The drive field for bubble domain propagation in T‐bar devices is proportional to 4πMs. From the definitions of the characteristic length, l, and of Q it can be shown that 4πM is proportional to AQ, where A is the exchange stiffness. We have found that the magnetic properties of ternary amorphous systems of the type Gd‐Co‐X, where X is a nonmagnetic element, eg. Au, Cu, Mo can be fine tuned for bubble device applications. It is possible to lower A by magnetic dilution as well as adjust 4πMs by varying the Co/Gd ratio as in the binary system. Because the system is amorphous, we are not restricted by equilibrium solubility limits.