Garnet films for micron and submicron magnetic bubbles with low damping constants

Two types of films for small bubbles have been grown without making use of the rare earth ions which are the cause of increased damping of the Bloch wall motion in the usual small bubble film compositions. Firstly, Bi-containing films were grown on (111) orientated GGG for 1 μm bubbles and secondly, Mn³⁺-containing films were grown under compression on (100) orientated GGG substrates for 0.4 μm bubbles. The damping constants in these films have been obtained by measuring the FMR line width. The correlation between the damping of the FMR and of the Bloch wall motion is determined in films with bubble diameters of, 2 to 4 μm. The damping constants are a factor 10 to 100 smaller than in the existing device films for small bubbles.