Stability of bubbles subjected to an in-plane field

A discussion is given of the consequences for the stability and behavior of bubbles and strip domains of an additional magnetic field which is parallel to the plane of the platelet. Apart from the instability of bubble domains, leading to a collapse or a running out into strip domains, a second kind of instability is discussed. This is due to the fact that inside a domain, the magnetization becomes unstable when a suitable in-plane field is applied and will be rotated to a direction parallel to the magnetization outside the domains.