SPIN-POLARIZED STM AND ITS FAMILY

Since STM was invented in 1982 it has proved to be the most powerful tool for studying local electronic surface structure and has also led to a number of related scanning tunneling microscopy methods to be developed. One of them is spin-polarized STM (SP-STM) which will image the local magnetic characteristics of the material surfaces. In 1992 we succeeded in detecting the tunneling current, which depends on the tip magnetization and the circular polarization of the light-pumping GaAs sample. These preliminary experiments and their results indicate the feasibility of SP-STM with a non-magnetic tip. Furthermore we are investigating exchange force microscopy which will play an important role in the evaluation of insulating surface magnetism. This paper outlines both investigations together with recent progress in these areas. We also report on the experimental results of SP-STM in a vacuum.