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ABSTRACT The deterministic creation and modification of domain walls in ferroelectric films have attracted broad interest due to their unprecedented potential as the active element in

non-volatile memory, logic computation and energy-harvesting technologies. However, the correlation between charged and antiphase states, and their hybridization into a single domain wall

still remain elusive. Here we demonstrate the facile fabrication of antiphase boundaries in BiFeO3 thin films using a He-ion implantation process. Cross-sectional electron microscopy,

spectroscopy and piezoresponse force measurement reveal the creation of a continuous in-plane charged antiphase boundaries around the implanted depth and a variety of atomic bonding

configurations at the antiphase interface, showing the atomically sharp 180° polarization reversal across the boundary. Therefore, this work not only inspires a domain-wall fabrication

strategy using He-ion implantation, which is compatible with the wafer-scale patterning, but also provides atomic-scale structural insights for its future utilization in domain-wall

nanoelectronics. SIMILAR CONTENT BEING VIEWED BY OTHERS IN-PLANE CHARGED DOMAIN WALLS WITH MEMRISTIVE BEHAVIOUR IN A FERROELECTRIC FILM Article 18 January 2023 GIANT SWITCHABLE NON

THERMALLY-ACTIVATED CONDUCTION IN 180° DOMAIN WALLS IN TETRAGONAL PB(ZR,TI)O3 Article Open access 24 November 2022 FERROELECTRIC DOMAIN WALL MEMORY WITH EMBEDDED SELECTOR REALIZED IN LINBO3

SINGLE CRYSTALS INTEGRATED ON SI WAFERS Article 15 June 2020 INTRODUCTION In comparison to the three-dimensional domains in ferroelectric thin films, the two-dimensional domain walls or

boundaries, which separate domains of distinct crystallographic and electronic features, typically have the reduced dimensionality of only a few atomic layers. These domain walls possess

broken local symmetry and perturbed chemical environments, rendering them with promising aspects for nanoelectronics and nano-optoelectronics1,2,3,4,5,6,7,8. A wealth of physico-chemical

properties have been discovered in ferroelectric domain walls, including domain-wall conductivity9,10,11,12,13,14,15, unconventional magnetism16, optical response17,18, giant

electromechanical19 and thermotropic behaviors20. These domain walls can be categorized as either electrically neutral or charged by the net bound charge accumulated from the normal

polarization of neighboring domains21. Specifically, the spontaneous polarization in ferroelectric materials here is defined as the dipole vector drawing from the negative to positive

centers of each unit cell (u.c.), and thus in general a domain wall in the head-to-head (or tail-to-tail) state tends to be positively (or negatively) charged, while the defect types

accumulating around may affect the charge states. In ferroelectric thin films with out-of-plane polarization, it is normal to observe the neutral domain wall elongating along the

polarization direction, while a charged domain wall extending perpendicular to the film polarization direction is barely found in as-grown films (although examples exist in capacitor

geometries22), because of the energetically unfavored larger area-to-body ratio and the extra electrostatic energy built up by charging. However, such in-plane charged domain walls are

appealing by their non-trivial charged properties and functionalities of more viable controllability, which are unavailable by out-of-plane domain walls, such as the ferroelectric tunnel

junction displaying discrete quantum-well energy levels23. Recently, Liu et al. also fabricated the smallest memristor of multiple resistance states facilitated by the layer-by-layer

migration of single in-plane charged domain wall in a 4 u.c. BiFeO3 (BFO) film24. Such fascinating quasi-two-dimensional nature of in-plane charged domain walls, in regardless of the film

thickness, may enable the design of the electronic circuitry at a sub-nano scale. On the other hand, the domain walls in ferroelectric thin films can be distinguished in respect of their

crystallographic geometries, such as antiphase25,26 and twin27 boundaries. In contrast to the twin boundaries involving a reflection of neighboring lattices, the antiphase boundaries feature

a planar defect by translating half-unit-cell of atomic registry in reference to the adjacent domain. In addition to the competing effects (either serving as nucleation sites28 or promoting

the retention failure29) of antiphase boundaries during the BFO domain switching, they also play critical roles in the anomalous magnetoresistance of Fe3O430 and the antiferromagnetic

coupling of NiFe2O431. Since BFO holds robust magnetoelectric coupling above the room temperature, the hybridization of both in-plane charged (i.e., electrically switchable) and antiphase

characteristics into a single-domain wall seems a charming idea and may pave way to the possibility of controlling magnetism with electric field at room temperature32,33. However, the

realization and integration of such in-plane charged antiphase boundary (IP-CAPB) in ferroelectric films has been rather challenging and, to our best knowledge, not reported yet. Since the

antiphase boundary physically requires the half-unit-cell shift of atomic registry across the boundary, its generation poses tough conditions on the technique to be used. As a technique of

tunable energy range, being compatible with the large-scale patterning and reversible by thermal annealing34, the He-ion implantation treatment has been widely applied to a multitude of

materials to engineer their microscopic structure and apparent properties to high precision. For example, the negatively charged boron vacancy (\({V}_{B}^{-}\)) spin defects in hexagonal

boron nitride was synthesized by the He-ion implantation to facilitate the coherent control of nitrogen nuclear spins at room temperature35. It has also been developed for ferroelectric

films to produce the single-domain super-tetragonal phase in BFO36 and to triple the energy storage density in PbZrO3 by breaking film polarization into polar nanoregions37, though its

implementation in the domain-wall generation remains largely unexplored. In this paper, we report the facile construction of a spatially continuous IP-CAPB in the BFO thin film using a

He-ion implantation technique. The ferroelectric-domain-modification effect of He implantation is demonstrated by comparing the piezoresponse force microscopy (PFM) and cross-sectional TEM

results of the same BFO/LAO film before and after the He-implantation treatment. PFM measurements reveal that the in-plane multi-domain structure is refined into a uniform out-of-plane

single-domain polarization near the surface of films. Cross-sectional scanning transmission electron microscopy (STEM) and atomic-resolution energy-dispersive X-ray spectroscopy (EDS)

together elucidate various configurations of atomic bonding at the antiphase interface, which interweave to form an IP-CAPB around the implanted depth. Through quantitative analysis of

atomic column positions, the atomically sharp 180° polarization reversal across the IP-CAPB is identified. We also discover a single-unit-cell thick antipolar Bi2O3 inside the bending region

of CAPB, which switches the nearest single-unit-cell BFO layer to form multiple charged interfaces, which relieve the electrostatic energy and stabilize the IP-CAPB. Our work thus sheds

light on the domain-wall engineering by He-ion implantation and provides the direct atomic-scale observation of such unique IP-CAPBs for their future utilization in domain-wall

nanoelectronics, spintronics and memory device applications. RESULTS AND DISCUSSION We grew BFO films of ~70 nm thickness on LaAlO3 (LAO) (001) substrates using the pulsed laser deposition

(PLD) technique as detailed in the Method section. The pristine BFO film is dominated by the tetragonal-like (MC) phase as indicated by the X-ray diffraction (XRD) results in Supplementary

Fig. S1, exhibiting the strong (002) MC (tetragonal-like phase) and weak (002) MA (rhombohedral-like phase) peaks near the (002) LAO substrate peak38,39,40,41. The topography measurement by

atomic force microscopy (AFM) in Supplementary Fig. S2a shows some dark patch contrast, which can be ascribed to the rhombohedral-like (R-like) phase naturally mixed into the MC matrix when

the film thickness exceeds ~40 nm and the substrate constraint relieves38,39. Because R-like phases come from the distortion of parent matrix to exhibit a smaller c parameter, manifesting

lower local height in the topographic AFM map38,39. As shown in the schematics and the in-plane piezoresponse force microscopy (IP-PFM) phase maps in Fig. 1a, the as-grown BFO film contains

stripe domains of distinct in-plane polarization components, evincing a phase difference of π (180°). After the characterization, the BFO/LAO heterostructure was bombarded by 8 kV He ions

with a fluence of 2.5 × 1015 ions per cm2. It can be seen that the in-plane domain structures disappear after the He-ion implantation, leaving a uniform IP-PFM contrast in Fig. 1a (some

horizontal stripes of tiny phase variation come from flyback artifacts in the slow scan direction). By XRD in Supplementary Fig. S1 and reciprocal space map (RSM) in Supplementary Fig. S5,

we notice that the BFO film transforms into the true tetragonal (T) phase after the He-ion implantation. This phase transition is consistent with the AFM topography measurement in

Supplementary Fig. S2b, where the interweaving bright-dark stripe domain contrast is gone, and the atomic terraces on the surface can be observed. The out-of-plane (OOP) PFM phase maps of

samples before and after the He-ion implantation, as shown in Supplementary Fig. S2, do not exhibit any phase reversal or detectable domain contrast, suggesting that the He-ion implantation

process did not alter the OOP polarization component near the surface of films42. Due to the insulating nature of LAO substrates, OOP-PFM signal is a bit noisy. However, the homogeneous

contrast in both IP- and OOP-PFM results indicates the single-domain state near the surface of BFO films after implantation. According to the motivation as discussed previously in the

introduction paragraph to hybridize the antiphase and the in-plane charged characteristics into a single-domain wall, we simulated the possible atomic structure by artificially constructing

one antiphase interface in the BFO matrix. After geometric and energy refinements, there is spontaneous head-to-head polarization initialized in BFO around the boundary as shown in Fig. 1b,

which is represented by the displacement of Fe atomic columns relative to the corresponding u.c. centers (the centers of Bi rectangles). Owing to the head-to-head OOP polarization aside the

antiphase interface, the CAPB is positively charged by bound charges, since we did not observe possible sources of screening electrons. Such atomic model is verified further by direct

atomic-scale observation. Using focused ion beam (FIB) techniques, we lifted out cross-sectional membranes from the He-ion implanted BFO/LAO films for the structure characterization by

scanning transmission electron microscopy (STEM), as the scanning electron microscopy (SEM) image in Supplementary Fig. S3 shows. The BFO membrane is cut out along its <100> direction

and viewed along its <010> zone axis. To avoid surface damage during the milling processes, the BFO is capped with both carbon paint and deposited Pt protection layer. In Fig. 1c, the

cross-sectional annular bright field (ABF) images of the BFO/LAO films before and after the He-ion implantation show a difference in the occurrence of a single dark line at ~60 nm depth of

the processed BFO film. This depth position is in consistence with our simulation of He implantation depth profiles as shown in Supplementary Fig. S6. The accumulation and migration of

oxygen vacancies and generated anti-site defects to a critical level by the He implantation compose the IP-CAPB at the implantation front, where the high-enough He-ion density can arrive

under 8 kV beam energy. Varied beam energies can lead to different implantation depths and profiles as shown in Supplementary Fig. S6. Thus a different IP-CAPB position can be expected if a

different energy is used for the implantation. A zoomed-in view by high-angle annular dark field (HAADF) imaging in Fig. 1d demonstrates the exact atomic configurations of antiphase

interface (marked by red zigzag lines) in high consistence with the calculated atomic model. Through fitting the HAADF intensity of atomic columns with 2D Gaussian functions, we are able to

extract the atomic coordinates and calculate the lattice parameters unit cell by unit cell24. The average and standard deviation values of every u.c. row are plotted as the function of

distance away from the CAPB on the right panel of Fig. 1d, by which we can see the evident change of c/a ratios across the CAPB in agreement with the split (002) sub-peaks in XRD. The

<100> polarization component is nearly zero while the <001> component switches its sign across the interface, indicating an atomically sharp head-to-head 180° domain wall,

instead of the gradual rotation of polarization across the reported in-plane charged domain wall24. The cross-sectional microscopic analysis of the BFO/LAO interface can be seen in

Supplementary Fig. S4, demonstrating the single-domain polarization of BFO between the boundary and the LAO surface. Besides the stacking faults (pointed out by red zigzag lines) along the

antiphase boundary, CAPB also features a chemical ordering of anti-site occupation in opposite domains as visualized by the atomic-resolution EDS mapping shown in Fig. 2. Integrating Bi-_M_,

Fe-_K_, O-_K_ excitation peaks generates a binary contrast of atomic columns of the respective element, with or without the specific element, in a chemically selective manner. There are

three kinds of bonding configurations found in the IP-CAPB: type-I Bi-bilayer, type-II Bi-tetralayer and type-III Fe-bilayer types as listed in Fig. 2a–c, respectively. The excellent

anti-site occupation in opposite BFO domains can be well distinguished. The type-II CAPB with Bi-ion tetralayer in the interface can be regarded as a heterostructure of BFO-single u.c.

Bi2O3-BFO, though the normal tetragonal Bi2O3 phase is a metastable non-polar semiconductor43. We also notice that the type-III CAPB involves the direct face-to-face connection of FeO6

octahedra and thus exhibits a high-energy state, making the Fe-bilayer interface rarely observed and spatially discontinuous. It has been reported that a charged domain wall tends to bend

its propagation path to reduce the net bound charge accumulated from the normal polarization of neighboring domains21. Our IP-CAPB is also not completely straight as shown in the large-scale

image in Fig. 3a. As shown by the geometric phase analysis (GPA) of atomic-resolution image in Fig. 3b, the antiphase configuration is maintained in regardless of the bending. The in-plane

π phase variation and half-unit-cell lattice displacement is kept (represented by the compressed in-plane strain _ε__xx_ and the rotation component _ε__xy_) even when the CAPB bends, while

the out-of-plane lattice expansion (represented by the tensile out-of-plane strain _ε__yy_) can only be tracked in the bending section, which is explained by the configuration switch between

type-I Bi-bilayer and type-II Bi-tetralayer in the bending antiphase interface. From the atomic-resolution EDS mapping of this bending region in Fig. 3c, the alternating interchange of

type-I and type-II bonding configurations of a few unit cells makes up of the bending boundary. The type-II CAPB is formed naturally in the overlapped region of two closest neighboring

type-I CAPBs. Although the bending behaviors actually imply the bi-stable and switchable states of IP-CAPBs when electric field applied, the propagation direction change does not affect the

head-to-head OOP polarization aside the antiphase interface and the charged state of domain walls. Therefore, the question remains why such IP-CAPB bends, even though the accumulated charge

and built-up electrostatic energy cannot be released through bending. The unit-cell-by-unit-cell analysis of polarization in type-I and type-II IP-CAPBs tells us the reason. In Fig. 4, the

polarization of each u.c. is divided into orthogonal components along <001> and <100> directions, and quantified by the B-site displacement away from the u.c. center. It is

self-evident that either CAPB manifest the atomically sharp head-to-head 180° polarization change across the boundary region (framed by the white dashed rectangle) and the similar

polarization strength in BFO domains. As shown in Fig. 5, the local polarization mapping around the same boundary based on the HAADF-STEM imaging clearly demonstrates the head-to-head and

charged states of the boundary. The type-II CAPB, however, contains one-unit-cell thick Bi2O3 inside the wider domain wall. Such Bi2O3 layer is spontaneously anti-polarized against the

surrounding BFO and induces the one-unit-cell thick BFO underneath to switch its polarization direction by 180°, forming an additional tail-to-tail charged boundary that is negatively

charged. The creation of antipolar Bi2O3 layer and the resulted head-to-head/tail-to-tail oppositely charged boundaries may compensate the electrostatic potential built up by single charged

domain walls (type-I CAPB), corroborating the stabilization mechanism of IP-CAPBs through bending. Combining these atomic observations and the switching experiments performed on the

implanted BFO film as shown in Supplementary Fig. S7, the He-implanted BFO is still ferroelectric and switchable. While the direct evidence to explain how the He-ion implantation produces

IP-CAPBs remains unclear, it has been observed that the oxygen-vacancy density (the average Fe oxidation state) on the top side of IP-CAPBs is higher (lower) than that on the bottom side.

This difference has been demonstrated by the lower chemical shift of Fe-_L__3,2_ onset and the larger _L__3_/_L__2_ ratio in the top region by the atomic-resolution electron energy-loss

spectroscopy (EELS) as shown in Fig. 644. Because an antiphase domain is actually a region of anti-site defects in the parent lattice, we thus propose that the switch of A- and B-site ions,

leading to anti-site defects, was caused by the high-energy ion bombardment and assisted by the generated oxygen vacancies. The accumulation and migration of oxygen vacancies and anti-site

defects finally compose the IP-CAPB at the implanted depth after the implantation process45. The He-implantation-induced IP-CAPB is reproducible as shown in Supplementary Fig. S8, where we

fabricated three batches of samples using the same implantation condition and observed similar IP-CAPBs by cross-sectional TEM. Despite the unclear interacting model between high-energy ions

and strongly correlated crystals, our discovery of the unique IP-CAPB, which possesses an atomically sharp 180° charged interface stabilized by antiphase configuration, provides an unusual

playground for studying unconventional domain wall properties and mechanisms, such as the CAPB-controlled magnetoelectric coupling and the electron-hole pair dynamics in a charged

domain-wall sequence4. Since the IP-CAPB is charged and possibly electrically conductive, its electronic properties can be probed by cross-sectional conductive AFM22 and exploited in

multiferroic tunnel junction devices23. To sum up, we demonstrate the facile fabrication of continuous IP-CAPBs in BFO thin films using the He-ion implantation process. This technique is

highly scalable, making it suitable for wafer-size lateral patterning. PFM data confirm the disappearance of stripe domain wall structures near the surface of films. Cross-sectional STEM and

EDS spectroscopy then reveal a variety of atomic bonding configurations at the implanted depth, where they interweave to create the antiphase interface. Besides the atomically sharp 180°

polarization reversal across the IP-CAPB, a single-unit-cell thick antipolar Bi2O3 resides in the bending region of CAPB, relieving the built-up electrostatic energy. Therefore, this work

not only proposes a domain-wall fabrication strategy by the He-ion implantation, but also provides direct atomic-scale observation on such IP-CAPBs for their future utilization in

domain-wall nanoelectronics. METHODS MATERIALS SYNTHESIS A series of epitaxial ~70-nm-thick BFO films on LAO (001) substrates were grown by the pulsed laser deposition (PLD) technique at 680

 °C under an O2 pressure of 100 mTorr and cooled under 1 atm oxygen atmosphere. After deposition, the He-ion implantation was carried out at 8 keV with a fluence of 2.5 × 1015 ions per cm2

at the Ion Beam Center (IBC) at the Helmholtz–Zentrum Dresden–Rossendorf. ATOMIC FORCE MICROSCOPY (AFM) The topographical measurement was conducted by the tapping mode of our Scanning Probe

Microscope (model: Asylum Research Cypher) using Al-coated Si probes. PIEZORESPONSE FORCE MICROSCOPY (PFM) The PFM measurement was conducted by the vector PFM mode of our Scanning Probe

Microscope (model: Asylum Research Cypher) using Pt-coated conductive probes. The cantilever of probes is coated with Al to enhance the reflectivity. During scanning, the tips were applied

with 800 mV AC voltage for reading the piezoresponse of BFO films. X-RAY CHARACTERIZATION The XRD and RSM data, including 2theta-omega line scan and 3D-RSM, were obtained from the six-circle

diffractometer equipped with both 0D and 2D detectors in the 1W1A beamline station of the Beijing Synchrotron Radiation Facility using the X-ray wavelength of ~1.548 Å. The 2D RSM images

were extracted from the 3D-RSM dataset using MATLAB. ELECTRON MICROSCOPY AND SPECTROSCOPY Focused ion beam (FIB) techniques by FEI Helios G4 UX were applied to prepare the cross-sectional

membranes of BFO/ALO films. Before the ion milling processes, the surface was coated with thin carbon paint and deposited 500-nm-thick Pt protecting straps using a low-energy (2 kV) electron

beam. Then thicker Pt protecting straps (1.5 μm thick) were deposited using the ion beam. After lifting out a 1-μm-thick plate of the chosen crystal orientation to a copper finger,

step-by-step thinning processes using 30, 5, 2, 1, and 0.5 kV ion beams well minimized the beam damage. STEM imaging and spectroscopy were performed using JEOL JEM ARM 200CF equipped with a

cold field emission gun and an ASCOR fifth-order probe corrector. HAADF imaging, STEM-EDS and STEM-EELS experiments were carried out under 200 kV accelerating voltage with a 26 mrad

convergence semi-angle and 24-120 pA probe currents for optimal information transfer and minimal electron irradiation damage. The collection semi-angles for ADF signal were set to 68–200

mrad. In STEM-EELS measurements, energy dispersion of 0.25 eV per channel and 91 mrad collection semi-angle of Gatan Enfinium ER spectrometer was set up. Zero-loss peak and core-loss edges

were simultaneously recorded in dual EELS mode. The simultaneous ADF signal was acquired with a 93 mrad inner collection semi-angle. REPORTING SUMMARY Further information on research design

is available in the Nature Portfolio Reporting Summary linked to this article. DATA AVAILABILITY The authors declare that all data supporting the findings of this study are available within

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  CAS  PubMed  Google Scholar  Download references ACKNOWLEDGEMENTS D.C. thanks the support from the National Natural Science Foundation of China (Grant Nos. 92163210, 91963102), Guangdong

Science and Technology Project (Grant No. 2019A050510036), Guangdong Provincial Key Laboratory of Optical Information Materials and Technology (No. 2017B030301007) and Science and Technology

Projects in Guangzhou (202201000008). Y.Z. thanks the financial support from the Research Grants Council of Hong Kong through the Early Career Scheme (Project No. 25301617) and the Hong

Kong Polytechnic University grant (Project No. 1-ZE6G). Y.G. thanks the funding from the State Key Laboratory of Nuclear Physics and Technology, Peking University (No. NPT2019ZZ01). S.Z.

thanks the financial support by the German Research Foundation (Grant No. ZH 225/10-1). X.C. acknowledges the support from the NTU Presidential Postdoctoral Fellowship (Grant No.

03INS001828C230). We hereby also acknowledge the support from 1W1A station of Beijing Synchrotron Radiation Facility. AUTHOR INFORMATION Author notes * These authors contributed equally:

Xiangbin Cai, Chao Chen. AUTHORS AND AFFILIATIONS * Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, and Institute for Advanced Materials, South China

Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, China Xiangbin Cai, Chao Chen, Zixin Gui, Guofu Zhou, Xingsen Gao, Jun-Ming Liu & Deyang Chen *

Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore Xiangbin Cai & Weibo Gao *

Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China Lin Xie * Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials

Research, Dresden, 01328, Germany Changan Wang, Ulrich Kentsch & Shengqiang Zhou * School of Electronics & Communication, Guangdong Mechanical and Electrical Polytechnic, Guangzhou,

510515, China Changan Wang * State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, 100871, China Yuan Gao * Institute of High Energy Physics,

Chinese Academy of Sciences, Beijing, 100049, China Yu Chen * Laboratory of Solid State Microstructures and Innovation Center of Advanced Microstructures, Nanjing University, Nanjing,

210093, China Jun-Ming Liu * Department of Applied Physics, Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hong Kong, China Ye Zhu Authors * Xiangbin Cai View

author publications You can also search for this author inPubMed Google Scholar * Chao Chen View author publications You can also search for this author inPubMed Google Scholar * Lin Xie

View author publications You can also search for this author inPubMed Google Scholar * Changan Wang View author publications You can also search for this author inPubMed Google Scholar *

Zixin Gui View author publications You can also search for this author inPubMed Google Scholar * Yuan Gao View author publications You can also search for this author inPubMed Google Scholar

* Ulrich Kentsch View author publications You can also search for this author inPubMed Google Scholar * Guofu Zhou View author publications You can also search for this author inPubMed 

Google Scholar * Xingsen Gao View author publications You can also search for this author inPubMed Google Scholar * Yu Chen View author publications You can also search for this author

inPubMed Google Scholar * Shengqiang Zhou View author publications You can also search for this author inPubMed Google Scholar * Weibo Gao View author publications You can also search for

this author inPubMed Google Scholar * Jun-Ming Liu View author publications You can also search for this author inPubMed Google Scholar * Ye Zhu View author publications You can also search

for this author inPubMed Google Scholar * Deyang Chen View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS X.C. and D.C. conceived the project.

C.C. and D.C. synthesized the films and conducted XRD, AFM and PFM measurements. X.C. performed the FIB sample fabrication, electron microscopy characterization and data analyses. L.X.

contributed to the structure simulations. Z.G. and Y.C. helped with the ion implantation simulation. G.Z., X.G., W.G., Y.Z. and J.L. supported the project by improving the experiments and

the data analysis. X.C. wrote the manuscripts. C.W., Y.G., U.K. and S.Z. conducted the He implantation experiments. All authors participated in the discussion of results and commented on the

paper. CORRESPONDING AUTHORS Correspondence to Xiangbin Cai or Deyang Chen. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. PEER REVIEW PEER REVIEW

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permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Cai, X., Chen, C., Xie, L. _et al._ In-plane charged antiphase boundary and 180° domain wall in a ferroelectric film. _Nat Commun_ 14, 8174

(2023). https://doi.org/10.1038/s41467-023-44091-4 Download citation * Received: 09 April 2023 * Accepted: 30 November 2023 * Published: 09 December 2023 * DOI:

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