Understanding and controlling of the magnetization reversal process and its time limits will provide new possibilities for ultrafast switching devices. It is important to develop method to image ultrafast magnetization dynamics with high spatial and temporal resolution. Time resolved spin polarized low energy electron microscopy is one of choices for this goal.

In this talk, we describe the design and commission of a novel aberration-corrected low electron emission microscope (AC-LEEM). A third magnetic prism array is implemented to the standard AC-LEEM with two prism arrays, allowing the introduce of a ultrafast spin-polarized electron sources besides the standard cold field emission electron source without degrading its spatial resolution. The high electron-optical symmetry of the AC-LEEM are considered while we design the electron optics of the ultrafast spin-polarized electron source, in order to minimize deleterious effects of space-charge and time broadening while maintaining full control of electron spin. A spatial resolution of 2 nm and temporal resolution of 10 ps are expected in the future time resolved aberration-corrected spin-polarized LEEM (TR-AC-SPLEEM). The commission of the AC-LEEM has been successfully finished with the cold ?eld emission source, with a spatial resolution below 2 nm. In parallel, studies on numerical calculations showed interesting results on magnetic vortex switching. The multiply vortex core switching process has been systematically studied in response to pulsed ?eld and alternating field.

Dr. Wen-Xin Tang received his Ph.D degree from Department of Physics, Fudan University in 2003. In 2012, he joined Chongqing University as a professor. Tang is recognized for his experimental contributions in surface physics, low dimensional spin dynamics field and low energy electron microscopy field. He discovered a new Body-Centered-Cubic Ni nanostructure by Molecular Beam Epitaxy at Fudan University in China. His breakthrough in discovery of the surface magnon dispersion in monolayer Fe system provided great opportunity for scientists to understand the origin of spin interaction in the low dimensional systems at Max Planck Institution in Germany. Envisaged the importance of III-V semiconductor in the future spintronics, he developed a unique and first III-V surface microscopy with his colleagues at Monash University in Australia, a novel technique to probe and manipulate surface dynamics for III-V quantum structures in real space and real-time. Recently, he and his collaborators proposed and designed an ultrafast aberration-corrected spin polarized low energy electron microscopy (TR-AC-SPLEEM), focusing on magnetic dynamics studies. He is appointed as deputy director of new Electron Microscopy Center of ChongqingUniversity (EMCCU) for promoting international collaboration.