Subterahertz collective dynamics of polar vortices

The collective dynamics of topological structures 1 – 6 are of interest from both fundamental and applied perspectives. For example, studies of dynamical properties of magnetic vortices and skyrmions 3 , 4 have not only deepened our understanding of many-body physics but also offered potential appli...

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Published in:Nature (London) Vol. 592; no. 7854; pp. 376 - 380
Main Authors: Li, Qian, Stoica, Vladimir A., Paściak, Marek, Zhu, Yi, Yuan, Yakun, Yang, Tiannan, McCarter, Margaret R., Das, Sujit, Yadav, Ajay K., Park, Suji, Dai, Cheng, Lee, Hyeon Jun, Ahn, Youngjun, Marks, Samuel D., Yu, Shukai, Kadlec, Christelle, Sato, Takahiro, Hoffmann, Matthias C., Chollet, Matthieu, Kozina, Michael E., Nelson, Silke, Zhu, Diling, Walko, Donald A., Lindenberg, Aaron M., Evans, Paul G., Chen, Long-Qing, Ramesh, Ramamoorthy, Martin, Lane W., Gopalan, Venkatraman, Freeland, John W., Hlinka, Jirka, Wen, Haidan
Format: Journal Article
Language:English
Published: London Nature Publishing Group UK 15.04.2021
Nature Publishing Group
Subjects:
639/301/119/996
639/766/119/2792/4129
Data processing
Dynamics
Electric fields
Electron spin
Ferroelectricity
First principles
Freezing
Humanities and Social Sciences
Magnetic properties
MATERIALS SCIENCE
multidisciplinary
Observations
Polar vortex
Polarization
Polarization (Electricity)
Polarization (spin alignment)
Satellites
Science
Science (multidisciplinary)
Topology
Vortices
Vorticity
X-ray diffraction
United States
ISSN:0028-0836, 1476-4687, 1476-4687
Online Access:Get full text
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Summary:The collective dynamics of topological structures 1 – 6 are of interest from both fundamental and applied perspectives. For example, studies of dynamical properties of magnetic vortices and skyrmions 3 , 4 have not only deepened our understanding of many-body physics but also offered potential applications in data processing and storage 7 . Topological structures constructed from electrical polarization, rather than electron spin, have recently been realized in ferroelectric superlattices 5 , 6 , and these are promising for ultrafast electric-field control of topological orders. However, little is known about the dynamics underlying the functionality of such complex extended nanostructures. Here, using terahertz-field excitation and femtosecond X-ray diffraction measurements, we observe ultrafast collective polarization dynamics that are unique to polar vortices, with orders-of-magnitude higher frequencies and smaller lateral size than those of experimentally realized magnetic vortices 3 . A previously unseen tunable mode, hereafter referred to as a vortexon, emerges in the form of transient arrays of nanoscale circular patterns of atomic displacements, which reverse their vorticity on picosecond timescales. Its frequency is considerably reduced (softened) at a critical strain, indicating a condensation (freezing) of structural dynamics. We use first-principles-based atomistic calculations and phase-field modelling to reveal the microscopic atomic arrangements and corroborate the frequencies of the vortex modes. The discovery of subterahertz collective dynamics in polar vortices opens opportunities for electric-field-driven data processing in topological structures with ultrahigh speed and density. A dynamical study shows that vortices of electrical polarization have higher frequencies and smaller size than their magnetic counterparts, properties that are promising for electric-field-driven data processing.
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National Research Foundation of Korea (NRF)
USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
SC0012375; FG02-04ER46147; AC02-05-15CH11231; AC02-06CH11357; AC02-76SF00515; SC0014664; 19-28594X; SC0020145; 2017R1A6A3A11030959; DMR-1720415; 51788104; DMR-1744213
USDOE Office of Science (SC), Basic Energy Sciences (BES)
National Science Foundation (NSF)
National Natural Science Foundation of China (NSFC)
Czech Science Foundation
ISSN:0028-0836
1476-4687
1476-4687
DOI:10.1038/s41586-021-03342-4