Regulating oxygen content and superconductivity in La3Ni2O7+δ

Peiyue Ma; Jingyuan Li; Xing Huang; Yixing Zhao; Yifeng Han; Mengwu Huo; Deyuan Hu; Chaoxin Huang; Hengyuan Zhang; Sihao Deng; Lunhua He; Juan Rodriguez-Carvajal; Abhisek Bandyopadhyay; Alessandro Puri; Devashibhai Adroja; Xiang Chen; Tao Xie; Zhen Chen; Hualei Sun; Meng Wang

doi:10.59717/j.tip.2026.100012

The Innovation Physics > 2026 Vol. 1 > No. 1 > 100012

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Regulating oxygen content and superconductivity in La₃Ni₂O_7+δ

1.
Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Institute of Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
2.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
3.
School of Chemistry and Chemical Engineering, Hainan University, Haikou 570228, China
4.
Spallation Neutron Source Science Center, Dongguan 523803, China
5.
Diffraction Group, Institut Laue-Langevin, 71, Avenue des Martyrs, Grenoble Cedex 9 20156-38042 , France
6.
Department of Physics, Ramashray Baleshwar College (A Constituent Unit of Lalit Narayan Mithila University, Darbhanga), Dalsingsarai, Samastipur, Bihar 848114, India
7.
ISIS Neutron and Muon Facility, STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, United Kingdom
8.
Department of Physics and Astronomy, Alma Mater Studiorumâ Universita di Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy
9.
CNR - Istituto Officina dei Materiali, Grenoble c/o ESRF, The European Synchrotron, 71 Avenue des Martyrs, Grenoble Cedex 9 40220-38043, France
10.
Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, Auckland Park 2006, South Africa
11.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
12.
School of Science, Sun Yat-Sen University, Shenzhen 518107, China

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13These authors contributed equally
Corresponding authors: sunhlei@mail.sysu.edu.cn(H.S.); wangmeng5@mail.sysu.edu.cn(M.W.)
Received Date: May 20, 2026

Accepted Date: September 08, 2026

Published Online: September 17, 2026

The Innovation Physics 1(1), https://doi.org/10.59717/j.tip.2026.100012 | Cite this article

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PUBLIC SUMMARY
1. High-quality Ruddlesden-Popper nickelates advance our understanding of their superconductivity.
  
  Synthesizing high-quality nickelates is challenging due to oxygen inhomogeneity and coexisting mixed phases.
  
  This work advances La₃Ni₂O_7+δ synthesis and achieves controllable oxygen modulation.
  
  Oxygen stoichiometry and microstructure affect superconductivity and upper critical field in nickelates.
  
  We built a phase diagram of superconducting temperature and upper critical field versus oxygen content.

ABSTRACT

ABSTRACT

The synthesis of high-quality Ruddlesden-Popper (RP) nickelates remains challenging due to variations in oxygen content and the prevalence of intergrown RP phases. Precisely controlling the stoichiometry and characterizing the resulting physical properties are essential for understanding the mechanism of high-T_c superconductivity in these materials. In this work, we synthesize a series of La₃Ni₂O_7+δ samples with systematically controlled averaged oxygen content across the range −0.34 ≤ δ ≤ 0.08 and perform comprehensive structural and compositional analyses. Tuning the averaged oxygen content drives the evolution of the microstructure from a mixture of bilayer and monolayer-bilayer phases, to a pure bilayer phase, and finally to a predominantly bilayer phase containing trilayer intergrowths. High-pressure transport measurements reveal distinct superconducting transitions with contrasting T_c values, corresponding to the bilayer phase, the hybrid phase, and trilayer inclusions. Notably, we find that the phase purity also modulates the upper critical field (H_c2) of the bilayer superconductivity. By establishing a phase diagram of T_c and H_c2 as functions of averaged oxygen content in La₃Ni₂O_7+δ, this work advances synthetic control and provides new insights into the superconducting mechanism of RP nickelates.
- La₃Ni₂O₇ /
- oxygen content /
- hybrid phases /
- trilayer intergrowths /
- bilayer superconducting upper critical field

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REFERENCES

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Ma P., Li J., Huang X., et al. (2026). Regulating oxygen content and superconductivity in La3Ni2O7+δ. The Innovation Physics 1:100012. https://doi.org/10.59717/j.tip.2026.100012

Ma P., Li J., Huang X., et al. (2026). Regulating oxygen content and superconductivity in La₃Ni₂O_7+δ. The Innovation Physics 1:100012. https://doi.org/10.59717/j.tip.2026.100012

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Regulating oxygen content and superconductivity in La₃Ni₂O_7+δ

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