Dear Yungeun Ha ,

Magnetic Force Microscopy is not a self-sustained technique. In a good MFM image (i.e. without tip-induced effects) you obtain a map of the magnetic charges, and you need to combine such a map with other information:

-The composition of your sample, the hysteresis loops and what you deduce from them, for instance what is the magnetic anisotropy.

-How the sample was prepared before the MFM imaging: is it a demagnetized state? Is it a remanent state after applying a certain magnetic field?

So, it is impossible to answer your question without knowing all these facts.

Besides, you should improve the MFM experiment, the magnetic contrast in your images is very small, i.e. we can barely distinguish the magnetic charges. You should try with different tips (i.e. having different characteristics) to enhance the signal, but without introducing irreversible changes.

Miguel's answer is quite complete. From the first (upper) row of images, we can only say that the coarse-grained or insular surface of your material may also affect the large-size magnetic structure in the sample in the right picture. In the lower series of drawings, we can only assume that smooth transitions of shades and weak contrast can be caused by a small-sized domain structure. Therefore, as was rightly mentioned above, it is necessary to increase the resolution and use additional research methods.

Dear Yungeun Ha - I fully agree with what Jose-Miguel Garcia-Martin suggested - also, I suggest the same as Alexander T. Morchenko : try to scan closer and slower and try to improve your contrast. Good luck!