Crystalline rhombohedral multilayer graphene (RMG) has emerged as an ideal platform for studying unconventional superconductivity. Here, we report the observation of superconductivity in moir\'eless rhombohedral heptalayer graphene (RHG) at zero magnetic field. The superconducting phases emerge at low displacement electric fields (|D| < 0.2 V/nm) and are symmetrically distributed about D = 0, with one robust state exhibiting zero resistance and two weaker superconducting features. Comparisons with rhombohedral pentalayer graphene (RPG) reveal distinct perpendicular magnetic-field responses, and quantum oscillation measurements indicate that superconductivity in RHG arises from a half-metallic normal state. These results highlight the strong dependence of superconductivity on layer number and electronic structure in RMG systems and provide new insights into its microscopic origin.
@article{arxiv.2605.17890,
title = {Multiple Superconducting Phases in Rhombohedral Heptalayer Graphene},
author = {Chuanqi Zheng and Chushan Li and Chenyu Zhang and Kenji Watanabe and Takashi Taniguchi and Hao Yang and Dandan Guan and Liang Liu and Shiyong Wang and Yaoyi Li and Hao Zheng and Canhua Liu and Jinfeng Jia and Zhiwen Shi and Guorui Chen and Tingxin Li and Xiaoxue Liu},
journal= {arXiv preprint arXiv:2605.17890},
year = {2026}
}