A new kind of bubble having two stable states for a bias field H
Bhas been found in thin garnet films. The bubble becomes smaller with increasing H
Band disappears abruptly at some critical field

. However, it does not collapse at

. When H
Bis lowered, it comes into sight suddenly at another critical field

. This means that for H
Bbetween

and

the bubble has two stable states, one for a large bubble and the other for an unobservably small bubble. This has been well explained in terms of the stability of bubbles containing a definite number of Bloch lines.