Large Scale Two-Dimensional Flux-Closure Domain Arrays in Oxide Multilayers and Their Controlled Growth

• Published in: Nano letters 2017-12, Vol.17 (12), p.7258-7266
• Main Authors: Liu, Ying, Wang, Yu-Jia, Zhu, Yin-Lian, Lei, Chi-Hou, Tang, Yun-Long, Li, Shuang, Zhang, Si-Rui, Li, Jiangyu, Ma, Xiu-Liang
• Format: Article
• Language: English
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.7b02615

Ferroelectric flux-closures are very promising in high-density storage and other nanoscale electronic devices. To make the data bits addressable, the nanoscale flux-closures are required to be periodic via a controlled growth. Although flux-closure quadrant arrays with 180° domain walls perpendicular to the interfaces (V-closure) have been observed in strained ferroelectric PbTiO3 films, the flux-closure quadrants therein are rather asymmetric. In this work, we report not only a periodic array of the symmetric flux-closure quadrants with 180° domain walls parallel to the interfaces (H-closure) but also a large scale alternative stacking of the V- and H-closure arrays in PbTiO3/SrTiO3 multilayers. On the basis of a combination of aberration-corrected scanning transmission electron microscopic imaging and phase field modeling, we establish the phase diagram in the layer-by-layer two-dimensional arrays versus the thickness ratio of adjacent PbTiO3 films, in which energy competitions play dominant roles. The manipulation of these flux-closures may stimulate the design and development of novel nanoscale ferroelectric devices with exotic properties.