  Epitaxial orthorhombic Hf0.5Zr0.5O2 (HZO) films on La0.67Sr0.33MnO3 (LSMO)
electrodes show robust ferroelectricity, with high polarization, endurance and
retention. However, no similar results have been achieved using other
perovskite electrodes so far. Here, LSMO and other perovskite electrodes are
compared. A small amount of orthorhombic phase and low polarization is found in
HZO films grown on La-doped BaSnO3 and Nb-doped SrTiO3, while null amounts of
orthorhombic phase and polarization are detected in films on LaNiO3 and SrRuO3.
The critical effect of the electrode on the stabilized phases is not
consequence of differences in the electrode lattice parameter. The interface is
critical, and engineering the HZO bottom interface on just a few monolayers of
LSMO permits the stabilization of the orthorhombic phase. Furthermore, while
the specific divalent ion (Sr or Ca) in the manganite is not relevant, reducing
the La content causes a severe reduction of the amount of orthorhombic phase
and the ferroelectric polarization in the HZO film.
