Source capture
Authors Feiyang Liu, Lixing Chen, Enkang Zhang, Ying-Jie Zhang, Jun Zhao
arXiv / Publisher https://arxiv.org/abs/2605.18524
PDF https://arxiv.org/pdf/2605.18524
Relevance score 5.471
Primary category cond-mat.str-el
Published 2026-05-19
Research paradigm Experimental
Sample form Single Crystal

Summary

This study employed the six-terminal method to perform high-precision transport measurements on Ruddlesden–Popper nickelate bilayer and trilayer single crystals, self-consistently extracting the in-plane and out-of-plane resistivities. The results reveal strong intrinsic electronic anisotropy, with out-of-plane resistivity exhibiting a non-monotonic temperature dependence that signals a universal interlayer coherent-to-incoherent crossover. Under pressure, the maximum superconducting transition temperature is inversely proportional to the resistivity anisotropy at ambient pressure, indicating that stronger interlayer electronic coherence favors superconductivity. Moreover, out-of-plane resistivity serves as a sensitive probe of magnetic and density-wave orders, whereas the in-plane resistivity shows a weaker response. These findings highlight interlayer coherence as a key tuning parameter that both tracks magnetic correlations and is closely linked to superconductivity, providing stringent constraints for microscopic theories of nickelate high-temperature superconductivity.

Materials

Methods

  • Six-terminal transport measurements
  • High-precision dc transport
  • Thermal expansion measurements

Keywords

  • interlayer electronic coherence
  • resistivity anisotropy
  • out of plane resistivity
  • density wave order
  • coherent to incoherent crossover
  • fermi liquid behavior

Highlights

  • First self-consistent determination of intrinsic in-plane and out-of-plane resistivities in RP nickelates using the six-terminal method, minimizing artifacts.
  • Establishes interlayer coherence as a key organizing parameter linking magnetism, dimensionality, and superconductivity in this family.

Conclusions

  • Strong intrinsic electronic anisotropy is observed in both bilayer and trilayer RP nickelates; out-of-plane resistivity exhibits nonmonotonic temperature dependence indicating a universal coherent-to-incoherent crossover in interlayer transport.
  • The maximum superconducting Tc under pressure is inversely correlated with the ambient-pressure resistivity anisotropy, suggesting stronger interlayer coherence is favorable for superconductivity.
  • Out-of-plane resistivity is an exceptionally sensitive probe of magnetic and density-wave orders, showing pronounced anomalies, while in-plane resistivity shows only weak signatures.

Main claims

  • Strong intrinsic electronic anisotropy is revealed in bilayer and trilayer RP nickelates, with resistivity anisotropy γ_ρ reaching 104 at low temperature in La4Ni3O10, much larger than previously inferred from four-probe measurements.
    • Evidence: Six-terminal geometry enables self-consistent extraction; large disparity between V_top and V_bot indicates strong current inhomogeneity; extracted γ_ρ values are 1.8×104, 1.8×103, and 1.7×102 for La4Ni3O10, Pr4Ni3O10, and La3Ni2O7 respectively
  • Out-of-plane resistivity exhibits a universal coherent-to-incoherent crossover with nonmonotonic temperature dependence, and is a sensitive probe of magnetic and density-wave orders.
    • Evidence: ρ⊥ increases upon cooling through DW transitions, showing pronounced anomalies, while ρ∥ shows weak signatures; at low T, ρ⊥ recovers Fermi-liquid T2 dependence
  • The maximum superconducting T_c under pressure is inversely correlated with ambient-pressure resistivity anisotropy, indicating stronger interlayer electronic coherence favors superconductivity.
    • Evidence: La4Ni3O10 (highest anisotropy) has lowest T_c; La3Ni2O7 (lowest anisotropy) has highest T_c; Pr4Ni3O10 is intermediate

Workflow

  • crystal_growth_and_preparation — High-quality single crystals of bilayer and trilayer RP nickelates.
    • Materials: La4Ni3O10; Pr4Ni3O10; La3Ni2O7
    • Methods: high-pressure optical floating-zone growth; Laue orientation; mechanical polishing
    • Observations: high-quality single crystals with optically flat surfaces
  • six_terminal_transport_measurements — Intrinsic transport anisotropy is much larger than previously reported.
    • Materials: gold contacts fabricated by sputtering
    • Methods: six-terminal geometry with contacts on top and bottom surfaces; self-consistent extraction of ρ∥ and ρ⊥
    • Observations: strong anisotropy: γ_ρ up to 104 for La4Ni3O10; nonmonotonic ρ⊥(T)
  • thermal_expansion_measurements — Anisotropy enhancement is electronic in origin, not structural.
    • Materials: La4Ni3O10 single crystal
    • Methods: capacitive dilatometry
    • Observations: out-of-plane lattice contraction through transition
  • correlation_with_superconductivity — Stronger interlayer electronic coherence favors superconductivity.
    • Materials: literature T_c values under pressure
    • Methods: comparison of low-T anisotropy with max T_c
    • Observations: inverse correlation between anisotropy and T_c