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 Sr2IrO4−δ with low-temperature scanning tunneling microscopy and find enhanced local density of states (LDOS) inside the Mott gap at the location of individual apical oxygen site defects. We visualize paths of enhanced conductance arising from the overlapping of defect states which induces finite LDOS at the Fermi level. By combining these findings with the typical spatial extension of isolated defects of about 2~nm, we show that the insulator to metal transition in Sr2IrO4−δ is of percolative nature.
@article{arxiv.1909.10207,
title = {Percolative Mott insulator-metal transition in doped Sr$_2$IrO$_4$},
author = {Zhixiang Sun and Jose M. Guevara and Steffen Sykora and Ekaterina M. Pärschke and Jeroen van den Brink and Kaustuv Manna and Andrey Maljuk and Sabine Wurmehl and Bernd Büchner and Christian Hess},
journal= {arXiv preprint arXiv:1909.10207},
year = {2021}
}