Topotactic Phase Transition Driving Memristive Behavior

Venkata R. Nallagatla, Thomas Heisig, Christoph Baeumer, Vitaliy Feyer, Matteo Jugovac, Giovanni Zamborlini, Claus M. Schneider, Rainer Waser, Miyoung Kim, Chang Uk Jung*, Regina Dittmann

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

58 Citations (Scopus)
18 Downloads (Pure)


Redox-based memristive devices are one of the most attractive candidates for future nonvolatile memory applications and neuromorphic circuits, and their performance is determined by redox processes and the corresponding oxygen-ion dynamics. In this regard, brownmillerite SrFeO2.5 has been recently introduced as a novel material platform due to its exceptional oxygen-ion transport properties for resistive-switching memory devices. However, the underlying redox processes that give rise to resistive switching remain poorly understood. By using X-ray absorption spectromicroscopy, it is demonstrated that the reversible redox-based topotactic phase transition between the insulating brownmillerite phase, SrFeO2.5, and the conductive perovskite phase, SrFeO3, gives rise to the resistive-switching properties of SrFeOx memristive devices. Furthermore, it is found that the electric-field-induced phase transition spreads over a large area in (001) oriented SrFeO2.5 devices, where oxygen vacancy channels are ordered along the in-plane direction of the device. In contrast, (111)-grown SrFeO2.5 devices with out-of-plane oriented oxygen vacancy channels, reaching from the bottom to the top electrode, show a localized phase transition. These findings provide detailed insight into the resistive-switching mechanism in SrFeOx-based memristive devices within the framework of metal–insulator topotactic phase transitions.

Original languageEnglish
Article number1903391
JournalAdvanced materials
Issue number40
Publication statusPublished - 1 Oct 2019
Externally publishedYes


  • brownmillerite
  • resistive switching
  • topotactic phase transition


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