  The design of the interfacial bondings at metal-oxide interfaces yields
exciting new phenomena and can be a route to sustain, and even promote,
ferroelectricity at the nanoscale. We study the impact of these interfaces on
the nature of the spontaneous polarization (single- vs. multi-domain) of
ferroelectric capacitors. We show that interfacial properties intertwine with
both ferrolectric and electrode parameters to determine the actual ground state
of the system. We find analytically the criterion that specifies if
ferroelectricity appears in a single- or multi- domain fashion as a result of
this intertwining. The physics behind this criterion suggests new means for
tailoring ferroelectric functionalities.
