Bubble domains in cobalt

The domain structures in thin single crystal foils of electropolished cobalt with the c axis normal to the plane have been observed by Lorentz electron microscopy. After the application of fields in the range of 5-25 kOe along the c axis, hexagonal arrays of cylindrical bubble domains were observed together with the more familiar plate-domain structure. The bubble structure was stable in the remanent state. Details of the magnetization configuration of the bubble together with measured dimensions are presented. The results are discussed in the light of calculation which shows that the energy of a hexagonal array of bubbles is a little higher than that of the plate domain structure. The bubble diameter is also calculated as a function of thickness.