  The switching of electric polarization induced by electric fields -a
fundamental functionality of ferroelectrics- is closely associated with the
motions of the domain walls that separate regions with distinct polarization
directions. Therefore, understanding domain-walls dynamics is of essential
importance for advancing ferroelectric applications. In this Letter, we show
that the topology of the multidomain structure can have an intrinsic impact on
the degree of switchable polarization. Using a combination of polarization
hysteresis measurements and piezoresponse force microscopy on a uniaxial
organic ferroelectric, alpha-6,6'-dimethyl-2,2'-bipyridinium chloranilate, we
found that the head-to-head (or tail-to-tail) charged domain walls are strongly
pinned and thus impede the switching process; in contrast, if the charged
domain walls are replaced with electrically neutral antiparallel domain walls,
bulk polarization switching is achieved. Our findings suggest that manipulation
of the multidomain topology can potentially control the switchable
polarization.
