Abstract：

　　Epitaxial heterostructures provide an exquisite platform to manipulate the structure and electronic properties of oxide perovskites. Interfacial structural coupling therein has attracted tremendous interests. Through such coupling, the epi layer can be induced in an otherwise unstable lattice structure in resemblance to the substrate material, thereby realizing emergent structural and electronic phases. Notably, such coupling is a short-range effect, being typically limited to an interfacial region of approximately 3 nm or below. With the film thickness increasing, the epi layer is supposed to relax into a misfit strain-dominated state. Therefore, a structural transition is likely to occur spatially along the thickness direction. In addition, as a result of the interfacial symmetry mismatch, the structure of the epi layer may exhibit degenerated orientation states, i.e., forming twin domains. In this talk, the consequences of these two effects will be discussed in a heterostructure containing a prototypical ferromagnetic metal, SrRuO3. First, I will discuss a polar ferromagnetic phase arising from the strain gradient accompanying the structural transition. Second, I will show that the symmetry-mismatch-induced twin domains in SrRuO3 are strongly coupled to its magnetism, resulting in robust magnetic domains. More interestingly, exotic spin textures with finite spin chirality emerge from these domain walls, which sustain a large magnetic field (up to 24 T) in a broad temperature window (from low temperature up to 160 K).

报告人简介：

　　报告人彭威博士于2011年从中国科学技术大学物理系取得学士学位后，获得全额奖学金进入阿卜杜拉国王科技大学（KAUST, 沙特）的材料科学与工程系进行博士学习。于博士学习期间，在Osman M. Bakr教授的指导下开展卤素钙钛矿材料的光电性质的研究。2017年加入首尔国立大学的强关联电子系统研究中心（CCES），在中心主任Tae Won Noh教授的指导下开展博士后研究，并于2020年晋升为研究小组组长。在此期间，主要从事氧化物钙钛矿外延薄膜的铁电，铁磁，以及低温输运性质的研究。2022年，彭博士提出的基于氧化物钙钛矿异质结中的局域应力效应调控磁性的研究方案成功获得英国皇家学会的资助，并以牛顿学者的身份与华威大学的Marin Alexe教授合作开展相关研究。彭博士自2011年至今共发表科技论文33篇，其中第一作者8篇（两篇为ESI高被引论文），包括 Nature Physics, Advanced Materials，Advanced Functional Materials，Nano Letters，等，总引用次数7226次。