The ambient-pressure superconductivity in La3Ni2O7 thin films via compressive epitaxial strain provides a highly accessible platform for diverse characterization techniques, facilitating the studies of high-temperature superconductivity. Here, we systematically map the phase diagram and reveal the superconducting dome with an electron-hole crossover in compressively strained La3−xSrxNi2O7−δ thin films by simultaneously tuning Sr doping and oxygen content. The maximum transition temperature (Tc) coincides with an anomalous sign change in the Hall coefficient (RH), reminiscent of electron-doped cuprates, which may signal a Fermi surface reconstruction. Beyond the superconducting dome, a ln1/T insulating regime and a T-linear resistivity regime are also resolved, resembling behaviors observed in cuprates and infinite-layer nickelates. This work reveals a dome-shaped relationship between Tc and RH and establishes a key framework for understanding unconventional superconductivity in nickelate systems.
@article{arxiv.2508.15284,
title = {Superconducting Dome in $\mathrm{La}_{3-x}\mathrm{Sr}_{x}\mathrm{Ni}_{2}\mathrm{O}_{7-\delta}$ Thin Films},
author = {Maosen Wang and Bo Hao and Wenjie Sun and Shengjun Yan and Shengwang Sun and Hongyi Zhang and Zhengbin Gu and Yuefeng Nie},
journal= {arXiv preprint arXiv:2508.15284},
year = {2026}
}