Refreshment of SrTiO₃ Substrate for Layer Peeling-off using Sacrificial Sr₃Al₂O₆

The use of water-soluble sacrificial layer of Sr₃Al₂O₆ has tremendously boosted the research on freestanding functional oxide thin films, especially thanks to its ultimate capability to produce high-quality epitaxial perovskite thin films. However, the costly single-crystalline substrates, e.g., SrTiO₃, are generally discarded after obtaining the freestanding thin films. Here, it is demonstrated that the SrTiO₃ substrates can be recycled to fabricate La_0.7Sr_0.3MnO₃ films with nearly identical structural and electrical properties. After attaining freestanding thin films, the residues on SrTiO₃ can be removed by 80 °C hot water soaking and rinsing treatments. Consequently, the surface of SrTiO₃ reverted to its original step-and-terrace structure.