Despite many efforts to rationalize the strongly correlated electronic ground states in doped Mott insulators, the nature of the doping-induced insulator-to-metal transition is still a subject under intensive investigation. Here, we probe the nanoscale electronic structure of the Mott insulator ${\mathrm{Sr}}_2{\mathrm{IrO}}_{4-\delta }$ with low-temperature scanning tunneling microscopy and find an enhanced local density of states (LDOS) inside the Mott gap at the location of individual defects which we interpret as defects at apical oxygen sites. A chiral behavior in the topography for those defects has been observed. We also visualize the local enhanced conductance arising from the overlapping of defect states which induces finite LDOS inside of the Mott gap. By combining these findings with the typical spatial extension of isolated defects of about 2 nm, our results indicate that the insulator-to-metal transition in ${\mathrm{Sr}}_2{\mathrm{IrO}}_{4-\delta }$ could be percolative in nature.

中文翻译：

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掺杂Sr2IrO4中渗流Mott绝缘体-金属跃迁的证据

尽管为使掺杂的Mott绝缘子中的强相关电子基态合理化做出了许多努力，但是掺杂引起的绝缘子到金属过渡的性质仍然是深入研究的主题。在这里，我们探讨了莫特绝缘子的纳米级电子结构$r_{\mathrm{2个}}{\mathrm{氧化铁}}_{4-\delta }$用低温扫描隧道显微镜，在单个缺陷的位置的Mott间隙内发现了增强的局部态密度（LDOS），我们将其解释为顶端氧位点处的缺陷。已经观察到这些缺陷在形貌上的手性行为。我们还可视化了由缺陷状态的重叠引起的局部增强电导，缺陷状态的重叠在Mott间隙内部引起了有限的LDOS。通过将这些发现与大约2 nm的典型隔离缺陷的空间扩展相结合，我们的结果表明绝缘子向金属的转变$r_{\mathrm{2个}}{\mathrm{氧化铁}}_{4-\delta }$ 本质上可能是渗透性的。