Abstract
Understanding the dynamic behavior of interfaces in ferroic materials is
an important field of research with widespread practical implications,
as the motion of domain walls and phase boundaries are associated with
substantial increases in dielectric and piezoelectric effects. Although commonly
studied in the macroscopic regime, the local dynamics of interfaces
have received less attention, with most studies limited to domain growth
and/or reversal by piezoresponse force microscopy (PFM). Here, spatial mapping
of local domain wall-related relaxation in a tensile-strained PbTiO3 thin
film using time-resolved band-excitation PFM is demonstrated, which allows
exploring of the field-induced strain (piezoresponse) as a function of applied
voltage and time. Through multivariate statistical analysis on the resultant
4-dimensional dataset (x,y,V,t) with functional fitting, it is determined that
the relaxation is strongly correleated with the distance to the domain walls,
and varies based on the type of domain wall present in the probed volume.
Phase-field modeling shows the relaxation behavior near and away from the
interfaces, and confirms the modulation of the z-component of polarization
by wall motion, yielding the observed piezoresponse relaxation. These studies
shed light on the local dynamics of interfaces in ferroelectric thin films, and
are therefore important for the design of ferroelectric-based components in
microelectromechanical systems.
