Figure 1. Magnetic states and domain structure of YIG:Co.

Orientations of the easy magnetization axes and the pattern of magnetic domains with the magnetization directions close to [111], [1-11], [11-1] and [1-1-1] axes measured at zero magnetic field with magneto-optical polarizing microscope. Due to a miscut of the gadolinium gallium garnet substrate by 4°, the degeneracy between the states is partly broken and different magnetic domains cover non-equivalent volumes at zero external magnetic field²². The shown pattern with all four magnetization states (M^(L)+, M^(L)−, M^(S)+, M^(S)−) can be obtained as follows. First, the sample is brought into M^(L)+ state by an external magnetic field of μ₀H = 80 mT applied along the [1-10] direction. Second, the field is removed and the sample turns into a state with M^(L)+ and M^(S) domains. Third, a magnetic field μ₀H = 2 mT for a short time applied along the [110] direction favors M^(L)- domains and results in the final pattern. After the magnetic field is removed, the pattern stays unchanged for at least several days. Magnetization orientations in the domains and type of the domain structure have been identified following the procedure explained in²².