Collective spin excitations in trilayer nickelate La₄Ni₃O₁₀

Summary

Resonant inelastic X-ray scattering (RIXS) at the Ni L edge on single crystals of the trilayer nickelate La₄Ni₃O₁₀ reveals collective spin excitations with a bandwidth of approximately 60 meV, comparable to that of the bilayer nickelate La₃Ni₂O₇, but with significantly reduced spectral weight, indicating weaker electronic correlations in the trilayer system. Localized spin excitations at around 100 and 200 meV are also observed, originating from local dipole and quadrupole excitations. The dispersive magnetic excitations exhibit three-dimensional characteristics, and fitting with linear spin-wave theory yields comparable in-plane and out-of-plane exchange coupling parameters, with the interlayer coupling being the strongest. The results indicate that La₄Ni₃O₁₀ possesses stronger three-dimensional magnetism, with its spin dynamics consistent with spin-density-wave order, while the reduced electronic correlations and three-dimensional multi-orbital character are key factors leading to differences in its magnetic excitation spectrum compared to the bilayer nickelate, providing important insights into the evolution of magnetism and its connection to superconductivity in the Ruddlesden-Popper nickelate family.

Materials

• La₄Ni₃O₁₀

Methods

• resonant inelastic X-ray scattering (RIXS)
• linear spin-wave theory
• exact diagonalization

Keywords

• collective spin excitations
• spin density wave
• three dimensional magnetism
• exchange coupling

Highlights

• Localized spin excitations at around 100 and 200 meV originate from local dipole and quadrupole excitations.
• The interlayer coupling is the strongest exchange parameter, pointing to enhanced three-dimensional magnetism.

Conclusions

• Collective spin excitations in La₄Ni₃O₁₀ have a bandwidth of about 60 meV but significantly reduced spectral weight compared to La₃Ni₂O₇, indicating weaker electronic correlations.
• The magnetic excitations exhibit three-dimensional characteristics with comparable in-plane and out-of-plane exchange couplings.

Main claims

• Collective spin excitations in La₄Ni₃O₁₀ have comparable bandwidth (≈60 meV) to La₃Ni₂O₇ but significantly reduced spectral weight
  • Evidence: RIXS measurements show dispersive excitations with zone boundary energy ≈60 meV,Spectral weight is nearly an order of magnitude weaker than in La₃Ni₂O₇
• La₄Ni₃O₁₀ exhibits stronger three-dimensional magnetism with comparable in-plane and out-of-plane exchange couplings
  • Evidence: LSWT fits yield J_in=46 meV, J_out=34 meV, J_⊥=62 meV,Dispersive excitations are three-dimensional

Workflow

• Sample growth and characterization
  • Materials: La₄Ni₃O₁₀ single crystals
  • Methods: High-pressure optical floating zone method; X-ray diffraction
• RIXS measurements — Collective spin excitations with 60 meV bandwidth observed
  • Materials: Ni L-edge RIXS at ID₃₂ and 41A₁
  • Methods: RIXS with polarization analysis; Energy resolution ≈40 meV
  • Observations: Localized spin excitations at ≈100 meV and ≈200 meV; Dispersive excitation at ≈60 meV
• Modeling — Three-dimensional magnetism with strongest interlayer coupling
  • Methods: Linear spin-wave theory (LSWT); Single-ion exact diagonalization
  • Observations: Intra- and inter-layer exchange couplings: J_in=46 meV, J_out=34 meV, J_⊥=62 meV