Topotactic reduction utilizing metal hydrides as reagents emerges as an effective approach to achieve exceptionally low oxidization states of metal ions and unconventional coordination networks. This method opens avenues to the development of entirely new functional materials, with one notable example being the infinite-layer nickelate superconductors. However, the reduction effect on the atomic reconstruction and electronic structures -- crucial for superconductivity -- remains largely unresolved. We design two sets of control Nd0.8Sr0.2NiO2 thin films and implement secondary ion mass spectroscopy to highlight the absence of reduction-induced hydrogen intercalation. X-ray absorption spectroscopy shows a significant linear dichroism with dominant Ni 3dx2−y2 orbitals on superconducting samples, indicating a Ni single-band nature of infinite-layer nickelates. Consistent with the superconducting Tc, the Ni 3d orbitals asymmetry manifests a dome-like reduction duration dependence. Our results unveil the critical role of reduction in modulating the Ni-3d orbital polarization and its impact on the superconducting properties.
@article{arxiv.2403.00960,
title = {On the origin of topotactic reduction effect for superconductivity in infinite-layer nickelates},
author = {Shengwei Zeng and Chi Sin Tang and Zhaoyang Luo and Lin Er Chow and Zhi Shiuh Lim and Saurav Prakash and Ping Yang and Caozheng Diao and Xiaojiang Yu and Zhenxiang Xing and Rong Ji and Xinmao Yin and Changjian Li and X. Renshaw Wang and Qian He and Mark B. H. Breese and A. Ariando and Huajun Liu},
journal= {arXiv preprint arXiv:2403.00960},
year = {2024}
}