Prediction of complex ferroelectric textures through second-principles simulations*

The combination of a ferroelectric, like PbTiO₃, and a dielectric, such as SrTiO₃, in a layered superlattice allows observing intrincate polarization patterns like vortex arrays¹ or bubble domains² that are sensitive to fields and strain³ and display exotic properties like negative capacitance.⁴ Understanding these systems requires complementing experiment with realistic simulations. This task is difficult due to the nanometric length scale of the characteristic dipole orders, the need for atomic resolution owing to strong coupling between various distortions of the underlying perovskite lattice and the small energy differences between the many stable configurations. Here, we tackle this problem using SCALE-UP⁵ an implementation of our second-principles DFT method⁶ that allows us studying the effect of periodicity/strain/external fields/temperature. Our predictions, fully consistent with experiment, show the presence of chirality and non-trivial topological structures.
1Yadav et al., Nature 530, 198 (2016)
2Zhang et al., Adv. Mater. 1702375 (2017)
3Damodaran et al., Nat. Mat. 16, 1003 (2017)
4Zubko et al., Nature 534, 524 (2016)
5https://www.secondprinciples.unican.es/
6Garcia-Fernandez et al., Phys. Rev. B 93, 195137 (2016)