Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

High-density switchable skyrmion-like polar nanodomains integrated on silicon

Abstract

Topological domains in ferroelectrics1,2,3,4,5 have received much attention recently owing to their novel functionalities and potential applications6,7 in electronic devices. So far, however, such topological polar structures have been observed only in superlattices grown on oxide substrates, which limits their applications in silicon-based electronics. Here we report the realization of room-temperature skyrmion-like polar nanodomains in lead titanate/strontium titanate bilayers transferred onto silicon. Moreover, an external electric field can reversibly switch these nanodomains into the other type of polar texture, which substantially modifies their resistive behaviours. The polar-configuration-modulated resistance is ascribed to the distinct band bending and charge carrier distribution in the core of the two types of polar texture. The integration of high-density (more than 200 gigabits per square inch) switchable skyrmion-like polar nanodomains on silicon may enable non-volatile memory applications using topological polar structures in oxides.

Your institute does not have access to this article

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Fig. 1: High-density polar nanodomains in a PTO20/STO10 bilayer from PFM measurements.
Fig. 2: Polarization mapping of polar nanodomains in a PTO20/STO10 bilayer by vector PFM and 4D STEM.
Fig. 3: Effective Hamiltonian model simulations of skyrmion-like nanodomains in PTO/STO bilayers.
Fig. 4: Resistive behaviours of the polar nanodomains integrated on silicon.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

Code availability

All the code or mathematical algorithm files within this paper are available from the corresponding authors upon reasonable request.

References

  1. Tang, Y. L. et al. Observation of a periodic array of flux-closure quadrants in strained ferroelectric PbTiO3 films. Science 348, 547–551 (2015).

    ADS  CAS  PubMed  Google Scholar 

  2. Yadav, A. K. et al. Observation of polar vortices in oxide superlattices. Nature 530, 198–201 (2016).

    ADS  CAS  PubMed  Google Scholar 

  3. Nahas, Y., Prokhorenko, S., Fischer, J., Xu, B. & Bellaiche, L. Inverse transition of labyrinthine domain patterns in ferroelectric thin films. Nature 577, 47–51 (2020).

    ADS  CAS  PubMed  Google Scholar 

  4. Das, S. et al. Observation of room-temperature polar skyrmions. Nature 568, 368–372 (2019).

    ADS  CAS  PubMed  Google Scholar 

  5. Wang, Y. J. et al. Polar meron lattice in strained oxide ferroelectrics. Nat. Mater. 19, 881–886 (2020).

    ADS  PubMed  Google Scholar 

  6. Seidel, J. et al. Conduction at domain walls in oxide multiferroics. Nat. Mater. 8, 229–234 (2009).

    ADS  CAS  PubMed  Google Scholar 

  7. Zubko, P. et al. Negative capacitance in multidomain ferroelectric superlattices. Nature 534, 524–528 (2016).

    ADS  CAS  PubMed  Google Scholar 

  8. Eliseev, E. A. et al. Labyrinthine domains in ferroelectric nanoparticles: manifestation of a gradient-induced morphological transition. Phys. Rev. B 98, 054101 (2018).

    ADS  CAS  Google Scholar 

  9. Wei, X. K. et al. Neel-like domain walls in ferroelectric Pb(Zr,Ti)O3 single crystals. Nat. Commun. 7, 12385 (2016).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  10. Prokhorenko, S., Nahas, Y. & Bellaiche, L. Fluctuations and topological defects in proper ferroelectric crystals. Phys. Rev. Lett. 118, 147601 (2017).

    ADS  CAS  PubMed  Google Scholar 

  11. Zhang, Q. et al. Nanoscale bubble domains and topological transitions in ultrathin ferroelectric films. Adv. Mater. 29, 1702375 (2017).

    Google Scholar 

  12. Peters, J. J. P., Apachitei, G., Beanland, R., Alexe, M. & Sanchez, A. M. Polarization curling and flux closures in multiferroic tunnel junctions. Nat. Commun. 7, 13484 (2016).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  13. Xu, R., Karthik, J., Damodaran, A. R. & Martin, L. W. Stationary domain wall contribution to enhanced ferroelectric susceptibility. Nat. Commun. 5, 3120 (2014).

    ADS  PubMed  Google Scholar 

  14. Wada, S., Yako, K., Yokoo, K., Kakemoto, H. & Tsurumi, T. Domain wall engineering in barium titanate single crystals for enhanced piezoelectric properties. Ferroelectrics 334, 17–27 (2006).

    CAS  Google Scholar 

  15. Naumov, I. I., Bellaiche, L. & Fu, H. Unusual phase transitions in ferroelectric nanodisks and nanorods. Nature 432, 737–740 (2004).

    ADS  CAS  PubMed  Google Scholar 

  16. Stachiotti, M. G. & Sepliarsky, M. Toroidal ferroelectricity in PbTiO3 nanoparticles. Phys. Rev. Lett. 106, 137601 (2011).

    ADS  CAS  PubMed  Google Scholar 

  17. Lu, D. et al. Synthesis of freestanding single-crystal perovskite films and heterostructures by etching of sacrificial water-soluble layers. Nat. Mater. 15, 1255–1260 (2016).

    ADS  CAS  PubMed  Google Scholar 

  18. Kim, K. E. et al. Configurable topological textures in strain graded ferroelectric nanoplates. Nat. Commun. 9, 403 (2018).

    ADS  PubMed  PubMed Central  Google Scholar 

  19. Kim, J., You, M., Kim, K.-E., Chu, K. & Yang, C.-H. Artificial creation and separation of a single vortex–antivortex pair in a ferroelectric flatland. npj Quantum Mater. 4, 29 (2019).

    ADS  Google Scholar 

  20. Tsuda, K., Yasuhara, A. & Tanaka, M. Two-dimensional mapping of polarizations of rhombohedral nanostructures in the tetragonal phase of BaTiO3 by the combined use of the scanning transmission electron microscopy and convergent-beam electron diffraction methods. Appl. Phys. Lett. 103, 082908 (2013).

    ADS  Google Scholar 

  21. Yadav, A. K. et al. Spatially resolved steady-state negative capacitance. Nature 565, 468–471 (2019).

    ADS  CAS  PubMed  Google Scholar 

  22. Kalinin, S. V. et al. Spatial resolution, information limit, and contrast transfer in piezoresponse force microscopy. Nanotechnology 17, 3400–3411 (2006).

    ADS  CAS  PubMed  Google Scholar 

  23. Tian, L. et al. Nanoscale polarization profile across a 180° ferroelectric domain wall extracted by quantitative piezoelectric force microscopy. J. Appl. Phys. 104, 074110 (2008).

    ADS  Google Scholar 

  24. Lee, D. et al. Emergence of room-temperature ferroelectricity at reduced dimensions. Science 349, 1314–1317 (2015).

    ADS  CAS  PubMed  Google Scholar 

  25. Kim, S. D., Hwang, G. T., Song, K., Chang, K. J. & Choi, S. Y. Inverse size-dependence of piezoelectricity in single BaTiO3 nanoparticles. Nano Energy 58, 78–84 (2019).

    CAS  Google Scholar 

  26. Zhong, W., Vanderbilt, D. & Rabe, K. M. Phase transitions in BaTiO3 from first principles. Phys. Rev. Lett. 73, 1861–1864 (1994).

    ADS  CAS  PubMed  Google Scholar 

  27. Bellaiche, L., Garcia, A. & Vanderbilt, D. Finite-temperature properties of Pb(Zr1−xTix)O3 alloys from first principles. Phys. Rev. Lett. 84, 5427–5430 (2000).

    ADS  CAS  PubMed  Google Scholar 

  28. Mermin, N. D. The topological theory of defects in ordered media. Rev. Mod. Phys. 51, 591–648 (1979).

    ADS  MathSciNet  CAS  Google Scholar 

  29. Prosandeev, S. & Bellaiche, L. Asymmetric screening of the depolarizing field in a ferroelectric thin film. Phys. Rev. B 75, 172109 (2007).

    ADS  Google Scholar 

  30. Nahas, Y. et al. Topology and control of self-assembled domain patterns in low-dimensional ferroelectrics. Nat. Commun. 11, 5779 (2020).

    ADS  CAS  PubMed  PubMed Central  Google Scholar 

  31. Kornev, I., Fu, H. & Bellaiche, L. Ultrathin films of ferroelectric solid solutions under a residual depolarizing field. Phys. Rev. Lett. 93, 196104 (2004).

    ADS  PubMed  Google Scholar 

  32. Hsing, G. H.-C. Strain and Defect Engineering for Tailored Electrical Properties in Perovskite Oxide Thin Films and Superlattices. PhD Thesis, State Univ. New York at Stony Brook (2017).

  33. Edwards, D. et al. Giant resistive switching in mixed phase BiFeO3 via phase population control. Nanoscale 10, 17629 (2018).

    CAS  PubMed  Google Scholar 

  34. Crassous, A., Sluka, T., Tagantsev, A. K. & Setter, N. Polarization charge as a reconfigurable quasi-dopant in ferroelectric thin films. Nat. Nanotechnol. 10, 614–618 (2015).

    ADS  CAS  PubMed  Google Scholar 

  35. Ma, J. et al. Controllable conductive readout in self-assembled, topologically confined ferroelectric domain walls. Nat. Nanotechnol. 13, 947–952 (2018).

    ADS  PubMed  Google Scholar 

  36. Zhang, Q. et al. Deterministic switching of ferroelectric bubble nanodomains. Adv. Funct. Mater. 29, 1808573 (2019).

    Google Scholar 

  37. Li, Z. et al. High-density array of ferroelectric nanodots with robust and reversibly switchable topological domain states. Sci. Adv. 3, e1700919 (2017).

    ADS  PubMed  PubMed Central  Google Scholar 

  38. Ding, L. L. et al. Characterization and control of vortex and antivortex domain defects in quadrilateral ferroelectric nanodots. Phys. Rev. Mater. 3, 104417 (2019).

    CAS  Google Scholar 

  39. Rodriguez, B. J., Callahan, C., Kalinin, S. V. & Proksch, R. Dual-frequency resonance-tracking atomic force microscopy. Nanotechnology 18, 475504 (2007).

    ADS  Google Scholar 

  40. Waghmare, U. V. & Rabe, K. M. Ab initio statistical mechanics of the ferroelectric phase transition in PbTiO3. Phys. Rev. B 55, 6161 (1997).

    ADS  CAS  Google Scholar 

  41. Zhong, W., Vanderbilt, D. & Rabe, K. M. First-principles theory of ferroelectric phase transitions for perovskites: the case of BaTiO3. Phys. Rev. B 52, 6301 (1995).

    ADS  CAS  Google Scholar 

  42. Nishimatsu, T., Grünebohm, A., Waghmare, U. V. & Kubo, M. Molecular dynamics simulations of chemically disordered ferroelectric (Ba,Sr)TiO3 with a semi-empirical effective Hamiltonian. J. Phys. Soc. Jpn 85, 114714 (2016).

    ADS  Google Scholar 

  43. Ponomareva, I., Naumov, I. I., Kornev, I., Fu, H. & Bellaiche, L. Atomistic treatment of depolarizing energy and field in ferroelectric nanostructures. Phys. Rev. B 72, 140102(R) (2005).

    ADS  Google Scholar 

  44. Xu, B. et al. Intrinsic polarization switching mechanisms in BiFeO3. Phys. Rev. B 95, 104104 (2017).

    ADS  Google Scholar 

  45. Prokhorenko, S., Kalke, K., Nahas, Y. & Bellaiche, L. Large scale hybrid Monte Carlo simulations for structure and property prediction. npj Comput. Mater. 4, 80 (2018).

    ADS  Google Scholar 

  46. Manton, N. & Schwarz, N. in Topological Solitons Ch. 3 (eds Manton, N. & Sutcliffe, P.) 506 (Cambridge Univ. Press, 2004).

  47. Nahas, Y. et al. Discovery of stable skyrmionic state in ferroelectric nanocomposites. Nat. Commun. 6, 8542 (2015).

    ADS  CAS  PubMed  Google Scholar 

  48. Berg, B. & Lüscher, M. Definition and statistical distributions of a topological number in the lattice O(3) σ-model. Nucl. Phys. B 190, 412–424 (1981).

    ADS  Google Scholar 

  49. Kiselev, N. S. Experimental observation of chiral magnetic bobbers in B20-type FeGe. Nat. Nanotechnol. 13, 451–455 (2018).

    ADS  PubMed  Google Scholar 

Download references

Acknowledgements

We thank L. Chen for discussions, and H. Huyan at UCI for assisting with the TEM experiments. This work was supported by the National Natural Science Foundation of China (grant numbers 11774153, 11861161004, 51772143, 51725203, 51721001, 11874207 and U1932115), the National Key R&D Program of China (grant numbers 2021YFA1400400 and 2020YFA0711504) and the Fundamental Research Funds for the Central Universities (0213-14380198). Y. Nie is supported by High Level Entrepreneurial and Innovative Talents Introduction, Jiangsu Province; C.A., X.Y. and X.P. acknowledge funding from the Department of Energy (DOE) under grant DE-SC0014430, and the NSF under grant number DMR-2034738. The 4D STEM experiments was conducted using facilities and instrumentation at the UC Irvine Materials Research Institute (IMRI) supported in part by the National Science Foundation through the Materials Research Science and Engineering Center programme (DMR-2011967); Researchers at the University of Arkansas acknowledge DARPA grant number HR0011727183-D18AP00010 (TEE Program), the Vannevar Bush Faculty Fellowship (VBFF) grant number N00014-20-1-2834 from the Department of Defense, and ARO grant number W911NF-21-2-0162 (ETHOS). Computations were made possible thanks to the use of the Arkansas High Performance Computing Center, HPCC resources of Nanjing University and the Arkansas Economic Development Commission. S.C. acknowledges the support of startup grants from the Department of Applied Physics at the Hong Kong Polytechnic University, the General Research Fund (grant number 15306021) from the Hong Kong Research Grant Council, the National Natural Science Foundation of China (grant number 12104381) and the open subject of the National Laboratory of Solid State Microstructures, Nanjing University (M34001).

Author information

Authors and Affiliations

Authors

Contributions

Y. Nie conceived the idea and directed the project with X.P., Y.C. and D.W. L.H. synthesized the samples and characterized the crystalline structure with the help of Y.F., H.L., D.J. and W.G. under the supervision of Y. Nie, X.P. and Z.G. L.H. performed the PFM and CAFM measurements and data analysis with the help of H.F. under the supervision of D.W. and Y. Nie. C.A. performed 4D STEM measurements and data analysis with the help of X.Y. under the supervision of X.P. M.W. performed the selected area electron diffraction and S/TEM measurements with the help of S.C. under the supervision of P.W. and X.P. S.P., Y. Nahas and Y.Y. performed and discussed the effective Hamiltonian model simulations under the supervision of L.B. T.W. helped with the lithography processing. Y. Nie and L.H. wrote the manuscript. All authors discussed the data and contributed to the manuscript.

Corresponding authors

Correspondence to Di Wu, Yuefeng Nie or Xiaoqing Pan.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature thanks Matthew Dawber, Si-Young Choi and Anna Morozovska for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 Growth and transfer of freestanding PTO/STO bilayers.

a, Schematic illustration of the process of heterostructure growth and membrane lift-off. The PTO/STO heterostructure is first grown on TiO2-terminated (001) STO substrates with a SAO water-soluble sacrificial layer (left) and then the bilayer is attached to a supporting polymer and released from the substrate by dissolving away the SAO layer by water (middle). Finally, the bilayer is transferred onto the desired substrate (right). b, The Reflection High Energy Electron Diffraction (RHEED) patterns for as-grown PTO(16 u.c.)/STO(10 u.c.)/SAO(6 u.c.) film on (001) STO substrate. c, Atomic force microscopy characterization of (001) STO substrate (left) and as-grown films (right) showing an atomically smooth surface with unit cell step terraces. Scale bar, 1 µm. d, Low-magnification planar-view HADDF image of the freestanding (PbTiO3)20/(SrTiO3)10 bilayer transferred to a holey carbon TEM grid and selected area electron diffraction (SAED) taken along [001] zone axis (inset), showing the single-crystal structure of the bilayer. Scale bar, 1 µm.

Extended Data Fig. 2 Simulation of vector fields for two distinct divergent domains.

a, Simulation of vector fields for a quad divergent domain. b, Simulation of vector fields for a skyrmion-like bubble domain. c, Calculation of the divergence from vector PFM image.

Extended Data Fig. 3 Direct visualization of topological polar textures by vector piezoelectric force microscope (PFM).

a, Schematic of angle-resolved lateral PFM. In-plane (IP) PFM real part signal was collected experimentally as a function of tip orientation angle φ and then the amplitude and the phase delay were determined by trigonometric curve fitting, i.e. A and θ in Acos(φ-θ+π/2). Piezoresponse vector field can be constructed by finding IP vector components (Acosθ, Asinθ) as a function of position. b, IP piezoresponse vector map for a centre-divergent domain showing the centre-divergent nanodomain. c, The trigonometric curve fitting for four representative points that are denoted as red spots in b.

Extended Data Fig. 4 Characterization of a centre-convergent type nanodomain.

a, Polarization mapping by 4D-STEM. b, The projected electric field calculated from the (000) diffraction peak. c, The projected charge density calculated from the electric field based on Gauss’s law. Scale bar, 5 nm. d, Atomically resolved plane-view HADDF-STEM image of the PTO20/STO10 bilayer. Scale bar, 2 nm. e, The PACBED pattern extracted from the region of the centre-convergent domain shown in ac.

Extended Data Fig. 5 Spatial resolution in PFM.

a, i) SEM image of an unused spherelike PFM tip. Scale bar, 500 nm. ii) The radius r of the contact circle for a weak indentation (h ~ 1–2 nm) is used to characterize the radius r of the tip. Scale bar, 50 nm. b, Electric field distribution at the tip simulated by finite element modelling (FEM). Labels near the curves designate potential values. Scale bar, 10 nm. c, Schematic image of the PFM tip scanning across a nanodomain. The measured size is proportional to the tip radius.

Extended Data Fig. 6 Topological characterization of the centre-divergent domains and interfacial skyrmion-like nanodomain (polar Bobber) obtained computationally (via the effective Hamiltonian).

a, (001)-plane resolved polar structure of the centre divergent domains in the vicinity of the STO/PTO interface. The first, second and third PTO layers counting from the interface are indicated with labels z = 1,2, and 3, respectively. b, The in-plane projected polar structure superimposed with the distribution of the Pontryagin topological charge density. The arrows correspond to the in-plane-projected dipoles coloured according to their out-of-plane component; red and purple colours correspond to [001] and [00–1] oriented dipoles, respectively. c, Dependence of the interpolated polar angle θ between the local dipole and [001] axis on the distance R from the central axis of the domain. d, The dependence of the interpolated Pontryagin charge density \({\rho }_{{Sk}}\) on the distance R from the central axis of the domain. e, The plane-resolved Skyrmion number of a single centre-divergent domain as a function of the distance from the domain centre. f, Schematic illustration of the topology of centre-divergent domains (left). Each z ≥ 2 cross section of the domain reveals a 2D Néel skyrmion-like structure characterized by an integer Skyrmion number. The domain tip at the PTO/STO interface pins an anti-hedgehog-like Bloch point.

Extended Data Fig. 7 Simulated dipolar structure of the centre-convergent domains.

a, The [100]–[001] cross-section of the simulated centre-divergent domain (Néel skyrmion). b, Artificially prepared partially switched dipolar configuration. c, Cross-section of the relaxed dipolar structure of the centre-convergent domain (submerged Néel bubble). d, Above and below the bubble (grey circle), the local dipoles are inclined (yellow arrows) towards and away from the central revolution axis (grey line), respectively. Red (purple) arrows indicate the polarization within (above) the bubble at its axis. e, The in-plane distribution of the thickness-averaged polarization. f, In-plane projection of the thickness averaged polarization.

Extended Data Fig. 8 Thickness dependence of the polar texture in PTOn/STO10 (n = 12, 16, 20) bilayers transferred on silicon and crystal structures of pure freestanding PTO and PTO/STO bilayer.

The surface morphology, in-plane PFM amplitude and phase images of (a) n = 20, (b) n = 16, (c) n = 12 bilayer films. Only the 20 u.c. PTO/10 u.c. STO shows circular shape polar textures. Scale bar, 30 nm. X-ray diffraction 2θ-ω scans around (002) (left) and (101) (right) diffraction peaks for (d) freestanding 20 u.c. PTO film and (e) freestanding (PbTiO3)20/(SrTiO3)10 bilayer. Schematic images showing the crystal structures of (f) freestanding 20 u.c. PTO film and (g) freestanding (PbTiO3)20/(SrTiO3)10 bilayer.

Extended Data Fig. 9 Reversible switching of topological nanodomains.

a, Schematic images illustrating the reversible switching of the topological domains by external electric field: The coexistence of two types of nanodomains in pristine bilayer (i) were first switched into all centre-divergent nanodomains by a scan with +5 V bias voltage (ii) and then further switched to all centre-convergent nanodomains by a scan with −5 V bias voltage (iii). bd, Vertical PFM amplitude (VPFM-amp.), vertical phase (VPFM-pha.), lateral PFM amplitude (LPFM-amp.) and lateral phase (LPFM-pha.) images for three corresponding cases shown in (a). The centre-divergent (centre-convergent) domains are marked by red (blue) circles. Scale bar, 100 nm. e, VPFM-amp. (upper left), VPFM-pha. (bottom left), LPFM-amp. (upper right) and LPFM-pha. (bottom right) images taken under an a.c. amplitude of 500 mV for one single skyrmion-like polar nanodomain after applying the 0 V, −1 V, −4 V, −2 V, +1 V and +4 V DC voltage. Scale bar, 20 nm. f, Hysteresis loop of the skyrmion-like polar nanodomain.

Extended Data Fig. 10 Domain structures and switching behaviour in a PTO/STO bilayer transferred on a P-doped silicon wafer after a standard electron beam lithography process.

a, Schematic images showing standard lithography process on the ferroelectric bilayer transferred on a P-doped silicon wafer. b, Quadrate patterns on a P-doped silicon wafer, inset shows the topography of a single piece. Scale bar, 10 μm. c, Vertical PFM amplitude (VPFM-amp.) and phase (VPFM-pha.), lateral PFM amplitude (LPFM-amp.) and phase (LPFM-pha.) images for the freestanding PTO20/STO10 bilayers transferred on P-doped silicon substrate. Scale bar, 100 nm.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Han, L., Addiego, C., Prokhorenko, S. et al. High-density switchable skyrmion-like polar nanodomains integrated on silicon. Nature 603, 63–67 (2022). https://doi.org/10.1038/s41586-021-04338-w

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-021-04338-w

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing