title: Hybrid improper ferroelectricity in SrZrO3/BaZrO3 superlattice.
abstract: Incipient ferroelectrics, which show a unique dielectric property, arouse tremendous interests due to their potential application in microwave dielectric devices. However, ferroelectric transition in incipient ferroelectrics is suppressed entirely by quantum fluctuation. Here, by means of first-principles calculations, we demonstrate that there exists hybrid improper ferroelectricity in a layered artificial superlattice composed of the incipient ferroelectrics of SrZrO3 and BaZrO3. The hybrid improper ferroelectric polarization stems from oxygen octahedral rotation and coexists with the strain-induced ferroelectric distortion. The coexistence of oxygen octahedral rotation and ferroelectric distortion results in an enhanced polarization in the superlattice. It is further found that the total polarization in the superlattice is mainly contributed by the oxygen octahedral rotation for zero or small strain, whereas the contribution from strain-induced ferroelectric distortion gradually becomes predominant as the strain increases. The phonon dispersion, energy surface and atomic displacements are calculated to shed light on the underlying mechanism of the hybrid improper ferroelectricity in the SrZrO3/BaZrO3 superlattice.
authors: Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310007, China. jw@zju.edu.cn.
authors: Yajun
authors: Y
authors: Zhang
authors: Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310007, China. jw@zju.edu.cn and Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province, Zhejiang University, Hangzhou 310007, China.
authors: Jie
authors: J
authors: Wang
authors: Department of Engineering Mechanics, School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310007, China. jw@zju.edu.cn.
authors: M P K
authors: MP
authors: Sahoo
authors: Institute of Systems Engineering, China Academy of Engineering Physics, Postbox 919-401, Mianyang 621900, China.
authors: Xiaoyuan
authors: X
authors: Wang
authors: Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
authors: Takahiro
authors: T
authors: Shimada
authors: Department of Mechanical Engineering and Science, Kyoto University, Nishikyo-ku, Kyoto 615-8540, Japan.
authors: Takayuki
authors: T
authors: Kitamura