  We investigate nanoscale domain engineering via epitaxial coupling in a set
of SrRuO$_3$/PbTiO$_3$/SrRuO$_3$ heterostructures epitaxially grown on
(110)$_o$-oriented DyScO$_3$ substrates. The SrRuO$_3$ layer thickness is kept
at 55 unit cells, whereas the PbTiO$_3$ layer is grown to thicknesses of 23, 45
and 90 unit cells. Through a combination of atomic force microscopy, x-ray
diffraction and high resolution scanning transmission electron microscopy
studies, we find that above a certain critical thickness of the ferroelectric
layer, the large structural distortions associated with the ferroelastic
domains propagate through the top SrRuO$_3$ layer, locally modifying the
orientation of the orthorhombic SrRuO$_3$ and creating a modulated structure
that extends beyond the ferroelectric layer boundaries.
