title: Electrical and mechanical switching of ferroelectric polarization in the 70 nm BiFeO3 film.
abstract: Ferroelectric polarization switching and its domain evolution play a key role on the macroscopic electric properties of ferroelectric or piezoelectric devices. Mechanical switching has been reported recently in ~5 nm BaTiO3 and PbZr0.2Ti0.8O3 epitaxial films; however it is still a challenge for a mechanical force to switch polarization of a slightly thicker film in the same way as an electric field. Here, we report that the polarization of a 70 nm BiFeO3 epitaxial film can be completely switched by a mechanical force, and its domain evolution is similar to that observed with electrical switching. With the gradual increase of the field/force, new domains nucleate preferentially at domain boundaries, the μm-size domains commonly decompose to a mass of nm-size domains, and finally they may reorganize to μm-size domains which undergo 180(°) polarization switching through multi steps. Importantly, the complete mechanical switching of polarization was also established in the (0 0 1) film with a smooth surface. Furthermore, either upward or downward polarization can be read out nondestructively by a constant current. Our study sheds light on prospective applications of ferroelectrics in the absence of an electric field, such as memory devices and other micro-electromechanical systems.
authors.affiliation: School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
authors.forename: Liufang
authors.initials: L
authors.lastname: Chen
authors.affiliation: School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Cheng
authors.affiliation: School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
authors.forename: Wenting
authors.initials: W
authors.lastname: Xu
authors.affiliation: National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Yu Tian Road 500, Shanghai 200083, P. R. China.
authors.forename: Xiangjian
authors.initials: X
authors.lastname: Meng
authors.affiliation: School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, P. R. China.
authors.forename: Guoliang
authors.initials: G
authors.lastname: Yuan
authors.affiliation: National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Junming
authors.initials: J
authors.lastname: Liu
authors.affiliation: National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Liu