论文标题

在外交士兵铁氧体超级晶格中精心制作的铁电孤子

Ferroelectric Solitons Crafted in Epitaxial Bismuth Ferrite Superlattices

论文作者

Govinden, V., Tong, P. R., Guo, X., Zhang, Q., Mantri, S., Prokhorenko, S., Nahas, Y., Wu, Y., Bellaiche, L., Tian, H., Hong, Z., Sando, D., Nagarajan, V.

论文摘要

在铁电基因中,各种自由度之间的复杂相互作用使拓扑保护的极化纹理能够凝结。这些类似粒子的结构称为铁电孤子,代表了一类新的材料,由于其超细尺寸和对外部刺激的敏感性,具有超越CMOS技术的希望。这种极化纹理几乎没有报道在多表象中。在这里,我们报告了二晶型钛酸钛酸盐超晶格中的一系列孤子拓扑。高分辨率的压电响应力显微镜和经CS校正的高角度环形扫描透射透射电子显微镜揭示了拓扑的动物园,平面样品的极化位移映射揭示了中心侧侧向和拓扑缺损的拓扑,并发散拓扑缺损小至3 nm。相位场模拟验证了其中一些拓扑可以归类为Bimerons,并具有PLUS和SINUS ONE的拓扑费用,基于第一原理的有效哈密顿计算表明,此类结构的共存可能会导致非直觉拓扑电荷,这是基于BifeO3的系统中的首次观察。我们的结果为多效拓扑学开辟了新的机会。

In ferroelectrics, complex interactions among various degrees of freedom enable the condensation of topologically protected polarization textures. Known as ferroelectric solitons, these particle-like structures represent a new class of materials with promise for beyond CMOS technologies due to their ultrafine size and sensitivity to external stimuli. Such polarization textures have scarcely been reported in multiferroics. Here, we report a range of soliton topologies in bismuth ferrite strontium titanate superlattices. High-resolution piezoresponse force microscopy and Cs-corrected high-angle annular dark-field scanning transmission electron microscopy reveal a zoo of topologies, and polarization displacement mapping of planar specimens reveals center-convergent and divergent topological defects as small as 3 nm. Phase field simulations verify that some of these topologies can be classed as bimerons, with a topological charge of plus and minus one, and first-principles-based effective Hamiltonian computations show that the co-existence of such structures can lead to non-integer topological charges, a first observation in a BiFeO3-based system. Our results open new opportunities in multiferroic topotronics.

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