Converse Flexoelectricity in van der Waals (vdW) Three-Dimensional Topological Insulator Nanoflakes

authored by

Qiong Liu, Srivilliputtur Subbiah Nanthakumar, Bin Li, Teresa Cheng, Florian Bittner, Chenxi Ma, Fei Ding, Lei Zheng, Bernhard Roth, Xiaoying Zhuang

Abstract

Low-dimensional van der Waals (vdW) three-dimensional (3D) topological insulators (TIs) have been overlooked, regarding their electromechanical properties. In this study, we experimentally investigate the electromechanical coupling of low-dimensional 3D TIs with a centrosymmetric crystal structure, where a binary compound, bismuth selenide (Bi₂Se₃), is taken as an example. Piezoresponse force microscopy (PFM) results of Bi₂Se₃ nanoflakes show that the material exhibits both out-of-plane and in-plane electromechanical responses. With careful analyses, the electromechanical responses are verified to arise from the converse flexoelectricity. The Bi₂Se₃ nanoflakes have a decreasing effective out-of-plane piezoelectric coefficient d₃₃^eff with the thickness increasing, with the d₃₃^eff value of ∼0.65 pm V^-1 for the 37 nm-thick sample. The measured effective out-of-plane piezoelectric coefficient is mainly contributed by the flexoelectric coefficient, μ₃₉, which is estimated to be approximately 0.13 nC m^-1. The results can help to understand the flexoelectricity of low-dimensional vdW TIs with centrosymmetric crystal structures, which is crucial for the design of nanoelectromechanical devices and spintronics built by vdW TIs.

Organisation(s)

Faculty of Mathematics and Physics
Institute of Plastics and Circular Economy
Institute of Solid State Physics
Photonics - Optical Analytics, Sensing and Spectroscopy
PhoenixD: Photonics, Optics, and Engineering - Innovation Across Disciplines
Hannover Centre for Optical Technologies (HOT)

External Organisation(s)

Tongji University

Type

Article

Journal

Journal of Physical Chemistry C

Volume

128

Pages

16265-16273

No. of pages

9

ISSN

1932-7447

Publication date

26.09.2024

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Energy(all), Physical and Theoretical Chemistry, Surfaces, Coatings and Films

Electronic version(s)

https://doi.org/10.1021/acs.jpcc.4c05690 (Access: Open)