On the origin of topotactic reduction effect for superconductivity in infinite-layer nickelates

Abstract

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 Nd${}_{0.8}$Sr${}_{0.2}$NiO${}_2$ 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 3d${}_{x2-y2}$ orbitals on superconducting samples, indicating a Ni single-band nature of infinite-layer nickelates. Consistent with the superconducting $T_c$, 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.

Main: 21 pages, 4 figure - Supplementary: 7 pages, 5 figure

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Cited by in corpus (5)

• Superconductivity in PrNiO2 infinite-layer nickelates
• Magnetic phase diagram of a two-orbital model for bilayer nickelates varying doping
• Capping effects on spin and charge excitations in parent and superconducting Nd1-xSrxNiO2
• Theoretical study on the possibility of high $T_c$ s$\pm$-wave superconductivity in the heavily hole-doped infinite layer nickelates
• Achieving superconductivity in infinite-layer nickelate thin films by aluminum sputtering deposition