Unconventional Ferroelectric Switching via Local Domain Wall Motion in Multiferroic ε‐Fe2O3 Films,Advanced Electronic Materials

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Unconventional Ferroelectric Switching via Local Domain Wall Motion in Multiferroic ε‐Fe2O3 Films
Advanced Electronic Materials ( IF 5.3 ) Pub Date : 2020-02-13 , DOI: 10.1002/aelm.201901134
Xiangxiang Guan _{1,

2,

3} , Lide Yao ₃ , Konstantin Z. Rushchanskii ₄ , Sampo Inkinen ₃ , Richeng Yu _{1,

2} , Marjana Ležaić ₄ , Florencio Sánchez ₅ , Martí Gich ₅ , Sebastiaan Dijken ₃

Affiliation

Deterministic polarization reversal in ferroelectric and multiferroic films is critical for their exploitation in nanoelectronic devices. While ferroelectricity has been studied for nearly a century, major discrepancies in the reported values of coercive fields and saturation polarization persist in literature for many materials. This raises questions about the atomic‐scale mechanisms behind polarization reversal. Unconventional ferroelectric switching in ε‐Fe₂O₃ films, a material that combines ferrimagnetism and ferroelectricity at room temperature, is reported. High‐resolution in situ scanning transmission electron microscopy experiments and first‐principles calculations demonstrate that polarization reversal in ε‐Fe₂O₃ occurs around pre‐existing domain walls only, triggering local domain wall motion in moderate electric fields of 250–500 kV cm⁻¹. Calculations indicate that the activation barrier for switching at domain walls is nearly a quarter of that corresponding to the most likely transition paths inside ε‐Fe₂O₃ domains. Moreover, domain walls provide symmetry lowering of the polar structure near the domain boundary, which is shown to be necessary for ferroelectric switching in ε‐Fe₂O₃. Local polarization reversal in ε‐Fe₂O₃ limits the macroscopic ferroelectric response and offers important hints on how to tailor ferroelectric properties by domain structure design in other relevant ferroelectric materials.

中文翻译：

多铁性ε-Fe2O3薄膜中通过局部畴壁运动实现的非常规铁电开关

铁电和多铁性薄膜中确定性的极化反转对其在纳米电子器件中的应用至关重要。尽管对铁电的研究已有近一个世纪，但在许多材料的文献中，矫顽场和饱和极化的报告值仍存在重大差异。这就提出了有关极化反转背后的原子尺度机制的问题。在ε -铁非常规铁电转换₂ ö ₃膜的材料，结合亚铁磁性和铁电性在室温下，进行报告。高分辨率原位扫描透射电子显微镜的实验和第一原理计算表明在极化反转ε -铁₂ ö ₃仅在预先存在的畴壁周围发生，在250–500 kV cm ^-1的中等电场中触发局部畴壁运动。计算表明，在磁畴壁的开关的激活屏障是几乎对应于最可能的转移路径ε -铁里面的四分之一_2个ö ₃结构域。此外，磁畴壁提供对称性降低域边界，这被示出为是必要的铁电转换在ε -铁附近的极性结构的₂ ö ₃。在本地极化反转ε -铁₂ ö ₃ 限制了宏观铁电响应，并为如何通过其他相关铁电材料中的畴结构设计来调整铁电特性提供了重要提示。

更新日期：2020-02-13

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