Spin polarized scanning tunneling microscopy (SPSTM) is the only technique presently available for probing the magnetic structure in real space with the atomic resolution. It is one of the most important tools for nanomagnetism exploration.There have been two successful approaches demonstrated; both are based on spin polarized tunneling, where the tunneling conductance between the tip and sample depends on their relative magnetization orientation. One approach operates in a differential magnetic model by switching the magnetization direction of the tip and the other utilizes spin dependent spectroscopy mode. SPSTM can not only probe the magnetic configuration of a ferromagnetic sample (Fig.a) , it can also be used for the antiferromagnetic structure measurements (Fig. b)