Zig-zag charged 180° domain wall in ferroelectric PbTiO₃

Domain walls in ferroelectrics are usually electrically neutral because charged walls lead to very strong depolarizing fields, which would effectively suppress such a domain arrangement. The experimental observations of charged walls (e.g. [1,2]) can be explained by the presence of different kinds of defects, which can compensate for the bound charge, originating from the polarization-variation at the wall. In previous theoretical studies of charged walls it was usually assumed that the compensation charges are very localized [3].

In this paper, we address a charged 180° domain wall in ferroelectric PbTiO₃, which is compensated by static charges distributed randomly in a relatively broad layer with thickness ranging from a few nanometers to several hundred nanometers. We use atomistic simulations to obtain details of the domain-wall microstructure [4], and for larger compensation-layer thicknesses, we utilize phase-field simulations within the framework of the Ginzburg-Landau-Devonshire model [5]. Both the atomistic and the phenomenological approaches predict a zig-zag domain wall located within the compensation layer. We discuss in detail the internal structure of the domain wall depending on the thickness of the compensation region and put it into the context of the available experimental observations.

This work was supported by the Czech Science Foundation (Project No. 20-05167Y).

[1] P.S. Bednyakov, B.I. Sturman, T. Sluka, A.K. Tagantsev, P.V. Yudin, npj Computational Materials, 4, 65 (2018).

[2] T. Denneulin and A.S. Everhardt, J. Phys. Cond. Mat. 34, (2022).

[3] X. Wu and D. Vanderbilt, Phys. Rev. B 87, 054110 (2013).

[4] M. Sepliarsky and R. E. Cohen J. Phys.: Condens. Matter 23, 435902 (2011).

[5] P. Ondrejkovic, P. Marton, V. Stepkova, and J. Hlinka: Domain Walls: From Fundamental Properties to Nanotechnology Concepts, 76 (2020).