  Epitaxial ferroelectric HfO2 films are the most suitable to investigate
intrinsic properties of the material and for prototyping emerging devices.
Ferroelectric Hf0.5Zr0.5O2(111) films have been epitaxially stabilized on
La2/3Sr1/3MnO3(001) electrodes. This epitaxy, considering the symmetry
dissimilarity and the huge lattice mismatch, is not compatible with
conventional mechanisms of epitaxy. To gain insight into the epitaxy mechanism,
scanning transmission electron microscopy characterization of the interface was
performed, revealing arrays of dislocations with short periodicities. These
observed periodicities agree with the expected for domain matching epitaxy,
indicating that this unconventional mechanism could be the prevailing factor in
the stabilization of ferroelectric Hf0.5Zr0.5O2 with (111) orientation in the
epitaxial Hf0.5Zr0.5O2(111)/La2/3Sr1/3MnO3(001) heterostructure.
