Probing Nontrivial Domain Structures in Strain-Modulated Ferroelectric Films by Scanning Probe Microscopy

Siang Ping Hong^1*, Sheng Zhu Ho¹, Yu Chen Liu¹, Yu Chiang Hsieh¹, Tse Ming Chen¹, Jan Chi Yang¹, Yi Chun Chen¹

¹Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Siang Ping Hong, email:L26094239@gs.ncku.edu.tw

Ferroelectric materials possess spontaneous polarization and ordered electric dipole orientation below Curie temperature. Since the electric ordering can be manipulated by external fields, ferroelectrics have a wide range of applications including memories, sensors, and actuators. In recent studies, attempts to find new types of topological domain structures has been pursued by applying various stimulus such as epitaxial strain, temperature, electric field, etc. As the result, one can further investigate the rich physical properties of such novel domain structures.
In the experiment, in order to manipulate the domain structures in a more systematical way, we adopt freestanding technique to transfer quantum paraelectric SrTiO₃ (STO) thin film onto arbitrary samples. We utilized ferroelectric thin film Pb(Zr_0.2Ti_0.8)O₃ (PZT) as the substrate of STO to create a periodic electric boundary to affect the upper STO layer. Moreover, periodic strain field is created by etched hBN caves where freestanding STO is capped. To reveal the domain structures of theses free-standing STO samples, we adopted contact-resonance piezoresponse force microscopy (CR-PFM) techniques. This study provides a new route to manipulate ferroic ordering structures through periodic boundaries.

Keywords: Ferroelectric material, domain structure, Piezoresponse Force Microscopy, periodic strain