electric field and more active sites on the catalyst, and reduced bandgap and adsorption energy arising from the etched through-holes and vacancies, respectively. The results convey new fundamental knowledge about the plasma effects and means to enhance the efficiency of catalysts in water splitting as well insights into the design of high-performance HER catalysts.
Collapse
Affiliation(s)
- Dezhi Xiao
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Qingdong Ruan
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - De-Liang Bao
- Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, 37235, USA
- Institute of Physics and University of the Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yang Luo
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Chao Huang
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Siying Tang
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| | - Jie Shen
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, China
| | - Cheng Cheng
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031, China
| | - Paul K Chu
- Department of Physics, Department of Materials Science and Engineering, and Department of Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, 999077, China
| |
Collapse
|