Scanning tunneling spectroscopy (STS) and scanning tunneling microscopy (STM) are perhaps the most promising ways to detect the superconducting gap size and structure in the canonical unconventional superconductor Sr₂RuO₄ directly. However, in many cases, researchers have reported being unable to detect the gap at all in STM conductance measurements. Recently, an investigation of this issue on various local topographic structures on a Sr-terminated surface found that superconducting spectra appeared only in the region of small nanoscale canyons, corresponding to the removal of one RuO surface layer. Here, we analyze the electronic structure of various possible surface structures using first principles methods, and argue that bulk conditions favorable for superconductivity can be achieved when removal of the RuO layer suppresses the RuO₄ octahedral rotation locally. We further propose alternative terminations to the most frequently reported Sr termination where superconductivity surfaces should be observed.

扫描隧道光谱 （STS） 和扫描隧道显微镜 （STM） 可能是直接检测经典非常规超导体 Sr₂RuO₄ 中超导间隙尺寸和结构的最有前途的方法。然而，在许多情况下，研究人员报告说在 STM 电导测量中根本无法检测到差距。最近，对 Sr 封端表面上的各种局部地形结构的这个问题进行调查发现，超导光谱只出现在小纳米级峡谷的区域，对应于去除一个 RuO 表面层。在这里，我们使用第一性原理方法分析了各种可能的表面结构的电子结构，并认为当去除 RuO 层局部抑制 RuO₄ 八面体旋转时，可以实现有利于超导的体条件。我们进一步提出了应观察超导表面的最频繁报告的 Sr 终端的替代终端。