Observation of room-temperature polar skyrmions

S Das^#¹, Y L Tang^#^{2

3}, Z Hong^#⁴, M A P Gonçalves^#⁵, M R McCarter⁶, C Klewe⁷, K X Nguyen⁸, F Gómez-Ortiz⁹, P Shafer⁷, E Arenholz⁷, V A Stoica¹⁰, S-L Hsu^{2

11}, B Wang⁴, C Ophus¹¹, J F Liu¹², C T Nelson¹³, S Saremi², B Prasad², A B Mei¹⁴, D G Schlom^{14

15}, J Íñiguez^{5

16}, P García-Fernández⁹, D A Muller^{15

17}, L Q Chen⁴, J Junquera⁹, L W Martin^{2

3}, R Ramesh^{18

19

20}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. sujitdas@berkeley.edu.
² Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
³ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁴ Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
⁵ Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Esch/Alzette, Luxembourg.
⁶ Department of Physics, University of California, Berkeley, CA, USA.
⁷ Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁸ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
⁹ Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Santander, Spain.
¹⁰ Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA.
¹¹ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
¹² Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
¹³ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
¹⁴ Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA.
¹⁵ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
¹⁶ Physics and Material Science Research Unit, University of Luxembourg, Belvaux, Luxembourg.
¹⁷ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
¹⁸ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. rramesh@berkeley.edu.
¹⁹ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. rramesh@berkeley.edu.
²⁰ Department of Physics, University of California, Berkeley, CA, USA. rramesh@berkeley.edu.

^# Contributed equally.

PMID: 30996320
DOI: 10.1038/s41586-019-1092-8

Free article

Observation of room-temperature polar skyrmions

S Das et al. Nature. 2019 Apr.

Free article

. 2019 Apr;568(7752):368-372.

doi: 10.1038/s41586-019-1092-8. Epub 2019 Apr 17.

Authors

Affiliations

¹ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. sujitdas@berkeley.edu.
² Department of Materials Science and Engineering, University of California, Berkeley, CA, USA.
³ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁴ Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
⁵ Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST), Esch/Alzette, Luxembourg.
⁶ Department of Physics, University of California, Berkeley, CA, USA.
⁷ Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
⁸ Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, USA.
⁹ Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Santander, Spain.
¹⁰ Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, USA.
¹¹ National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
¹² Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
¹³ Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
¹⁴ Department of Materials Science and Engineering, Cornell University, Ithaca, NY, USA.
¹⁵ Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA.
¹⁶ Physics and Material Science Research Unit, University of Luxembourg, Belvaux, Luxembourg.
¹⁷ School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.
¹⁸ Department of Materials Science and Engineering, University of California, Berkeley, CA, USA. rramesh@berkeley.edu.
¹⁹ Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA. rramesh@berkeley.edu.
²⁰ Department of Physics, University of California, Berkeley, CA, USA. rramesh@berkeley.edu.

^# Contributed equally.

PMID: 30996320
DOI: 10.1038/s41586-019-1092-8

Abstract

Complex topological configurations are fertile ground for exploring emergent phenomena and exotic phases in condensed-matter physics. For example, the recent discovery of polarization vortices and their associated complex-phase coexistence and response under applied electric fields in superlattices of (PbTiO₃)_n/(SrTiO₃)_n suggests the presence of a complex, multi-dimensional system capable of interesting physical responses, such as chirality, negative capacitance and large piezo-electric responses^1-3. Here, by varying epitaxial constraints, we discover room-temperature polar-skyrmion bubbles in a lead titanate layer confined by strontium titanate layers, which are imaged by atomic-resolution scanning transmission electron microscopy. Phase-field modelling and second-principles calculations reveal that the polar-skyrmion bubbles have a skyrmion number of +1, and resonant soft-X-ray diffraction experiments show circular dichroism, confirming chirality. Such nanometre-scale polar-skyrmion bubbles are the electric analogues of magnetic skyrmions, and could contribute to the advancement of ferroelectrics towards functionalities incorporating emergent chirality and electrically controllable negative capacitance.

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Comment in

Electrifying skyrmion bubbles.
Zubko P. Zubko P. Nature. 2019 Apr;568(7752):322-323. doi: 10.1038/d41586-019-01139-0. Nature. 2019. PMID: 30996308 No abstract available.

References

1. Yadav, A. K. et al. Observation of polar vortices in oxide superlattices. Nature 530, 198–201 (2016); corrigendum 534, 138 (2016). - DOI
1. Damodaran, A. et al. Phase coexistence and electric-field control of toroidal order in oxide superlattices. Nat. Mater. 16, 1003–1009 (2017). - DOI
1. Shafer, P. et al. Emergent chirality in polar vortex superlattices. Proc. Natl Acad. Sci. USA 115, 915 (2018). - DOI
1. Rößler, U. K., Bogdanov, A. N. & Pfleiderer, C. Spontaneous skyrmion ground states in magnetic metals. Nature 442, 797–801 (2006). - DOI
1. Mühlbauer, S. et al. Skyrmion lattice in a chiral magnet. Science 323, 915–919 (2009). - DOI

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Observation of room-temperature polar skyrmions

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Observation of room-temperature polar skyrmions

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