- Physical Review Journals
All JournalsPhysics Magazine

Physical Review B

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Letter
  • Open Access

Linear dichroic soft x-ray microscopy of ferroelectric stripe domains in epitaxial K0.6Na0.4NbO3

M. Schneider1, T. A. Butcher1,*, S. Wagner1, D. Metternich1,2,3, C. Klose1, E. Malm4, R. Battistelli2,3, V. Deinhart1, J. Fuchs1 et al.

S. Wittrock2, T. Karaman2,3, K. Puzhekadavil Joy2,3, M. Patra2,3, F. Büttner2,3, S. Wintz2, M. Weigand2, C. M. Günther5, D. Engel1, P. Gaal6,7, J. Schwarzkopf6, B. Pfau1, and S. Eisebitt1,8

  • *Contact author: tim.butcher@mbi-berlin.de
PDF

Phys. Rev. B 114, L231401 – Published 2 October, 2026

DOI: https://doi.org/10.1103/kcjc-dtj6

Abstract

Functional properties of ferroelectric thin films are governed by domains that can be engineered by epitaxial strain. Soft x-ray microscopy can image domain structures with elemental and electronic sensitivity, but hitherto its application to strain-stabilized domains has been hindered by the absorption of soft x-rays in epitaxial substrates. Here, it is demonstrated how this limitation can be overcome by locally back-thinning the (110) TbScO3 substrate of epitaxial K0.6Na0.4NbO3 ferroelectric thin films to achieve soft x-ray transparency at the O K-edge around 530 eV. Strain-induced ferroelectric stripe domains with periods down to 44 nm were resolved by scanning transmission x-ray microscopy and coherent diffractive imaging by exploiting the x-ray linear dichroism of hybridized O 2p–Nb 4d states, providing sensitivity to in-plane polarization components under normal incidence. The results establish soft x-ray microscopy for nanoscale imaging of epitaxial ferroelectric domain structures and open perspectives for time-resolved studies thereof.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (62)

  1. J. F. Scott, Applications of modern ferroelectrics, Science 315, 954 (2007).
  2. L. W. Martin and A. M. Rappe, Thin-film ferroelectric materials and their applications, Nat. Rev. Mater. 2, 16087 (2016).
  3. A. Gruverman, M. Alexe, and D. Meier, Piezoresponse force microscopy and nanoferroic phenomena, Nat. Commun. 10, 1661 (2019).
  4. A. J. Pattison, C. C. S. Pedroso, B. E. Cohen, J. C. Ondry, A. P. Alivisatos, W. Theis, and P. Ercius, Advanced techniques in automated high-resolution scanning transmission electron microscopy, Nanotechnology 35, 015710 (2024).
  5. R. Moubah, M. Elzo, S. El Moussaoui, D. Colson, N. Jaouen, R. Belkhou, and M. Viret, Direct imaging of both ferroelectric and antiferromagnetic domains in multiferroic BiFeO3 single crystal using x-ray photoemission electron microscopy, Appl. Phys. Lett. 100, 042406 (2012).
  6. H. Simons, A. King, W. Ludwig, C. Detlefs, W. Pantleon, S. Schmidt, F. Stöhr, I. Snigireva, A. Snigirev, and H. F. Poulsen, Dark-field x-ray microscopy for multiscale structural characterization, Nat. Commun. 6, 6098 (2015).
  7. H. Simons, A. B. Haugen, A. C. Jakobsen, S. Schmidt, F. Stöhr, M. Majkut, C. Detlefs, J. E. Daniels, D. Damjanovic, and H. F. Poulsen, Long-range symmetry breaking in embedded ferroelectrics, Nat. Mater. 17, 814 (2018).
  8. L. von Helden, M. Schmidbauer, S. Liang, M. Hanke, R. Wördenweber, and J. Schwarzkopf, Ferroelectric monoclinic phases in strained K0.70Na0.30NbO3 thin films promoting selective surface acoustic wave propagation, Nanotechnology 29, 415704 (2018).
  9. B. Guzelturk, T. Yang, Y.-C. Liu, C.-C. Wei, G. Orenstein, M. Trigo, T. Zhou, B. T. Diroll, M. V. Holt, H. Wen, L.-Q. Chen, J.-C. Yang, and A. M. Lindenberg, Sub-nanosecond reconfiguration of ferroelectric domains in bismuth ferrite, Adv. Mater. 35, 2306029 (2023).
  10. M. O. Hill Landberg, B. Yan, H. Chen, I. Efe, M. Trassin, and J. Wallentin, Direct imaging of nanoscale ferroelectric domains and polarization reversal in ferroelectric capacitors, Nano Lett. 25, 16304 (2025).
  11. S. O. Hruszkewycz, M. J. Highland, M. V. Holt, D. Kim, C. M. Folkman, C. Thompson, A. Tripathi, G. B. Stephenson, S. Hong, and P. H. Fuoss, Imaging local polarization in ferroelectric thin films by coherent x-ray Bragg projection ptychography, Phys. Rev. Lett. 110, 177601 (2013).
  12. T. A. Butcher, S. Finizio, L. Heller, N. W. Phillips, B. Sarafimov, C. A. F. Vaz, A. Kleibert, B. Watts, M. Holler, and J. Raabe, Soft x-ray ptychography with sophie: Guide and instrumentation, Rev. Sci. Instrum. 96, 123704 (2025).
  13. T. A. Butcher, N. W. Phillips, C.-C. Wei, S.-C. Chang, I. Beinik, K. Thånell, J.-C. Yang, S.-W. Huang, J. Raabe, and S. Finizio, Imaging ferroelectric domains with soft-x-ray ptychography at the oxygen K-edge, Phys. Rev. Appl. 23, L011002 (2025).
  14. H. Jani, J. Harrison, S. Hooda, S. Prakash, P. Nandi, J. Hu, Z. Zeng, J.-C. Lin, C. Godfrey, G. J. Omar, T. A. Butcher, J. Raabe, S. Finizio, A. V.-Y. Thean, A. Ariando, and P. G. Radaelli, Spatially reconfigurable antiferromagnetic states in topologically rich free-standing nanomembranes, Nat. Mater. 23, 619 (2024).
  15. J. Harrison, J. Hu, C. Godfrey, J.-C. Lin, T. A. Butcher, J. Raabe, S. Finizio, H. Jani, and P. G. Radaelli, Room temperature control of axial and basal antiferromagnetic anisotropies using strain, ACS Nano 19, 42118 (2025).
  16. T. A. Butcher, N. W. Phillips, C.-C. Chiu, C.-C. Wei, S.-Z. Ho, Y.-C. Chen, E. Fröjdh, F. Baruffaldi, M. Carulla, J. Zhang, A. Bergamaschi, C. A. F. Vaz, A. Kleibert, S. Finizio, J.-C. Yang, S.-W. Huang, and J. Raabe, Ptychographic nanoscale imaging of the magnetoelectric coupling in freestanding BiFeO3, Adv. Mater. 36, 2311157 (2024).
  17. S. Finizio, T. A. Butcher, M. Cocconcelli, E. Müller, L. J. Riddiford, J. A. Brock, C.-C. Wei, L.-S. Wang, J.-C. Yang, S.-W. Huang, F. Maspero, R. Bertacco, and J. Raabe, In situ straining of epitaxial freestanding ferroic films by a microelectromechanical device, Phys. Rev. B 113, 134408 (2026).
  18. D. Guenzing, D. Y. Sasaki, A. S. Ditter, A. L. Levitan, E. M. Gullikson, S. Dhuey, A. Gashi, H. Ohldag, S. Roy, D. A. Shapiro, R. Comin, and S. A. Morley, Soft x-ray reflection ptychography, Opt. Express 34, 30230 (2026).
  19. Y. Saito, H. Takao, T. Tani, T. Nonoyama, K. Takatori, T. Homma, T. Nagaya, and M. Nakamura, Lead-free piezoceramics, Nature (London) 432, 84 (2004).
  20. Y. Wang, S. Bin Anooz, G. Niu, M. Schmidbauer, L. Wang, W. Ren, and J. Schwarzkopf, Thickness effect on ferroelectric domain formation in compressively strained K0.65Na0.35NbO3 epitaxial films, Phys. Rev. Mater. 6, 084413 (2022).
  21. Y. Wang, S. B. Anooz, G. Niu, J. Zhao, M. Schmidbauer, L. Wang, W. Ren, and J. Schwarzkopf, Evolution of domain structure in epitaxial ferroelectric K0.5Na0.5NbO3 films grown by metal-organic vapor-phase epitaxy, Phys. Rev. Mater. 8, 054409 (2024).
  22. M. de Oliveira Guimaraes, C. Richter, J. Schwarzkopf, M. Engl, S. Slesazeck, and M. Schmidbauer, Ferroelectric switching and temperature-dependent electrical properties of K0.7Na0.3NbO3 capacitor devices, Phys. Rev. Mater. 10, 014413 (2026).
  23. J. Kong, J. Liu, F. Marlton, M. R. V. Jørgensen, and A. Pramanick, Local structural mechanism for phase transition and ferroelectric polarization in the mixed oxide K0.5Na0.5NbO3, Phys. Rev. B 103, 184104 (2021).
  24. L. Douillard, F. Jollet, C. Bellin, M. Gautier, and J. P. Duraud, The electronic structure of KNbO3: An XPS and XAS study, J. Phys.: Condens. Matter 6, 5039 (1994).
  25. J. Purans, A. Kuzmin, P. Parent, and C. Laffone, Study of the electronic structure of rhenium and tungsten oxides on the O K-edge, Ionics 4, 101 (1998).
  26. D. Bach, H. Störmer, R. Schneider, D. Gerthsen, and J. Verbeeck, Eels investigations of different niobium oxide phases, Microsc. Microanal. 12, 416 (2006).
  27. R. Tao, R. Todorovic, J. Liu, R. J. Meyer, A. Arnold, W. Walkosz, P. Zapol, A. Romanenko, L. D. Cooley, and R. F. Klie, Electron energy-loss spectroscopy study of metallic Nb and Nb oxides, J. Appl. Phys. 110, 124313 (2011).
  28. M. J. Olszta, J. Wang, and E. C. Dickey, Stoichiometry and valence measurements of niobium oxides using electron energy-loss spectroscopy, J. Microsc. 224, 233 (2006).
  29. F. Frati, M. O. J. Y. Hunault, and F. M. F. de Groot, Oxygen K-edge x-ray absorption spectra, Chem. Rev. 120, 4056 (2020).
  30. X. Fang, J.-S. Oh, M. Kramer, A. Romanenko, A. Grassellino, J. Zasadzinski, and L. Zhou, Understanding mechanism of performance improvement in nitrogen-doped niobium superconducting radio frequency cavity, Mater. Res. Lett. 11, 108 (2023).
  31. Y. Yoneda, T. Kobayashi, T. Tsuji, D. Matsumura, Y. Saitoh, and Y. Noguchi, Local and electronic structures of NaNbO3, AgNbO3, and KNbO3, Jpn. J. Appl. Phys. 63, 09SP12 (2024).
  32. J. Schwarzkopf, D. Braun, M. Schmidbauer, A. Duk, and R. Wördenweber, Ferroelectric domain structure of anisotropically strained NaNbO3 epitaxial thin films, J. Appl. Phys. 115, 204105 (2014).
  33. J. Schwarzkopf, D. Braun, M. Hanke, A. Kwasniewski, J. Sellmann, and M. Schmidbauer, Monoclinic MA domains in anisotropically strained ferroelectric K0.75Na0.25NbO3 films on (110) TbScO3 grown by MOCVD, J. Appl. Cryst. 49, 375 (2016).
  34. See Supplemental Material at http://link.aps.org/supplemental/10.1103/kcjc-dtj6 for KNN thin film and additional soft x-ray characterization.
  35. M. Fohler, S. Frömmel, M. Schneider, B. Pfau, C. M. Günther, M. Hennecke, E. Guehrs, L. Shemilt, D. Mishra, D. Berger, S. Selve, D. Mitin, M. Albrecht, and S. Eisebitt, A general approach to obtain soft x-ray transparency for thin films grown on bulk substrates, Rev. Sci. Instrum. 88, 103701 (2017).
  36. S. Mayr, S. Finizio, J. Reuteler, S. Stutz, C. Dubs, M. Weigand, A. Hrabec, J. Raabe, and S. Wintz, Xenon plasma focused ion beam milling for obtaining soft x-ray transparent samples, Crystals 11, 546 (2021).
  37. J. Suntivich, W. T. Hong, Y.-L. Lee, J. M. Rondinelli, W. Yang, J. B. Goodenough, B. Dabrowski, J. W. Freeland, and Y. Shao-Horn, Estimating hybridization of transition metal and oxygen states in perovskites from O K-edge X-ray absorption spectroscopy, J. Phys. Chem. C 118, 1856 (2014).
  38. E. Arenholz, G. van der Laan, A. Fraile-Rodríguez, P. Yu, Q. He, and R. Ramesh, Probing ferroelectricity in PbZr0.2Ti0.8O3 with polarized soft x rays, Phys. Rev. B 82, 140103(R) (2010).
  39. P. Shafer, P. García-Fernández, P. Aguado-Puente, A. R. Damodaran, A. K. Yadav, C. T. Nelson, S.-L. Hsu, J. C. Wojdeł, J. Íñiguez, L. W. Martin, E. Arenholz, J. Junquera, and R. Ramesh, Emergent chirality in the electric polarization texture of titanate superlattices, Proc. Natl. Acad. Sci. USA 115, 915 (2018).
  40. S. W. Lovesey and G. van der Laan, Resonant x-ray diffraction from chiral electric-polarization structures, Phys. Rev. B 98, 155410 (2018).
  41. J.-Y. Chauleau, T. Chirac, S. Fusil, V. Garcia, W. Akhtar, J. Tranchida, P. Thibaudeau, I. Gross, C. Blouzon, A. Finco, M. Bibes, B. Dkhil, D. D. Khalyavin, P. Manuel, V. Jacques, N. Jaouen, and M. Viret, Electric and antiferromagnetic chiral textures at multiferroic domain walls, Nat. Mater. 19, 386 (2020).
  42. G. Catalan, B. Noheda, J. McAneney, L. J. Sinnamon, and J. M. Gregg, Strain gradients in epitaxial ferroelectrics, Phys. Rev. B 72, 020102(R) (2005).
  43. D. Sando, M. Han, V. Govinden, O. Paull, F. Appert, C. Carrétéro, J. Fischer, A. Barthélémy, M. Bibes, V. Garcia, S. Fusil, B. Dkhil, J. Juraszek, Y. Zhu, X. Ma, and V. Nagarajan, Interfacial strain gradients control nanoscale domain morphology in epitaxial BiFeO3 multiferroic films, Adv. Funct. Mater. 30, 2000343 (2020).
  44. Y.-H. Chu, Q. He, C.-H. Yang, P. Yu, L. W. Martin, P. Shafer, and R. Ramesh, Nanoscale control of domain architectures in BiFeO3 thin films, Nano Lett. 9, 1726 (2009).
  45. S. Fusil, J.-Y. Chauleau, X. Li, J. Fischer, P. Dufour, C. Léveillé, C. Carrétéro, N. Jaouen, M. Viret, A. Gloter, and V. Garcia, Polar chirality in BiFeO3 emerging from a peculiar domain wall sequence, Adv. Electron. Mater. 8, 2101155 (2022).
  46. R. Battistelli, D. Metternich, M. Schneider, L.-M. Kern, K. Litzius, J. Fuchs, C. Klose, K. Gerlinger, K. Bagschik, C. M. Günther, D. Engel, C. Ropers, S. Eisebitt, B. Pfau, F. Büttner, and S. Zayko, Coherent x-ray magnetic imaging with 5 nm resolution, Optica 11, 234 (2024).
  47. S. Eisebitt, J. Lüning, W. Schlotter, M. Lörgen, O. Hellwig, W. Eberhardt, and J. Stöhr, Lensless imaging of magnetic nanostructures by x-ray spectro-holography, Nature (London) 432, 885 (2004).
  48. C. Klose, F. Büttner, W. Hu, C. Mazzoli, K. Litzius, R. Battistelli, S. Zayko, I. Lemesh, J. M. Bartell, M. Huang, C. M. Günther, M. Schneider, A. Barbour, S. B. Wilkins, G. S. D. Beach, S. Eisebitt, and B. Pfau, Coherent correlation imaging for resolving fluctuating states of matter, Nature (London) 614, 256 (2023).
  49. C. von Korff Schmising, B. Pfau, M. Schneider, C. M. Günther, M. Giovannella, J. Perron, B. Vodungbo, L. Müller, F. Capotondi, E. Pedersoli, N. Mahne, J. Lüning, and S. Eisebitt, Imaging ultrafast demagnetization dynamics after a spatially localized optical excitation, Phys. Rev. Lett. 112, 217203 (2014).
  50. A. S. Johnson, D. Perez-Salinas, K. M. Siddiqui, S. Kim, S. Choi, K. Volckaert, P. E. Majchrzak, S. Ulstrup, N. Agarwal, K. Hallman, R. F. Haglund, C. M. Günther, B. Pfau, S. Eisebitt, D. Backes, F. Maccherozzi, A. Fitzpatrick, S. S. Dhesi, P. Gargiani, M. Valvidares, et al., Ultrafast x-ray imaging of the light-induced phase transition in VO2, Nat. Phys. 19, 215 (2023).
  51. S. Zayko, O. Kfir, M. Heigl, M. Lohmann, M. Sivis, M. Albrecht, and C. Ropers, Ultrafast high-harmonic nanoscopy of magnetization dynamics, Nat. Commun. 12, 6337 (2021).
  52. A. Apseros, V. Scagnoli, M. Holler, M. Guizar-Sicairos, Z. Gao, C. Appel, L. J. Heyderman, C. Donnelly, and J. Ihli, X-ray linear dichroic tomography of crystallographic and topological defects, Nature (London) 636, 354 (2024).
  53. T. A. Butcher, N. W. Phillips, A. L. Levitan, M. Weigand, S. Wintz, J. Raabe, and S. Finizio, Nanoscale domain-wall dynamics in micromagnetic structures with weak perpendicular anisotropy, Phys. Rev. B 111, L220409 (2025).
  54. E. N. Mansbach, R. J. Harrison, T. A. Butcher, S. Finizio, S. Valencia, and T. Ginnis, Resolving the internal magnetic domain structure of cloudy zone tetrataenite, Geophys. Res. Lett. 53, e2026GL122183 (2026).
  55. V. Ukleev, O. I. Utesov, L. Ubilla, C. Luo, R.-M. Abrudan, P. Wild, H. Kropf, M. Winter, S. Schneider, A. Tahn, B. Rellinghaus, T. A. Butcher, S. Finizio, S. Wintz, M. Weigand, M. T. Birch, Y. Tokura, Y. Taguchi, K. Karube, and F. Radu, Vector-field control and emergent basal-plane anisotropy of magnetic textures in noncentrosymmetric (Fe0.63Ni0.3Pd0.07)3P, Adv. Funct. Mater. e77809 (2026).
  56. F. Baruffaldi, A. Bergamaschi, M. Boscardin, M. Brückner, T. A. Butcher, M. Carulla, M. Centis Vignali, R. Dinapoli, S. Finizio, E. Fröjdh, D. Greiffenberg, A. Mozzanica, G. Paternoster, N. W. Philips, J. Raabe, B. Schmitt, and J. Zhang, Single-photon counting pixel detector for soft x-rays, Commun. Phys. 8, 321 (2025).
  57. A. Gruverman, D. Wu, and J. F. Scott, Piezoresponse force microscopy studies of switching behavior of ferroelectric capacitors on a 100-ns time scale, Phys. Rev. Lett. 100, 097601 (2008).
  58. M. Weigand, S. Wintz, J. Gräfe, M. Noske, H. Stoll, B. Van Waeyenberge, and G. Schütz, TimeMaxyne: A shot-noise limited, time-resolved pump-and-probe acquisition system capable of 50 GHz frequencies for synchrotron-based x-ray microscopy, Crystals 12, 1029 (2022).
  59. S. Finizio, J. B. Bailey, B. Olsthoorn, and J. Raabe, Periodogram-based detection of unknown frequencies in time-resolved scanning transmission x-ray microscopy, ACS Nano 16, 21071 (2022).
  60. S. Finizio, T. A. Butcher, S. Wintz, M. Weigand, and J. Raabe, Scanning through space and time: Past, present, and future of time-resolved scanning transmission soft x-ray microscopy, J. Phys. D: Appl. Phys. 59, 383002 (2026).
  61. P. Gaal, D. Schmidt, M. Khosla, C. Richter, P. Boesecke, D. Novikov, M. Schmidbauer, and J. Schwarzkopf, Self-stabilization of the equilibrium state in ferroelectric thin films, Appl. Surf. Sci. 613, 155891 (2023).
  62. M. Schneider, T. A. Butcher, S. Wagner, D. Metternich, C. Klose, E. Malm, R. Battistelli, V. Deinhart, J. Fuchs, S. Wittrock, T. Karaman, K. Puzhekadavil Joy, M. Patra, F. Büttner, S. Wintz, M. Weigand, C. M. Günther, D. Engel, P. Gaal, J. Schwarzkopf, et al., Linear dichroic soft x-ray microscopy of ferroelectric stripe domains in epitaxial K0.6Na0.4NbO3 [Dataset], Zenodo, 2026, https://doi.org/10.5281/zenodo.22250213.

Outline

Information

Phys. Rev. B 114, L231401– Published 2 October, 2026
  • Received 28 March 2026
  • Revised 4 September 2026
  • Accepted 8 September 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation