Domain growth and domain wall roughness along different directions in LiNbO3 single crystal

Linear domains are grown along two different directions (x and y) in z-cut LiNbO3 single crystal by piezoresponse force microscope. Compared with linear domains along x direction, those along y direction possess larger average domain width, higher regularity and lower roughness exponent. These results indicate that domain growth along y direction is more favorable in LiNbO3, which are attributed to the smaller energy of Y domain walls and the layer-by-layer step growth of the hexagonal domains.