title: 180° Ferroelectric Stripe Nanodomains in BiFeO3 Thin Films.
abstract: There is growing evidence that domain walls in ferroics can possess emergent properties that are absent in the bulk. For example, 180° ferroelectric domain walls in the ferroelectric-antiferromagnetic BiFeO3 are particularly interesting because they have been predicted to possess a range of intriguing behaviors, including electronic conduction and enhanced magnetization. To date, however, ordered arrays of such domain structures have not been reported. Here, we report the observation of 180° stripe nanodomains in (110)-oriented BiFeO3 thin films grown on orthorhombic GdScO3 (010)O substrates and their impact on exchange coupling to metallic ferromagnets. Nanoscale ferroelectric 180° stripe domains with {112̅} domain walls were observed in films <32 nm thick. With increasing film thickness, we observed a domain structure crossover from the depolarization field-driven 180° stripe nanodomains to 71° ferroelastic domains determined by the elastic energy. These 180° domain walls (which are typically cylindrical or meandering in nature due to a lack of strong anisotropy associated with the energy of such walls) are found to be highly ordered. Additional studies of Co0.9Fe0.1/BiFeO3 heterostructures reveal exchange bias and exchange enhancement in heterostructures based on BiFeO3 with 180° domain walls and an absence of exchange bias in heterostructures based on BiFeO3 with 71° domain walls; suggesting that the 180° domain walls could be the possible source for pinned uncompensated spins that give rise to exchange bias. This is further confirmed by X-ray circular magnetic dichroism studies, which demonstrate that films with predominantly 180° domain walls have larger magnetization than those with primarily 71° domain walls. Our results could be useful to extract the structure of domain walls and to explore domain wall functionalities in BiFeO3.
authors: Zuhuang
authors: Z
authors: Chen
authors: Jian
authors: J
authors: Liu
authors: Hubei Collaborative Innovation Centre for Advanced Organic Chemical Materials, Key Laboratory of Green Preparation and Application for Materials, Ministry of Education, Department of Materials Science and Engineering, Hubei University , Wuhan 430062, P. R. China.
authors: Yajun
authors: Y
authors: Qi
authors: Deyang
authors: D
authors: Chen
authors: Shang-Lin
authors: SL
authors: Hsu
authors: Anoop R
authors: AR
authors: Damodaran
authors: Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois , Urbana-Champaign, Urbana, Illinois 61801, United States.
authors: Xiaoqing
authors: X
authors: He
authors: Alpha T
authors: AT
authors: N'Diaye
authors: Department of Materials Science and Engineering and Materials Research Laboratory, University of Illinois , Urbana-Champaign, Urbana, Illinois 61801, United States.|International Institute for Carbon Neutral Research, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
authors: Angus
authors: A
authors: Rockett
authors: International Institute for Carbon Neutral Research, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
authors: Lane W
authors: LW
authors: Martin
keywords: BiFeO3; domain walls; exchange bias; ferroelectric; multiferroic; strain