Visualizing the electronic structure of infinite-layer cuprate by scanning tunnelling spectroscopy

Infinite layer Sr_1-xLa_xCuO_2+δ is a prototype to study the high-T_c superconductivity in cuprates. Using oxide-MBE technique, we fabricate Sr_1-xLa_xCuO_2+δ films with different doping levels. Mottness has been observed in lightly electron-doped Sr_1-xLa_xCuO₂ by in-situ STM. We also find a phase transition to hole-doped Sr_1-xLa_xCuO_2+δ when x exceeds 0.1. Apical oxygens are responsible for this electron- to hole-cuprate transition, which is supported by transmission electron microscope measurements. By comparing the electronic structures in electron- and hole-doped Sr_1-xLa_xCuO_2+δ, we give some clues to understand the e-h asymmetry in cuprates.

This work is financially supported by the Ministry of Science and Technology of China (Grants No. 2017YFA0304600, 2015CB921001, 2016YFA0301004), the National Natural Science Foundation of China (Grants No. 11427903, 11504196, 11634007, 11774192), and in part by the Beijing Advanced Innovation Center for Future Chip (ICFC).