Nanodomain faceting in ferroelectrics

We show that after long times (24 h), individual circular domains in 50 nm thick [001] epitaxial films of ferroelectric lead zirconate titanate (PZT) develop facets due to the crystalline anisotropy, e.g. along [100] directions. This appears to be a creep process (Tybell et al 2002 Phys. Rev. Lett. 89 097601; Paruch et al 2006 J. Appl. Phys. 100 051608) and was first seen in a nanoarray of 180 ◦ domains (Ganpule et al 2002 Phys. Rev. B 65 014101). The effect is independent of polarity and thus rules out any electronic dependence on different work functions for top and bottom electrodes. The phenomenon is interpreted instead as a mechanical relaxation due to highly inhomogeneous stress distributions on the nanodisks, assumed to have stress-free edges. 1