Sr₂RuO₄ (SRO₂₁₄) is a prototypical unconventional superconductor. However, since the discovery of its superconductivity a quarter of a century ago, the symmetry of the bulk and surface superconducting states in single crystal SRO₂₁₄ remains controversial. Solving this problem is massively impeded by the fact that superconducting SRO₂₁₄ is extremely challenging to achieve in thin-films as structural defects and impurities sensitively annihilate superconductivity. Here we report a protocol for the reliable growth of superconducting SRO₂₁₄ thin-films by pulsed laser deposition and identify universal materials properties that are destructive to the superconducting state. We demonstrate that careful control of the starting material is essential in order to achieve superconductivity and use a single crystal target of Sr₃Ru₂O₇ (SRO₃₂₇). By systematically varying the SRO₂₁₄ film thickness, we identify mosaic twist as the key in-plane defect that suppresses superconductivity. The results are central to the development of unconventional superconductivity.

Sr ₂ RuO ₄（SRO ₂₁₄）是典型的非常规超导体。然而，自四分之一世纪前发现其超导性以来，单晶SRO _214中体态和表面超导态的对称性仍存在争议。由于结构缺陷和杂质灵敏地消除了超导性，因此在薄膜中实现超导SRO ₂₁₄极具挑战性，这一事实在很大程度上阻碍了该问题的解决。在这里，我们报告了超导SRO ₂₁₄可靠增长的协议通过脉冲激光沉积形成薄膜，并确定破坏超导状态的通用材料特性。我们证明了对原材料的仔细控制对于实现超导性至关重要，并使用Sr ₃ Ru ₂ O ₇（SRO ₃₂₇）单晶靶。通过系统地改变SRO _214的膜厚，我们将马赛克扭曲识别为抑制超导性的关键面内缺陷。这些结果对于非常规超导性的发展至关重要。