Direct atomic-scale visualization of the 90° domain walls and their migrations in Hf_0.5Zr_0.5O₂ ferroelectric thin films

Domain walls (DWs) play an essential role in altering the polarization and related properties of ferroelectric materials, and are regulated by the mechanism of changing atomic configuration. However, compared with perovskite ferroelectrics, the DWs in hafnia-based fluorite-structure ferroelectric is experimentally lacking, especially with regard to detailed studies of atomic-scale structures. The present work used spherical aberration-corrected transmission electron microscope combined with in-situ technique to ascertain the origin, atomic arrangements of 90° DWs in Hf_0.5Zr_0.5O₂ thin films. Different types of 90° DWs were found to exhibit varying migration behaviors in response to the concentration of oxygen vacancies. Point defects and corresponding changes in the local strain field are proposed to drive DW switching in this material. These new insights into the atomic-scale characteristics of 90° DWs are expected to assist in elucidating the structure of DWs and improve our understanding of the ferroelectric characteristics of new type hafnia-based materials.