Ultra‐Thin Cubic Ti₃Al Buffer/Template Layer Achieving Giant Polarization of Epitaxial Pb(Zr_0.40Ti_0.60)O₃ Film

Abstract Interface strain significantly affects polarization in ferroelectric devices. In this paper, an innovative strategy is proposed to substantially enhance ferroelectric polarization using an ultra‐thin “soft‐buffer‐layer” (SBL), which reduces dislocation density and increases the tetragonality of ferroelectric thin films because of small elastic constants of Ti 3 Al along x and y axes. And in this work, it is demonstrated that PbZr 0.4 Ti 0.6 O 3 (PZT) thin films are perfect c‐axis‐oriented epitaxial structures on (001) SrTiO 3 (STO) substrates. The PZT capacitor with Ti 3 Al buffer layer exhibits a remarkable remnant polarization, reaching up to 131.93 µC cm −2 at an applied voltage of 5.00 V. Surprisingly, under the clamping effect of SrRuO 3 and STO, Ti 3 Al films exhibit cubic structure and facilitate matching to the PZT film. It is proposed that the introduction of the Ti 3 Al buffer layer notably improves the tetragonality ( c/a ) ratio from 1.002 to 1.024, and significantly enhancing the polarization. There is no doubt that this adjustment reduces dislocation density and decreases stress influence from STO substrate. Given these advantages, the SBL method presents a compelling option for epitaxial PZT films, and also for enhancing the physical properties of other functional thin film materials.