Magnetic Sgminon is a topological spin structure with quasi-particle properties. Analogous to the magnetic Sgmin composed of spin, the polar Sgmin composed of electric dipoles. In 2019, professor S. Das, professor R. Ramesh and collaborators of the university of California, Berkeley, found room-temperature polar sgminzi in lead titanate layer wrapped by strontium titanate layer by changing epitaxial constraints and using atomic fraction scanning transmission electron microscope. the relevant research results were published in Nature as "Observation of room-temperature polar skyrmions. Polar Sgmin has chiral, negative capacitance, topological protection, and relatively small size (a few nanometers), which is expected to be used in high-performance, low-power nano-electronic devices. In the development of nano-electronic devices based on polar Sgmer, it is a prerequisite to understand the phase transition behavior of polar Sgmer under external field excitation and to master the manipulation of polar Sgmer under external field excitation. Recently, Professor Gao Peng's team and collaborators from the School of Physics of Peking University used in situ scanning transmission electron microscopy (In situ scanning transmission electron microscopy, STEM) to observe the dynamic evolution and topological phase transition behavior of polar Sgminzi under external electric field, and combined with phase field simulation to reveal the phase transition mechanism and interaction of polar Sgminzi under electric field excitation, guidance information is provided for its potential application in next-generation nanoelectronic devices. The relevant research results were published in Physical Review Letters under the title of "Dynamics of Polar Skyrmion Bubbles under Electric Fields. Zhu Ruixue, Quantum Materials Science Center, School of Physics, Peking University, Jiang Zhexin, School of Aeronautics and Astronautics, Zhejiang University, Zhang Xinxin, joint guidance graduate student of Peking University and Tianjin University of Technology, and Professor Zhong Xiangli, School of Materials Science and Engineering, Xiangtan University are the co-authors of the paper. Associate Professor Tan Congbing of Hunan University of Science and Technology, Professor Gao Peng of Peking University, Professor Wang Jie of Zhejiang University, and researcher Bai Xuedong of Physics Institute of Chinese Academy of Chinese Academy of Science and Chinese Academy of Science.

in-situ linkage: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.107601

researchers observed the evolution process of polar Sgoming sub driven by electric field using in-situ scanning transmission electron microscopy. they found that Sgoming sub strip would shrink and fracture under the action of electric field to form Sgoming sub bubble. with the increase of electric field strength, the polar Sgming sub-bubble will shrink and annihilate to form an ordinary ferroelectric single domain. On the contrary, under the action of the reverse electric field, they will expand, merge and form a single domain. The evolution behavior of polar Sgming bubbles, Sgming strips, and ferroelectric single domains under one electric field cycle is reversible, so they believe that electric fields can be used to regulate polar Sgming at room temperature, and nano-devices based on polar Sgming can be designed.

This research work realizes the in-situ observation of the dynamic evolution behavior of the polar Sgmer driven by the external electric field on the nanometer scale, proves that the generation, erasure and shape control of the polar Sgmer can be realized by using the appropriate electric field, and shows the reversible transformation interaction of topological monomers and the effect of lattice defects in real space, it provides important information for the regulation of polar Sgminon and future applications of nanoelectronic devices.

Figure 2 The PicoFemto of Zeyu Technology (ZepTools) was used in this study.®The series of in-situ TEM-STM sample rods set up an in-situ test environment.

Figure 3 In-situ sample rod used in this article