Source capture, zotero
Authors Yang Zhang, Ling-Fang Lin, Thomas A. Maier, Elbio Dagotto
arXiv / Publisher http://arxiv.org/abs/2604.18385v2
PDF https://arxiv.org/pdf/2604.18385v2
Relevance score 5.867
Primary category Not available in this batch.
Published 2026-04-20
Research paradigm Both
Sample form Thin Film

Summary

In recent years, significant breakthroughs have been achieved in the study of Ruddlesden-Popper (RP) nickel oxide superconductors. This article systematically reviews the experimental and theoretical progress in this field, with a particular focus on thin-film systems. Key findings include the emergence of superconductivity in bilayer La3Ni2O7 (T_c ~ 80 K) and trilayer La4Ni3O10 under high pressure, and, critically, the realization of ambient-pressure superconductivity in ultra-thin films of La3Ni2O7 grown on substrates providing compressive strain—a breakthrough that overcomes the high-pressure limitation and enables the use of experimental techniques previously inaccessible in the superconducting state, such as angle-resolved photoemission spectroscopy (ARPES). On the theoretical side, the system requires simultaneous consideration of both the Ni e_g and a1g orbitals, as well as the strong interlayer coupling within bilayers that gives rise to a "dimer" picture, and exhibits strange metal behavior and strong correlation features reminiscent of cuprates. By comparing the similarities and differences among various RP nickel oxides, this article offers a new perspective on understanding the mechanism of high-temperature superconductivity in correlated electron systems and outlines future research directions.

Materials

Methods

Keywords

Highlights

  • Ambient-pressure superconductivity is achieved in ultra-thin La3Ni2O7 films on compressively strained LSAO substrates, enabling ARPES studies.
  • Record Tc up to 63 K in thin films at ambient pressure.
  • Remarkably, ambient-pressure superconductivity was observed in La3Ni2O7 ultra-thin films under compressive strain.

Conclusions

  • Superconductivity in bilayer RP nickelates requires compressive strain or high pressure to straighten Ni-O-Ni bonds and enhance interlayer coupling.
  • Strange metal behavior with linear resistivity is observed in optimal-pressure bulk and optimal-strain thin films.
  • The pairing symmetry is debated, with most evidence favoring s± wave, though some studies suggest d-wave.
  • The discovery of superconductivity with Tc ≈ 80 K in the nickelate Ruddlesden-Popper bilayer La3Ni2O7 at high pressure has opened a new platform for unconventional superconductivity.
  • Ambient-pressure superconductivity was also observed recently in La3Ni2O7 ultra-thin films when grown on substrates that provide compressive strain.
  • This discovery significantly extends the type of experimental techniques that can be used in nickelates.

Main claims

  • Superconductivity in bilayer La3Ni2O7 was first discovered under high pressure with Tc ≈ 80 K.
    • Evidence: Key findings include the emergence of superconductivity in bilayer La3Ni2O7 (T_c ≈ 80 K) and trilayer La4Ni3O10 under high pressure
  • Ambient-pressure superconductivity in ultra-thin films of La3Ni2O7 was realized on compressively strained substrates, enabling ARPES and other techniques.
    • Evidence: ambient-pressure superconductivity in ultra-thin films of La3Ni2O7 grown on substrates providing compressive strain—a breakthrough that overcomes the high-pressure limitation and enables the use of experimental techniques previously inaccessible in the superconducting state, such as angle-resolved photoemission spectroscopy (ARPES).
  • The system requires consideration of both Ni e_g and a1g orbitals and strong interlayer coupling, giving rise to a dimer picture.
    • Evidence: On the theoretical side, the system requires simultaneous consideration of both the Ni e_g and a1g orbitals, as well as the strong interlayer coupling within bilayers that gives rise to a 'dimer' picture

Workflow

Not available in this batch.