Interfacial coincidence structure between rocksalt TiN and perovskite oxide <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>YAlO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> studied at the atomic scale

Uncovering the interfacial structures at the atomic scale is crucial for understanding and tailoring the emergent phenomena at the interfaces between nitrides and oxides. However, synthesizing high-quality interfaces with extremely large lattice mismatch and varied crystal symmetries remains a challenge. In this study, we reveal a rare interfacial coincidence structure with periodic misfit dislocations between the rocksalt nitride TiN and the perovskite oxide ${\mathrm{YAlO}}_{3}$, utilizing a combination of high-resolution x-ray diffraction and atomic resolution scanning transmission electron microscopy. The coincidence structure, with 3.5 units of TiN matching 4 units of ${\mathrm{YAlO}}_{3}$, facilitates the formation of high-quality interfaces, despite a lattice mismatch as large as $\ensuremath{-}15.4%$ between TiN and ${\mathrm{YAlO}}_{3}$. Furthermore, compared the TiN films coherently grown on MgO substrates, electrical transport measurements uncover that the coincidence interface between TiN and ${\mathrm{YAlO}}_{3}$ with strain relaxation can lead to a higher superconducting transition temperature of 5.33 K compared to 5.02 K. Our work reveals an unconventional interfacial mechanism for forming high-quality heterostructures composed of materials with extremely large lattice mismatch. Moreover, it paves a way to tailor the electronic properties of functional layers by controlling the interfacial structures.