Source capture
Authors Yidi Liu, Bai Yang Wang, Jiarui Li, Yaoju Tarn, Lopa Bhatt, Michael Colletta, Yi-Ming Wu, Cheng-Tai Kuo, Jun-Sik Lee, Berit H. Goodge, David A. Muller, Zhi-Xun Shen, Srinivas Raghu, Harold Y. Hwang, Yijun Yu
arXiv / Publisher https://arxiv.org/abs/2603.12196
PDF https://arxiv.org/pdf/2603.12196
Relevance score 5.425
Primary category cond-mat.supr-con
Published 2026-03-13
Research paradigm Experimental
Sample form Thin Film

Summary

In compressively strained bilayer nickelate thin films, by continuously tuning the oxygen stoichiometry, researchers have discovered a superconducting half-dome. Starting from the optimal superconducting state, increasing the oxygen content progressively suppresses superconductivity, driving a transition toward a metallic phase; conversely, decreasing the oxygen content induces a granular superconductor-insulator transition while the onset superconducting temperature remains unchanged. This half-dome structure originates from the distinct roles of interstitial oxygen and oxygen vacancies: the former primarily regulates carrier concentration through doping effects, whereas the latter introduces strong scattering that leads to electronic inhomogeneity. Experiments show that this half-dome consistently appears across different rare-earth combinations and with or without alkaline-earth doping, revealing a universal feature of the bilayer nickelate phase diagram. This finding offers new perspectives for understanding the emergence and suppression of superconductivity in correlated electron systems.

Materials

Methods

Keywords

Highlights

  • The study reveals a half-dome structure consistently across samples with different rare-earth combinations and doping.
  • Oxygen stoichiometry exhibits two qualitatively distinct manifestations: excess oxygen acts as an electronic tuning parameter, while oxygen deficiency introduces strong scattering and electronic inhomogeneity.

Conclusions

  • A superconducting half-dome is observed in compressively strained bilayer nickelate thin films as a function of continuous tuning of oxygen stoichiometry.
  • Increasing oxygen stoichiometry suppresses superconductivity toward a metallic phase, whereas decreasing oxygen stoichiometry drives a granular superconductor-to-insulator transition while leaving the superconducting onset intact.
  • The half-dome structure arises from contrasting roles of interstitial oxygen (doping) versus oxygen vacancies (scattering).
  • The half-dome emerges consistently across samples with different rare-earth combinations, with or without alkaline-earth doping, revealing a general feature of the bilayer nickelate phase diagram.

Main claims

  • Oxygen excess suppresses superconductivity toward a metallic phase through doping; oxygen deficiency drives a granular superconductor-insulator transition.
    • Evidence: Abstract,Full text: increasing oxygen stoichiometry gradually suppresses superconductivity toward a metallic phase, whereas decreasing oxygen stoichiometry drives a granular superconductor-to-insulator transition.
  • The superconducting half-dome is a universal feature across different rare-earth combinations and alkaline-earth doping.
    • Evidence: Abstract,Full text: half-dome emerges consistently across samples with different rare-earth combinations, with or without alkaline-earth doping.
  • Interstitial oxygen acts as a dopant while oxygen vacancies introduce strong disorder.
    • Evidence: Abstract,Full text: The pronounced asymmetry suggests that oxygen vacancies play a fundamentally different role from oxygen interstitials.

Workflow

  • sample_preparation
    • Materials: LSNO; LPNO; LPCNO; SLAO substrate
    • Methods: pulsed laser deposition; molecular beam epitaxy
  • oxygen_stoichiometry_tuning
    • Methods: ozone annealing; vacuum annealing; EELS; XAS
    • Observations: two-stage evolution of transport
  • transport_characterization
    • Methods: resistivity measurements; Hall effect measurements
    • Observations: superconducting half-dome; SIT scaling
  • phase_diagram_construction
    • Methods: normalization of conductivity; contour mapping
    • Observations: universal half-dome across different compositions