Suppression of Hard Bubbles in Magnetic Garnet Films by Ion Implantation

Hard bubbles are cylindrical magnetic domains which differ from normal bubbles in their static and dynamic properties.1–3They form and collapse at fields considerably higher than normal bubble domains (hence the name “hard bubbles”) and, under the action of a gradient in the perpendicularly directed magnetic field, they have a component of motion either to the right or to the left rather than straight down the gradient (right- and left-handed hard bubbles). Under the influence of a small alternating field superimposed on the dc bias field, normal bubbles oscillate in size or strip out in a random manner, whereas hard bubbles tend to strip out in an S-shape and rotate in either a counterclockwise direction for the normal S-shape or clockwise for the reverse S-shape. It has been found that high-speed propagation using permalloy overlay circuits is impossible in materials which are prone to hard bubble formation.