多端YBa$_2$Cu$_3$O$_{7-δ}$结中氧化学计量比的电学调控
Electrical manipulation of oxygen stoichiometry in multiterminal YBa$_2$Cu$_3$O$_{7-δ}$ junctions
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中文总结 AI 辅助
研究在YBa₂Cu₃O₇₋δ Y形三端器件中实现了氧空位迁移的电学调控，可定向创建氧耗尽前沿，为局域调控超导多端器件性质提供了后制备途径。
中文摘要 AI 辅助
氧化学计量比的局域调控为调控复杂氧化物的电子性质提供了途径，但在多端高温超导结中，通过氧再分布对单个载流分支进行选择性修饰的研究仍未被探索。在YBa$_2$Cu$_3$O$_{7-δ}$ Y形三端器件中，我们证明了可通过电学方式调控选定端上的氧空位迁移，同时基本保留另外两个端的状态。氧耗尽的传播前沿可通过光学反射率的变化直接可视化，且与电响应的演变相关联。该过程具有高度方向性，由施加电流的极性决定，可从Y形器件的中心节点创建会聚或发散的传播前沿。相关的电阻变化表现出分钟级的弛豫时间，由空位浓度梯度驱动。氧迁移的效应还通过开尔文探针力显微镜（探测功函数变化）和扫描激光显微镜（探测空间分辨的超导转变变化）进行了表征。值得注意的是，后者揭示的Tc对比为潜在的氧含量提供了定量表征手段，能够直接可视化氧再分布。有限元建模和纳米探针X射线衍射定性再现了观测到的空位再分布。这些结果确立了一种后制备途径，可用于局域调控超导多端器件的性质，如纳米 cryotrons、yTron 和可调弱连接。
英文摘要
Local manipulation of oxygen stoichiometry offers a route to control the electronic properties of complex oxides, yet the selective modification of individual current-carrying branches through oxygen redistribution remains unexplored in multiterminal high-temperature superconducting junctions. In a YBa$_2$Cu$_3$O$_{7-δ}$ Y-shaped three-terminal device, we demonstrate the possibility to electrically control oxygen vacancy migration on a hand-picked terminal while largely preserving the other two. Oxygen-depleted propagating fronts are directly visualized by the resulting change in optical reflectivity and they are linked to the evolution of the electrical response. The process is highly directional and determined by the polarity of the applied current, allowing for the creation of either a converging or a diverging propagating front from the central node of the Y-shaped device. The associated changes in resistance exhibit relaxation on a timescale of minutes, driven by the vacancy concentration gradient. Effects of oxygen migration are also mapped by Kelvin Probe Force Microscopy and Scanning Laser Microscopy, which probe work-function changes and spatially resolved variations in the superconducting transition, respectively. Notably, the Tc contrast revealed by the latter provides a quantitative handle on the underlying oxygen content, enabling direct visualization of oxygen redistribution. Finite-element modeling and nanoprobe X-ray diffraction qualitatively reproduce the observed vacancy redistribution. These results establish a post-fabrication route to locally tune properties of superconducting multiterminal devices such as nanocryotrons, yTron, and tunable weak links.
