Nanodomain faceting in ferroelectrics

Abstract

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.

Shear effects in lateral piezoresponse force microscopy at 180° ferroelectric domain walls

“…Although quantitative measurements of piezoelectric coefficients via PFM are challenging, the technique has provided valuable information about the behavior of domain walls and switching dynamics both in thin films 7,8 and in device structures. [9][10][11] In this context, understanding the origins of the PFM signal observed at ferroelectric domain walls is an important issue.Considering only piezoelectric effects, in a c-axis-oriented tetragonal ferroelectric film with an electric field applied along the polarization axis, the piezoelectric response is determined by the d 33 coefficient, leading to a purely vertical PFM signal. However, in such films, a nonzero lateral PFM response has been observed specifically at the position of 180°domain walls.…”

“…Although quantitative measurements of piezoelectric coefficients via PFM are challenging, the technique has provided valuable information about the behavior of domain walls and switching dynamics both in thin films 7,8 and in device structures. [9][10][11] In this context, understanding the origins of the PFM signal observed at ferroelectric domain walls is an important issue.…”

Crystallographic and magnetic identification of secondary phase in orientated Bi5Fe0.5Co0.5Ti3O15 ceramics

“…Such leakage may result from mixed valence Fe 2þ and Fe 3þ or oxygen vacancies and even both, as observed in BiFeO 3 . 25 Note, however, that as the loops are not saturated, PE loops are unable to provide evidence of ferroelectricity in this case.…”

Correlation between nanoscale and nanosecond resolved ferroelectric domain dynamics and local mechanical compliance

“…Such directionality for domain growth has separately been correlated to particular crystal directions. 2,7,19,20 These observations provide strong evidence for: (i) the presence of a dominant defect at the nucleation site with an activation energy barrier for domain switching that is diminished compared to the surrounding film; (ii) a short range influence by this defect on domain growth, to a distance on the order of 100 nm or less; and (iii) growth beyond this radius unimpeded by the initiating defect, determined instead by the surrounding energy landscape. 8,13,20 Once a domain has nucleated at a low activation energy defect site, during further poling the advancing domain wall should thus encounter a distribution of activation energies from the various defects that may exist at the domain periphery, locally enhancing or retarding growth in specific directions.…”