  Ferroelectrics are technologically important, with wide application in
micromechanical systems, nonlinear optics, and information storage. Recent
discoveries of exotic polarisation textures in these materials, which can
strongly influence their properties, have brought to the forefront questions
about the nature of their domain walls -- long believed to be primarily Ising,
with locally null polarisation. Here, combining three complementary techniques
-- second harmonic generation microscopy, piezoresponse force microscopy, and
transmission electron microscopy - to cover all the relevant lengthscales, we
reveal the N\'eel character (non-Ising polarisation oriented perpendicular to
the wall) of 180{\deg} domain walls in c-phase tetragonal ferroelectric lead
titanate epitaxial thin films, for both artificial and intrinsic domains at
room temperature. Furthermore, we show that variations in the domain density --
detected both optically and via local piezoresponse, then quantified by radial
autocorrelation analysis -- can give us insight into the underlying defect
potential present in these materials.
