Electronic correlations and Hund’s rule coupling in trilayer nickelate La₄Ni₃O₁₀

Summary

Trilayer Ruddlesden-Popper phase La₄Ni₃O₁₀ has been observed with T_c of ∼30 K at high pressure in a recent experiment, which further expanded the family of nickelate superconductors. In this study, we explored the effects of electronic correlations in La₄Ni₃O₁₀ using density functional theory plus dynamical mean-field theory at ambient and high pressures. Our derived spectral functions and Fermi surface of the ambient pressure phase are nicely consistent with the experimental results by angle-resolved photoemission spectroscopy, which emphasized the importance of electronic correlations in La₄Ni₃O₁₀. We also found the electronic correlations in pressurized La₄Ni₃O₁₀ are both orbital-dependent and layer-dependent due to the presence of Hund’s rule coupling. There is a competition between the Hund’s rule coupling and the crystal-field splitting, and therefore, the Ni–O layers with weaker crystal-field splitting energy would have stronger electronic correlations.

Materials

• La₄Ni₃O₁₀

Methods

• DFT
• DMFT

Keywords

• electronic correlations
• hund's rule coupling
• orbital dependent
• layer dependent
• crystal field splitting

Highlights

• The derived spectral functions and Fermi surface of the ambient pressure phase are nicely consistent with experimental results by angle-resolved photoemission spectroscopy, emphasizing the importance of electronic correlations.

Conclusions

• Electronic correlations in pressurized La₄Ni₃O₁₀ are both orbital-dependent and layer-dependent due to the presence of Hund's rule coupling.
• Ni–O layers with weaker crystal-field splitting energy would have stronger electronic correlations.

Main claims

• Electronic correlations in pressurized La₄Ni₃O₁₀ are both orbital-dependent and layer-dependent, primarily due to Hund's rule coupling.
  • Evidence: DFT+DMFT self-energy analysis shows larger mass enhancement for dz2 orbitals and outer layers; effect diminishes when J=0.
• There is a competition between Hund's rule coupling and crystal-field splitting, with Ni-O layers having weaker crystal-field splitting showing stronger electronic correlations.
  • Evidence: Inner layers have larger crystal-field splitting and lower mass enhancement; transition value of J for high-spin state is higher for inner layers.

Workflow

• DFT+DMFT Calculations — DFT+DMFT provides improved description over DFT.
  • Materials: La₄Ni₃O₁₀
  • Methods: DFT (Wien2k) + DMFT (eDMFT package); CTQMC solver; full charge self-consistent
  • Observations: Spectral functions and Fermi surface for P₂₁/a phase match ARPES; orbital-dependent and layer-dependent correlations in I₄/mmm phase
• Analysis of Self-Energy and Quasiparticle Weight — Orbital- and layer-dependent electronic correlations originate from Hund's rule coupling.
  • Materials: La₄Ni₃O₁₀
  • Methods: extraction of self-energy on Matsubara axis; quasiparticle weight Z from polynomial fit
  • Observations: Ni dz2 orbitals more correlated than dx2-y2; outer layers more correlated than inner layers; effect mainly from Hund's coupling J
• Atomic Spin-State Analysis — Competition between Hund's coupling and crystal-field splitting controls spin states.
  • Materials: La₄Ni₃O₁₀
  • Methods: probability of atomic configurations from DMFT; instantaneous local magnetic moment
  • Observations: Transition from low-spin to high-spin with increasing J; inner layers require larger J for transition