AI 中文总结
研究通过太赫兹场相互作用和BNT铁电势垒对YBCO/BNT/YBCO约瑟夫森结中超导能隙动力学进行系统调制，展示了稳健的约瑟夫森耦合，确定BNT是下一代高温超导量子器件可行的可调谐势垒材料。
AI 中文摘要
将铁电势垒集成到高温约瑟夫森结中为可调谐超导量子器件提供了一条途径。在此，我们展示了在包含40nm铁电BNT势垒的YBa2Cu3O7-x（YBCO）/Bi0.5Na0.5TiO3（BNT）/YBCO三层结中存在稳健的约瑟夫森耦合。通过脉冲激光沉积在SrTiO3衬底上制备外延三层结，并在宽带太赫兹（THz）辐射（0.5 - 2.5THz）下进行研究。在1.5THz（接近约瑟夫森等离子体共振）时，30K下BNT极化从33.4增加到46.4uC/cm2，增强了超导输运。结表现出明确的零电压超电流分支，临界电流Ic(T)在高达60K时几乎保持恒定，在1.5THz激发下达到468.2uA，证明了强相位相干性。扫描隧道光谱显示YBCO/BNT/YBCO中的超导能隙增强（Δ = 1.3meV），而光学电导率测量表明电导率和能隙随温度升高而降低，与THz激发下的BCS理论一致。原子力显微镜和X射线反射率证实了均匀的形态和清晰的界面，排除了缺陷介导的输运。Ic(B)的磁场调制呈现出典型的夫琅禾费干涉图案，电阻映射显示出高低耗散交替的瓣，表明存在相干约瑟夫森隧穿。这些结果表明约瑟夫森耦合是YBCO/BNT/YBCO结所固有的，由BNT势垒的偶极特性和动态THz响应实现。本研究确定BNT是下一代高温超导量子器件的一种可行的、可调谐的势垒材料。
英文摘要
The integration of ferroelectric barriers into high-temperature Josephson junctions offers a pathway to tunable superconducting quantum devices. Here, we demonstrate robust Josephson coupling in YBa2Cu3O7-x (YBCO)/Bi0.5Na0.5TiO3 (BNT)/YBCO trilayer junctions incorporating a 40 nm ferroelectric BNT barrier. Epitaxial trilayers were fabricated by pulsed laser deposition on SrTiO3 substrates and investigated under broadband terahertz (THz) irradiation (0.5-2.5 THz). At 1.5 THz, close to the Josephson plasma resonance, the BNT polarization increased from 33.4 to 46.4 uC/cm2 at 30 K, enhancing superconducting transport. The junctions exhibited a well-defined zero-voltage supercurrent branch, with the critical current Ic(T) remaining nearly constant up to 60 K and reaching 468.2 uA under 1.5 THz excitation, evidencing strong phase coherence. Scanning tunneling spectroscopy revealed an enhanced superconducting gap in YBCO/BNT/YBCO (Delta = 1.3 meV) compared with pure YBCO (Delta = 1.05 meV), while optical conductivity measurements showed a reduction in conductivity and gap with increasing temperature, consistent with BCS theory under THz excitation. Atomic force microscopy and X-ray reflectivity confirmed uniform morphology and sharp interfaces, excluding defect-mediated transport. Magnetic field modulation of Ic(B) exhibited a canonical Fraunhofer interference pattern, and resistance mapping revealed alternating lobes of high and low dissipation, indicating coherent Josephson tunneling. These results establish that Josephson coupling is intrinsic to the YBCO/BNT/YBCO junctions, enabled by the dipolar character and dynamic THz response of the BNT barrier. This study identifies BNT as a viable, tunable barrier material for next-generation high-Tc superconducting quantum devices.
