学术报告（ 2026年4月22日10:30）：Ruddlesden-Popper镍氧化物超导材料的电子结构研究

主 持 人：侯玉升 副教授

报告摘要：

The discovery of superconductivity in Ruddlesden–Popper (RP) nickelates offers a new frontier for exploring high-Tc mechanisms. In this talk, we present electronic structure studies driven by the unique experimental capabilities of the state-of-the-art BL-03U beamline at SSRF, which integrates micro-focused spectroscopy with in-situ preparation of epitaxial thin films.

The high-spatial resolution of our micro-ARPES system was instrumental in overcoming the longstanding challenge of material inhomogeneity and multi-domain averaging. By performing measurements on single-domain Pr₄Ni₃O₁₀, we disentangled the complex hierarchy of intrinsic and back-folded bands, providing decisive evidence that the density-wave (DW) reconstruction is driven by inter-band nesting between α and β bands. We resolved a ~44 meV gap on the α pocket and successfully captured the intrinsic trilayer β-band splitting, establishing a critical lower bound for interlayer hopping.

Furthermore, the seamless integration of in-situ ARPES allowed for the precise characterization of atomically engineered thin films, leading to two collaborative breakthroughs. In collaboration with Prof. Yuefeng Nie at Nanjing University, we utilized the high sensitivity of our system to provide the first spectroscopic evidence of a 1-2 meV superconductivity induced leading edge shift along the Brillouin zone diagonal and slightly away from the zone diagonal of Sr-doped La₃Ni₂O₇, deviating from the d-wave gap structure. Besides, in collaboration with Prof. Zhuoyu Chen at Southern University of Science and Technology, we performed comparative studies on 1212, 2323, and 1313 nickelate superstructures, establishing that a dispersive Ni dz²-derived Fermi pocket is a critical prerequisite for superconductivity.

These results demonstrate that the combination of micro-scale precision and in-situ synthesis is essential for uncovering the structural and orbital physics governing emergent superconductivity and density waves in nickelates.

报告人简历：

沈大伟教授分别于2003年和2008年获得复旦大学凝聚态物理专业学士及博士学位。2011 年至2022年间，他在中国科学院上海微系统与信息技术研究所（SIMIT）先后担任副研究员和研究员，并于 2023 年加入中国科学技术大学担任教授。他的研究兴趣是利用角分辨光电子能谱以及其他同步辐射先进谱学手段研究量子材料的电子结构。他设计并在上海光源建造完成了国际首条原位ARPES束线站BL-03U，关键指标和科学产出国际领先。目前已在《Nature》、《Nature Physics/Materials》和《PRL》等顶级期刊发表论文160 余篇，总引用次数超过7000次。