Interlayer‐Mediated Stabilization of Metastable P6₃cm ScFeO₃ on Al₂O₃

Abstract The metastable P6₃cm phase of ScFeO₃ has potential for multiferroic applications not possible in the ground state if stabilization routes can be identified. This work demonstrates that the P6₃cm phase of ScFeO₃ is stabilized on (0001) Al₂O₃ by the spontaneous formation of two atomic layers of (111) Fmm FeO during pulsed laser deposition, as observed via scanning transmission electron microscopy and a shift in the Fe L‐edge on approaching the interface. The matching oxygen sublattice and reduced strain of the FeO interlayer enable a ScFeO₃ [110] || [2] FeO || Al₂O₃ [110] orientation relationship despite a −17.1% lattice mismatch. Temperature‐dependent X‐ray diffraction further support interlayer‐mediated stabilization, as FeO forms above 850 °C, preceding the formation of the P6₃cm ScFeO₃ phase at 1000 °C. The identification of the FeO interlayer provides insights into the phase stabilization mechanism of P6₃cm ScFeO₃ and presents a strategy for stabilizing other metastable materials that lack epitaxial substrates.