Source capture
Authors Yu-Han Cao, Kai-Yue Jiang, Hong-Yan Lu, Da Wang, Qiang-Hua Wang
arXiv / Publisher http://arxiv.org/abs/2604.05590v1
PDF https://arxiv.org/pdf/2604.05590v1
Relevance score 5.779
Primary category Not available in this batch.
Published Not available in this batch.
Research paradigm Theoretical
Sample form Thin Film

Summary

Using first-principles calculations and the singular-mode functional renormalization group method, we systematically investigate the effect of interlayer nickel-nickel distance on the ground state in La3Ni2O7/LaAlO3 thin films. The results show that a smaller interlayer distance leads to a C-type spin density wave (interlayer ferromagnetic coupling), while a larger interlayer distance yields a G-type spin density wave (interlayer antiferromagnetic coupling). Between these two phases, an s±-wave superconducting state emerges, dominated by pairing in the Ni 3d3z2-ᵣ2 orbital. This finding explains the origin of superconductivity observed in the thin films under ambient pressure and predicts that applying pressure will suppress the superconducting transition temperature until the system enters the C-type spin density wave. If confirmed experimentally, this prediction will provide deep insight into the nature of electronic correlations in this system, as the C-type spin density wave naturally emerges within the itinerant electron picture, whereas it is difficult to realize within the local magnetic moment picture (where interlayer spins remain antiferromagnetically coupled).

Materials

Methods

Keywords

Highlights

  • The study predicts that applied pressure will decrease the superconducting transition temperature until the system enters the C-type spin density wave.
  • The C-type SDW is naturally achieved in the itinerant picture, whereas it would be difficult in the local moment picture.

Conclusions

  • For smaller interlayer distance, the ground state is a C-type spin density wave (interlayer ferromagnetic), while a larger distance yields a G-type spin density wave (interlayer antiferromagnetic).
  • Between these phases, s±-wave superconductivity emerges, dominated byNi 3d_z2 orbital pairing.

Main claims

  • The ground state of La3Ni2O7/LAO thin films tunes from C-type SDW through s±-wave SC to G-type SDW with increasing interlayer Ni-Ni distance
    • Evidence: SM-FRG calculations show that for smaller d_Ni the leading instability is C-type SDW with interlayer ferromagnetic coupling, for larger d_Ni it is G-type SDW with interlayer antiferromagnetic coupling, and at intermediate d_Ni an s±-wave SC state emerges dominated by dz2 orbital pairing

Workflow

  • First-principles calculations — Electronic structure depends sensitively on d_Ni
    • Materials: La3Ni2O7 thin film with in-plane lattice constant 3.78 Å
    • Methods: DFT using VASP; Maximally localized Wannier functions
    • Observations: Band structure, Fermi surfaces, density of states
  • Singular-mode functional renormalization group (SM-FRG) — Ground state evolves from C-type SDW to SC to G-type SDW with increasing d_Ni
    • Materials: Tight-binding model from DFT
    • Methods: SM-FRG including Coulomb interactions (U=5 eV, J_H=1 eV)
    • Observations: For small d_Ni: C-type SDW (interlayer FM); for large d_Ni: G-type SDW (interlayer AFM); intermediate: s±-wave SC