  Mechanical pressure controls the structural, electric, and magnetic order in
solid state systems, allowing to tailor and improve their physical properties.
A well-established example is ferroelastic ferroelectrics, where the coupling
between pressure and the primary symmetry breaking order parameter enables
hysteretic switching of the strain state and ferroelectric domain engineering.
Here, we study the pressure-driven response in a non-ferroelastic
ferroelectric, ErMnO3, where the classical stress-strain coupling is absent,
and the domain formation is governed by creation-annihilation processes of
topological defects. By annealing ErMnO3 polycrystals under variable pressures
in the MPa-regime, we transform non-ferroelastic vortex-like domains into
stripe-like domains. The width of the stripe-like domains is determined by the
applied pressure as we confirm by three-dimensional phase field simulations,
showing that pressure leads to highly oriented layer-like periodic domains. Our
work demonstrates the possibility to utilize mechanical pressure for domain
engineering in non-ferroelastic ferroelectrics, providing a
processing-accessible lever to control their dielectric, electromechanical, and
piezoelectric response.
