Separating the Density Wave Phase from Zero-Resistance Superconductivity in La₄Ni₃O₁₀

Summary

High-quality single crystals of the trilayer Ruddlesden–Popper nickelate La₄Ni₃O₁₀ were studied using a diamond anvil cell to explicitly tune the nonhydrostatic pressure component, combined with high-pressure electrical transport and synchrotron X-ray diffraction, thereby distinguishing out-of-plane-dominated compression from enhanced in-plane biaxial compression. Enhanced in-plane biaxial compression induced a uniform, reproducible zero-resistance superconducting state at 17.2 and 18.9 GPa, with the required pressure reduced by about 60% compared with previous reports; meanwhile, the density-wave phase under low compression was completely suppressed and separated from the superconducting state, which the authors interpret as effectively ruling out soft quantum critical fluctuations of the density-wave order parameter as a pairing glue in this system. In contrast, out-of-plane-dominated compression only slowly suppressed the density wave, and zero resistance was still not achieved up to 34 GPa, with superconducting signatures being filamentary and inhomogeneous. High-pressure XRD showed that the ambient-pressure monoclinic phase transforms into a tetragonal phase under high pressure, whereas an orthorhombic phase appears as an intermediate under enhanced in-plane compression. On this basis, the authors conclude that in-plane biaxial compression is an effective means to tune nickelate superconductivity, unifies the pressure scales of bilayer and trilayer Ruddlesden–Popper structures, and is linked to results on strained thin films.

Materials

• La₄Ni₃O₁₀
• La₄Ni₃O_10−x

Methods

• high-pressure electrical transport measurements
• diamond anvil cell (DAC)
• synchrotron X-ray diffraction (XRD)
• STEM
• ruby fluorescence pressure determination
• van der Pauw transport measurements

Keywords

• zero resistance superconductivity
• density wave phase
• quantum critical fluctuations
• pairing glue
• biaxial in plane compression
• non hydrostatic pressure
• monoclinic to tetragonal structural transition
• orthorhombic intermediate phase
• pressure scale unification
• ruddlesden popper nickelates

Highlights

• The authors achieve zero resistance under all van der Pauw current directions under enhanced in-plane pressure, suggesting a homogeneous superconducting phase.
• They identify an intermediate pressure regime between about 10 and 17 GPa where the density wave phase is already suppressed but superconductivity is not yet observed.
• The results suggest previous high-pressure transport studies on nickelates experienced strong but unreported out-of-plane pressure components, challenging interpretation of prior comparative studies.
• The ambient-pressure crystals show a residual resistivity ratio exceeding previous reports on La₄Ni₃O₁₀, indicating high crystal quality.
• The superconducting transition width becomes sharp above 20 GPa under enhanced in-plane compression.

Conclusions

• Enhanced biaxial in-plane compression induces a robust, reproducible zero-resistance superconducting state in La₄Ni₃O₁₀ single crystals at 17.2 and 18.9 GPa, about 60% lower pressure than previous reports.
• The low-pressure density wave phase is completely separated from superconductivity, ruling out soft quantum critical fluctuations of the density-wave order parameter as the pairing glue in this system.
• Dominant out-of-plane compression only slowly suppresses the density wave and does not produce zero resistance up to 34 GPa; any superconducting signatures under those conditions are filamentary and inhomogeneous.
• High-pressure XRD shows that the ambient-pressure monoclinic phase transforms to a tetragonal phase under high pressure, with an orthorhombic intermediate phase appearing under enhanced in-plane compression.
• Biaxial in-plane pressure is an effective tuning parameter for nickelate superconductivity, unifies the pressure scales for bilayer and trilayer Ruddlesden-Popper structures, and links bulk crystals to strained thin-film samples.

Main claims

• Enhanced in-plane biaxial compression induces a reproducible zero-resistance superconducting state in La₄Ni₃O₁₀ at 17.2 and 18.9 GPa, about 60% lower pressure than previous reports.
  • Evidence: Zero resistance was achieved under all van-der-Pauw current directions in runs #4 and #5.,The lowest pressures for zero resistance were 17.2 GPa and 18.9 GPa, corresponding to about 60% less pressure compared with previous reports.
• The low-pressure density-wave phase is completely separated from superconductivity under enhanced in-plane compression, effectively ruling out soft quantum critical fluctuations of the density-wave order parameter as the pairing glue.
  • Evidence: The density wave was suppressed completely in the 8-10 GPa range under enhanced in-plane compression.,An intermediate regime between about 10 GPa and 17 GPa showed no superconductivity signature after density-wave suppression.,Zero resistance appeared only above about 17 GPa.
• Dominant out-of-plane compression slowly suppresses the density wave and does not produce a homogeneous zero-resistance state up to 34 GPa.
  • Evidence: Runs #1-#3 showed density-wave signatures persisting up to about 20 GPa under dominant out-of-plane pressure.,Resistance did not reach zero up to 34 GPa, and different van-der-Pauw directions gave incongruent results.,The authors conclude that superconductivity under these conditions is filamentary only.
• High-pressure XRD reveals a monoclinic-to-tetragonal transition and an intermediate orthorhombic phase under enhanced in-plane compression.
  • Evidence: At ambient pressure the monoclinic space group was confirmed; beyond 20 GPa the tetragonal space group was resolved.,For enhanced in-plane pressure, new half-integer reflections appear beyond 10 GPa and disappear beyond 16 GPa, consistent with an intermediate orthorhombic structure.,The monoclinic-to-tetragonal transition is located around 10-15 GPa depending on pressure environment.
• Previous high-pressure transport studies on La₄Ni₃O₁₀ likely experienced strong unreported out-of-plane pressure components.
  • Evidence: The dominant out-of-plane pressure runs reproduce the slow density-wave suppression and the superconducting onsets without zero resistance seen in previous reports.,The authors state that previous experiments were likely conducted under similar pressure environments.
• Biaxial in-plane pressure unifies the pressure scales for superconductivity in bilayer and trilayer Ruddlesden-Popper nickelates and connects bulk crystals to compressively strained thin films.
  • Evidence: The reduced zero-resistance pressure in La₄Ni₃O₁₀ is compared with the pressure scale of bilayer La₃Ni₂O₇.,The authors connect the results to ambient-pressure superconductivity in compressively strained La₃Ni₂O₇ thin films.

Workflow

• sample_preparation — High-quality La₄Ni₃O₁₀ single crystals were prepared and characterized for pressure-dependent transport and structural studies.
  • Materials: La₄Ni₃O₁₀ single crystals; Ag epoxy electrical contacts; FIB lift-out STEM specimens
  • Methods: Cleaving crystals to expose a shiny terrace-free plane; Fabrication of in-plane five-contact and van-der-Pauw transport geometries; FIB preparation of electron-transparent specimens
  • Observations: STEM resolved trilayer perovskite blocks without stacking disorder or intergrowth; Transport samples showed high residual resistivity ratio and metallic in-plane resistivity
• ambient_structural_and_transport_characterization — Ambient-pressure measurements established crystal quality, anisotropic transport, and the density-wave transition.
  • Materials: La₄Ni₃O₁₀ single crystals
  • Methods: STEM-HAADF imaging; In-plane and out-of-plane electrical resistivity measurements; Van-der-Pauw geometry
  • Observations: Sharp density-wave signature in in-plane resistivity; Out-of-plane resistivity semimetallic at room temperature and increasing into the density-wave phase; Large resistivity anisotropy indicating quasi-2D electronic structure
• high_pressure_transport_measurements — Enhanced in-plane biaxial compression produces a reproducible zero-resistance state at much lower pressure and separates the density-wave phase from superconductivity.
  • Materials: La₄Ni₃O₁₀ single crystals; Diamond anvil cells; Rhenium and composite gaskets; Ruby pressure sensors
  • Methods: Diamond anvil cell transport measurements; Van-der-Pauw electrode geometry inside pressure chamber; PPMS resistance option or LockIn method; Ruby fluorescence pressure determination
  • Observations: Out-of-plane-dominated compression slowly suppressed the density wave and did not achieve zero resistance up to 34 GPa; superconducting signatures were filamentary and inhomogeneous; Enhanced in-plane compression suppressed the density wave completely around 8-10 GPa; Enhanced in-plane compression produced zero resistance at 17.2 and 18.9 GPa under all van-der-Pauw directions
• high_pressure_xrd_measurements — High-pressure XRD shows pressure-environment-dependent structural transitions and quantifies the anisotropic pressure conditions.
  • Materials: La₄Ni₃O₁₀ single crystals; Diamond anvil cells; Helium pressure medium for isotropic compression; Rhenium gaskets for enhanced in-plane compression
  • Methods: Synchrotron single-crystal X-ray diffraction at ESRF ID27; Continuous rotation with EIGER2 detector; CeO₂ and vanadinite calibration; Ruby fluorescence pressure determination
  • Observations: Ambient monoclinic phase transforms to tetragonal at high pressure; Enhanced in-plane compression stabilizes an intermediate orthorhombic phase before the tetragonal phase; Estimated pressure anisotropy of approximately 10% between in-plane and out-of-plane components
• analysis_and_interpretation — The authors interpret in-plane biaxial compression as a powerful tuning parameter and exclude soft quantum critical density-wave fluctuations as the pairing glue in this system.
  • Materials: Transport phase diagrams; XRD lattice parameters; Literature pressure data
  • Methods: Comparison of density-wave suppression rates; Comparison of zero-resistance pressures with prior reports; Estimation of pressure tensor components from lattice shrinkage
  • Observations: Density-wave suppression rate under out-of-plane pressure is slower than the hydrostatic reference; Density-wave suppression rate under enhanced in-plane pressure is about twice the hydrostatic reference; An intermediate regime exists where the density wave is suppressed but superconductivity is absent