Zhu Jing group and Duan Wenhui and Xue Qikun group of Tsinghua University have made the latest progress in the research of Bi SR Ca Cu o superconducting oxides

Recently, Professor Zhu Jing of Tsinghua University, Professor Duan Wenhui and Professor Xue Qikun have worked together to directly observe Bi 2sr 2cacu 2O 8 + δ using idpc-stem imaging and simulation technology in spherical aberration correction electron microscope (based on the integral differential phase contrast method of scanning transmission imaging)（ The position of the doped oxygen atom in Bi-2212) superconducting oxide lattice The research results were published in advanced functional materials (DOI: 10.1002 / ADFM 201903843) under the title of visualization of dopant oxygen atoms in a bi 2 Sr 2 CaCu 2O 8 + δ superconductor The appropriate concentration of doped oxygen atoms is very important for the concentration of hole carriers and the superconductivity of copper based superconducting oxides Therefore, it is of great significance to understand the formation mechanism of superconductivity by measuring the position of the doped oxygen atom and understanding the influence of the doped oxygen atom on the symmetry and the electric and magnetic order parameters of the original crystal In this work, using idpc-stem technology, the position of doped oxygen atom in Bi 2sr 2cacu2o8 + δ is directly observed on the atomic scale (as shown in Figure 1) The results show that at room temperature, the doped oxygen atoms are located in the tensile stress region between bio and SRO atomic layers, and the distribution is not uniform Some regions have pairs of oxygen atoms and some regions have single oxygen atoms This shows that there is a superconducting hole carrier library between bio and SRO atoms Based on the experimental data, the atomic configuration of the cell is constructed Using the first principle calculation, the influence of doped oxygen atoms on lattice, orbit and charge order parameters is studied The results show that on the basis of the original incommensurate modulation structure, the introduction of doped oxygen atoms aggravates the distortion of bio and SRO layers, resulting in the distortion of COO 5 coordination field At the same time, there is a charge transfer between the Bi atom and the doped oxygen atom The distortion of coordinative field of CuO 5 is also conducive to the transfer of charge from bio layer to CuO 2 layer This work is helpful to understand the mechanism of superconductivity Fig 1 The atomic structure model of idpc-stem image (a) Bi-2212 [010] with axis (B, c) Bi2212 and the image simulation based on the atomic model (D, e) uneven distribution of the doped oxygen atom in different positions (source: Advanced Functional Materials) the first author of this paper is Dr Song Dongsheng (completed during the doctoral period), Dr Zhang Xuefeng and Dr Lian Chaosheng (completed during the postdoctoral period), and the corresponding authors are Professor Zhu Jing and Professor Duan Wenhui The research work was supported by NSFC basic science center project, NSFC major project and 973 project.