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Hu L, Huang Y, Wu Y, Hong Z. Quantifying the polar skyrmion motion barrier in an oxide heterostructure. NANOSCALE 2024; 17:533-539. [PMID: 39569649 DOI: 10.1039/d4nr03686g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2024]
Abstract
Exotic polar topologies such as polar skyrmions have been widely observed in ferroelectric superlattice systems. The dynamic motion of polar skyrmions under external forces holds promise for applications in advanced electronic devices such as race-track memory. Meanwhile, the polar skyrmion motion has proven to be challenging due to the strong skyrmion-skyrmion interaction and a lack of a mechanism similar to the spin-transfer torque. In this study, we have developed a nudged elastic band (NEB) method to quantify the polar skyrmion motion barrier along a specific trajectory. It is indicated that the skyrmion motion barrier can be significantly reduced with the reduction of the periodicity to 8 uc, due to the large reduction of the skyrmion size. Moreover, this barrier can also be greatly reduced with a small external electric potential. Following the analysis, we further performed phase-field simulation to verify the collective motion of the polar skyrmion. We have demonstrated the collective skyrmion motion by applying a 5 μN mechanical force using a blade-shaped indenter with a periodicity of 8 unit cells, under an external applied voltage of 1.5 V. This study further paves the way for the design of polar skyrmion-based electronic devices.
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Affiliation(s)
- Lizhe Hu
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Yuhui Huang
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| | - Yongjun Wu
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China.
- Zhejiang Key Laboratory of Advanced Solid State Energy Storage Technology and Applications, Taizhou Institute of Zhejiang University, Taizhou, Zhejiang 318000, China
| | - Zijian Hong
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310058, China.
- Zhejiang Key Laboratory of Advanced Solid State Energy Storage Technology and Applications, Taizhou Institute of Zhejiang University, Taizhou, Zhejiang 318000, China
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Hu L, Wu Y, Huang Y, Tian H, Hong Z. Dynamic Motion of Polar Skyrmions in Oxide Heterostructures. NANO LETTERS 2023. [PMID: 38048141 DOI: 10.1021/acs.nanolett.3c04021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Polar skyrmions have been widely investigated in oxide heterostructures due to their exotic properties and intriguing physical insights. However, the field-driven motion of polar skyrmions, akin to that of the magnetic counterpart, remains elusive. Herein, using phase-field simulations, we demonstrate the dynamic motion of polar skyrmions with integrated external thermal, electrical, and mechanical stimuli. External heating reduced the spontaneous polarization, while an applied electric field decreased the skyrmion size and weakened the interactions between the skyrmions. Together, the skyrmion motion barrier is significantly reduced from 40 to 2 eV under 9 V at 500 K. An applied mechanical force transformed the skyrmions into a c-domain region near the indenter center under the electric field, providing the space and driving force needed for the motion of the skyrmions. This study confirms that polar skyrmions can move like particles and provides concrete design principles for polar skyrmion-based electronic devices.
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Affiliation(s)
- Lizhe Hu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Yongjun Wu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, Zhejiang University, Hangzhou 310027, China
| | - Yuhui Huang
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - He Tian
- Center of Electron Microscopy, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Zijian Hong
- School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
- State Key Laboratory of Silicon and Advanced Semiconductor Materials, Zhejiang University, Hangzhou 310027, China
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Luo W, Akbarzadeh A, Nahas Y, Prokhorenko S, Bellaiche L. Quantum criticality at cryogenic melting of polar bubble lattices. Nat Commun 2023; 14:7874. [PMID: 38036499 PMCID: PMC10689468 DOI: 10.1038/s41467-023-43598-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 11/13/2023] [Indexed: 12/02/2023] Open
Abstract
Quantum fluctuations (QFs) caused by zero-point phonon vibrations (ZPPVs) are known to prevent the occurrence of polar phases in bulk incipient ferroelectrics down to 0 K. On the other hand, little is known about the effects of QFs on the recently discovered topological patterns in ferroelectric nanostructures. Here, by using an atomistic effective Hamiltonian within classical Monte Carlo (CMC) and path integral quantum Monte Carlo (PI-QMC), we unveil how QFs affect the topology of several dipolar phases in ultrathin Pb(Zr0.4Ti0.6)O3 (PZT) films. In particular, our PI-QMC simulations show that the ZPPVs do not suppress polar patterns but rather stabilize the labyrinth, bimeron and bubble phases within a wider range of bias field magnitudes. Moreover, we reveal that quantum fluctuations induce a quantum critical point (QCP) separating a hexagonal bubble lattice from a liquid-like state characterized by spontaneous motion, creation and annihilation of polar bubbles at cryogenic temperatures. Finally, we show that the discovered quantum melting is associated with anomalous physical response, as, e.g., demonstrated by a negative longitudinal piezoelectric coefficient.
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Affiliation(s)
- Wei Luo
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Alireza Akbarzadeh
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
- Science, Engineering, and Geosciences, Lonestar College, 9191 Barker Cypress Road, Cypress, TX, 77433, USA
| | - Yousra Nahas
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Sergei Prokhorenko
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, 72701, USA.
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Govinden V, Tong P, Guo X, Zhang Q, Mantri S, Seyfouri MM, Prokhorenko S, Nahas Y, Wu Y, Bellaiche L, Sun T, Tian H, Hong Z, Valanoor N, Sando D. Ferroelectric solitons crafted in epitaxial bismuth ferrite superlattices. Nat Commun 2023; 14:4178. [PMID: 37443322 DOI: 10.1038/s41467-023-39841-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 06/29/2023] [Indexed: 07/15/2023] Open
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.
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Affiliation(s)
- Vivasha Govinden
- School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia
| | - Peiran Tong
- Center of Electron Microscopy, School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiangwei Guo
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China
- Institute of Advanced Semiconductors & Zhejiang Provincial Key Laboratory of Power Semiconductor Materials and Devices, Hangzhou Innovation Center, Zhejiang University, Hangzhou, Zhejiang, China
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qi Zhang
- School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia
| | - Sukriti Mantri
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Mohammad Moein Seyfouri
- School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia
- Solid State and Elemental Analysis Unit, Mark Wainwright Analytical Center, University of New South Wales, Sydney, NSW, Australia
| | - Sergei Prokhorenko
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Yousra Nahas
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Yongjun Wu
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Tulai Sun
- Center of Electron Microscopy, School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China
- 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
| | - He Tian
- Center of Electron Microscopy, School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China.
- School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, Henan, China.
| | - Zijian Hong
- School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China.
- Cyrus Tang Center for Sensor Materials and Applications, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, Zhejiang, China.
| | - Nagarajan Valanoor
- School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia.
| | - Daniel Sando
- School of Materials Science and Engineering, University of New South Wales Sydney, Kensington, NSW, Australia.
- School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand.
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Gong FH, Tang YL, Wang YJ, Chen YT, Wu B, Yang LX, Zhu YL, Ma XL. Absence of critical thickness for polar skyrmions with breaking the Kittel's law. Nat Commun 2023; 14:3376. [PMID: 37291226 PMCID: PMC10250330 DOI: 10.1038/s41467-023-39169-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 05/31/2023] [Indexed: 06/10/2023] Open
Abstract
The period of polar domain (d) in ferroics was commonly believed to scale with corresponding film thicknesses (h), following the classical Kittel's law of d ∝ [Formula: see text]. Here, we have not only observed that this relationship fails in the case of polar skyrmions, where the period shrinks nearly to a constant value, or even experiences a slight increase, but also discovered that skyrmions have further persisted in [(PbTiO3)2/(SrTiO3)2]10 ultrathin superlattices. Both experimental and theoretical results indicate that the skyrmion periods (d) and PbTiO3 layer thicknesses in superlattice (h) obey the hyperbolic function of d = Ah + [Formula: see text] other than previous believed, simple square root law. Phase-field analysis indicates that the relationship originates from the different energy competitions of the superlattices with PbTiO3 layer thicknesses. This work exemplified the critical size problems faced by nanoscale ferroelectric device designing in the post-Moore era.
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Affiliation(s)
- Feng-Hui Gong
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
- School of Materials Science and Engineering, University of Science and Technology of China, Wenhua Road 72, Shenyang, 110016, China
| | - Yun-Long Tang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
| | - Yu-Jia Wang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
| | - Yu-Ting Chen
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
- School of Materials Science and Engineering, University of Science and Technology of China, Wenhua Road 72, Shenyang, 110016, China
| | - Bo Wu
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China
| | - Li-Xin Yang
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China
| | - Yin-Lian Zhu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China.
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China.
| | - Xiu-Liang Ma
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, Shenyang, 110016, China.
- Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China.
- Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
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