Imaging ferroic domain structures with an acoustic microscope:: Example of PPLN

It is shown that acoustic microscopy at 130 MHz is able to display the domain structure of PPLN samples from the local detection of mechanical properties variations. Specific defocusing settings can improve this detection. Acoustic signatures are useful to measure the elastic parameters of the substrate in a non destructive way. Artificial domain structures with different periods have been detected, and acoustic signatures of these structures show that they induce variations of the ultrasonic wave propagation conditions. These results are interpreted by mechanical properties of the ferroelectric domain walls that are different from the bulk.