Weakly anisotropic superconductivity of Pr₄Ni₃O₁₀ single crystals

摘要

本研究通过定制金刚石对顶砧旋转器，对Pr₄Ni₃O₁₀单晶进行原位高压角度依赖电输运测量，证实了其超导各向异性。在50.2 GPa压力下，样品出现超导转变，临界温度约31 K。通过测量垂直和平行于ab面的上临界场，得到各向异性参数γ约为1.6，该值随温度升高而减小，在接近超导临界温度时趋近于1。根据Ginzburg‑Landau模型拟合，零温上临界场平行和垂直于ab面分别为89.9 T和57.3 T，并计算出ab面内和c轴方向的相干长度分别为2.4 nm和1.5 nm。与铜氧化物及铁基超导体对比发现，Pr₄Ni₃O₁₀的各向异性行为符合双带模型，其中层内量子限域诱导了层间相干性，从而呈现出三维超导特性。该研究不仅证实了块体Ruddlesden‑Popper镍酸盐中存在各向异性超导，而且为理解维度对高温超导机制的影响提供了关键见解。

材料

• Pr₄Ni₃O₁₀

方法

• In situ high-pressure angle-dependent electrical transport
• Diamond anvil cell
• Ginzburg-Landau fitting
• WHH model
• GGA+U
• DFT+eDMFT

关键词

• superconducting anisotropy
• upper critical field
• two band model
• three dimensional superconductivity
• interlayer coherence

亮点

• This study not only confirms the existence of anisotropic superconductivity in bulk Ruddlesden-Popper nickelates but also provides critical insight into the role of dimensionality in high-temperature superconductivity.
• The weak anisotropy is comparable to that of iron-based superconductors, despite structural similarities with cuprates.

结论

• The anisotropy parameter γ is about 1.6, decreasing with increasing temperature and approaches 1 near T_c.
• Pr₄Ni₃O₁₀ conforms to a two-band model, where intralayer quantum confinement induces interlayer coherence, resulting in three-dimensional superconducting characteristics.
• Zero-temperature upper critical fields are 89.9 T (parallel) and 57.3 T (perpendicular), with coherence lengths of 2.4 nm (in-plane) and 1.5 nm (out-of-plane).

主要论断

• Pr₄Ni₃O₁₀ single crystals show weakly anisotropic superconductivity with anisotropy parameter γ ≈ 1.6 at zero temperature.
  • 证据: Abstract: 'an anisotropy parameter γ of about 1.6 was obtained'
• The anisotropic behavior conforms to a two-band model where in-plane quantum confinement induces interlayer coherence, leading to 3D superconductivity.
  • 证据: Abstract: 'the anisotropic behavior of Pr₄Ni₃O₁₀ conforms to a two-band model, where in-plane quantum confinement induces interlayer coherence, resulting in three-dimensional superconducting characteristics'

研究流程

• Sample synthesis
  • 材料: Pr₄Ni₃O₁₀ single crystals
  • 方法: Vertical optical-image floating zone method; High oxygen pressure (140-150 bar)
  • 观察: Monoclinic crystal structure, high quality confirmed by XRD and EDS
• High-pressure transport with rotation
  • 材料: Single crystals; Diamond anvil cell (DAC)
  • 方法: In situ high-pressure angle-dependent electrical transport; Custom DAC rotator; Helium pressure transmitting medium
  • 观察: Superconducting transition at approximately 31K; Angular dependence of upper critical field
• Data analysis — Pr₄Ni₃O₁₀ exhibits weakly anisotropic superconductivity consistent with 3D two-band model
  • 材料: Resistance vs temperature at various angles and fields
  • 方法: Ginzburg-Landau (GL) model fitting; Werthamer-Helfand-Hohenberg (WHH) model
  • 观察: Anisotropy parameter γ ≈ 1.6; Coherence lengths: ξab(0)=2.4 nm, ξc(0)=1.5 nm