B.S.T.J. Briefs: Suppression of Hard Bubbles in Magnetic Garnet Films by IonImplantation

Hard bubbles are cylindrical magnetic domains which differ from normal bubbles in their static and dynamic properties. 1-3 They 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.