Utilizing quantum effects in complex oxides, such as magnetism, multiferroicity and superconductivity, requires atomic-level control of the material’s structure and composition. In contrast, the continuous conductivity changes that enable artificial oxide-based synapses and multiconfigurational devices are driven by redox reactions and domain reconfigurations, which entail long-range ionic migration and changes in stoichiometry or structure. Although both concepts hold great technological potential, combined applications seem difficult due to the mutually exclusive requirements. Here we demonstrate a route to overcome this limitation by controlling the conductivity in the functional oxide hexagonal Er(Mn,Ti)O3 by using conductive atomic force microscopy to generate electric-field induced anti-Frenkel defects, that is, charge-neutral interstitial–vacancy pairs. These defects are generated with nanoscale spatial precision to locally enhance the electronic hopping conductivity by orders of magnitude without disturbing the ferroelectric order. We explain the non-volatile effects using density functional theory and discuss its universality, suggesting an alternative dimension to functional oxides and the development of multifunctional devices for next-generation nanotechnology.
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Computer codes used for simulations and data evaluation are available from the sources cited; data in formats other than those presented within this paper are available from the corresponding authors upon request.
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We thank T. Grande for fruitful discussions. D.R.S. and S.M.S. were supported by the Research Council of Norway (project no. 231430/F20 and 275139) and acknowledge UNINETT Sigma2 (project no. NN9264K and ntnu243) for providing the computational resources. A.B.M. was supported by NTNU’s Enabling technologies: Nanotechnology. The Research Council of Norway is acknowledged for the support to the Norwegian Micro- and Nano-Fabrication Facility, NorFab, project no. 245963/F50 and Norwegian Centre for Transmission Electron Microscopy, NORTEM, Grant no. 197405. A.L.D. was funded by the Norwegian Research Council under project no. 274459 Translate. K.S. acknowledges the support of the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 724529), Ministerio de Economia, Industria y Competitividad through grant nos. MAT2016-77100-C2-2-P and SEV-2015-0496, and the Generalitat de Catalunya (grant no. 2017SGR 1506). Z.Y. and E.B. were supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under contract no. DE-AC02-05-CH11231 within the Quantum Materials program KC2202. J.A. was supported by the Academy of Finland under project no. 322832. D.M. thanks NTNU for support through the Onsager Fellowship Programme and NTNU Stjerneprogrammet.
The authors declare no competing interests.
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Evans, D.M., Holstad, T.S., Mosberg, A.B. et al. Conductivity control via minimally invasive anti-Frenkel defects in a functional oxide. Nat. Mater. 19, 1195–1200 (2020). https://doi.org/10.1038/s41563-020-0765-x
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