Solid-state electrochemical redox control of the optoelectronic properties for SrFeOx thin films
Solid-state electrochemical redox control of the optoelectronic properties for SrFeOx thin films
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DOI：
10.1063/5.0053939
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发表时间：
2021-06
影响因子：
3.2
通讯作者：
Qian Yang;H. Cho;H. Jeen;H. Ohta
中科院分区：
文献类型：
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作者：
Qian Yang;H. Cho;H. Jeen;H. Ohta
通过利用氧化还原反应，几种过渡金属氧化物的物理性质可以发生巨大变化，这对于开发多功能存储器件是有用的。锶铁氧化物（SrFeOx）从反铁磁绝缘体（x = 2.5）到螺旋磁金属（x = 3）呈现出明显的相变，是多功能存储器件中活性材料的良好候选者。然而，由于泄漏问题，先前在SrFeOx中氧化还原反应的演示因使用液态电解质而在实际应用中受到限制。在此，我们展示了在SrFeOx中使用氧化钇稳定的氧化锆（YSZ）单晶衬底作为固体电解质的固态电化学氧化还原反应。我们在YSZ衬底上制备了SrFeO2.5薄膜，并使用金电极施加电流。相逐渐从SrFeO2.5转变为SrFeO2.5 + x和SrFeO3 - x。薄膜的颜色从微黄透明变为深棕色。尽管生长态的SrFeO2.5薄膜显示出高电阻率（ρ>101Ω·cm），但随着施加电荷密度的增加，ρ急剧下降（约10 - 2Ω·cm）。同时，热电势从约+200大幅下降到约 - 10 μV·K - 1。目前的结果将为未来基于SrFeOx的固态多功能存储器件提供一个设计理念。
By utilizing redox reactions, the physical properties of several transition metal oxides can be drastically changed, which is useful for developing multifunctional memory devices. Strontium iron oxide (SrFeOx), which exhibits a clear phase transition from antiferromagnetic insulator (x = 2.5) to helimagnetic metal (x = 3), is a good candidate for the active material in multifunctional memory devices. However, practical applications using previous demonstrations of redox reactions in SrFeOx are limited by the use of a liquid electrolyte due to the leakage problem. Here, we demonstrate solid-state electrochemical redox reaction in SrFeOx using a yttria-stabilized zirconia (YSZ) single-crystal substrate as the solid electrolyte. We fabricated the SrFeO2.5 film on the YSZ substrate and the applied electric current using Au electrodes. The phase gradually changed from SrFeO2.5 to SrFeO2.5+x and SrFeO3−x. The color of the film changed from yellowish-transparent to dark brown. Although the as-grown SrFeO2.5 film showed high resistivity (ρ > 101 Ω cm), the ρ dramatically decreased (∼10−2 Ω cm) with increasing the applied charge density. Simultaneously, the thermopower greatly decreased from ∼+200 to ∼−10 μV K−1. The present results would provide a design concept for future SrFeOx-based solid-state multifunctional memory devices.