  Multiple structure and symmetry types and their transformations are
discovered in quasi-two-dimensional (quasi-2D) Cr2Ge2Te6 crystal in
surprisingly very narrow temperature range of 2 K and magnetic field range of
0.07 T using a homebuilt magnetic force microscope (MFM). A series of basic
domain patterns are extracted from the MFM images. Some of them seem unique to
2-D materials as they are not observed in 3-D materials, such as self-fitting
disks, and fine ladder structure within Y-connected walls. Based on these
findings, a phase map is drawn for the magnetic phase structures. The symmetry
of the patterns are discussed. The results are not only important in developing
new theories but also highly desirable in applications.
