A device for propagating magnetic domains includes a monocrystalline nonmagnetic substrate of a rare earth gallium garnet bearing a layer of an iron garnet capable of supporting local enclosed magnetic domains. The iron garnet layer is grown in compression on a (100) face of the nonmagnetic substrate. The iron garnet comprises manganese in part of the iron sites of its crystal lattice, and comprises yttrium and at least one representative selected from the group comprising bismuth and the rare earth metals in the dodecahedral lattice sites. Such a magnetic garnet has a very high uniaxial anisotropy and a high domain mobility. These properties make the device extremely suitable for propagating submicron magnetic domains having diameters as small as 0.4 .mu.m.