Salia Cherifi-Hertel
Université de Strasbourg and CNRS
Institut de Physique et Chimie des Matériaux de Strasbourg, France
Structures with swirling polarization textures such as vortices, flux-closure domains, bubbles, and skyrmions have recently been reported in various ferroelectric systems. This unexpected degree of freedom of the polarization opens new perspectives for applications [1]. Complex polar structures developing within ferroelectric domain walls have also attracted interest in this context. The experimental evidence of the non-Ising character of ferroelectric domain walls, with Néel or chiral Bloch-type internal structure, has further impacted the development of this topic over the past years. Our group in Strasbourg has contributed to this research by demonstrating that nonlinear optical microscopy with polarization analysis can be used to detect the spectral signature of Néel or Bloch-type walls as well as topological structures such as Bloch lines [2]. We use second-harmonic generation microscopy and polarimetry analysis in conjunction with simulations which account for the reduction of the local symmetry to investigate the internal structure of ferroelectric domain walls [3,4]. In this talk, I will present recent results showing how the polarization structure within domain walls can change locally, depending on the three-dimensional curvature of the walls [5]. Moreover, I will address the possibility of modifying the internal structure of ferroelectric domain walls in uniaxial ferroelectrics from Bloch- to Néel-type, or vice versa, and discuss the mechanisms at play in such a process. In particular, the interaction of the local polarization with defects and the impact of electrostatics on the stability of the domain wall type will be emphasized.
References
[1] J. Seidel, Nature Materials 18, 188 (2019); S. Das et al., APL Materials 8, 120902 (2020); G. Tian et al., APL Materials 9, 020907 (2021).
[2] S. Cherifi-Hertel et al., Nature Communications 8, 15768 (2017). [3] S. Cherifi-Hertel et al., Journal of Applied Physics 129, 081101 (2021). [4] Y. Zhang and S. Cherifi-Hertel, Opt. Mater. Express 11, 3736 (2021). [5] U. Acevedo-Salas et al., arXiv:2207.01307