Source capture
Authors Motoki Osada, Chieko Terakura, Hsiao-Yi Chen, Akiko Kikkawa, Masamichi Nakajima, Ryoma Asai, Jean-Baptiste Morée, Yusuke Nomura, Ryotaro Arita, Yoshinori Tokura, Atsushi Tsukazaki
arXiv / Publisher https://arxiv.org/abs/2605.20653
PDF https://arxiv.org/pdf/2605.20653
Relevance score 5.596
Primary category cond-mat.supr-con
Published 2026-05-21
Research paradigm Experimental
Sample form Thin Film

Summary

In this study, Pr3Ni2O7 thin films were successfully synthesized on LaAlO3 substrates via epitaxial stabilization, overcoming the thermodynamic stability limitations that hinder bulk synthesis of this compound. Under ambient pressure, the Pr3Ni2O7 films exhibited insulating behavior regardless of ozone annealing treatment; however, under a high pressure of 22 GPa, the films displayed T-linear metallic transport and superconductivity, with an onset superconducting transition temperature of 66 K and a zero-resistance temperature of approximately 40 K. Further investigation revealed that while Nd3Ni2O7 films incorporating the smaller rare-earth ion Nd could also be epitaxially stabilized, no superconductivity was observed within the measured pressure range. Comparison of La, Pr, and Nd Ln3Ni2O7 films showed that the critical pressure Pc required for superconductivity increases with decreasing Ln ionic radius, a trend consistent with Ln substitution studies in bulk materials. This work demonstrates that epitaxial stabilization is an effective approach for expanding the bilayer nickelate superconductor family, offering an important pathway for exploring novel superconducting materials.

Materials

Methods

Keywords

Highlights

  • First realization of Pr3Ni2O7 phase and observation of pressure-induced superconductivity.
  • Achieves Tc above that of La-based counterpart in thin films under similar pressure.
  • Demonstrates that epitaxial stabilization overcomes thermodynamic instability for synthesizing new bilayer nickelates.

Conclusions

  • Pr3Ni2O7 thin films, stabilized by epitaxy on LaAlO3, exhibit insulating behavior at ambient pressure but show superconductivity with onset Tc of 66 K and zero resistance near 40 K at 22 GPa.
  • Nd3Ni2O7 films can also be stabilized but do not show superconductivity up to 20 GPa.
  • Higher critical pressure Pc is required for smaller Ln ions, consistent with bulk Ln substitution trends.
  • Epitaxial stabilization is a powerful technique to expand the family of superconducting bilayer nickelates.

Main claims

  • Pr3Ni2O7 thin films exhibit superconductivity with onset Tc66 K and zero resistance at 37 K under 22 GPa
    • Evidence: From abstract: 'they show T-linear metallic transport and superconductivity reaching an onset Tc of 66 K and zero-resistance at nearly 40 K at 22 GPa'
  • Critical pressure Pc increases with decreasing Ln ionic radius in Ln3Ni2O7 films
    • Evidence: From abstract: 'a higher Pc is required for smaller Ln ions, consistent with trends observed in bulk studies'

Workflow

  • thin_film_deposition — Pr3Ni2O7 thin film stabilized on LaAlO3
    • Materials: LaAlO3 substrate; Pr3Ni2O7 target
    • Methods: pulsed-laser deposition
    • Observations: epitaxial Pr3Ni2O7 film
  • structural_characterization — Film is epitaxial with predominant bilayer stacking
    • Materials: Pr3Ni2O7/LaAlO3
    • Methods: X-ray diffraction; scanning transmission electron microscopy
    • Observations: crystal structure; bilayer stacking; strain state
  • high_pressure_resistivity_measurements — Superconductivity emerges at 22 GPa with onset Tc66K
    • Materials: Pr3Ni2O7 film on LaAlO3
    • Methods: cubic-anvil cell; liquid pressure medium
    • Observations: resistivity vs temperature; superconducting transition