Effect of oxygen stoichiometry on the ferroelectric property of epitaxial all-oxide $La0.7Sr0.3MnO3/Pb(Zr0.52Ti0.48)O3/La0.7Sr0.3MnO3$ thin-film capacitors

Epitaxial all-oxide ferroelectric thin-film capacitors, $La0.7Sr0.3MnO3/Pb(Zr0.52Ti0.48)O3/La0.7Sr0.3MnO3$ (LSMO/PZT/LSMO), have been grown on $LaAlO3(001)$ substrates by pulsed-laser deposition. By changing the deposition oxygen pressure, we varied the oxygen content in the oxide electrodes and ferroelectric film, respectively, and studied their effect on switching and fatigue behavior of the epitaxial capacitors. The capacitors were also cooled at various oxygen pressures in the range of $5×10−6–10$ Torr to examine their tendency to process-induced imprint. It is found that all the capacitors show almost square hysteresis loops with remnant polarization of 35–40 μC/cm² and a coercive field of 40–50 kV/cm, irrespective of the oxygen concentration in the ferroelectric and electrode films. Contrary to the capacitors using $La0.5Sr0.5CoO3$ as electrodes, when cooled at reduced oxygen pressures, the LSMO/PZT/LSMO capacitors show a strong resistance to the process-induced imprint failure, which is ascribed to the high thermal stability of the LSMO films. On the other hand, the oxygen content in the electrodes is shown to be an important factor that controls the fatigue behavior of the epitaxial all-oxide ferroelectric capacitors.