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Local negative permittivity and topological-phase transition in polar skyrmions
Published
Author(s)
Sujit Das, Zijian Hong, Vladimir Stoica, Mauro A. Goncalves, Yu-Tsun Shao, Eric Parsonnet, Eric J. Marksz, Sahar Saremi, Margaret McCarter, A Reynoso, Chris Long, Aaron Hagerstrom, D Meyers, V Ravi, B Prasad, H Zhou, Z Zhang, H Wen, F Gomez-Ortiz, P Garcia-Fernandez, J Bokor, J Iniguez, J Freeland, Nate Orloff, J Junquera, Long-Qing Chen, Sayeef Salahuddin, David A. Muller, L Martin, R. Ramesh
Abstract
Topological solitons such as magnetic skyrmions have drawn enormous attention as stable quasi- particle-like objects. The recent discovery of polar vortices and skyrmions in ferroelectric- oxide superlattices, exhibiting exotic physical phenomena, has opened up new vistas to explore topology, emergent phenomena, and approaches for manipulating such features with electric fields. , Using macroscopic dielectric measurements, coupled with direct scanning convergent- beam electron diffraction (SCBED) imaging of the local polarization and electric-field profiles at the atomic scale, theoretical phase-field simulations, and second-principles calculations, we demonstrate that polar skyrmions in (PbTiO3)n/(SrTiO3)n superlattices are distinguished by a sheath of negative permittivity at the periphery of each skyrmion. This enables a strong enhancement of the effective dielectric permittivity as compared to individual SrTiO3 and PbTiO3 layers. Moreover, the response of these topologically protected structures to electric field and temperature reveal a reversible phase transition from a topologically protected skyrmion state (with a topological charge of +1) to a trivial uniform ferroelectric state (topological charge of 0), accompanied by a large tunability of the dielectric permittivity. Pulsed-switching measurements show a time-dependent evolution and recovery of the skyrmion state (and the macroscopic dielectric response). The interrelationship between the topological and the dielectric properties presents a unique opportunity to simultaneously manipulate both of both of them by a single, and easily controlled, stimulus, the applied electric field.
Das, S.
, Hong, Z.
, Stoica, V.
, Goncalves, M.
, Shao, Y.
, Parsonnet, E.
, Marksz, E.
, Saremi, S.
, McCarter, M.
, Reynoso, A.
, Long, C.
, Hagerstrom, A.
, Meyers, D.
, Ravi, V.
, Prasad, B.
, Zhou, H.
, Zhang, Z.
, Wen, H.
, Gomez-Ortiz, F.
, Garcia-Fernandez, P.
, Bokor, J.
, Iniguez, J.
, Freeland, J.
, Orloff, N.
, Junquera, J.
, Chen, L.
, Salahuddin, S.
, Muller, D.
, Martin, L.
and Ramesh, R.
(2020),
Local negative permittivity and topological-phase transition in polar skyrmions, Nature Materials, [online], https://doi.org/10.1038/s41563-020-00818-y
(Accessed October 7, 2025)