Spatially-resolved investigations of domain switching in the ferroelectric relaxor SBN by photorefractive self-focusing

We carry out spatially-resolved investigations of the domain-switching behavior of strontium-barium niobate (SBN) crystals. Photorefractive self-focusing is suggested as a powerful method to check the polarization state of a crystal in a spatially resolved way. In addition, frequency-doubling micrographs of the 180 degrees domain walls in SBN are shown with a lateral resolution up to 250 nm. It is demonstrated that after usual poling procedures part of the crystal may still remain unpoled. Generally, there exists a considerable spatial inhomogeneity in the amount of the switchable polarization, which usually decreases from the positive towards the negative poling electrode.