Interplay between charge ordering and geometric ferroelectricity in LuFe2O4/LuFeO3 superlattices
Interplay between charge ordering and geometric ferroelectricity in LuFe2O4/LuFeO3 superlattices
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LuFe2O4/LuFeO3 超晶格中电荷排序与几何铁电性之间的相互作用
DOI：
10.1103/physrevmaterials.5.094412
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发表时间：
2021
影响因子：
3.4
通讯作者：
Zhu Yimei
中科院分区：
文献类型：
--
作者：
Li Menglei;Cheng Shaobo;Wang Wenbin;Li Xing;Wang Na;Zhu Yimei
氧化物超晶格由于界面处的弹性、电性和磁性有序之间的有趣耦合以及不适当的铁电性的出现而引起了人们的极大关注。本文通过密度泛函理论计算研究了六角晶系超晶格。H-是一种著名的多铁性材料，只有在薄膜或掺杂体状态下才是稳定的，而H-是一种电荷有序(CO)材料，其铁电性的存在仍然存在争议。我们发现，在不同周期的超晶格中，CO诱导的层内极化与层内的几何极化共存，并且在超晶格中，铁电态普遍优于反铁电态。H-层中的离面极化趋于平行排列，并且总的极化随着比的增加而增大。层状极化对局部静电势的影响不明显，但在FeO双层膜中检测到CO诱导极化引起的小趋势。此外，局域电子结构表明，某一层中的费米能级位置可以通过该层中Fe的价态和邻近层中的极化分布来调节，夹在厚层之间的层更容易受到影响。超晶格的计算构型得到了原子分辨电子显微镜实验的支持。我们的结果为超晶格系统中的可调谐铁电性铺平了道路，并为操纵不同自由度之间的耦合创造了一个游乐场。
Oxide superlattices have drawn great attention owing to the intriguing coupling among elastic, electrical, and magnetic orderings at the interfaces and the emergence of improper ferroelectricity. Here, superlattices composed of hexagonalandare investigated via density functional theory calculations. h-is a well-known multiferroic material that is stable only in thin film or doped bulk state, whileis a charge ordered (CO) material where the existence of ferroelectricity is still a controversy. We have found that the CO-induced polarizations inlayers coexist with the geometric polarizations inlayers in thesuperlattices with different periodicities, and the ferroelectric states are generally preferred over the antiferroelectric states forin superlattices. The out-of-plane polarizations in h-andlayers tend to be aligned in parallel, and the overall polarization increases with the ratio of. The influence of layered polarizations on the local electrostatic potential is not significant except the detected small trend caused by the CO-induced polarization within a FeO bilayer. Additionally, the local electronic structures show that the Fermi level position in a certain layer can be tuned by the valences of Fe in this layer and the polarization distributions in neighboring layers.layers sandwiched between thicklayers are more susceptible. The calculated configurations of the superlattices are supported by atomic-resolution transmission electron microscopy experiments. Our results pave the way for tunable ferroelectricity in superlattice systems and create a playground for manipulating the coupling between various degrees of freedom.