Ferroelectric solitons crafted in epitaxial bismuth ferrite superlattices

Vivasha Govinden; Peiran Tong; Xiangwei Guo; Qi Zhang; Sukriti Mantri; Mohammad Moein Seyfouri; Sergei Prokhorenko; Yousra Nahas; Yongjun Wu; Laurent Bellaiche; Tulai Sun; He Tian; Zijian Hong; Nagarajan Valanoor; Daniel Sando

doi:10.1038/s41467-023-39841-3

Ferroelectric solitons crafted in epitaxial bismuth ferrite superlattices

Nat Commun. 2023 Jul 13;14(1):4178. doi: 10.1038/s41467-023-39841-3.

Authors

Vivasha Govinden^#¹, Peiran Tong^#², Xiangwei Guo^#^{3

4

5}, Qi Zhang¹, Sukriti Mantri⁶, Mohammad Moein Seyfouri^{1

7}, Sergei Prokhorenko⁶, Yousra Nahas⁶, Yongjun Wu^{3

5}, Laurent Bellaiche⁶, Tulai Sun^{2

8}, He Tian^{9

10}, Zijian Hong^{11

12}, Nagarajan Valanoor¹³, Daniel Sando^{14

15}

Affiliations

¹ School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia.
² Center of Electron Microscopy, School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China.
³ School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China.
⁴ Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, Hangzhou Innovation Center, Zhejiang University, Hangzhou, Zhejiang, China.
⁵ Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China.
⁶ Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA.
⁷ Solid State and Elemental Analysis Unit, Mark Wainwright Analytical Center, University of New South Wales, Sydney, NSW, Australia.
⁸ Center for Electron Microscopy, State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology and College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang, China.
⁹ Center of Electron Microscopy, School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China. hetian@zju.edu.cn.
¹⁰ School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, Henan, China. hetian@zju.edu.cn.
¹¹ School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China. hongzijian100@zju.edu.cn.
¹² Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China. hongzijian100@zju.edu.cn.
¹³ School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia. nagarajan@unsw.edu.au.
¹⁴ School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia. daniel.sando@canterbury.ac.nz.
¹⁵ School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand. daniel.sando@canterbury.ac.nz.

^# Contributed equally.

Abstract

In ferroelectrics, complex interactions among various degrees of freedom enable the condensation of topologically protected polarization textures. Known as ferroelectric solitons, these particle-like structures represent a new class of materials with promise for beyond-CMOS technologies due to their ultrafine size and sensitivity to external stimuli. Such polarization textures have scarcely been demonstrated in multiferroics. Here, we present evidence for ferroelectric solitons in (BiFeO₃)/(SrTiO₃) superlattices. High-resolution piezoresponse force microscopy and Cs-corrected high-angle annular dark-field scanning transmission electron microscopy reveal a zoo of topologies, and polarization displacement mapping of planar specimens reveals center-convergent/divergent topological defects as small as 3 nm. Phase-field simulations verify that some of these structures can be classed as bimerons with a topological charge of ±1, and first-principles-based effective Hamiltonian computations show that the coexistence of such structures can lead to non-integer topological charges, a first observation in a BiFeO₃-based system. Our results open new opportunities in multiferroic topotronics.

MeSH terms

Bismuth*
Microscopy, Atomic Force
Technology*

Substances

ferrite
Bismuth