Characterization methods for submicron diameter magnetic bubbles

Several new methods have been developed for characterizing fundamental properties of garnet films supporting submicron (0.3-1-μm diameter) magnetic bubbles. These properties are film thickness h, bubble collapse field H0, and strip width w. Film thicknesses were measured by both the fluorescent X-ray (FLX) method and the optical reflectance interference (ORI) method. Absolute thicknesses for experimental standard films were obtained by observing rectangular cross sections of films with both an optical microscope and a scanning electron microscope (SEM). Bubble collapse fields were measured by the ferromagnetic resonance (FMR) method, taking into consideration the bubble-bubble interaction effect. Strip widths were measured by observing Bitter patterns of strip domains with a low acceleration scanning electron microscope (LASEM). With these new techniques, important parameters were determined for submicron bubble garnet film with a 0.35-μm strip width and 0.33-μm thickness.