来源 自动抓取
作者 Yidi Liu, Bai Yang Wang, Jiarui Li, Yaoju Tarn, Lopa Bhatt, Michael Colletta, Yi-Ming Wu, Cheng-Tai Kuo, Jun-Sik Lee, Berit H. Goodge, David A. Muller, Zhi-Xun Shen, Srinivas Raghu, Harold Y. Hwang, Yijun Yu
arXiv / 出版方 https://arxiv.org/abs/2603.12196
PDF https://arxiv.org/pdf/2603.12196
相关度评分 5.425
主分类 cond-mat.supr-con
发布日期 2026-03-13
研究范式 实验研究
样品形态 薄膜

摘要

在压缩应变双层镍酸盐薄膜中，通过连续调控氧化学计量，研究人员发现了一个超导半圆顶。从最优超导态出发，增加氧含量会逐渐抑制超导，使其向金属相转变；而减少氧含量则驱动颗粒状超导体-绝缘体转变，但超导起始温度保持不变。这种半圆顶结构源于间隙氧与氧空位的不同作用：前者主要通过掺杂效应调控载流子浓度，后者则引入强散射导致电子不均匀性。实验表明，这一半圆顶在不同稀土组合及有无碱土掺杂的样品中一致出现，揭示了双层镍酸盐相图的普遍特征。该发现为理解相关电子体系中超导的涌现与消亡提供了新视角。

材料

方法

关键词

亮点

  • The study reveals a half-dome structure consistently across samples with different rare-earth combinations and doping.
  • Oxygen stoichiometry exhibits two qualitatively distinct manifestations: excess oxygen acts as an electronic tuning parameter, while oxygen deficiency introduces strong scattering and electronic inhomogeneity.

结论

  • A superconducting half-dome is observed in compressively strained bilayer nickelate thin films as a function of continuous tuning of oxygen stoichiometry.
  • Increasing oxygen stoichiometry suppresses superconductivity toward a metallic phase, whereas decreasing oxygen stoichiometry drives a granular superconductor-to-insulator transition while leaving the superconducting onset intact.
  • The half-dome structure arises from contrasting roles of interstitial oxygen (doping) versus oxygen vacancies (scattering).
  • The half-dome emerges consistently across samples with different rare-earth combinations, with or without alkaline-earth doping, revealing a general feature of the bilayer nickelate phase diagram.

主要论断

  • Oxygen excess suppresses superconductivity toward a metallic phase through doping; oxygen deficiency drives a granular superconductor-insulator transition.
    • 证据: Abstract,Full text: increasing oxygen stoichiometry gradually suppresses superconductivity toward a metallic phase, whereas decreasing oxygen stoichiometry drives a granular superconductor-to-insulator transition.
  • The superconducting half-dome is a universal feature across different rare-earth combinations and alkaline-earth doping.
    • 证据: Abstract,Full text: half-dome emerges consistently across samples with different rare-earth combinations, with or without alkaline-earth doping.
  • Interstitial oxygen acts as a dopant while oxygen vacancies introduce strong disorder.
    • 证据: Abstract,Full text: The pronounced asymmetry suggests that oxygen vacancies play a fundamentally different role from oxygen interstitials.

研究流程

  • sample_preparation
    • 材料: LSNO; LPNO; LPCNO; SLAO substrate
    • 方法: pulsed laser deposition; molecular beam epitaxy
  • oxygen_stoichiometry_tuning
    • 方法: ozone annealing; vacuum annealing; EELS; XAS
    • 观察: two-stage evolution of transport
  • transport_characterization
    • 方法: resistivity measurements; Hall effect measurements
    • 观察: superconducting half-dome; SIT scaling
  • phase_diagram_construction
    • 方法: normalization of conductivity; contour mapping
    • 观察: universal half-dome across different compositions