High-Resolution Optical Microscopy Of Ba_XSr_1−xTio₃ Films

Abstract

The ferroelectric polarization of thin films of BaxSr1−xTiO3 is imaged using confocal scanning optical microscopy (CSOM). The thin films are grown by pulsed laser deposition (PLD) on SrTiO3 substrates. Ferroelectric domain structure is imaged by applying a small ac electric field across interdigitated electrodes, and measuring induced reflectivity changes in the film, which are directly related to the polarization. Domain re-orientation is observed by acquiring CSOM images as a function of the dc electric field. Local hysteresis loops are obtained by sweeping the dc electric field at fixed positions on the sample. Micrometer-sized regions exhibit both ferroelectric and paraelectric response, indicating that thermal broadening of the phase transition is largely due to inhomogeneities in the thin films.