Figure 3: Polarimetry analysis of the DWs’ SHG signal in tetragonal PZT.
From: Non-Ising and chiral ferroelectric domain walls revealed by nonlinear optical microscopy
A systematic analysis of the local SHG is conducted for different polarizer and analyzer settings, at horizontal (HDW), vertical (VDW) and oblique (ODW) domain walls, as schematically illustrated in a,b. SHG measurements conducted in c rectangular-shape c-domains exhibit maximum signal at HDWs and VDWs when the analyzer (blue arrow) is perpendicular to the walls. The same result is observed at HDWs and VDWs in d triangular-shape c-domains, while oblique walls referred to as ODW1 and ODW2 exhibit a different behaviour. The corresponding polar plots (scattered dots) of the normalized SHG intensity measured are shown in case of (e) rectangles and (f) angle triangles at a fundamental polarization angle ϕ=0°. The continuous lines are fits of the experimental data to the analytic expression of the SHG intensity expected for Néel-type walls with horizontal, vertical or oblique orientations. (g) 3D SHG polarimetry simulated in the case of a planar ferroelectric polarization along the y-axis (Néel-type), represented in cylindrical coordinates (x=ISHG cos α, y=ISHG sin α and z=ϕ). The z-axis has been scaled with a factor 10 to allow for a better visibility. The colour map represents the SHG intensity in a.u. and the continuous lines result from plane cuts at ϕ=0° (red colour), ϕ=90° and 180° (grey). The normalized intensity of the calculated polar plots at ϕ=0° is displayed in h to facilitate the comparison with the experimental results.
