학술논문
Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO3
Document Type
article
Author
Chen, F; Zhu, Y; Liu, S; Qi, Y; Hwang, HY; Brandt, NC; Lu, J; Quirin, F; Enquist, H; Zalden, P; Hu, T; Goodfellow, J; Sher, MJ; Hoffmann, MC; Zhu, D; Lemke, H; Glownia, J; Chollet, M; Damodaran, AR; Park, J; Cai, Z; Jung, IW; Highland, MJ; Walko, DA; Freeland, JW; Evans, PG; Vailionis, A; Larsson, J; Nelson, KA; Rappe, AM; Sokolowski-Tinten, K; Martin, LW; Wen, H; Lindenberg, AM
Source
Physical Review B. 94(18)
Subject
Language
Abstract
The dynamical processes associated with electric field manipulation of the polarization in a ferroelectric remain largely unknown but fundamentally determine the speed and functionality of ferroelectric materials and devices. Here we apply subpicosecond duration, single-cycle terahertz pulses as an ultrafast electric field bias to prototypical BaTiO3 ferroelectric thin films with the atomic-scale response probed by femtosecond x-ray-scattering techniques. We show that electric fields applied perpendicular to the ferroelectric polarization drive large-amplitude displacements of the titanium atoms along the ferroelectric polarization axis, comparable to that of the built-in displacements associated with the intrinsic polarization and incoherent across unit cells. This effect is associated with a dynamic rotation of the ferroelectric polarization switching on and then off on picosecond time scales. These transient polarization modulations are followed by long-lived vibrational heating effects driven by resonant excitation of the ferroelectric soft mode, as reflected in changes in the c-axis tetragonality. The ultrafast structural characterization described here enables a direct comparison with first-principles-based molecular-dynamics simulations, with good agreement obtained.