Three-Dimensional Optical Analysis of Ferroelectric Domain Walls

This chapter presents the latest results demonstrating the flexibility and sensitivity of optical methods for the investigation of the physical properties of DWs in 3D. Domain walls in ferroelectric materials are nanoscale interfaces separating regions with different orientation of the polarization. They have long been considered as imperfections affecting the overall macroscopic properties of ferroelectrics. However, the recently discovered rich and diverse local physical properties of ferroelectric DWs have transformed these domain boundary regions into individual nanostructures with significant fundamental interest and potentially viable application in nanoelectronic device components. This chapter emphasizes the important contribution of both nonlinear and linear optical microscopy in different geometries (transmission, reflection, and non-collinear geometry) to access the detailed morphology of ferroelectric domain walls, obtain their 3D profile, access their internal structure, and establish correlations with their electronic properties.