摘要
Stabilizing and tuning superconductivity in La3Ni2O7−δ films: Oxygen recycling protocol reveals hole-doping analogue
材料
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方法
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关键词
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亮点
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结论
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主要论断
- A two-step recycling protocol (oxygen removal in air followed by ozone annealing) effectively restores superconductivity in degraded La3Ni2O7-δ films.
- 证据: Transport and XRD show recovery of superconducting transition and structural peaks after the two-step process.
- Oxygen addition in La3Ni2O7-δ films acts as an analog to hole doping via Sr substitution, revealed by an electronic phase diagram with asymmetric superconducting region.
- 证据: XAS shows changes in Ni dz2 bonding band; transport phase diagram shows similar behavior to Sr-doped films.
研究流程
- Film Growth — Compressive strain and oxygen stoichiometry are key factors.
- 材料: La3Ni2O7-δ; SrLaAlO4 (SLAO) substrate
- 方法: pulsed laser deposition (PLD)
- 观察: films grown on SLAO show compressive strain
- Ozone Annealing — Ozone annealing tunes oxygen content and induces superconductivity.
- 材料: La3Ni2O7-δ films
- 方法: ozone annealing post-growth
- 观察: films evolve from insulator to metal to superconductor
- Transport Measurements — Superconductivity is achieved in thin films on SLAO with Tc ≈40 K.
- 材料: La3Ni2O7-δ films
- 方法: four-probe resistivity; magnetic field up to 9T
- 观察: superconducting transition at ≈42 K; upper critical field ≈27-58T
- X-ray Diffraction (XRD) — Two-step process restores crystalline structure.
- 材料: La3Ni2O7-δ films
- 方法: out-of-plane XRD
- 观察: diffraction peaks weaken upon degradation and recover after two-step process
- X-ray Absorption Spectroscopy (XAS) — Oxygen addition mimics hole doping by La substitution with Sr.
- 材料: La3Ni2O7-δ films on SLAO
- 方法: XAS at O-K and Ni-L3 edges; linear dichroism (XLD)
- 观察: holes in Ni dz2 bonding band in as-grown films; suppressed in superconducting films