Hao Gu, Lin Chen, Chao Chen(陈超), Zhen Wang, Jian Wang, Tong Zhu, Yu Chen, Minghui Qin, Jiyan Dai, Xubing Lu, Xingsen Gao, Jun-Ming Liu(刘俊明), Deyang Chen(陈德杨)
Engineering Pseudo-c/a Twin Boundaries in Super-Tetragonal BiFeO3 for Domain-Wall Nanoelectronics
Advanced Functional Materials, e31891 (2026)
Ferroelectric domain walls have emerged as promising building blocks for next-generation nanoelectronics. Recent studies have revealed that large-angle c/a twin boundaries in lead-based ferroelectric thin films exhibit superior physical properties, including enhanced piezoelectric responses, flexoelectric effects, and multi-caloric behaviors. However, the realization of analogous c/a ferroelastic structures in lead-free BiFeO3 (BFO) thin films remains challenging. Here, we report the successful construction of coherent pseudo-c/a twin domain walls in highly tetragonal Ga-doped BFO thin films. These domain boundaries are found to accommodate cross-hatched polarization arrays that effectively compensate domain wall electrostatics, along with a markedly enhanced flexoelectric effect. Moreover, these twin boundaries exhibit polarization-gated switchable conductivity, highlighting their potential for use in memory devices. Our work offers new insights into the design of large-angle ferroelectric domain walls and lays a foundation for future domain-wall-based electronic applications.