Subterahertz collective dynamics of polar vortices

Abstract

The collective dynamics of topological structures have been of great interest from both fundamental and applied perspectives. For example, the studies of dynamical properties of magnetic vortices and skyrmions not only deepened the understanding of many-body physics but also led to potential applications in data processing and storage. Topological structures constructed from electrical polarization rather than spin have recently been realized in ferroelectric superlattices, promising for ultrafast electric-field control of topological orders. However, little is known about the dynamics of such complex extended nanostructures which in turn underlies their functionalities. 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. A previously unseen soft mode, hereafter referred to as a vortexon, emerges as transient arrays of nanoscale circular patterns of atomic displacements, which reverse their vorticity on picosecond time scales. Its frequency is significantly reduced at a critical strain, indicating a condensation of structural dynamics. First-principles-based atomistic calculations and phase-field modeling reveal the microscopic atomic arrangements and frequencies of the vortex modes. The discovery of subterahertz collective dynamics in polar vortices opens up opportunities for applications of electric-field driven data processing in topological structures with ultrahigh speed and density.

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• Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO${}_3$
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Cited by in corpus (20)

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• Field-driven skyrmion motion through velocity equipartition between skyrmions and a domain wall
• Superorders and acoustic modes folding in BiFeO${}_3$/LaFeO${}_3$ superlattices
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• Intrinsic Dipole Hall effect in twisted MoTe${}_2$: magnetoelectricity and contact-free signatures of topological transitions
• Unconventional superconducting diode effects via antisymmetry and antisymmetry breaking
• Terahertz-field activation of polar skyrons
• Theory of nonlinear terahertz susceptibility in ferroelectrics
• Inhomogeneous Electric Fields for Precise Control and Displacement of Polar Textures
• Theory of terahertz pulse transmission through ferroelectric nanomembranes
• A simple method to find temporal overlap between THz and X-ray pulses using X-ray-induced carrier dynamics in semiconductors
• Theory of Polar Skyrmions in Layered Structure of Ferroelectric Perovskites
• Strong coupling between coherent ferrons and cavity acoustic phonons