Because graphene is as thin as a single layer of carbon atoms, it has rich and diverse physical and chemical properties. After its appearance, various single-layer two-dimensional materials have sprung up like mushrooms. However, the ultra-thin two-dimensional material with atomic layer thickness is still a problem that has not been overcome. On June 6, the international top journal "Nature" published a result of the research team of Nanjing University. They successfully prepared two-dimensional oxide perovskite materials with atomic layer thickness. This achievement opens a door to two-dimensional quantum phenomena with rich strong correlations. According to Professor Pan Xiaoqing, the leader of the research team, since the discovery of graphene in 2004, various types of two-dimensional atomic crystal materials represented by it have been greatly appreciated by people due to their extensive application prospects in the fields of information transmission and energy storage devices. attention. Among them, the perovskite oxide exhibits various special physical effects such as multiferroicity and giant magnetoresistance due to the electron-electron interaction in the transition metal ion. However, the ultrathin two-dimensional material with atomic layer thickness still needs to be overcome. Professor Nie Yuefeng's research group adopted a molecular beam epitaxy film growth technique to obtain high-quality oxide perovskite two-dimensional materials with atomic layer thickness. Professor Wang Peng's research group used a variety of advanced spherical aberration correction transmission electron microscope structure analysis techniques to directly observe some novel phenomena under the two-dimensional limit of the perovskite BiFeO3 (bismuth ferrite) film. According to Nie Yuefeng, the movement of electrons in a material determines the performance of the material. In traditional two-dimensional materials such as graphene, the movement of electrons is relatively free and is not affected by other electrons; in many oxide perovskite materials, there is a strong interaction between electrons. The strong correlation between them has contributed to various novel quantum states including high-temperature superconductivity. The preparation of two-dimensional perovskite materials and the addition of this strong correlation between electrons in the two-dimensional system is expected to find more abundant and interesting two-dimensional quantum phenomena with strong correlation. (Qi Qi reporter Zhang Ye) CHANGZHOU CLD AUTO ELECTRICAL CO.,LTD , https://www.cld-led.com