Electric Field Control of Phase Transition and Tunable Resistive Switching in SrFeO 2.5

作者：Muhammad Shahrukh Saleem, Bin Cui, Cheng Song, Yiming Sun, Youdi Gu, Ruiqi Zhang, Muhammad Umer Fayaz, Xiaofeng Zhou, P. Werner, S. Parkin, Feng Pan · 发表于：ACS Applied Materials & Interfaces · 年份：2019 · DOI：10.1021/acsami.8b18251 · 被引用次数：64 · 研究领域：Advanced Memory and Neural Computing、Electronic and Structural Properties of Oxides、Ferroelectric and Negative Capacitance Devices

SrFeO x (SFO x ) compounds exhibit ionic conduction and oxygen-related phase transformation, having potential applications in solid oxide fuel cells, smart windows, and memristive devices. The phase transformation in SFO x typically requires a thermal annealing process under various pressure conditions, hindering their practical applications. Here, we have achieved a reversible phase transition from brownmillerite (BM) to perovskite (PV) in SrFeO 2.5 (SFO 2.5 ) films through ionic liquid (IL) gating. The real-time phase transformation is imaged using in situ high-resolution transmission electron microscopy. The magnetic transition in SFO 2.5 is identified by fabricating an assisted La 0.7 Sr 0.3 MnO 3 (LSMO) bottom layer. The IL-gating-converted PV phase of a SrFeO 3−δ (SFO 3−δ ) layer shows a ferromagnetic-like behavior but applies a huge pinning effect on LSMO magnetic moments, which consequently leads to a prominent exchange bias phenomenon, suggesting an uncompensated helical magnetic structure of SFO 3−δ . On the other hand, the suppression of both magnetic and exchange coupling signals for a BM-phased SFO 2.5 layer elucidates its fully compensated G-type antiferromagnetic nature. We also demonstrated that the phase transition by IL gating is an effective pathway to tune the resistive switching parameters, such as set, reset, and high/low-resistance ratio in SFO 2.5 -based resistive random-access memory devices.