来源 自动抓取
作者 Zhen Liang, Tianheng Wei, Wei Ren, Haoran Ji, Zheyuan Xie, Yanzhao Liu, Ziqiang Wang, Jian Wang
arXiv / 出版方 https://arxiv.org/abs/2605.15703
PDF https://arxiv.org/pdf/2605.15703
相关度评分 5.834
主分类 cond-mat.supr-con
发布日期 2026-05-18
研究范式 实验研究
样品形态 薄膜

摘要

利用极低温扫描隧道显微镜/谱和电输运测量，本研究首次在（La,Pr）3Ni2O7薄膜中观测到能量对称、平底U形超导能隙，其零残余态密度且能隙大小超过40 meV。输运测量显示该薄膜在常压下具有超过40 K的起始超导转变温度和超过20 K的零电阻温度。隧穿谱呈现非常规的温度演化：随温度升高，U形能隙迅速填充并转变为V形能隙；同时，在14特斯拉的c轴磁场下能隙减小。这些温度与磁场依赖特性符合超导能隙行为，表明在极低温下存在无节点能隙函数。该发现揭示了双层镍氧化物高温超导的本质，并为在常压或零压下实现液氮沸点以上超导温度提供了重要启示。

材料

方法

  • Ultra-low temperature scanning tunneling microscopy/spectroscopy
  • Electrical transport
  • Gigantic-oxidative atomic-layer-by-layer epitaxy

关键词

  • u shaped gap
  • flat bottom gap
  • nodeless gap
  • coherence peaks
  • gap size >40 mev
  • unconventional temperature evolution
  • v shaped gap

亮点

  • First observation of an extremely large U-shaped superconducting gap in bilayer nickelate thin films, suggesting potential for ambient-pressure superconductivity above 77 K.
  • Unconventional temperature evolution from U-shaped to V-shaped gap, not explainable by thermal broadening alone.

结论

  • Observed an energy-symmetric, flat-bottom U-shaped gap with zero residual density of states and gap size ≈41.6 meV, consistent with a nodeless superconducting gap function.
  • The gap reduces under a 14 T magnetic field and exhibits unconventional temperature evolution: rapid filling from U-shaped to V-shaped with increasing temperature.
  • If the gap corresponds to the onset Tc, the ratio 2Δ/kBTc ≈20 indicates strong coupling; if compared to ARPES results, it suggests a potential local Tc above liquid nitrogen boiling point.

主要论断

  • An energy-symmetric, flat-bottom U-shaped gap with zero residual density of states and coherence peaks at ≈41.6 meV is observed in (La,Pr)3Ni2O7 thin films, indicating a nodeless superconducting gap.
    • 证据: STS at 60 mK shows U-shaped gap with fully suppressed zero-bias conductance; gap size determined by peak separation
  • The gap is reduced by magnetic field (14 T) and exhibits unconventional temperature evolution: rapid filling from U-shaped to V-shaped as temperature increases from 60 mK to 45 K.
    • 证据: Temperature-dependent STS show gap filling and shape change; thermal broadening alone cannot explain the transformation; magnetic field reduces gap
  • The observed large gap suggests potential for superconductivity above liquid nitrogen temperature at near-zero pressure.
    • 证据: If2Δ/kBTc ≈ 9 as in ARPES, T_c would be ≈107 K; even with transport T_c ≈46 K, the strong-coupling ratio is unusually large

研究流程

  • thin_film_growth — High-quality films with ambient-pressure superconductivity.
    • 材料: (La,Pr)3Ni2O7; SrLaAlO4 substrate
    • 方法: gigantic-oxidative atomic-layer-by-layer epitaxy
    • 观察: superconducting thin films with onset T_c > 40K
  • transport_characterization — Robust superconductivity preserved throughout experiments.
    • 材料: same films before and after STM
    • 方法: four-probe resistivity measurement
    • 观察: zero resistance T_c > 20 K; onset T_c > 40K
  • stm_sts_measurements — Observation of nodeless superconducting gap with unconventional temperature evolution.
    • 材料: tip-treated local regions
    • 方法: STM imaging and STS spectroscopy; temperature and magnetic field dependence
    • 观察: energy-symmetric U-shaped gap with coherence peaks; gap size Δ ≈ 41.6 meV; rapid filling with temperature; reduction under field