Controllable conductive readout in self-assembled, topologically confined ferroelectric domain walls

Abstract

Charged domain walls in ferroelectrics exhibit a quasi-two-dimensional conduction path coupled to the surrounding polarization. They have been proposed for use as non-volatile memory with non-destructive operation and ultralow energy consumption. Yet the evolution of domain walls during polarization switching makes it challenging to control their location and conductance precisely, a prerequisite for controlled read–write schemes and for integration in scalable memory devices. Here, we explore and reversibly switch the polarization of square BiFeO3 nanoislands in a self-assembled array. Each island confines cross-shaped, charged domain walls in a centre-type domain. Electrostatic and geometric boundary conditions induce two stable domain configurations: centre-convergent and centre-divergent. We switch the polarization deterministically back and forth between these two states, which alters the domain wall conductance by three orders of magnitude, while the position of the domain wall remains static because of its confinement within the BiFeO3 islands.

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Fig. 1: Structural analysis of the BiFeO3 nanoislands.
Fig. 2: Centre-convergent quad-domain structures of BiFeO3 nanoislands.
Fig. 3: Domain structure of BiFeO3 nanoislands after polarization switching.
Fig. 4: Large conductance at charged domain walls in BiFeO3 nanoislands.
Fig. 5: Stability and repeatability of high conductance in charged DWs.

Change history

  • 31 July 2018

    In the version of this Article originally published, the corresponding author names in the author list appeared in the reverse order; they should have read ‘Jinxing Zhang and Ce-Wan Nan’. The order of these authors’ initials in the ‘Correspondence and requests for materials’ statement were similarly affected. These errors have now been corrected in all versions of the Article.

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Acknowledgements

This work was supported by the Basic Science Center Program of NSFC (grant no. 51788104), NSFC (grant no. 51332001 and 51472140), the National Basic Research Program of China (grant no. 2016YFA0300103, 2016YFA0302300, and 2015CB921700) and the US DOE (grant no. DE-FG02-07ER46417). We thank H. Zhou for his discussion on band diagrams.

Author information

C.-W.N., J.Z. and J.M. conceived the project and designed the experiments. J.M. grew the thin films and performed the electrical characterization. Q.Z. fabricated the TEM samples and performed the scanning TEM measurements with help from L.G. R.P. and X.C. performed the phase-field simulations under the supervision of L.-Q.C. and C.-W.N. N.L. carried out digital analysis of the STEM data under the supervision of P.G. M.W. performed the reciprocal-space mapping measurement under the supervision of P.Y. J.M., J.W., C.L., M.C. and P.Y. contributed to the PFM and c-AFM measurements and analysis. J.Z. and C.-W.N. wrote the manuscript, with input from all authors.

Correspondence to Jinxing Zhang or Ce-Wen Nan.

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