Dimensionality of vortex matter in superconducting infinite-layer nickelates

摘要

该研究通过绘制超导Pr₀.8Sr₀.2NiO₂薄膜的涡旋相图，从不同角度探究了无限层镍氧化物的超导态维度。实验发现，低无序薄膜存在准二维性质的涡旋液体-玻璃转变，而增加无序度则会驱动体系进入纯二维态。这一结果表明，纯二维性并非本征属性，而是由NiO₂层间因无序增强而解耦所导致的外在现象。该工作确立了无序度作为无限层镍氧化物超导的关键调控参数，并指出无序主要存在于NiO₂层内，为理解该类材料提供了两个基础性见解。

材料

• Pr₀.8Sr₀.2NiO₂

方法

• X-ray diffraction
• electrical transport (R-T、R-H)
• current-voltage (I-V) measurements
• vortex-glass scaling analysis
• Arrhenius plot analysis
• upper critical field analysis
• PLD
• topotactic reduction

关键词

• vortex matter dimensionality
• vortex glass transition
• quasi 2d to 2d crossover
• disorder driven decoupling
• nio2 plane superconductivity
• pancake vortices
• pauli limited superconductivity

亮点

• For low-disorder films, the vortex glass transition temperature Tg is finite and critical exponents match q2D theory; for higher disorder, Tg=0 K and pure 2D scaling applies.
• The vortex length scale shortens with disorder, becoming comparable to the interplane distance.
• The results suggest that superconductivity is confined to NiO₂ planes with weak interplane coupling, and disorder enhances decoupling.

结论

• Superconducting Pr₀.8Sr₀.2NiO₂ thin films with low disorder exhibit a vortex liquid-to-glass transition of a quasi-two-dimensional nature.
• Increasing disorder drives a crossover into a pure 2D state.
• This demonstrates that pure bidimensionality is an extrinsic property, resulting from the decoupling of NiO₂ planes due to enhanced disorder.
• Disorder is a key control parameter of superconductivity in IL nickelates and suggests that it resides within the NiO₂ planes.

主要论断

• Low-disorder films exhibit a quasi-two-dimensional vortex liquid-to-glass transition.
  • 证据: Abstract,Full text: Low-disorder films exhibit a vortex liquid-to-glass transition of a quasi-2D nature.
• Increasing disorder drives a crossover into a pure 2D state.
  • 证据: Abstract,Full text: increasing disorder drives a crossover into a pure 2D state.
• Pure bidimensionality is an extrinsic property resulting from decoupling of NiO₂ planes due to enhanced disorder.
  • 证据: Abstract,Full text: pure bidimensionality is an extrinsic property, resulting from the decoupling of NiO₂ planes due to enhanced disorder.

研究流程

• sample_preparation
  • 材料: Pr₀.8Sr₀.2NiO₂; SrTiO₃ substrate; STO capping layer; Al overlayer
  • 方法: pulsed laser deposition; ex situ CaH₂ reduction; Al-assisted reduction
• transport_measurement
  • 方法: resistivity measurements; V-I measurements
  • 观察: vortex liquid-to-glass transition
• vortex_phase_analysis
  • 方法: Arrhenius analysis; vortex-glass scaling theory
  • 观察: quasi-2D behavior in low-disorder films; pure 2D behavior in high-disorder films
• interpretation — Disorder drives a dimensional crossover from quasi-2D to pure 2D vortex behavior.