Structural transition, electric transport, and electronic structures in the compressed trilayer nickelate La₄Ni₃O₁₀

摘要

Atomic structure and electronic band structure are fundamental properties for understanding the mechanism of superconductivity. Motivated by the discovery of pressure-induced high-temperature superconductivity at 80 K in the bilayer Rud-dlesden-Popper nickelate La₃Ni₂O₇, the atomic structure and electronic band structure of the trilayer nickelate La₄Ni₃O₁₀ under pressure up to 44.3 GPa are investigated. A structural transition from the monoclinic P₂₁/a space group to the tetragonal I₄/mmm around 12.6–13.4 GPa is identified, accompanied by a drop of resistance below 7 K. Density functional theory calculations suggest that the bonding state of Ni 3d_z2orbital rises and crosses the Fermi level at high pressures, which may give rise to possible superconductivity observed in resistance under pressure in La₄Ni₃O₁₀. The trilayer nickelate La₄Ni₃O₁₀ shows some similarities with the bilayer La₃Ni₂O₇ and has unique properties, providing a new platform to investigate the underlying mechanism of superconductivity in nickelates.

材料

• La₄Ni₃O₁₀

方法

• X-ray diffraction
• resistivity measurements
• DFT

关键词

• structural transition
• monoclinic to tetragonal
• resistance drop
• ni 3dz2 bonding state

亮点

• The trilayer nickelate La₄Ni₃O₁₀ shows similarities with bilayer La₃Ni₂O₇, providing a new platform to investigate the mechanism of superconductivity.

结论

• A structural transition from monoclinic P₂₁/a to tetragonal I₄/mmm occurs around 12.6–13.4 GPa, accompanied by a drop of resistance below 7 K.
• DFT calculations suggest that the bonding state of Ni 3dz2 orbital rises and crosses the Fermi level at high pressures, which may give rise to possible superconductivity.

主要论断

• La₄Ni₃O₁₀ undergoes a structural phase transition from monoclinic P₂₁/a to tetragonal I₄/mmm around 12.6-13.4 GPa, accompanied by a drop in resistance below 7 K indicative of possible superconductivity.
  • 证据: In situ XRD shows merging of (020) and (20-1) peaks; transport shows resistance drop above 10 GPa suppressed by 1 T.
• The structural transition leads to the dz2 bonding band crossing the Fermi level, similar to the scenario in bilayer La₃Ni₂O₇.
  • 证据: DFT calculations show dz2 bonding band rises and crosses EF at 44.3 GPa; additional electron pocket appears.

研究流程

• Crystal Growth and Ambient Characterization — La₄Ni₃O₁₀ exhibits intertwined charge/spin density wave transition at T* ≈136.5 K.
  • 材料: La₄Ni₃O₁₀ single crystals
  • 方法: floating zone growth at 20 bar O₂; powder XRD; magnetic susceptibility and resistivity
  • 观察: Monoclinic P₂₁/a structure; metallic behavior with anomaly at ≈136.5K
• High-Pressure Synchrotron XRD — Structural transition to tetragonal I₄/mmm occurs under pressure.
  • 材料: La₄Ni₃O₁₀ powder
  • 方法: in situ synchrotron XRD; Rietveld refinement
  • 观察: Structural transition from P₂₁/a to I₄/mmm around 12.6-13.4 GPa; Ni-O-Ni angle becomes 180°
• High-Pressure Transport Measurements — Evidence of possible superconductivity with onset around 7 K after structural transition.
  • 材料: La₄Ni₃O₁₀ single crystals
  • 方法: four-probe van der Pauw in DAC
  • 观察: Resistance drop below 7 K above 10 GPa; suppressed by magnetic field
• DFT Electronic Structure Calculations — Pressure-induced dz2 σ-bond metallization may give rise to superconductivity.
  • 材料: La₄Ni₃O₁₀
  • 方法: DFT (VASP) with LDA+U (U=0.5 eV)
  • 观察: dz2 bonding band rises and crosses Fermi level at high pressure; additional electron pocket appears at Γ