Spin-density-wave transition in monolayer-trilayer La₃Ni₂O₇ single crystals

Summary

This study successfully synthesized high-quality, long-range ordered hybrid 1313-type La₃Ni₂O₇ single crystals (with an alternating monolayer-trilayer structure) and systematically characterized their physical properties. At ambient pressure, the material exhibits typical semiconducting behavior and displays distinct anomalies in resistivity, magnetic susceptibility, and specific heat at 170 K. ¹³⁹La nuclear magnetic resonance spectroscopy unambiguously confirms that these anomalies originate from a spin-density wave (SDW) transition. High-pressure electrical transport measurements indicate that the application of pressure can induce metallization; however, no superconductivity is observed up to 65 GPa. These findings establish hybrid 1313-type La₃Ni₂O₇ as a new member of the Ruddlesden-Popper nickelate family featuring a unique SDW transition, offering a platform for investigating the interplay among crystal structure, electronic order, and superconductivity in hybrid nickelates.

Materials

• La₃Ni₂O₇
• 1313-type La₃Ni₂O₇

Methods

• Optical floating zone growth
• Powder X-ray diffraction
• Single crystal XRD
• STEM
• EDS
• Electrical transport
• Magnetic susceptibility
• Heat capacity
• 139La NMR
• High-pressure transport
• magnetic susceptibility measurement
• specific heat measurement
• nuclear magnetic resonance (NMR) spectroscopy
• high-pressure electrical transport

Keywords

• spin density wave transition
• hybrid 1313 type
• monolayer trilayer stacking
• semiconducting behavior
• pressure induced metallization
• spin density wave (sdw) transition
• anomaly at 170 k
• metallization under pressure

Highlights

• These findings establish hybrid 1313-type La₃Ni₂O₇ as a new member of the Ruddlesden-Popper nickelate family featuring a unique SDW transition.
• Provides a platform for investigating the interplay among crystal structure, electronic order, and superconductivity in hybrid nickelates.
• First identification of SDW in 1313-type La₃Ni₂O₇, establishing it as a new member of RP nickelate family with distinct electronic order.

Conclusions

• Hybrid 1313-type La₃Ni₂O₇ exhibits semiconducting behavior and displays distinct anomalies at 170 K in resistivity, magnetic susceptibility, and specific heat.
• 139La NMR unambiguously indicates a spin-density-wave transition occurring at 170 K.
• High-pressure electrical transport demonstrates pressure-induced metallization but no superconductivity is observed up to 65 GPa.
• 1313-type La₃Ni₂O₇ exhibits a spin-density-wave transition at 170 K at ambient pressure and becomes metallic under pressure, but no superconductivity is observed up to 65 GPa.

Main claims

• Hybrid 1313-type La₃Ni₂O₇ exhibits a spin-density-wave transition at approximately 170 K, confirmed by 139La NMR.
  • Evidence: Abstract: '139La nuclear magnetic resonance spectroscopy unambiguously confirms that these anomalies originate from a spin-density wave transition'
• No superconductivity is observed up to 65 GPa, indicating that superconductivity near 80 K in La₃Ni₂O₇ originates from the bilayer (2222) phase.
  • Evidence: Abstract: 'high-pressure electrical transport measurements… reveal no discernible traces of superconductivity up to 65 GPa' and Discussion: 'demonstrate the superconductivity near 80 K originates exclusively in bilayer (2222) La₃Ni₂O₇ phase'
• Hybrid 1313-type La₃Ni₂O₇ exhibits a spin-density-wave transition at 170 K.
  • Evidence: NMR spectra show broadening and peak in 1/T₁T at 170 K; transport and specific heat also show anomaly at same temperature.
• No superconductivity is observed in the 1313 phase up to 65 GPa.
  • Evidence: High-pressure resistance measurements up to 65 GPa show metallization but no zero-resistance or dropout indicating superconductivity.
• Superconductivity near 80 K in La₃Ni₂O₇ originates exclusively in the bilayer (2222) phase.
  • Evidence: The pure 1313 phase does not show superconductivity, so the 80 K superconductivity in mixed samples must come from bilayer phase contamination.

Workflow

• Crystal growth
  • Materials: La₃Ni₂O₇-1313 single crystals
  • Methods: Optical floating zone method; Elevated oxygen pressures
  • Observations: High-quality, long-range ordered hybrid 1313-type structure; Phase purity confirmed by XRD and STEM
• Characterization
  • Materials: Single crystals
  • Methods: X-ray diffraction; Scanning transmission electron microscopy; Energy-dispersive X-ray spectroscopy
  • Observations: Cmmm space group with alternating monolayer-trilayer stacking; Ni-O-Ni angle 180°
• Physical property measurements — SDW transition at approximately 170K
  • Materials: Single crystals
  • Methods: Resistivity; Magnetic susceptibility; Heat capacity; 139La-NMR
  • Observations: Semiconducting behavior with anomaly at 170K; SDW transition confirmed by NMR
• High-pressure transport — Superconductivity near 80 K originates from bilayer (2222) phase, not 1313 phase
  • Materials: Single crystals
  • Methods: Electrical transport in diamond anvil cell; Helium and solid pressure media
  • Observations: Pressure-induced metallization but no superconductivity up to 65 GPa
• sample_growth — Successfully grew high-quality 1313 single crystals with no bilayer contamination.
  • Materials: La₂O₃; NiO; oxygen
  • Methods: optical floating zone method; elevated oxygen pressure
  • Observations: High-quality, phase-pure hybrid 1313-type La₃Ni₂O₇ single crystals
• structural_characterization — Crystals are phase-pure 1313 with fully ordered stacking.
  • Materials: single crystals
  • Methods: powder XRD; single crystal XRD; ABF-STEM; EDS; 139La NMR
  • Observations: Cmmm space group; Alternating monolayer-trilayer stacking; Long-range order; Three distinct La sites; No bilayer phase detected
• ambient_pressure_transport_and_thermodynamics — A density-wave transition occurs at 170 K.
  • Materials: single crystals
  • Methods: resistivity; magnetic susceptibility; heat capacity
  • Observations: Semiconducting behavior; Anomaly at 170 K in all three measurements; Magnetic susceptibility suppression near 170K; Heat capacity peak at 170K
• NMR_identification_of_SDW — The transition is a spin-density-wave transition at T_SDW ≈ 170 K.
  • Materials: single crystals
  • Methods: 139La NMR; NQR; temperature-dependent spectra
  • Observations: Broadening of NMR lines below 170K; Coexistence of paramagnetic and magnetic phases between 130-170K; Peak in 1/T₁T near 170K
• high_pressure_transport — Pressure induces metallization but no superconductivity in the 1313 phase.
  • Materials: single crystals; helium; cubic boron nitride
  • Methods: DAC; electrical transport
  • Observations: Suppression of semiconducting behavior; Metallization; No superconductivity up to 65 GPa