ABO₃ perovskite materials and their derivatives have inherent structural flexibility due to the corner sharing network of the BO₆ octahedron, and the large variety of possible structural distortions and strong coupling between lattice and charge/spin degrees of freedom have led to the emergence of intriguing properties, such as high‐temperature superconductivity, colossal magnetoresistance, and improper ferroelectricity. Here, an unprecedented polar ferromagnetic metal phase in SrRuO₃ (SRO) thin films is presented, arising from the strain‐controlled oxygen octahedral rotation (OOR) pattern. For compressively strained SRO films grown on SrTiO₃ substrate, oxygen octahedral network relaxation is accompanied by structural phase separation into strained tetragonal and bulk‐like orthorhombic phases, and the asymmetric OOR evolution across the phase boundary allows formation of the polar phase, while bulk metallic and ferromagnetic properties are maintained. From the results, it is expected that other oxide perovskite thin films will also yield similar structural environments with variation of OOR patterns, and thereby provide promising opportunities for atomic scale control of material properties through strain engineering.

中文翻译：

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氧八面体网络弛豫在氧化物薄膜中诱导的极性金属相。

由于BO ₆八面体的拐角共享网络，ABO ₃钙钛矿材料及其衍生物具有固有的结构灵活性，并且各种可能的结构变形以及晶格与电荷/自旋自由度之间的强耦合导致了有趣的出现。特性，例如高温超导性，巨大的磁阻和不正确的铁电性。在此，SrRuO ₃（SRO）薄膜中出现了前所未有的极性铁磁金属相，这是由应变控制的氧八面体旋转（OOR）模式引起的。对于在SrTiO _3上生长的SRO压应变薄膜在基体上，氧八面体网络弛豫伴随着结构相分离成应变四方相和块状正交相，跨相边界的不对称OOR演化允许形成极性相，同时保持了大块金属和铁磁特性。从结果可以预期，其他氧化物钙钛矿薄膜也将产生相似的结构环境，并且OOR图案有所变化，从而通过应变工程为材料性能的原子尺度控制提供了有希望的机会。