Electron-doped infinite-layer Sr1−xEuxCuO2+y films over a wide doping range have been prepared epitaxially on SrTiO3(001) using reactive molecular beam epitaxy. In-plane transport measurements of the single crystalline samples reveal a dome-shaped nodeless superconducting phase centered at x∼ 0.15, a Fermi-liquid behavior and pronounced upturn in low temperature resistivity. We show that the resistivity upturn follows square-root temperature dependence, suggesting the emergence of superconductivity via a three-dimensional percolation process. The percolative superconductivity is corroborated spectroscopically by imaging the electronic phase separation between superconducting and metallic phases with low-temperature scanning tunneling microscopy. Furthermore, we visualize interstitial and apical oxygen anions that rapidly increase in number as x> 0.12, and elucidate their impacts on the superconductivity and normal-state resistivity.
@article{arxiv.2205.01844,
title = {Percolative Superconductivity in Electron-Doped Sr$_{1-x}$Eu$_{x}$CuO$_{2+y}$ Films},
author = {Xue-Qing Yu and Hang Yan and Li-Xuan Wei and Ze-Xian Deng and Yan-Ling Xiong and Jia-Qi Fan and Pu Yu and Xu-Cun Ma and Qi-Kun Xue and Can-Li Song},
journal= {arXiv preprint arXiv:2205.01844},
year = {2022}
}