Wang Heng, Zhu Yuying, Bai Zhonghua, Wang Zechao, Hu Shuxu, Xie Hong-Yi, Hu Xiaopeng, Cui Jian, Huang Miaoling, Chen Jianhao, Ding Ying, Zhao Lin, Li Xinyan, Zhang Qinghua, Gu Lin, Zhou X J, Zhu Jing, Zhang Ding, Xue Qi-Kun
State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, China.
Beijing Academy of Quantum Information Sciences, Beijing, 100193, China.
Nat Commun. 2023 Aug 25;14(1):5201. doi: 10.1038/s41467-023-40525-1.
Josephson tunneling in twisted cuprate junctions provides a litmus test for the pairing symmetry, which is fundamental for understanding the microscopic mechanism of high temperature superconductivity. This issue is rekindled by experimental advances in van der Waals stacking and the proposal of an emergent d+id-wave. So far, all experiments have been carried out on BiSrCaCuO (Bi-2212) with double CuO planes but show controversial results. Here, we investigate junctions made of BiSrLaCuO (Bi-2201) with single CuO planes. Our on-site cold stacking technique ensures uncompromised crystalline quality and stoichiometry at the interface. Junctions with carefully calibrated twist angles around 45° show strong Josephson tunneling and conventional temperature dependence. Furthermore, we observe standard Fraunhofer diffraction patterns and integer Fiske steps in a junction with a twist angle of 45.0±0.2°. Together, these results pose strong constraints on the d or d+id-wave pairing and suggest an indispensable isotropic pairing component.
扭曲铜酸盐结中的约瑟夫森隧穿为配对对称性提供了一种检验标准，这对于理解高温超导的微观机制至关重要。范德华堆叠方面的实验进展以及新兴的d + id波的提出，重新引发了这个问题。到目前为止，所有实验都是在具有双层CuO平面的BiSrCaCuO（Bi - 2212）上进行的，但结果存在争议。在这里，我们研究由具有单层CuO平面的BiSrLaCuO（Bi - 2201）制成的结。我们的原位冷堆叠技术确保了界面处晶体质量和化学计量比不受影响。具有精心校准的约45°扭曲角的结表现出强约瑟夫森隧穿和常规的温度依赖性。此外，我们在扭曲角为45.0±0.2°的结中观察到了标准的夫琅禾费衍射图案和整数菲斯克台阶。这些结果共同对d波或d + id波配对施加了严格限制，并表明存在不可或缺的各向同性配对成分。
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